/* vi: set ts=2 shiftwidth=2 expandtab:
 *
 * Copyright (C) 2003-2007  Simon Baldwin and Mark J. Tilford
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 */

/*
 * Module notes:
 *
 * o Ensure module messages precisely match the real Runner ones.  This
 *   matters for ALRs.
 *
 * o Capacity checks on the player and on containers are implemented, but
 *   may not be right.
 */

#include <assert.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>

#include "scare.h"
#include "scprotos.h"
#include "scgamest.h"


/* Assorted definitions and constants. */
static const sc_char NUL = '\0';
static const sc_char COMMA = ',';
static const sc_int SECS_PER_MINUTE = 60,
                    MINS_PER_HOUR = 60,
                    SECS_PER_HOUR = 3600;
enum { LIB_ALLOCATION_AVOIDANCE_SIZE = 128 };

/* NPC gender enumerations. */
enum
{ NPC_MALE = 0,
  NPC_FEMALE = 1,
  NPC_NEUTER = 2
};

/* Openable object openness enumerations. */
enum
{ OBJ_OPEN = 5,
  OBJ_CLOSED = 6,
  OBJ_LOCKED = 7
};

/* Perspective enumerations. */
enum
{ FIRST_PERSON = 0,
  SECOND_PERSON = 1,
  THIRD_PERSON = 2
};

/* Enumeration of TAF file versions. */
enum
{ TAF_VERSION_400 = 400,
  TAF_VERSION_390 = 390,
  TAF_VERSION_380 = 380
};

/* Trace flag, set before running. */
static sc_bool lib_trace = FALSE;


/*
 * lib_warn_battle_system()
 *
 * Display a warning when the battle system is detected in a game.  Print
 * directly rather than using the printfilter to avoid possible clashes
 * with ALRs.
 */
void
lib_warn_battle_system (void)
{
  if_print_tag (SC_TAG_FONT, "size=16");
  if_print_string ("SCARE WARNING");
  if_print_tag (SC_TAG_ENDFONT, "");
  
  if_print_string (
    "\n\nThe game uses Adrift's Battle System, something not fully supported"
    " by this release of SCARE.\n\n");

  if_print_string (
    "SCARE will still run the game, but it will not create character"
    " battles where they would normally occur.  For some games, this may"
    " be perfectly okay, as the Battle System is sometimes turned on"
    " by accident in a game, but never actually used.  For others, though,"
    " the omission of this feature may be more serious.\n\n");

  if_print_string ("Please press a key to continue...\n\n");
  if_print_tag (SC_TAG_WAITKEY, "");
}


/*
 * lib_random_roomgroup_member()
 *
 * Return a random member of a roomgroup.
 */
sc_int
lib_random_roomgroup_member (sc_gameref_t game, sc_int roomgroup)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[4];
  sc_int count, room;

  /* Get the count of rooms in the group. */
  vt_key[0].string = "RoomGroups";
  vt_key[1].integer = roomgroup;
  vt_key[2].string = "List2";
  count = prop_get_child_count (bundle, "I<-sis", vt_key);
  if (count == 0)
    {
      sc_fatal ("lib_random_roomgroup_member:"
                " no rooms in group %ld\n", roomgroup);
    }

  /* Pick a room at random and return it. */
  vt_key[3].integer = sc_randomint (0, count - 1);
  room = prop_get_integer (bundle, "I<-sisi", vt_key);

  if (lib_trace)
    {
      sc_trace ("Library: random room for group %ld is %ld\n",
                roomgroup, room);
    }

  return room;
}


/*
 * lib_use_room_alt()
 *
 * Return TRUE if a particular alternate room description should be used.
 */
static sc_bool
lib_use_room_alt (sc_gameref_t game, sc_int room, sc_int alt)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_int type;
  sc_bool retval;

  /* Get alternate type. */
  vt_key[0].string = "Rooms";
  vt_key[1].integer = room;
  vt_key[2].string = "Alts";
  vt_key[3].integer = alt;
  vt_key[4].string = "Type";
  type = prop_get_integer (bundle, "I<-sisis", vt_key);

  /* Select based on type. */
  retval = FALSE;
  switch (type)
    {
    case 0:                    /* Task. */
      {
        sc_int var2, var3;

        vt_key[4].string = "Var2";
        var2 = prop_get_integer (bundle, "I<-sisis", vt_key);
        if (var2 == 0)          /* No task. */
          retval = TRUE;
        else
          {
            vt_key[4].string = "Var3";
            var3 = prop_get_integer (bundle, "I<-sisis", vt_key);

            retval = gs_task_done (game, var2 - 1) == !(var3 != 0);
          }
        break;
      }

    case 1:                    /* Stateful object. */
      {
        sc_int var2, var3, object;

        vt_key[4].string = "Var2";
        var2 = prop_get_integer (bundle, "I<-sisis", vt_key);
        if (var2 == 0)          /* No object. */
          retval = TRUE;
        else
          {
            vt_key[4].string = "Var3";
            var3 = prop_get_integer (bundle, "I<-sisis", vt_key);

            object = obj_stateful_index (game, var2);
            retval = restr_pass_task_object_state (game, object, var3 - 1);
          }
        break;
      }

    case 2:                    /* Player condition. */
      {
        sc_int var2, var3, object;

        vt_key[4].string = "Var2";
        var2 = prop_get_integer (bundle, "I<-sisis", vt_key);
        vt_key[4].string = "Var3";
        var3 = prop_get_integer (bundle, "I<-sisis", vt_key);

        if (var3 == 0)
          {
            switch (var2)
              {
              case 0: case 2: case 5:
                retval = TRUE;
                break;
              case 1: case 3: case 4:
                retval = FALSE;
                break;
              default:
                sc_fatal ("lib_use_room_alt:"
                          " invalid player condition, %ld\n", var2);
              }
            break;
          }

        object = obj_dynamic_object (game, var3 - 1);
        switch (var2)
          {
          case 0:              /* Isn't holding. */
            retval = gs_object_position (game, object) != OBJ_HELD_PLAYER;
            break;
          case 1:              /* Is holding. */
            retval = gs_object_position (game, object) == OBJ_HELD_PLAYER;
            break;
          case 2:              /* Isn't wearing. */
            retval = gs_object_position (game, object) != OBJ_WORN_PLAYER;
            break;
          case 3:              /* Is wearing. */
            retval = gs_object_position (game, object) == OBJ_WORN_PLAYER;
            break;
          case 4:              /* Isn't in the same room as. */
            retval = !obj_indirectly_in_room (game,
                                              object, gs_playerroom (game));
            break;
          case 5:              /* Is in the same room as. */
            retval = obj_indirectly_in_room (game,
                                             object, gs_playerroom (game));
            break;
          default:
            sc_fatal ("lib_use_room_alt:"
                      " invalid player condition, %ld\n", var2);
          }
        break;
      }

    default:
      sc_fatal ("lib_use_room_alt: invalid type, %ld\n", type);
    }

  return retval;
}


/*
 * lib_get_room_name()
 * lib_print_room_name()
 *
 * Get/print out the name for a given room.
 */
const sc_char *
lib_get_room_name (sc_gameref_t game, sc_int room)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_int alt_count, alt, index_;
  const sc_char *name;

  /* Start with a null name. */
  name = NULL;

  /* Get count of room alternates. */
  vt_key[0].string = "Rooms";
  vt_key[1].integer = room;
  vt_key[2].string = "Alts";
  alt_count = prop_get_child_count (bundle, "I<-sis", vt_key);

  /* Try each type-0, then type-1, alternate. */
  for (index_ = 0; index_ <= 1; index_++)
    {
      for (alt = alt_count - 1; alt >= 0; alt--)
        {
          sc_int type;

          vt_key[3].integer = alt;
          vt_key[4].string = "Type";
          type = prop_get_integer (bundle, "I<-sisis", vt_key);
          if (type == index_)
            {
              if (lib_use_room_alt (game, room, alt))
                {
                  const sc_char *changed;

                  vt_key[4].string = "Changed";
                  changed = prop_get_string (bundle, "S<-sisis", vt_key);
                  if (!sc_strempty (changed))
                    {
                      name = changed;
                      break;
                    }
                }
              else
                {
                  vt_key[2].string = "Short";
                  name = prop_get_string (bundle, "S<-sis", vt_key);
                  break;
                }
            }
        }
      if (name)
        break;
    }

  /* If no name yet, try type-2 alternates. */
  if (!name)
    {
      for (alt = alt_count - 1; alt >= 0; alt--)
        {
          sc_int type;

          vt_key[3].integer = alt;
          vt_key[4].string = "Type";
          type = prop_get_integer (bundle, "I<-sisis", vt_key);
          if (type == 2)
            {
              if (lib_use_room_alt (game, room, alt))
                {
                  const sc_char *changed;

                  vt_key[4].string = "Changed";
                  changed = prop_get_string (bundle, "S<-sisis", vt_key);
                  if (!sc_strempty (changed))
                    {
                      name = changed;
                      break;
                    }
                }
            }
        }
    }

  /* If still no name, fall through to default short. */
  if (!name)
    {
      vt_key[2].string = "Short";
      name = prop_get_string (bundle, "S<-sis", vt_key);
    }

  /* Return the name. */
  return name;
}

void
lib_print_room_name (sc_gameref_t game, sc_int room)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_char *name;

  /* Get the room name. */
  name = lib_get_room_name (game, room);

  /* Print the room name, possibly in bold). */
  if (game->bold_room_names)
    {
      pf_buffer_tag (filter, SC_TAG_BOLD);
      pf_buffer_string (filter, name);
      pf_buffer_tag (filter, SC_TAG_ENDBOLD);
    }
  else
    pf_buffer_string (filter, name);
  pf_buffer_character (filter, '\n');
}


/*
 * lib_print_object_np
 * lib_print_object
 *
 * Convenience functions to print out an object's name, with a "normalized"
 * prefix -- any "a"/"an"/"some" is replaced by "the" -- and with the full
 * prefix.
 */
static void
lib_print_object_np (sc_gameref_t game, sc_int object)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  const sc_char *prefix, *normalized, *name;

  /* Get the object's prefix. */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Prefix";
  prefix = prop_get_string (bundle, "S<-sis", vt_key);

  /*
   * Normalize by skipping any leading "a"/"an"/"some", replacing it instead
   * with "the", and skipping any odd "the" already present.  If no prefix at
   * all, add a "the " anyway.
   *
   * TODO This is empirical, based on observed Adrift Runner behavior, and
   * what it's _really_ supposed to do is a mystery.  This routine has been a
   * real PITA.
   */
  normalized = prefix;
  if (sc_compare_word (prefix, "a"))
    {
      normalized = prefix + 1;
      pf_buffer_string (filter, "the");
    }
  else if (sc_compare_word (prefix, "an"))
    {
      normalized = prefix + 2;
      pf_buffer_string (filter, "the");
    }
  else if (sc_compare_word (prefix, "the"))
    {
      normalized = prefix + 3;
      pf_buffer_string (filter, "the");
    }
  else if (sc_compare_word (prefix, "some"))
    {
      normalized = prefix + 4;
      pf_buffer_string (filter, "the");
    }
  else if (sc_strempty (prefix))
    pf_buffer_string (filter, "the ");

  /*
   * If the remaining normalized prefix isn't empty, print it, and a space.
   * If it is, then consider adding a space to any "the" printed above, except
   * for the one done for empty prefixes, that is.
   */
  if (!sc_strempty (normalized))
    {
      pf_buffer_string (filter, normalized);
      pf_buffer_character (filter, ' ');
    }
  else if (normalized > prefix)
    pf_buffer_character (filter, ' ');

  /*
   * Print the object's name; here we also look for a leading article and
   * strip if found -- some games may avoid prefix and do this instead.
   */
  vt_key[2].string = "Short";
  name = prop_get_string (bundle, "S<-sis", vt_key);
  if (sc_compare_word (name, "a"))
    name += 1;
  else if (sc_compare_word (name, "an"))
    name += 2;
  else if (sc_compare_word (name, "the"))
    name += 3;
  else if (sc_compare_word (name, "some"))
    name += 4;
  pf_buffer_string (filter, name);
}

static void
lib_print_object (sc_gameref_t game, sc_int object)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  const sc_char *prefix, *name;

  /*
   * Get the object's prefix, and print if not empty, otherwise default to an
   * "a " prefix, as that's what Adrift seems to do.
   */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Prefix";
  prefix = prop_get_string (bundle, "S<-sis", vt_key);
  if (!sc_strempty (prefix))
    {
      pf_buffer_string (filter, prefix);
      pf_buffer_character (filter, ' ');
    }
  else
    pf_buffer_string (filter, "a ");

  /* Print object name. */
  vt_key[2].string = "Short";
  name = prop_get_string (bundle, "S<-sis", vt_key);
  pf_buffer_string (filter, name);
}


/*
 * lib_print_npc_np
 * lib_print_npc
 *
 * Convenience functions to print out an NPC's name, with and without
 * any prefix.
 */
static void
lib_print_npc_np (sc_gameref_t game, sc_int npc)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  const sc_char *name;

  /* Get the NPC's short description, and print it. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Name";
  name = prop_get_string (bundle, "S<-sis", vt_key);

  pf_buffer_string (filter, name);
}

#if 0
static void
lib_print_npc (sc_gameref_t game, sc_int npc)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  const sc_char *prefix;

  /* Get the NPC's prefix. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Prefix";
  prefix = prop_get_string (bundle, "S<-sis", vt_key);

  /* If the prefix isn't empty, print it, then print NPC name. */
  if (!sc_strempty (prefix))
    {
      pf_buffer_string (filter, prefix);
      pf_buffer_character (filter, ' ');
    }
  lib_print_npc_np (game, npc);
}
#endif


/*
 * lib_get_npc_inroom_text()
 *
 * Returns the inroom description to be use for an NPC; if the NPC has
 * gone walkabout and offers a changed description, return that; otherwise
 * return the standard inroom text.
 */
static const sc_char *
lib_get_npc_inroom_text (sc_gameref_t game, sc_int npc)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_int walk_count, walk;
  const sc_char *inroomtext;

  /* Get the count of NPC walks. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Walks";
  walk_count = prop_get_child_count (bundle, "I<-sis", vt_key);

  /* Check for any active walk with a description, return if found. */
  for (walk = walk_count - 1; walk >= 0; walk--)
    {
      if (gs_npc_walkstep (game, npc, walk) > 0)
        {
          const sc_char *changeddesc;

          /* Get and check any walk active description. */
          vt_key[3].integer = walk;
          vt_key[4].string = "ChangedDesc";
          changeddesc = prop_get_string (bundle, "S<-sisis", vt_key);
          if (!sc_strempty (changeddesc))
            return changeddesc;
        }
    }

  /* Return the standard inroom text. */
  vt_key[2].string = "InRoomText";
  inroomtext = prop_get_string (bundle, "S<-sis", vt_key);
  return inroomtext;
}


/*
 * lib_print_room_contents()
 *
 * Print a list of the contents of a room.
 */
static void
lib_print_room_contents (sc_gameref_t game, sc_int room)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[4];
  sc_int object, npc, count, trail;

  /* List all objects that show their initial description. */
  count = 0;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (obj_directly_in_room (game, object, room)
          && obj_shows_initial_description (game, object))
        {
          const sc_char *inroomdesc;

          /* Find and print in room description. */
          vt_key[0].string = "Objects";
          vt_key[1].integer = object;
          vt_key[2].string = "InRoomDesc";
          inroomdesc = prop_get_string (bundle, "S<-sis", vt_key);
          if (!sc_strempty (inroomdesc))
            {
              if (count == 0)
                pf_buffer_character (filter, '\n');
              else
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter, inroomdesc);
              count++;
            }
        }
    }
  if (count > 0)
    pf_buffer_character (filter, '\n');

  /*
   * List dynamic objects directly located in the room, and not already listed
   * above since they lack, or suppress, an in room description.
   *
   * If an object sets ListFlag, then if dynamic it's suppressed from the list
   * where it would normally be included, but if static it's included where it
   * would normally be excluded.
   */
  count = 0;
  trail = -1;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (obj_directly_in_room (game, object, room))
        {
          const sc_char *inroomdesc;

          vt_key[0].string = "Objects";
          vt_key[1].integer = object;
          vt_key[2].string = "InRoomDesc";
          inroomdesc = prop_get_string (bundle, "S<-sis", vt_key);

          if (!obj_shows_initial_description (game, object)
              || sc_strempty (inroomdesc))
            {
              sc_bool listflag;

              vt_key[2].string = "ListFlag";
              listflag = prop_get_boolean (bundle, "B<-sis", vt_key);

              if (listflag == obj_is_static (game, object))
                {
                  if (count > 0)
                    {
                      if (count == 1)
                        pf_buffer_string (filter, "\nAlso here is ");
                      else
                        pf_buffer_string (filter, ", ");
                      lib_print_object (game, trail);
                    }
                  trail = object;
                  count++;
                }
            }
        }
    }
  if (count >= 1)
    {
      if (count == 1)
        pf_buffer_string (filter, "\nAlso here is ");
      else
        pf_buffer_string (filter, " and ");
      lib_print_object (game, trail);
      pf_buffer_string (filter, ".\n");
    }

  /* List NPCs directly in the room that have an in room description. */
  count = 0;
  for (npc = 0; npc < gs_npc_count (game); npc++)
    {
      if (npc_in_room (game, npc, room))
        {
          const sc_char *description;

          /* Print any non='#' in-room description. */
          description = lib_get_npc_inroom_text (game, npc);
          if (!sc_strempty (description) && sc_strcasecmp (description, "#"))
            {
              if (count == 0)
                pf_buffer_character (filter, '\n');
              else
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter, description);
              count++;
            }
        }
    }
  if (count > 0)
    pf_buffer_character (filter, '\n');

  /*
   * List NPCs in the room that don't have an in room description and that
   * request a default "...is here" with "#".
   *
   * TODO Is this right?
   */
  count = 0;
  trail = -1;
  for (npc = 0; npc < gs_npc_count (game); npc++)
    {
      if (npc_in_room (game, npc, room))
        {
          const sc_char *description;

          /* Print name for descriptions marked '#'. */
          description = lib_get_npc_inroom_text (game, npc);
          if (!sc_strempty (description) && !sc_strcasecmp (description, "#"))
            {
              if (count > 0)
                {
                  if (count > 1)
                    pf_buffer_string (filter, ", ");
                  else
                    {
                      pf_buffer_character (filter, '\n');
                      pf_new_sentence (filter);
                    }
                  lib_print_npc_np (game, trail);
                }
              trail = npc;
              count++;
            }
        }
    }
  if (count >= 1)
    {
      if (count == 1)
        {
          pf_buffer_character (filter, '\n');
          pf_new_sentence (filter);
          lib_print_npc_np (game, trail);
          pf_buffer_string (filter, " is here");
        }
      else
        {
          pf_buffer_string (filter, " and ");
          lib_print_npc_np (game, trail);
          pf_buffer_string (filter, " are here");
        }
      pf_buffer_string (filter, ".\n");
    }
}


/*
 * lib_print_room_description()
 *
 * Print out the long description for a given room.
 */
void
lib_print_room_description (sc_gameref_t game, sc_int room)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_bool showobjects, keepprinting, is_described;
  sc_int alt_count, alt, index_, event;
  const sc_char *description;

  /* Begin by defaulting to printing everything. */
  showobjects = TRUE;
  keepprinting = TRUE;
  is_described = FALSE;

  /* Get count of room alternates. */
  vt_key[0].string = "Rooms";
  vt_key[1].integer = room;
  vt_key[2].string = "Alts";
  alt_count = prop_get_child_count (bundle, "I<-sis", vt_key);

  /* Check alts with DisplayRoom type-0. */
  for (alt = alt_count - 1; alt >= 0 && keepprinting; alt--)
    {
      sc_int displayroom;

      vt_key[3].integer = alt;
      vt_key[4].string = "DisplayRoom";
      displayroom = prop_get_integer (bundle, "I<-sisis", vt_key);
      if (displayroom == 0)
        {
          if (lib_use_room_alt (game, room, alt))
            {
              const sc_char *m1;
              sc_int hideobjects;

              vt_key[4].string = "M1";
              m1 = prop_get_string (bundle, "S<-sisis", vt_key);
              if (!sc_strempty (m1))
                {
                  if (is_described)
                    pf_buffer_string (filter, "  ");
                  pf_buffer_string (filter, m1);
                  is_described = TRUE;
                }
              keepprinting = FALSE;

              vt_key[4].string = "Res1";
              res_handle_resource (game, "sisis", vt_key);

              vt_key[4].string = "HideObjects";
              hideobjects = prop_get_integer (bundle, "I<-sisis", vt_key);
              if (hideobjects == 1)
                showobjects = FALSE;
            }
          else
            {
              const sc_char *m2;

              vt_key[4].string = "M2";
              m2 = prop_get_string (bundle, "S<-sisis", vt_key);
              if (!sc_strempty (m2))
                {
                  if (is_described)
                    pf_buffer_string (filter, "  ");
                  pf_buffer_string (filter, m2);
                  is_described = TRUE;
                }

              vt_key[4].string = "Res2";
              res_handle_resource (game, "sisis", vt_key);
            }
        }
    }

  /* Print the standard long room description. */
  if (keepprinting)
    {
      vt_key[2].string = "Long";
      description = prop_get_string (bundle, "S<-sis", vt_key);
      if (!sc_strempty (description))
        {
          if (is_described)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter, description);
          is_described = TRUE;
        }

      vt_key[2].string = "Res";
      res_handle_resource (game, "sis", vt_key);
    }

  /* Back to handling alts. */
  vt_key[2].string = "Alts";

  /* Check alts with DisplayRoom type-1 and type 2. */
  for (index_ = 1; index_ <= 2; index_++)
    {
      for (alt = alt_count - 1; alt >= 0 && keepprinting; alt--)
        {
          sc_int displayroom;

          vt_key[3].integer = alt;
          vt_key[4].string = "DisplayRoom";
          displayroom = prop_get_integer (bundle, "I<-sisis", vt_key);
          if (displayroom == index_)
            {
              if (lib_use_room_alt (game, room, alt))
                {
                  const sc_char *m1;
                  sc_int hideobjects;

                  vt_key[4].string = "M1";
                  m1 = prop_get_string (bundle, "S<-sisis", vt_key);
                  if (!sc_strempty (m1))
                    {
                      if (is_described)
                        pf_buffer_string (filter, "  ");
                      pf_buffer_string (filter, m1);
                      is_described = TRUE;
                    }
                  if (displayroom == 1)
                    keepprinting = FALSE;

                  vt_key[4].string = "Res1";
                  res_handle_resource (game, "sisis", vt_key);

                  vt_key[4].string = "HideObjects";
                  hideobjects = prop_get_integer (bundle, "I<-sisis", vt_key);
                  if (hideobjects == 1)
                    showobjects = FALSE;
                }
              else
                {
                  const sc_char *m2;

                  vt_key[4].string = "M2";
                  m2 = prop_get_string (bundle, "S<-sisis", vt_key);
                  if (!sc_strempty (m2))
                    {
                      if (is_described)
                        pf_buffer_string (filter, "  ");
                      pf_buffer_string (filter, m2);
                      is_described = TRUE;
                    }

                  vt_key[4].string = "Res2";
                  res_handle_resource (game, "sisis", vt_key);
                }
            }
        }
      if (!keepprinting)
        break;
    }

  /* Print out any relevant event look text. */
  for (event = 0; event < gs_event_count (game); event++)
    {
      if (gs_event_state (game, event) == ES_RUNNING
          && evt_can_see_event (game, event))
        {
          const sc_char *looktext;

          vt_key[0].string = "Events";
          vt_key[1].integer = event;
          vt_key[2].string = "LookText";
          looktext = prop_get_string (bundle, "S<-sis", vt_key);
          if (is_described)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter, looktext);
          is_described = TRUE;

          vt_key[2].string = "Res";
          vt_key[3].integer = 1;
          res_handle_resource (game, "sisi", vt_key);
        }
    }
  if (is_described)
    pf_buffer_character (filter, '\n');

  /* Finally, print room contents. */
  if (showobjects)
    lib_print_room_contents (game, room);
}


/*
 * lib_can_go()
 *
 * Return TRUE if the player can move in the given direction.
 */
static sc_bool
lib_can_go (sc_gameref_t game, sc_int room, sc_int direction)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_int restriction;
  sc_bool is_restricted = FALSE;

  /* Set up invariant parts of key. */
  vt_key[0].string = "Rooms";
  vt_key[1].integer = room;
  vt_key[2].string = "Exits";
  vt_key[3].integer = direction;

  /* Check for any movement restrictions. */
  vt_key[4].string = "Var1";
  restriction = prop_get_integer (bundle, "I<-sisis", vt_key) - 1;
  if (restriction >= 0)
    {
      sc_int type;

      if (lib_trace)
        sc_trace ("Library: hit move restriction\n");

      /* Get restriction type. */
      vt_key[4].string = "Var3";
      type = prop_get_integer (bundle, "I<-sisis", vt_key);
      switch (type)
        {
        case 0:                /* Task type restriction */
          {
            sc_int check;

            /* Get the expected completion state. */
            vt_key[4].string = "Var2";
            check = prop_get_integer (bundle, "I<-sisis", vt_key);

            if (lib_trace)
              {
                sc_trace ("Library:_ task %ld, check %ld\n",
                          restriction, check);
              }

            /* Restrict if task isn't done/not done as expected. */
            if ((check != 0) == gs_task_done (game, restriction))
              is_restricted = TRUE;
            break;
          }

        case 1:                /* Object state restriction */
          {
            sc_int object, check, openable;

            /* Get the target object. */
            object = obj_stateful_object (game, restriction);

            /* Get the expected object state. */
            vt_key[4].string = "Var2";
            check = prop_get_integer (bundle, "I<-sisis", vt_key);

            if (lib_trace)
              sc_trace ("Library:_ object %ld, check %ld\n", object, check);

            /* Check openable and lockable objects. */
            vt_key[0].string = "Objects";
            vt_key[1].integer = object;
            vt_key[2].string = "Openable";
            openable = prop_get_integer (bundle, "I<-sis", vt_key);
            if (openable > 0)
              {
                sc_int lockable;

                /* See if lockable. */
                vt_key[2].string = "Key";
                lockable = prop_get_integer (bundle, "I<-sis", vt_key);
                if (lockable >= 0)
                  {
                    /* Lockable. */
                    if (check <= 2)
                      {
                        if (gs_object_openness (game, object) != check + 5)
                          is_restricted = TRUE;
                      }
                    else
                      {
                        if (gs_object_state (game, object) != check - 2)
                          is_restricted = TRUE;
                      }
                  }
                else
                  {
                    /* Not lockable, though openable. */
                    if (check <= 1)
                      {
                        if (gs_object_openness (game, object) != check + 5)
                          is_restricted = TRUE;
                      }
                    else
                      {
                        if (gs_object_state (game, object) != check - 1)
                          is_restricted = TRUE;
                      }
                  }
              }
            else
              {
                /* Not openable. */
                if (gs_object_state (game, object) != check + 1)
                  is_restricted = TRUE;
              }
            break;
          }
        }
    }

  /* Return TRUE if not restricted. */
  return !is_restricted;
}


/*
 * lib_select_response()
 * lib_select_plurality()
 *
 * Convenience functions for multiple handlers.  Returns the appropriate
 * response string for a game, based on perspective or object plurality.
 */
static const sc_char *
lib_select_response (sc_gameref_t game,
                     const sc_char *second_person,
                     const sc_char *first_person,
                     const sc_char *third_person)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[2];
  sc_int perspective;
  const sc_char *response;

  /* Return the response appropriate for Perspective. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "Perspective";
  perspective = prop_get_integer (bundle, "I<-ss", vt_key);
  switch (perspective)
    {
    case FIRST_PERSON:
      response = first_person;
      break;
    case SECOND_PERSON:
      response = second_person;
      break;
    case THIRD_PERSON:
      response = third_person;
      break;
    default:
      sc_error ("lib_select_response:"
                " unknown perspective, %ld\n", perspective);
      response = second_person;
      break;
    }

  return response;
}

static const sc_char *
lib_select_plurality (sc_gameref_t game, sc_int object,
                      const sc_char *singular, const sc_char *plural)
{
  return obj_appears_plural (game, object) ? plural : singular;
}


/* List of direction names, for printing and counting exits. */
static const sc_char *const DIRNAMES_4[] = {
  "north", "east", "south", "west", "up", "down", "in", "out",
  NULL
};
static const sc_char *const DIRNAMES_8[] = {
  "north", "east", "south", "west", "up", "down", "in", "out",
  "northeast", "southeast", "southwest", "northwest",
  NULL
};


/*
 * lib_cmd_print_room_exits()
 *
 * Print a list of exits from the player room.
 */
sc_bool
lib_cmd_print_room_exits (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[4];
  sc_bool eightpointcompass;
  const sc_char *const *dirnames;
  sc_int count, index_, trail;

  /* Decide on four or eight point compass names list. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "EightPointCompass";
  eightpointcompass = prop_get_boolean (bundle, "B<-ss", vt_key);
  dirnames = eightpointcompass ? DIRNAMES_8 : DIRNAMES_4;

  /* Poll for an exit for each valid direction name. */
  count = 0;
  trail = -1;
  for (index_ = 0; dirnames[index_]; index_++)
    {
      sc_vartype_t vt_rvalue;

      vt_key[0].string = "Rooms";
      vt_key[1].integer = gs_playerroom (game);
      vt_key[2].string = "Exits";
      vt_key[3].integer = index_;
      if (prop_get (bundle, "I<-sisi", &vt_rvalue, vt_key)
          && lib_can_go (game, gs_playerroom (game), index_))
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  /* Vary text slightly for DispFirstRoom. */
                  if (game->turns == 0)
                    pf_buffer_string (filter, "There are exits ");
                  else
                    pf_buffer_string (filter,
                                      lib_select_response (game,
                                                         "You can move ",
                                                         "I can move ",
                                                         "%player% can move "));
                }
              else
                pf_buffer_string (filter, ", ");
              pf_buffer_string (filter, dirnames[trail]);
            }
          trail = index_;
          count++;
        }
    }
  if (count >= 1)
    {
      if (count == 1)
        {
          /* Vary text slightly for DispFirstRoom. */
          if (game->turns == 0)
            pf_buffer_string (filter, "There is an exit ");
          else
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You can only move ",
                                                   "I can only move ",
                                                   "%player% can only move "));
        }
      else
        pf_buffer_string (filter, " and ");
      pf_buffer_string (filter, dirnames[trail]);
      pf_buffer_string (filter, ".\n");
    }
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                      "You can't go in any direction!\n",
                                      "I can't go in any direction!\n",
                                      "%player% can't go in any direction!\n"));
    }

  return TRUE;
}


/*
 * lib_describe_player_room()
 *
 * Print out details of the player room, in brief if verbose not set and the
 * room has already been visited.
 */
static void
lib_describe_player_room (sc_gameref_t game, sc_bool force_verbose)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[2];

  /* Print the room name. */
  lib_print_room_name (game, gs_playerroom (game));

  /* Print other room details if applicable. */
  if (force_verbose
      || game->verbose || !gs_room_seen (game, gs_playerroom (game)))
    {
      sc_bool showexits;

      /* Print room description, and objects and NPCs. */
      lib_print_room_description (game, gs_playerroom (game));

      /* Print exits if the ShowExits global requests it. */
      vt_key[0].string = "Globals";
      vt_key[1].string = "ShowExits";
      showexits = prop_get_boolean (bundle, "B<-ss", vt_key);
      if (showexits)
        {
          pf_buffer_character (filter, '\n');
          lib_cmd_print_room_exits (game);
        }
    }
}


/*
 * lib_cmd_look()
 *
 * Command handler for "look" command.
 */
sc_bool
lib_cmd_look (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_character (filter, '\n');
  lib_describe_player_room (game, TRUE);
  return TRUE;
}


/*
 * lib_cmd_quit()
 *
 * Called on "quit".  Exits from the game main loop.
 */
sc_bool
lib_cmd_quit (sc_gameref_t game)
{
  if (if_confirm (SC_CONF_QUIT))
    game->is_running = FALSE;

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_restart()
 *
 * Called on "restart".  Exits from the game main loop with restart
 * request set.
 */
sc_bool
lib_cmd_restart (sc_gameref_t game)
{
  if (if_confirm (SC_CONF_RESTART))
    {
      game->is_running = FALSE;
      game->do_restart = TRUE;
    }

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_undo()
 *
 * Called on "undo".  Restores any undo game or memo to the main game.
 */
sc_bool
lib_cmd_undo (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_memo_setref_t memento = gs_get_memento (game);

  /* If an undo buffer is available, restore it. */
  if (game->undo_available)
    {
      gs_copy (game, game->undo);
      game->undo_available = FALSE;

      lib_print_room_name (game, gs_playerroom (game));
      pf_buffer_string (filter, "[The previous turn has been undone.]\n");

      /* Undo can't properly unravel layered sounds... */
      game->stop_sound = TRUE;

      game->is_admin = TRUE;
      return TRUE;
    }

  /*
   * If there is no undo buffer, try to restore one saved previously in a
   * memo.  If that works, treat as for restore from file, since that's
   * effectively what it is.
   */
  if (memo_load_game (memento, game))
    {
      lib_print_room_name (game, gs_playerroom (game));
      pf_buffer_string (filter, "[The previous turn has been undone.]\n");

      game->is_running = FALSE;
      game->do_restore = TRUE;
    }

  else if (game->turns == 0)
    pf_buffer_string (filter, "You can't undo what hasn't been done.\n");
  else
    pf_buffer_string (filter, "Sorry, no more undo is available.\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_history_common()
 * lib_cmd_history_number()
 * lib_cmd_history()
 *
 * Prints a history of saved commands for the game.  Print directly rather
 * than using the printfilter to avoid possible clashes with ALRs.
 */
static sc_bool
lib_cmd_history_common (sc_gameref_t game, sc_int limit)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_memo_setref_t memento = gs_get_memento (game);
  const sc_char *command;
  sc_int first, count, timestamp;

  /*
   * The runner main loop will add an entry for the "history" command that
   * got us here, but it hasn't done so yet.  To keep the history list
   * accurate for recalling commands, we add a surrogate "history" command
   * to the history here, and remove it when we've done listing.  This matches
   * the c-shell, which always shows 'history' listed last.
   */
  timestamp = var_get_elapsed_seconds (vars);
  memo_save_command (memento, "[history]", timestamp, game->turns);

  /* Decide on the first history to display; all if limit is 0 or less. */
  if (limit > 0)
    {
      /*
       * Get a count of the history length recorded.  Because of the surrogate
       * "history" above, this is always at least one.  From this, choose a
       * start point for the display; all if not enough history.
       */
      count = memo_get_command_count (memento);
      first = (count > limit) ? count - limit : 0;
    }
  else
    first = 0;

  if_print_string ("These are your most recent game commands:\n\n");

  /* Display history starting at the first entry determined above. */
  memo_first_command (memento);
  for (count = 0; memo_more_commands (memento); count++)
    {
      sc_int sequence, turns;

      /* Obtain the history entry, and write if included. */
      memo_next_command (memento, &command, &sequence, &timestamp, &turns);
      if (count >= first)
        {
          sc_int hr, min, sec;
          sc_char buffer[64];

          /* Write the history entry sequence. */
          sprintf (buffer, "%4ld -- Time ", sequence);
          if_print_string (buffer);

          /* Separate the timestamp out into components. */
          hr = timestamp / SECS_PER_HOUR;
          min = (timestamp % SECS_PER_HOUR) / MINS_PER_HOUR;
          sec = timestamp % SECS_PER_MINUTE;

          /* Print playing time as "[HHh ][M]Mm SSs". */
          if (hr > 0)
            sprintf (buffer, "%ldh %02ldm %02lds", hr, min, sec);
          else
            sprintf (buffer, "%ldm %02lds", min, sec);
          if_print_string (buffer);

          /* Follow up with the turns count, and the command string itself. */
          sprintf (buffer, ", turn %ld : ", turns);
          if_print_string (buffer);
          if_print_string (command);
          if_print_character ('\n');
        }
    }

  /* Remove the surrogate "history"; the main loop will add the real one. */
  memo_unsave_command (memento);

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_history_number (sc_gameref_t game)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int limit;

  /* Get requested length of history list, and complain if not valid. */
  limit = var_get_ref_number (vars);
  if (limit < 1)
    {
      if_print_string ("That's not a valid history length.\n");

      game->is_admin = TRUE;
      return TRUE;
    }

  return lib_cmd_history_common (game, limit);
}

sc_bool
lib_cmd_history (sc_gameref_t game)
{
  return lib_cmd_history_common (game, 0);
}


/*
 * lib_cmd_again()
 * lib_cmd_redo_number()
 * lib_cmd_redo_text_last_common()
 * lib_cmd_redo_text()
 * lib_cmd_redo_last()
 *
 * The first function is called on "again", and simply sets the game do_again
 * flag.  The others allow the user to select a command from the history list
 * to re-run.
 */
sc_bool
lib_cmd_again (sc_gameref_t game)
{
  game->do_again = TRUE;
  game->redo_sequence = 0;

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_redo_number (sc_gameref_t game)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_memo_setref_t memento = gs_get_memento (game);
  sc_int sequence;

  /*
   * Get the history sequence entry requested and validate it.  The sequence
   * may be positive (absolute) or negative (relative to history end), but
   * not zero.
   */
  sequence = var_get_ref_number (vars);
  if (sequence != 0 && memo_find_command (memento, sequence))
    {
      game->do_again = TRUE;
      game->redo_sequence = sequence;
    }
  else
    {
      if_print_string ("No matching entry found in the command history.\n");

      /*
       * This is a failed redo, but returning FALSE will cause the game's
       * unknown command message to come up.  However, returning TRUE will
       * cause the runner main loop to add this to its history, and at some
       * point a "redo 7" could cause problems (say, when it's at sequence 7,
       * where it'll cause an infinite loop).  To work round this, here we'll
       * return a redo_sequence _without_ do_again, and have the runner catch
       * that as an indication not to save the command in its history.  Sorry
       * for the ugliness.
       */
      game->do_again = FALSE;
      game->redo_sequence = INT_MAX;
    }

  game->is_admin = TRUE;
  return TRUE;
}

static sc_bool
lib_cmd_redo_text_last_common (sc_gameref_t game, const sc_char *target)
{
  const sc_memo_setref_t memento = gs_get_memento (game);
  sc_bool is_do_last, is_contains;
  sc_int length, matched_sequence;

  /* Make a special case of "!!", rerun the final command in the history. */
  is_do_last = (strcmp (target, "!") == 0);

  /*
   * Differentiate starts-with and contains searches, setting is_contains and
   * advancing by one if the target begins '?' (word search).  Note target
   * string length.
   */
  is_contains = (target[0] == '?');
  target += is_contains ? 1 : 0;
  length = strlen (target);

  /* If there's no text left to search for, reject this call now. */
  if (length == 0)
    {
      if_print_string ("No matching entry found in the command history.\n");

      /* As with failed numeric redo above, special-case this return. */
      game->do_again = FALSE;
      game->redo_sequence = INT_MAX;

      game->is_admin = TRUE;
      return TRUE;
    }

  /*
   * Search saved commands for one that matches the target string in the
   * required way.  We want to return the most recently saved match, so ideally
   * we'd search backwards, but the iterator is only forwards, so we do it the
   * hard way.
   */
  matched_sequence = 0;
  memo_first_command (memento);
  while (memo_more_commands (memento))
    {
      const sc_char *command;
      sc_int sequence, timestamp, turns;
      sc_bool is_matched;

      /* Get the command; only command and sequence are relevant. */
      memo_next_command (memento, &command, &sequence, &timestamp, &turns);

      /*
       * If this is the "!!" special case, match everything.  Otherwise,
       * either search the command for the target, or match if the command
       * begins with the target.
       */
      if (is_do_last)
        is_matched = TRUE;
      else if (is_contains)
        {
          sc_int index_;

          /* Search this command for an occurrence of target anywhere. */
          is_matched = FALSE;
          for (index_ = strlen (command) - length; index_ >= 0; index_--)
            {
              if (sc_strncasecmp (command + index_, target, length) == 0)
                {
                  is_matched = TRUE;
                  break;
                }
            }
        }
      else
        is_matched = (sc_strncasecmp (command, target, length) == 0);

      /* If the command matched the target criteria, note it and continue. */
      if (is_matched)
        matched_sequence = sequence;
    }

  /* If we found a match, set the redo values accordingly. */
  if (matched_sequence > 0)
    {
      game->do_again = TRUE;
      game->redo_sequence = matched_sequence;
    }
  else
    {
      if_print_string ("No matching entry found in the command history.\n");

      /* As with failed numeric redo above, special-case this return. */
      game->do_again = FALSE;
      game->redo_sequence = INT_MAX;
    }

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_redo_text (sc_gameref_t game)
{
  const sc_var_setref_t vars = gs_get_vars (game);

  /* Call the common redo with the referenced text from %text%. */
  return lib_cmd_redo_text_last_common (game, var_get_ref_text (vars));
}

sc_bool
lib_cmd_redo_last (sc_gameref_t game)
{
  /* Call the common redo with, literally, "!", forming "!!" . */
  return lib_cmd_redo_text_last_common (game, "!");
}


/*
 * lib_cmd_hints()
 *
 * Called on "hints".  Requests the interface to display any available hints.
 */
sc_bool
lib_cmd_hints (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int task;
  sc_bool game_has_hints;

  /*
   * Check for the presence of any game hints at all, no matter whether the
   * task is runnable or not.
   */
  game_has_hints = FALSE;
  for (task = 0; task < gs_task_count (game); task++)
    {
      if (task_has_hints (game, task))
        {
          game_has_hints = TRUE;
          break;
        }
    }

  /* If the game has hints, display any relevant ones. */
  if (game_has_hints)
    {
      if (run_hint_iterate (game, NULL))
        {
          if (if_confirm (SC_CONF_VIEW_HINTS))
            if_display_hints (game);
        }
      else
        pf_buffer_string (filter, "There are currently no hints available.\n");
    }
  else
    {
      pf_buffer_string (filter,
                        "There are no hints available for this adventure.\n");
      pf_buffer_string (filter,
                        "You're just going to have to work it out for"
                        " yourself...\n");
    }

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_print_string_bold()
 * lib_print_string_italics()
 *
 * Convenience helpers for printing licensing and game information.
 */
static void
lib_print_string_bold (const sc_char *string)
{
  if_print_tag (SC_TAG_BOLD, "");
  if_print_string (string);
  if_print_tag (SC_TAG_ENDBOLD, "");
}

static void
lib_print_string_italics (const sc_char *string)
{
  if_print_tag (SC_TAG_ITALICS, "");
  if_print_string (string);
  if_print_tag (SC_TAG_ENDITALICS, "");
}


/*
 * lib_cmd_help()
 * lib_cmd_license()
 *
 * A form of standard help output for games that don't define it themselves,
 * and the GPL licensing.  Print directly rather than using the printfilter
 * to avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_help (sc_gameref_t game)
{
  if_print_string (
    "These are some of the typical commands used in this adventure:\n\n");

  if_print_string (
    "  [N]orth, [E]ast, [S]outh, [W]est, [U]p, [D]own, [In], [O]ut,"
    " [L]ook, [Exits]\n  E[x]amine <object>, [Get <object>],"
    " [Drop <object>], [...it], [...all]\n  [Where is <object>]\n"
    "  [Give <object> to  <character>], [Open...], [Close...],"
    " [Ask <character> about <subject>]\n"
    "  [Wear <object>], [Remove <object>], [I]nventory\n"
    "  [Put <object> into <object>], [Put <object> onto <object>]\n");

  if_print_string ("\nUse the ");
  lib_print_string_italics ("Save");
  if_print_string (", ");
  lib_print_string_italics ("Restore");
  if_print_string (", ");
  lib_print_string_italics ("Undo");
  if_print_string (", and ");
  lib_print_string_italics ("Quit");
  if_print_string (
    " commands to save and restore games, undo a move, and leave the "
    " game.  Use ");
  lib_print_string_italics ("History");
  if_print_string (" and ");
  lib_print_string_italics ("Redo");
  if_print_string (
    " to view and repeat recent game commands.\n");

  if_print_string ("\nThe ");
  lib_print_string_italics ("Hint");
  if_print_string (" command displays any game hints, ");
  lib_print_string_italics ("Notify");
  if_print_string (" provides score change notification, and ");
  lib_print_string_italics ("Verbose");
  if_print_string (" and ");
  lib_print_string_italics ("Brief");
  if_print_string (" control room descriptions.\n");

  if_print_string ("\nUse ");
  lib_print_string_italics ("License");
  if_print_string (
    " to view SCARE's licensing terms and conditions, and ");
  lib_print_string_italics ("Version");
  if_print_string (
    " to print both SCARE's and the game's version number.\n");

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_license (sc_gameref_t game)
{
  lib_print_string_bold ("SCARE");
  if_print_string (" is ");
  lib_print_string_italics (
    "Copyright (C) 2003-2007  Simon Baldwin and Mark J. Tilford");
  if_print_string (".\n\n");

  if_print_string (
    "This program is free software; you can redistribute it and/or modify"
    " it under the terms of version 2 of the GNU General Public License"
    " as published by the Free Software Foundation.\n\n");

  if_print_string (
    "This program is distributed in the hope that it will be useful, but ");
  lib_print_string_bold ("WITHOUT ANY WARRANTY");
  if_print_string ("; without even the implied warranty of ");
  lib_print_string_bold ("MERCHANTABILITY");
  if_print_string (" or ");
  lib_print_string_bold ("FITNESS FOR A PARTICULAR PURPOSE");
  if_print_string (
    ".  See the GNU General Public License for more details.\n\n");

  if_print_string (
    "You should have received a copy of the GNU General Public License"
    " along with this program; if not, write to the Free Software"
    " Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307"
    " USA\n\n");

  if_print_string ("Please report any bugs, omissions, or misfeatures to ");
  lib_print_string_italics ("simon_baldwin@yahoo.com");
  if_print_string (".\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_information()
 *
 * Display a few small pieces of game information, done by a dialog GUI
 * in real Adrift.  Prints directly rather than using the printfilter to
 * avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_information (sc_gameref_t game)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_vartype_t vt_key[2];
  const sc_char *gamename, *gameauthor, *modified;
  sc_char *filtered;

  vt_key[0].string = "Globals";
  vt_key[1].string = "GameName";
  gamename = prop_get_string (bundle, "S<-ss", vt_key);
  filtered = pf_filter_for_info (gamename, vars);
  pf_strip_tags (filtered);

  if_print_string ("This is ");
  lib_print_string_bold (filtered);
  sc_free (filtered);

  vt_key[0].string = "Globals";
  vt_key[1].string = "GameAuthor";
  gameauthor = prop_get_string (bundle, "S<-ss", vt_key);
  filtered = pf_filter_for_info (gameauthor, vars);
  pf_strip_tags (filtered);

  if_print_string (", by ");
  lib_print_string_bold (filtered);
  sc_free (filtered);
  if_print_string (".\n");

  vt_key[0].string = "CompileDate";
  modified = prop_get_string (bundle, "S<-s", vt_key);
  if (!sc_strempty (modified))
    {
      if_print_string ("The game was last modified on ");
      if_print_string (modified);
      if_print_string (".\n");
    }

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_clear()
 *
 * Clear the main game window (almost).
 */
sc_bool
lib_cmd_clear (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_tag (filter, SC_TAG_CLS);
  pf_buffer_string (filter, "Screen cleared.\n");
  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_statusline()
 *
 * Display the status line as would be shown by the Runner.  Useful for
 * interpreter builds that can't offer a true status line.  Prints directly
 * rather than using the printfilter to avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_statusline (sc_gameref_t game)
{
  const sc_char *name, *author, *room, *status;
  sc_int score;

  /*
   * Retrieve the game's name and author, the description of the current
   * game room, and any formatted game status line.
   */
  run_get_attributes (game, &name, &author, NULL,
                      &score, NULL, &room, &status, NULL, NULL, NULL, NULL);

  /* If nothing is yet determined, print the game name and author. */
  if (!room)
    {
      if_print_string (name);
      if_print_string (" | ");
      if_print_string (author);
    }
  else
    {
      /* Print the player location, and a separator. */
      if_print_string (room);
      if_print_string (" | ");

      /* If the game offers a status line, print it, otherwise the score. */
      if (status)
        if_print_string (status);
      else
        {
          sc_char buffer[32];

          if_print_string ("Score: ");
          sprintf (buffer, "%ld", score);
          if_print_string (buffer);
        }
    }
  if_print_character ('\n');

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_version()
 *
 * Display the "Runner version".  Prints directly rather than using the
 * printfilter to avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_version (sc_gameref_t game)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key;
  sc_char buffer[64];
  sc_int major, minor, point;
  const sc_char *version;

  if_print_string ("You are running the game with SCARE ");
  if_print_string (SCARE_VERSION SCARE_PATCH_LEVEL);
  if_print_string (" [Adrift ");
  major = SCARE_EMULATION / 1000;
  minor = (SCARE_EMULATION % 1000) / 100;
  point = SCARE_EMULATION % 100;
  sprintf (buffer, "%ld.%02ld.%02ld", major, minor, point);
  if_print_string (buffer);
  if_print_string (" compatible].\n");

  vt_key.string = "VersionString";
  version = prop_get_string (bundle, "S<-s", &vt_key);
  if_print_string ("The game was created with Adrift version ");
  if_print_string (version);
  if_print_string (".\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_wait()
 * lib_cmd_wait_number()
 *
 * Set game waitcounter to a count of turns for which the main loop will run
 * without taking input.  Many Adrift Runners ignore any WaitTurns setting in
 * the game, and use always use one; this might make a game misbehave, so to
 * try to cover this case we supply 'wait N' as a player control to override
 * the game's setting.  The latter prints directly rather than using the
 * printfilter to avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_wait (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[2];
  sc_int waitturns;

  /* Note if wait turns is different from the game's setting. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "WaitTurns";
  waitturns = prop_get_integer (bundle, "I<-ss", vt_key);
  if (waitturns != game->waitturns)
    {
      sc_char buffer[32];

      pf_buffer_string (filter, "(");
      sprintf (buffer, "%ld", game->waitturns);
      pf_buffer_string (filter, buffer);
      pf_buffer_string (filter,
                        game->waitturns == 1 ? " turn)\n" : " turns)\n");
    }

  /* Reset the wait counter to the current waitturns setting. */
  game->waitcounter = game->waitturns;

  pf_buffer_string (filter, "Time passes...\n");
  return TRUE;
}

sc_bool
lib_cmd_wait_number (sc_gameref_t game)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int waitturns;
  sc_char buffer[32];

  /* Get and validate the waitturns setting. */
  waitturns = var_get_ref_number (vars);
  if (waitturns < 1 || waitturns > 20)
    {
      if_print_string ("You can only wait between 1 and 20 turns.\n");
      game->is_admin = TRUE;
      return TRUE;
    }

  /* Update the game setting, and confirm for the player. */
  game->waitturns = waitturns;

  if_print_string ("The game will now wait ");
  sprintf (buffer, "%ld", waitturns);
  if_print_string (buffer);
  if_print_string (waitturns == 1 ? " turn" : " turns");
  if_print_string (" for each 'wait' command you enter.\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_verbose()
 * lib_cmd_brief()
 *
 * Set/clear game verbose flag.  Print directly rather than using the
 * printfilter to avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_verbose (sc_gameref_t game)
{
  /* Set game verbose flag and return. */
  game->verbose = TRUE;
  if_print_string ("The game is now in its ");
  if_print_tag (SC_TAG_ITALICS, "");
  if_print_string ("verbose");
  if_print_tag (SC_TAG_ENDITALICS, "");
  if_print_string (" mode, which always gives long descriptions of locations"
                   " (even if you've been there before).\n");

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_brief (sc_gameref_t game)
{
  /* Clear game verbose flag and return. */
  game->verbose = FALSE;
  if_print_string ("The game is now in its ");
  if_print_tag (SC_TAG_ITALICS, "");
  if_print_string ("brief");
  if_print_tag (SC_TAG_ENDITALICS, "");
  if_print_string (" mode, which gives long descriptions of places never"
                   " before visited and short descriptions otherwise.\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_notify_on_off()
 * lib_cmd_notify()
 *
 * Set/clear/query game score change notification flag.  Print directly
 * rather than using the printfilter to avoid possible clashes with ALRs.
 */
sc_bool
lib_cmd_notify_on_off (sc_gameref_t game)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_char *control;

  /* Get the text following the notify command, and check for "on"/"off". */
  control = var_get_ref_text (vars);
  if (sc_strcasecmp (control, "on") == 0)
    {
      /* Set score change notification. */
      game->notify_score_change = TRUE;
      if_print_string ("Game score change notification is now ");
      if_print_tag (SC_TAG_ITALICS, "");
      if_print_string ("on");
      if_print_tag (SC_TAG_ENDITALICS, "");
      if_print_string (", and the game will tell you of any changes in the"
                       " score.\n");
    }
  else if (sc_strcasecmp (control, "off") == 0)
    {
      /* Clear score change notification. */
      game->notify_score_change = FALSE;
      if_print_string ("Game score change notification is now ");
      if_print_tag (SC_TAG_ITALICS, "");
      if_print_string ("off");
      if_print_tag (SC_TAG_ENDITALICS, "");
      if_print_string (", and the game will be silent on changes in the"
                       " score.\n");
    }
  else
    {
      if_print_string ("Use 'notify on' or 'notify off' to control game"
                       " score notification.\n");
    }

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_notify (sc_gameref_t game)
{
  /* Report the current state of notification. */
  if_print_string ("Game score change notification is ");
  if_print_tag (SC_TAG_ITALICS, "");
  if_print_string (game->notify_score_change ? "on" : "off");
  if_print_tag (SC_TAG_ENDITALICS, "");

  if (game->notify_score_change)
    {
      if_print_string (", and the game will tell you of any changes in the"
                       " score.\n");
    }
  else
    {
      if_print_string (", and the game will be silent on changes in the"
                       " score.\n");
    }

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_time()
 * lib_cmd_date()
 *
 * Print elapsed game time, and smart-alec "date" response.  The Adrift
 * Runner responds here with the system time and date, but we'll do something
 * different.
 */
sc_bool
lib_cmd_time (sc_gameref_t game)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_uint seconds;
  sc_int hr, min, sec;
  sc_char buffer[64];

  /* Get elapsed game time and convert to hour, minutes, and seconds. */
  seconds = var_get_elapsed_seconds (vars);
  hr = seconds / SECS_PER_HOUR;
  min = (seconds % SECS_PER_HOUR) / MINS_PER_HOUR;
  sec = seconds % SECS_PER_MINUTE;
  if (hr > 0)
    sprintf (buffer, "%ldh %02ldm %02lds", hr, min, sec);
  else
    sprintf (buffer, "%ldm %02lds", min, sec);

  /* Print the game's elapsed time. */
  if_print_string ("You have been running the game for ");
  if_print_string (buffer);
  if_print_string (".\n");

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_date (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Maybe we should just be good friends.\n");
  return TRUE;
}


/*
 * Direction enumeration.  Used by movement commands, to multiplex them all
 * into a single function.  The values are explicit to ensure they match
 * enumerations in the game data.
 */
typedef enum
{
  DIR_NORTH = 0, DIR_EAST = 1,
  DIR_SOUTH = 2, DIR_WEST = 3,
  DIR_UP = 4, DIR_DOWN = 5,
  DIR_IN = 6, DIR_OUT = 7,
  DIR_NORTHEAST = 8, DIR_SOUTHEAST = 9,
  DIR_SOUTHWEST = 10, DIR_NORTHWEST = 11
} sc_direction_t;


/*
 * lib_go()
 *
 * Central movement command, called by all movement handlers.
 */
static sc_bool
lib_go (sc_gameref_t game, sc_direction_t direction)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5], vt_rvalue;
  sc_bool eightpointcompass, is_trapped, is_exitable[12];
  sc_int destination, index_;
  const sc_char *const *dirnames;

  /* Decide on four or eight point compass names list. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "EightPointCompass";
  eightpointcompass = prop_get_boolean (bundle, "B<-ss", vt_key);
  dirnames = eightpointcompass ? DIRNAMES_8 : DIRNAMES_4;

  /* Start by seeing if there are any exits at all available. */
  is_trapped = TRUE;
  for (index_ = 0; dirnames[index_]; index_++)
    {
      vt_key[0].string = "Rooms";
      vt_key[1].integer = gs_playerroom (game);
      vt_key[2].string = "Exits";
      vt_key[3].integer = index_;
      if (prop_get (bundle, "I<-sisi", &vt_rvalue, vt_key)
          && lib_can_go (game, gs_playerroom (game), index_))
        {
          is_exitable[index_] = TRUE;
          is_trapped = FALSE;
        }
      else
        is_exitable[index_] = FALSE;
    }
  if (is_trapped)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                      "You can't go in any direction!\n",
                                      "I can't go in any direction!\n",
                                      "%player% can't go in any direction!\n"));
      return TRUE;
    }

  /*
   * Check for the exit, and if it doesn't exist, refuse, and list the possible
   * options.
   */
  vt_key[0].string = "Rooms";
  vt_key[1].integer = gs_playerroom (game);
  vt_key[2].string = "Exits";
  vt_key[3].integer = direction;
  vt_key[4].string = "Dest";
  if (prop_get (bundle, "I<-sisis", &vt_rvalue, vt_key))
    destination = vt_rvalue.integer - 1;
  else
    {
      sc_int count, trail;

      pf_buffer_string (filter,
                        lib_select_response (game,
                         "You can't go in that direction, but you can move ",
                         "I can't go in that direction, but I can move ",
                         "%player% can't go in that direction, but can move "));

      /* List available exits, found in exit test loop earlier. */
      count = 0;
      trail = -1;
      for (index_ = 0; dirnames[index_]; index_++)
        {
          if (is_exitable[index_])
            {
              if (count > 0)
                {
                  if (count > 1)
                    pf_buffer_string (filter, ", ");
                  pf_buffer_string (filter, dirnames[trail]);
                }
              trail = index_;
              count++;
            }
        }
      if (count >= 1)
        {
          if (count > 1)
            pf_buffer_string (filter, " and ");
          pf_buffer_string (filter, dirnames[trail]);
        }
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Check for any movement restrictions. */
  if (!lib_can_go (game, gs_playerroom (game), direction))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                        "You can't go in that direction (at present).\n",
                        "I can't go in that direction (at present).\n",
                        "%player% can't go in that direction (at present).\n"));
      return TRUE;
    }

  if (lib_trace)
    {
      sc_trace ("Library: moving player from %ld to %ld\n",
                gs_playerroom (game), destination);
    }

  /* Indicate if getting off something or standing up first. */
  if (gs_playerparent (game) != -1)
    {
      pf_buffer_string (filter, "(Getting off ");
      lib_print_object_np (game, gs_playerparent (game));
      pf_buffer_string (filter, " first)\n");
    }
  else if (gs_playerposition (game) != 0)
    pf_buffer_string (filter, "(Standing up first)\n");

  /* Confirm and then make move. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You move ",
                                         "I move ",
                                         "%player% moves "));
  pf_buffer_string (filter, dirnames[direction]);
  pf_buffer_string (filter, ".\n");

  gs_move_player_to_room (game, destination);

  /* Describe the new room and return. */
  lib_describe_player_room (game, FALSE);
  return TRUE;
}


/*
 * lib_cmd_go_*()
 *
 * Direction-specific movement commands.
 */
sc_bool
lib_cmd_go_north (sc_gameref_t game)
{
  return lib_go (game, DIR_NORTH);
}

sc_bool
lib_cmd_go_east (sc_gameref_t game)
{
  return lib_go (game, DIR_EAST);
}

sc_bool
lib_cmd_go_south (sc_gameref_t game)
{
  return lib_go (game, DIR_SOUTH);
}

sc_bool
lib_cmd_go_west (sc_gameref_t game)
{
  return lib_go (game, DIR_WEST);
}

sc_bool
lib_cmd_go_up (sc_gameref_t game)
{
  return lib_go (game, DIR_UP);
}

sc_bool
lib_cmd_go_down (sc_gameref_t game)
{
  return lib_go (game, DIR_DOWN);
}

sc_bool
lib_cmd_go_in (sc_gameref_t game)
{
  return lib_go (game, DIR_IN);
}

sc_bool
lib_cmd_go_out (sc_gameref_t game)
{
  return lib_go (game, DIR_OUT);
}

sc_bool
lib_cmd_go_northeast (sc_gameref_t game)
{
  return lib_go (game, DIR_NORTHEAST);
}

sc_bool
lib_cmd_go_southeast (sc_gameref_t game)
{
  return lib_go (game, DIR_SOUTHEAST);
}

sc_bool
lib_cmd_go_northwest (sc_gameref_t game)
{
  return lib_go (game, DIR_NORTHWEST);
}

sc_bool
lib_cmd_go_southwest (sc_gameref_t game)
{
  return lib_go (game, DIR_SOUTHWEST);
}


/*
 * lib_compare_rooms()
 *
 * Helper for lib_cmd_go_room().  Compare the name of the passed in room
 * with the string passed in, and return TRUE if they match.  The routine
 * requires that string is filtered, stripped, trimmed and normalized.
 */
static sc_bool
lib_compare_rooms (sc_gameref_t game, sc_int room, const sc_char *string)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_char *name, *compare_name;
  sc_bool status;

  /* Get the name of the room, and filter it down to a plain string. */
  name = pf_filter (lib_get_room_name (game, room), vars, bundle);
  pf_strip_tags (name);
  sc_normalize_string (sc_trim_string (name));

  /* Bypass any prefix on the room name. */
  if (sc_compare_word (name, "a"))
    compare_name = name + 1;
  else if (sc_compare_word (name, "an"))
    compare_name = name + 2;
  else if (sc_compare_word (name, "the"))
    compare_name = name + 3;
  else
    compare_name = name;
  sc_trim_string (compare_name);

  /* Compare strings, then free the allocated name. */ 
  status = sc_strcasecmp (compare_name, string) == 0; 
  sc_free (name);

  return status;
}


/*
 * lib_cmd_go_room()
 *
 * A weak replica of the Runner's claimed ability to go to a named room via
 * rooms that have already been visited using a shortest-path search.  This
 * version scans adjacent rooms for accessibility, and then generates the
 * required directional move for any unique match.
 *
 * Note that rooms can have the same name after they've been cleaned up for
 * text comparisons, for example, two "Manor Grounds" at the start of Humbug,
 * differentiated within the game with trailing "<some_tag>" components.
 */
sc_bool
lib_cmd_go_room (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5], vt_rvalue;
  sc_bool eightpointcompass, is_trapped, is_ambiguous;
  sc_int direction, index_;
  const sc_char *const *dirnames;
  sc_char *name, *compare_name;

  /* Determine the requested room, and filter it down to a plain string. */
  name = pf_filter (var_get_ref_text (vars), vars, bundle);
  pf_strip_tags (name);
  sc_normalize_string (sc_trim_string (name));

  /* Bypass any prefix on the request room name. */
  if (sc_compare_word (name, "a"))
    compare_name = name + 1;
  else if (sc_compare_word (name, "an"))
    compare_name = name + 2;
  else if (sc_compare_word (name, "the"))
    compare_name = name + 3;
  else
    compare_name = name;
  sc_trim_string (compare_name);

  /* See if the named room is the current player room. */
  if (lib_compare_rooms (game, gs_playerroom (game), compare_name))
    {
      pf_buffer_string (filter, "You are already there!\n");
      sc_free (name);
      return TRUE;
    }

  /* Decide on four or eight point compass names list. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "EightPointCompass";
  eightpointcompass = prop_get_boolean (bundle, "B<-ss", vt_key);
  dirnames = eightpointcompass ? DIRNAMES_8 : DIRNAMES_4;

  /* Search adjacent and available rooms for a name match. */
  is_trapped = TRUE;
  is_ambiguous = FALSE;
  direction = -1;
  for (index_ = 0; dirnames[index_]; index_++)
    {
      vt_key[0].string = "Rooms";
      vt_key[1].integer = gs_playerroom (game);
      vt_key[2].string = "Exits";
      vt_key[3].integer = index_;
      if (prop_get (bundle, "I<-sisi", &vt_rvalue, vt_key)
          && lib_can_go (game, gs_playerroom (game), index_))
        {
          is_trapped = FALSE;

          /* Room is available; compare its name with that requested. */
          vt_key[4].string = "Dest";
          if (prop_get (bundle, "I<-sisis", &vt_rvalue, vt_key))
            {
              sc_int destination;

              destination = vt_rvalue.integer - 1;
              if (lib_compare_rooms (game, destination, compare_name))
                {
                  if (direction != -1)
                    is_ambiguous = TRUE;
                  direction = index_;
                }
            }
        }
    }
  sc_free (name);

  /* If trapped or it's unclear where to go, handle these cases. */
  if (is_trapped)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                      "You can't go in any direction!\n",
                                      "I can't go in any direction!\n",
                                      "%player% can't go in any direction!\n"));
      return TRUE;
    }
  else if (is_ambiguous)
    {
      pf_buffer_string (filter,
                        "I'm not clear about where you want to go."
                        "  Please try using just a direction.\n");
      pf_buffer_character (filter, '\n');
      lib_cmd_print_room_exits (game);
      return TRUE;
     }

  /* If no match, note it, otherwise handle as standard directional move. */
  if (direction == -1)
    {
      pf_buffer_string (filter, "I don't know how to get there from here.\n");
      pf_buffer_character (filter, '\n');
      lib_cmd_print_room_exits (game);
      return TRUE;
    }

  return lib_go (game, direction);
}


/*
 * lib_cmd_examine_self()
 *
 * Show the long description of a player.
 */
sc_bool
lib_cmd_examine_self (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[2];
  sc_int task, object, count, trail;
  const sc_char *description, *position = NULL;

  /* Get selection task. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "Task";
  task = prop_get_integer (bundle, "I<-ss", vt_key) - 1;

  /* Select either the main or the alternate description. */
  if (task >= 0 && gs_task_done (game, task))
    vt_key[1].string = "AltDesc";
  else
    vt_key[1].string = "PlayerDesc";

  /* Print the description, or default response. */
  description = prop_get_string (bundle, "S<-ss", vt_key);
  if (!sc_strempty (description))
    pf_buffer_string (filter, description);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                       "You are as well as can be expected,"
                                       " considering the circumstances.",
                                       "I am as well as can be expected,"
                                       " considering the circumstances.",
                                       "%player% is as well as can be expected,"
                                       " considering the circumstances."));
    }

  /* If not just standing on the floor, say more. */
  switch (gs_playerposition (game))
    {
    case 0:
      position = lib_select_response (game,
                                      "You are standing",
                                      "I am standing",
                                      "%player% is standing");
      break;
    case 1:
      position = lib_select_response (game,
                                      "You are sitting down",
                                      "I am sitting down",
                                      "%player% is sitting down");
      break;
    case 2:
      position = lib_select_response (game,
                                      "You are lying down",
                                      "I am lying down",
                                      "%player% is lying down");
      break;
    }

  if (position
      && !(gs_playerposition (game) == 0 && gs_playerparent (game) == -1))
    {
      pf_buffer_string (filter, "  ");
      pf_buffer_string (filter, position);
      if (gs_playerparent (game) != -1)
        {
          pf_buffer_string (filter, " on ");
          lib_print_object_np (game, gs_playerparent (game));
        }
      pf_buffer_character (filter, '.');
    }

  /* Find and list each object worn by the player. */
  count = 0;
  trail = -1;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (gs_object_position (game, object) == OBJ_WORN_PLAYER)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  pf_buffer_string (filter,
                                    lib_select_response (game,
                                                     "  You are wearing ",
                                                     "  I am wearing ",
                                                     "  %player% is wearing "));
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "  You are wearing ",
                                                 "  I am wearing ",
                                                 "  %player% is wearing "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object (game, trail);
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_disambiguate_npc()
 *
 * Filter, then search the set of NPC matches.  If only one matched, note
 * and return it.  If multiple matched, print a disambiguation message and
 * the list, and return -1 with *is_ambiguous TRUE.  If none matched, return
 * -1 with *is_ambiguous FALSE if requested, otherwise print a message then
 * return -1.
 */
static sc_int
lib_disambiguate_npc (sc_gameref_t game,
                      const sc_char *verb, sc_bool *is_ambiguous)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int count, index_, npc, listed;

  /*
   * Filter out all referenced NPCs not actually visible or seen.  Count the
   * number of NPCs remaining as referenced by the last command, and note the
   * last referenced NPC, for where count is 1.
   */
  count = 0;
  npc = -1;
  for (index_ = 0; index_ < gs_npc_count (game); index_++)
    {
      if (game->npc_references[index_]
          && gs_npc_seen (game, index_)
          && npc_in_room (game, index_, gs_playerroom (game)))
        {
          count++;
          npc = index_;
        }
      else
        game->npc_references[index_] = FALSE;
    }

  /* If the reference is unambiguous, set in variables and return it. */
  if (count == 1)
    {
      /* Set this NPC as the referenced character. */
      var_set_ref_character (vars, npc);

      /* Return, setting no ambiguity. */
      if (is_ambiguous)
        *is_ambiguous = FALSE;
      return npc;
    }

  /* If nothing referenced, return no NPC. */
  if (count == 0)
    {
      if (is_ambiguous)
        *is_ambiguous = FALSE;
      else
        {
          pf_buffer_string (filter,
                            "Please be more clear, who do you want to ");
          pf_buffer_string (filter, verb);
          pf_buffer_string (filter, "?\n");
        }
      return -1;
    }

  /* The NPC reference is ambiguous, so list the choices. */
  pf_buffer_string (filter, "Please be more clear, who do you want to ");
  pf_buffer_string (filter, verb);
  pf_buffer_string (filter, "?  ");

  pf_new_sentence (filter);
  listed = 0;
  for (index_ = 0; index_ < gs_npc_count (game); index_++)
    {
      if (game->npc_references[index_])
        {
          lib_print_npc_np (game, index_);
          listed++;
          if (listed < count)
            pf_buffer_string (filter, (listed < count - 1) ? ", " : " or ");
        }
    }
  pf_buffer_string (filter, "?\n");

  /* Return no NPC for an ambiguous reference. */
  if (is_ambiguous)
    *is_ambiguous = TRUE;
  return -1;
}


/*
 * lib_disambiguate_object_common()
 * lib_disambiguate_object()
 * lib_disambiguate_object_extended()
 *
 * Filter, then search the set of object matches.  If only one matched, note
 * and return it.  If multiple matched, print a disambiguation message and
 * the list, and return -1 with *is_ambiguous TRUE.  If none matched, return
 * -1 with *is_ambiguous FALSE if requested, otherwise print a message then
 * return -1.
 *
 * Extended disambiguation operates as normal disambiguation, except that if
 * normal disambiguation returns more than one object, the resolver function,
 * if supplied, is used to see if the multiple objects can be resolved into
 * just one object.  The resolver function can normally be the same as the
 * function used to filter objects for multiple references.
 */
static sc_int
lib_disambiguate_object_common (sc_gameref_t game, const sc_char *verb,
                               sc_bool (*resolver)
                                   (sc_gameref_t, sc_int, sc_int),
                               sc_int resolver_arg,
                               sc_bool *is_ambiguous)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int count, index_, object, listed;

  /*
   * Filter out all referenced objects not actually visible or seen.  Count
   * the number of objects remaining as referenced by the last command, and
   * note the last referenced object, for where count is 1.
   */
  count = 0;
  object = -1;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (game->object_references[index_]
          && gs_object_seen (game, index_)
          && obj_indirectly_in_room (game, index_, gs_playerroom (game)))
        {
          count++;
          object = index_;
        }
      else
        game->object_references[index_] = FALSE;
    }

  /*
   * If this reference is ambiguous and a resolver was supplied, try to
   * resolve it unambiguously by calling the resolver filter on the remaining
   * set references.
   */
  if (resolver && count > 1)
    {
      sc_int retry_count;

      /*
       * Search for objects accepted by the resolver filter, but don't filter
       * references just yet.  Again, note the last referenced.
       */
      retry_count = 0;
      object = -1;
      for (index_ = 0; index_ < gs_object_count (game); index_++)
        {
          if (game->object_references[index_]
              && resolver (game, index_, resolver_arg))
            {
              retry_count++;
              object = index_;
            }
        }

      /* See if we narrowed the field without eliminating every object. */
      if (retry_count > 0 && retry_count < count)
        {
          /*
           * If we got down to a single object, the ambiguity is resolved.
           * In this case, set count to 1 so that 'object' is returned.
           */
          if (retry_count == 1)
            count = retry_count;
          else
            {
              /*
               * We got down to fewer objects; reduce references so that the
               * disambiguation message is clearer.  Note that here we still
               * leave with count greater than 1.
               */
              count = 0;
              for (index_ = 0; index_ < gs_object_count (game); index_++)
                {
                  if (game->object_references[index_]
                      && resolver (game, index_, resolver_arg))
                    count++;
                  else
                    game->object_references[index_] = FALSE;
                }
            }
        }
    }

  /* If the reference is unambiguous, set in variables and return it. */
  if (count == 1)
    {
      /* Set this object as referenced. */
      var_set_ref_object (vars, object);

      /* Return, setting no ambiguity. */
      if (is_ambiguous)
        *is_ambiguous = FALSE;
      return object;
    }

  /* If nothing referenced, return no object. */
  if (count == 0)
    {
      if (is_ambiguous)
        *is_ambiguous = FALSE;
      else
        {
          pf_buffer_string (filter,
                            "Please be more clear, what do you want to ");
          pf_buffer_string (filter, verb);
          pf_buffer_string (filter, "?\n");
        }
      return -1;
    }

  /* The object reference is ambiguous, so list the choices. */
  pf_buffer_string (filter, "Please be more clear, what do you want to ");
  pf_buffer_string (filter, verb);
  pf_buffer_string (filter, "?  ");

  pf_new_sentence (filter);
  listed = 0;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (game->object_references[index_])
        {
          lib_print_object_np (game, index_);
          listed++;
          if (listed < count)
            pf_buffer_string (filter, (listed < count - 1) ? ", " : " or ");
        }
    }
  pf_buffer_string (filter, "?\n");

  /* Return no object for an ambiguous reference. */
  if (is_ambiguous)
    *is_ambiguous = TRUE;
  return -1;
}

static sc_int
lib_disambiguate_object (sc_gameref_t game,
                         const sc_char *verb, sc_bool *is_ambiguous)
{
  return lib_disambiguate_object_common (game, verb, NULL, -1, is_ambiguous);
}

static sc_int
lib_disambiguate_object_extended (sc_gameref_t game, const sc_char *verb,
                                  sc_bool (*resolver)
                                      (sc_gameref_t, sc_int, sc_int),
                                  sc_int resolver_arg,
                                  sc_bool *is_ambiguous)
{
  return lib_disambiguate_object_common (game, verb,
                                         resolver, resolver_arg, is_ambiguous);
}


/*
 * lib_list_npc_inventory()
 *
 * List objects carried and worn by an NPC.
 */
static sc_bool
lib_list_npc_inventory (sc_gameref_t game, sc_int npc, sc_bool is_described)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, count, trail;
  sc_bool wearing;

  /* Find and list each object worn by the NPC. */
  count = 0;
  trail = -1;
  wearing = FALSE;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (gs_object_position (game, object) == OBJ_WORN_NPC
          && gs_object_parent (game, object) == npc)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  if (is_described)
                    pf_buffer_string (filter, "  ");
                  pf_new_sentence (filter);
                  lib_print_npc_np (game, npc);
                  pf_buffer_string (filter, " is wearing ");
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          if (is_described)
            pf_buffer_string (filter, "  ");
          pf_new_sentence (filter);
          lib_print_npc_np (game, npc);
          pf_buffer_string (filter, " is wearing ");
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object (game, trail);
      wearing = TRUE;
    }

  /* Find and list each object owned by the NPC. */
  count = 0;
  trail = -1;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (gs_object_position (game, object) == OBJ_HELD_NPC
          && gs_object_parent (game, object) == npc)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  if (!wearing)
                    {
                      if (is_described)
                        pf_buffer_string (filter, "  ");
                      pf_new_sentence (filter);
                      lib_print_npc_np (game, npc);
                    }
                  else
                    pf_buffer_string (filter, ", and");
                  pf_buffer_string (filter, " is carrying ");
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          if (!wearing)
            {
              if (is_described)
                pf_buffer_string (filter, "  ");
              pf_new_sentence (filter);
              lib_print_npc_np (game, npc);
            }
          else
            pf_buffer_string (filter, ", and");
          pf_buffer_string (filter, " is carrying ");
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object (game, trail);
      pf_buffer_character (filter, '.');
    }
  else
    {
      if (wearing)
        pf_buffer_character (filter, '.');
    }

  /* Return TRUE if anything worn or carried. */
  return wearing || count > 0;
}


/*
 * lib_cmd_examine_npc()
 *
 * Show the long description of the most recently referenced NPC, and a
 * list of what they're wearing and carrying.
 */
sc_bool
lib_cmd_examine_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[4];
  sc_int npc, task, resource;
  sc_bool is_ambiguous;
  const sc_char *description;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "examine", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  /* Get selection task. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Task";
  task = prop_get_integer (bundle, "I<-sis", vt_key) - 1;

  /* Select either the main or the alternate description. */
  if (task >= 0 && gs_task_done (game, task))
    {
      vt_key[2].string = "AltText";
      resource = 1;
    }
  else
    {
      vt_key[2].string = "Descr";
      resource = 0;
    }

  /* Print the description, or a default message if none. */
  description = prop_get_string (bundle, "S<-sis", vt_key);
  if (!sc_strempty (description))
    pf_buffer_string (filter, description);
  else
    {
      pf_buffer_string (filter, "There's nothing special about ");
      lib_print_npc_np (game, npc);
      pf_buffer_character (filter, '.');
    }

  /* Handle any associated resource. */
  vt_key[2].string = "Res";
  vt_key[3].integer = resource;
  res_handle_resource (game, "sisi", vt_key);

  /* Print what the NPC is wearing and carrying. */
  lib_list_npc_inventory (game, npc, TRUE);

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_list_in_object_normal()
 *
 * List the objects in a given container object, normal format listing.
 */
static sc_bool
lib_list_in_object_normal (sc_gameref_t game,
                           sc_int container, sc_bool is_described)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, count, trail;

  /* List out the containers contained in this container. */
  count = 0;
  trail = -1;
  for (object = 0; object < gs_object_count (game); object++)
    {
      /* Contained? */
      if (gs_object_position (game, object) == OBJ_IN_OBJECT
          && gs_object_parent (game, object) == container)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  if (is_described)
                    pf_buffer_string (filter, "  ");
                  pf_buffer_string (filter, "Inside ");
                  lib_print_object_np (game, container);
                  pf_buffer_string (filter, " is ");
                }
              else
                pf_buffer_string (filter, ", ");

              /* Print out the current list object. */
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          if (is_described)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter, "Inside ");
          lib_print_object_np (game, container);
          pf_buffer_string (filter, " is ");
        }
      else
        pf_buffer_string (filter, " and ");

      /* Print out the final object. */
      lib_print_object (game, trail);
      pf_buffer_character (filter, '.');
    }

  /* Return TRUE if anything listed. */
  return count > 0;
}


/*
 * lib_list_in_object_alternate()
 *
 * List the objects in a given container object, alternate format listing.
 */
static sc_bool
lib_list_in_object_alternate (sc_gameref_t game,
                              sc_int container, sc_bool is_described)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, count, trail;

  /* List out the objects contained in this object. */
  count = 0;
  trail = -1;
  for (object = 0; object < gs_object_count (game); object++)
    {
      /* Contained? */
      if (gs_object_position (game, object) == OBJ_IN_OBJECT
          && gs_object_parent (game, object) == container)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  if (is_described)
                    pf_buffer_string (filter, "  ");
                  pf_new_sentence (filter);
                }
              else
                pf_buffer_string (filter, ", ");

              /* Print out the current list object. */
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          if (is_described)
            pf_buffer_string (filter, "  ");
          pf_new_sentence (filter);
          lib_print_object (game, trail);
          pf_buffer_string (filter,
                            lib_select_plurality (game, trail,
                                                  " is inside ",
                                                  " are inside "));
        }
      else
        {
          pf_buffer_string (filter, " and ");
          lib_print_object (game, trail);
          pf_buffer_string (filter, " are inside ");
        }

      /* Print out the container. */
      lib_print_object_np (game, container);
      pf_buffer_character (filter, '.');
    }

  /* Return TRUE if anything listed. */
  return count > 0;
}


/*
 * lib_list_in_object()
 *
 * List the objects in a given container object.
 *
 * TODO The Adrift Runner has two distinct styles it uses for listing objects
 * within a container, but which it picks at any one point is, frankly, a
 * mystery.  The selection below seems to work with the few games checked for
 * this, and in particular works with the ALR magic in "To Hell in a Hamper",
 * but it's almost certainly wrong.  Or, at minimum, incomplete.
 */
static sc_bool
lib_list_in_object (sc_gameref_t game, sc_int container, sc_bool is_described)
{
  sc_bool use_alternate_format = FALSE;

  /*
   * Switch if the object is static and part of an NPC or the player, or if
   * the count of contained objects in a dynamic container is exactly one.
   */
  if (obj_is_static (game, container))
    {
      sc_int object_position;

      object_position = gs_object_position (game, container);

      if (object_position == OBJ_PART_NPC || object_position == OBJ_PART_PLAYER)
        use_alternate_format = TRUE;
    }
  else
    {
      sc_int object, count;

      count = 0;
      for (object = 0; object < gs_object_count (game); object++)
        {
          if (gs_object_position (game, object) == OBJ_IN_OBJECT
              && gs_object_parent (game, object) == container)
            count++;
          if (count > 1)
            break;
        }

      if (count == 1)
        use_alternate_format = TRUE;
    }

  /* List contained objects using the selected handler. */
  return use_alternate_format
         ? lib_list_in_object_alternate (game, container, is_described)
         : lib_list_in_object_normal (game, container, is_described);
}


/*
 * lib_list_on_object()
 *
 * List the objects on a given surface object.
 */
static sc_bool
lib_list_on_object (sc_gameref_t game, sc_int supporter, sc_bool is_described)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, count, trail;

  /* List out the objects standing on this object. */
  count = 0;
  trail = -1;
  for (object = 0; object < gs_object_count (game); object++)
    {
      /* Standing on? */
      if (gs_object_position (game, object) == OBJ_ON_OBJECT
          && gs_object_parent (game, object) == supporter)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  if (is_described)
                    pf_buffer_string (filter, "  ");
                  pf_new_sentence (filter);
                }
              else
                pf_buffer_string (filter, ", ");

              /* Print out the current list object. */
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          if (is_described)
            pf_buffer_string (filter, "  ");
          pf_new_sentence (filter);
          lib_print_object (game, trail);
          pf_buffer_string (filter,
                            lib_select_plurality (game, trail,
                                                  " is on ",
                                                  " are on "));
        }
      else
        {
          pf_buffer_string (filter, " and ");
          lib_print_object (game, trail);
          pf_buffer_string (filter, " are on ");
        }

      /* Print out the surface. */
      lib_print_object_np (game, supporter);
      pf_buffer_character (filter, '.');
    }

  /* Return TRUE if anything listed. */
  return count > 0;
}


/*
 * lib_list_object_state()
 *
 * Describe the state of a stateful object.
 */
static sc_bool
lib_list_object_state (sc_gameref_t game, sc_int object, sc_bool is_described)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  sc_bool is_statussed;
  sc_char *state;

  /* Get object statefulness. */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "CurrentState";
  is_statussed = prop_get_integer (bundle, "I<-sis", vt_key) != 0;

  /* Ensure this is a stateful object. */
  if (is_statussed)
    {
      if (is_described)
        pf_buffer_string (filter, "  ");
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object, " is ", " are "));

      /* Add object state string. */
      state = obj_state_name (game, object);
      if (state)
        {
          pf_buffer_string (filter, state);
          sc_free (state);
          pf_buffer_string (filter, ".");
        }
      else
        {
          sc_error ("lib_list_object_state: invalid object state\n");
          pf_buffer_string (filter, "[invalid state].");
        }
    }

  /* Return TRUE if a state was printed. */
  return is_statussed;
}


/*
 * lib_cmd_examine_object()
 *
 * Show the long description of the most recently referenced object.
 */
sc_bool
lib_cmd_examine_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  sc_int object, task, openness;
  sc_bool is_described, is_statussed, is_mentioned, is_ambiguous, should_be;
  const sc_char *description, *resource;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "examine", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Begin assuming no description printed. */
  is_described = FALSE;

  /*
   * Get selection task and expected state; for the expected task state, FALSE
   * indicates task completed, TRUE not completed.
   */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Task";
  task = prop_get_integer (bundle, "I<-sis", vt_key) - 1;
  vt_key[2].string = "TaskNotDone";
  should_be = !prop_get_boolean (bundle, "B<-sis", vt_key);

  /* Select either the main or the alternate description. */
  if (task >= 0 && gs_task_done (game, task) == should_be)
    {
      vt_key[2].string = "AltDesc";
      resource = "Res2";
    }
  else
    {
      vt_key[2].string = "Description";
      resource = "Res1";
    }

  /* Print the description, or a default response. */
  description = prop_get_string (bundle, "S<-sis", vt_key);
  if (!sc_strempty (description))
    {
      pf_buffer_string (filter, description);
      is_described |= TRUE;
    }

  /* Handle any associated resource. */
  vt_key[2].string = resource;
  res_handle_resource (game, "sis", vt_key);

  /* If the object is openable, print its openness state. */
  openness = gs_object_openness (game, object);
  switch (openness)
    {
    case OBJ_OPEN:
      if (is_described)
        pf_buffer_string (filter, "  ");
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is open.", " are open."));
      is_described |= TRUE;
      break;

    case OBJ_CLOSED:
      if (is_described)
        pf_buffer_string (filter, "  ");
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is closed.", " are closed."));
      is_described |= TRUE;
      break;

    case OBJ_LOCKED:
      if (is_described)
        pf_buffer_string (filter, "  ");
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is locked.", " are locked."));
      is_described |= TRUE;
      break;

    default:
      break;
    }

  /* Add any extra details for stateful objects. */
  vt_key[1].integer = object;
  vt_key[2].string = "CurrentState";
  is_statussed = prop_get_integer (bundle, "I<-sis", vt_key) != 0;
  if (is_statussed)
    {
      vt_key[2].string = "StateListed";
      is_mentioned = prop_get_boolean (bundle, "B<-sis", vt_key);
      if (is_mentioned)
        {
          is_described |= lib_list_object_state (game, object, is_described);
        }
    }

  /* For open container objects, list out what's in them. */
  if (obj_is_container (game, object) && openness <= OBJ_OPEN)
    {
      is_described |= lib_list_in_object (game, object, is_described);
    }

  /* For surface objects, list out what's on them. */
  if (obj_is_surface (game, object))
    {
      is_described |= lib_list_on_object (game, object, is_described);
    }

  /* If nothing yet said, print a default response. */
  if (!is_described)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                       "You see nothing special about ",
                                       "I see nothing special about ",
                                       "%player% sees nothing special about "));
      lib_print_object_np (game, object);
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_save_game_references()
 * lib_restore_game_references()
 *
 * Helpers for trying game commands.  Save and restore game references
 * so that parsing game commands doesn't interfere with backend loops that
 * are working through game references set by prior commands.  Saving
 * references uses the buffer passed in if possible, otherwise allocates
 * its own buffer; testing the return value shows which happened.
 */
static sc_bool *
lib_save_object_references (sc_gameref_t game, sc_bool buffer[], sc_int length)
{
  sc_int required, available;
  sc_bool *references;

  /*
   * Calculate the required bytes for references, and then either allocate or
   * use the buffer supplied.
   */
  required = gs_object_count (game) * sizeof (*references);
  available = length * sizeof (buffer[0]);
  references = required > available ? sc_malloc (required) : buffer;

  /* Copy over references from the game, and return the saved copy. */
  memcpy (references, game->object_references, required);
  return references;
}

static void
lib_restore_object_references (sc_gameref_t game, const sc_bool references[])
{
  sc_int bytes;

  /* Calculate the bytes in the references array, and copy back to the game. */
  bytes = gs_object_count (game) * sizeof (references[0]);
  memcpy (game->object_references, references, bytes);
}


/*
 * lib_try_game_command_common()
 * lib_try_game_command_short()
 * lib_try_game_command_with_object()
 * lib_try_game_command_with_npc()
 *
 * Try a game command with a standard verb.  Used by get and drop handlers
 * to retry game commands using standard "get " and "drop " commands.  This
 * makes "take/pick up/put down" work with a game's overridden get/drop.
 */
static sc_bool
lib_try_game_command_common (sc_gameref_t game,
                             const sc_char *verb, sc_int object,
                             const sc_char *preposition,
                             sc_int associate,
                             sc_bool is_associate_object,
                             sc_bool is_associate_npc)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  sc_char buffer[LIB_ALLOCATION_AVOIDANCE_SIZE];
  sc_bool references_buffer[LIB_ALLOCATION_AVOIDANCE_SIZE];
  const sc_char *prefix, *name;
  sc_char *command;
  sc_bool *references, status;
  assert (!is_associate_object || !is_associate_npc);

  /* Save the game's references, for restore later on. */
  references = lib_save_object_references (game, references_buffer,
                                           LIB_ALLOCATION_AVOIDANCE_SIZE);

  /* Get the addressed object's prefix and main name. */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Prefix";
  prefix = prop_get_string (bundle, "S<-sis", vt_key);
  vt_key[2].string = "Short";
  name = prop_get_string (bundle, "S<-sis", vt_key);

  /* Construct and try for game commands with a standard verb. */
  if (is_associate_object || is_associate_npc)
    {
      const sc_char *associate_prefix, *associate_name;
      sc_int required;

      /* Get the associate's prefix and main name. */
      if (is_associate_object)
        {
          vt_key[0].string = "Objects";
          vt_key[1].integer = associate;
          vt_key[2].string = "Prefix";
          associate_prefix = prop_get_string (bundle, "S<-sis", vt_key);
          vt_key[2].string = "Short";
          associate_name = prop_get_string (bundle, "S<-sis", vt_key);
        }
      else
        {
          assert (is_associate_npc);
          vt_key[0].string = "NPCs";
          vt_key[1].integer = associate;
          vt_key[2].string = "Prefix";
          associate_prefix = prop_get_string (bundle, "S<-sis", vt_key);
          vt_key[2].string = "Name";
          associate_name = prop_get_string (bundle, "S<-sis", vt_key);
        }

      assert (preposition);
      required = strlen (verb) + strlen (prefix) + strlen (name)
                 + strlen (preposition) + strlen (associate_prefix)
                 + strlen (associate_name) + 6;
      command = required > (sc_int) sizeof (buffer)
                ? sc_malloc (required) : buffer;

      /*
       * Try the command with and without prefixes on both the target object
       * and the associate.
       */
      sprintf (command, "%s %s %s %s %s %s", verb,
               prefix, name, preposition, associate_prefix, associate_name);
      status = run_game_task_commands (game, command);
      if (!status)
        {
          sprintf (command, "%s %s %s %s %s",
                   verb, prefix, name, preposition, associate_name);
          status = run_game_task_commands (game, command);
        }
      if (!status)
        {
          sprintf (command, "%s %s %s %s %s",
                   verb, name, preposition, associate_prefix, associate_name);
          status = run_game_task_commands (game, command);
        }
      if (!status)
        {
          sprintf (command, "%s %s %s %s",
                   verb, name, preposition, associate_name);
          status = run_game_task_commands (game, command);
        }
    }
  else
    {
      sc_int required;

      required = strlen (verb) + strlen (prefix) + strlen (name) + 3;
      command = required > (sc_int) sizeof (buffer)
                ? sc_malloc (required) : buffer;

      /* Try the command with and without prefixes on the addressed object. */
      sprintf (command, "%s %s %s", verb, prefix, name);
      status = run_game_task_commands (game, command);
      if (!status)
        {
          sprintf (command, "%s %s", verb, name);
          status = run_game_task_commands (game, command);
        }
    }

  /* Restore the game object references back to their state on entry. */
  lib_restore_object_references (game, references);

  /* Free any allocations, and return the game command status. */
  if (command != buffer)
    sc_free (command);
  if (references != references_buffer)
    sc_free (references);
  return status;
}

static sc_bool
lib_try_game_command_short (sc_gameref_t game,
                            const sc_char *verb, sc_int object)
{
  return lib_try_game_command_common (game, verb, object,
                                      NULL, -1, FALSE, FALSE);
}

static sc_bool
lib_try_game_command_with_object (sc_gameref_t game,
                                  const sc_char *verb, sc_int object,
                                  const sc_char *preposition,
                                  sc_int other_object)
{
  return lib_try_game_command_common (game, verb, object,
                                      preposition, other_object, TRUE, FALSE);
}

static sc_bool
lib_try_game_command_with_npc (sc_gameref_t game,
                               const sc_char *verb, sc_int object,
                               const sc_char *preposition, sc_int npc)
{
  return lib_try_game_command_common (game, verb, object,
                                      preposition, npc, FALSE, TRUE);
}


/*
 * lib_parse_next_object()
 *
 * Helper for lib_parse_multiple_objects().  Extracts the next object, if any,
 * from referenced text, and returns it.  Disambiguates any ambiguous objects
 * using the verb supplied, and sets are_more_objects if we found an object
 * but there appear to be more following it.
 */
static sc_bool
lib_parse_next_object (sc_gameref_t game, const sc_char *verb,
                       sc_bool (*resolver) (sc_gameref_t, sc_int, sc_int),
                       sc_int resolver_arg,
                       sc_int *object,
                       sc_bool *are_more_objects, sc_bool *is_ambiguous)
{
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_char *list;
  sc_bool is_matched;

  /* Look for "object" or "object and ...", and set match and more flags. */
  list = var_get_ref_text (vars);
  if (uip_match ("%object%", list, game))
    {
      *are_more_objects = FALSE;
      is_matched = TRUE;
    }
  else if (uip_match ("%object% and %text%", list, game))
    {
      *are_more_objects = TRUE;
      is_matched = TRUE;
    }
  else
    is_matched = FALSE;

  /* If we extracted an object from referenced text, disambiguate. */
  if (is_matched)
    *object = lib_disambiguate_object_extended (game, verb,
                                                resolver, resolver_arg,
                                                is_ambiguous);
  else
    *is_ambiguous = FALSE;

  /* Return TRUE if we matched anything. */
  return is_matched;
}


/*
 * lib_parse_multiple_objects()
 *
 * Parser for commands that take multiple object targets from a %text% match.
 * Parses object lists such as "object" and "object and object" and returns
 * the multiple objects in the game's multiple_references.
 */
static sc_bool
lib_parse_multiple_objects (sc_gameref_t game, const sc_char *verb,
                            sc_bool (*resolver) (sc_gameref_t, sc_int, sc_int),
                            sc_int resolver_arg,
                            sc_int *count)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int count_, object;
  sc_bool are_more_objects, is_ambiguous;

  /* Initialize variables to avoid gcc warnings. */
  object = -1;
  are_more_objects = FALSE;

  /* Clear all current multiple object references, and the count. */
  gs_clear_multiple_references (game);
  count_ = 0;

  /*
   * Parse the first object from the list.  If we get nothing here, return
   * FALSE if it didn't look like a multiple object list, TRUE if ambiguous.
   * Beyond here, we always return TRUE, since after this point _something_
   * looked believable...
   */
  if (!lib_parse_next_object (game, verb,
                              resolver, resolver_arg,
                              &object, &are_more_objects, &is_ambiguous))
    return FALSE;
  else if (object == -1)
    {
      if (is_ambiguous)
        {
          /*
           * Return TRUE, with zero count, to cause caller to return.  We get
           * here if the first parsed object was ambiguous.  In this case,
           * the disambiguation has printed a message, so we want our caller
           * to simply return TRUE to indicate that the command was handled,
           * albeit not fully successfully.
           */
          *count = count_;
          return TRUE;
        }
      else
        /*
         * No object matched after disambiguation, so return FALSE to have
         * our caller ignore the command.
         */
        return FALSE;
    }

  /* Mark this first object as referenced in the return array. */
  game->multiple_references[object] = TRUE;
  count_++;

  /* Now parse each additional object from the list. */
  while (are_more_objects)
    {
      sc_int last_object;

      /*
       * If no next object, leave the loop.  If no disambiguation message
       * then it was probably garble, so print a message for that case.  We
       * also catch repeated objects here.
       */
      last_object = object;
      if (!lib_parse_next_object (game, verb,
                                  resolver, resolver_arg,
                                  &object, &are_more_objects, &is_ambiguous)
          || object == -1
          || game->multiple_references[object])
        {
          if (!is_ambiguous)
            {
              pf_buffer_string (filter,
                                "I only understood you as far as wanting to ");
              pf_buffer_string (filter, verb);
              pf_buffer_character (filter, ' ');
              lib_print_object_np (game, last_object);
              pf_buffer_string (filter, ".\n");
            }

          /* Zero count to indicate an error somewhere in the list. */
          count_ = 0;
          break;
        }

      /* Mark the object as referenced in the return array. */
      game->multiple_references[object] = TRUE;
      count_++;
    }

  /* We found at least enough of an object list to say we matched. */
  *count = count_;
  return TRUE;
}


/*
 * lib_apply_multiple_filter()
 * lib_apply_except_filter()
 *
 * Apply filters for multiple object frontends.  Transfer multiple object
 * references into standard object references, using the supplied filter.
 * The first is inclusive, the second exclusive.
 */
static sc_int
lib_apply_multiple_filter (sc_gameref_t game,
                           sc_bool (*filter) (sc_gameref_t, sc_int, sc_int),
                           sc_int filter_arg, sc_int *references)
{
  sc_int count, object, references_;

  /* Clear all object references initially. */
  gs_clear_object_references (game);

  /*
   * Find objects included by the filter, and transfer the reference of each
   * from the multiple references into standard references.
   */
  count = 0;
  references_ = references ? *references : 0;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (filter (game, object, filter_arg))
        {
          /* Transfer the reference. */
          if (game->multiple_references[object])
            {
              game->object_references[object] = TRUE;
              count++;
              game->multiple_references[object] = FALSE;
              references_--;
            }
        }
    }

  /* Copy back the updated reference count, return count. */
  if (references)
    *references = references_;
  return count;
}

static sc_int
lib_apply_except_filter (sc_gameref_t game,
                         sc_bool (*filter) (sc_gameref_t, sc_int, sc_int),
                         sc_int filter_arg, sc_int *references)
{
  sc_int count, object, references_;

  /* Clear all object references initially. */
  gs_clear_object_references (game);

  /*
   * Find objects included by the filter, and transfer the reference of each
   * from the multiple references into standard references.
   */
  count = 0;
  references_ = references ? *references : 0;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (filter (game, object, filter_arg))
        {
          /* If excepted, remove from exceptions, else add to references. */
          if (game->multiple_references[object])
            {
              game->multiple_references[object] = FALSE;
              references_--;
            }
          else
            {
              game->object_references[object] = TRUE;
              count++;
            }
        }
    }

  /* Copy back the updated reference count, return count. */
  if (references)
    *references = references_;
  return count;
}


/*
 * lib_cmd_count()
 *
 * Display player weight and size limits and amounts currently carried.
 */
sc_bool
lib_cmd_count (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int index_, size, weight;
  sc_char buffer[32];

  /* Sum sizes for objects currently held or worn by player. */
  size = 0;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (gs_object_position (game, index_) == OBJ_HELD_PLAYER
          || gs_object_position (game, index_) == OBJ_WORN_PLAYER)
        size += obj_get_size (game, index_);
    }

  /* Sum weights for objects currently held or worn by player. */
  weight = 0;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (gs_object_position (game, index_) == OBJ_HELD_PLAYER
          || gs_object_position (game, index_) == OBJ_WORN_PLAYER)
        weight += obj_get_weight (game, index_);
    }

  /* Print the player limits and amounts used. */
  pf_buffer_string (filter, "Size:    You have ");
  sprintf (buffer, "%ld", size);
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, ".  The most you can hold is ");
  sprintf (buffer, "%ld", obj_get_player_size_limit (game));
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, ".\n");

  pf_buffer_string (filter, "Weight:  You have ");
  sprintf (buffer, "%ld", weight);
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, ".  The most you can hold is ");
  sprintf (buffer, "%ld", obj_get_player_weight_limit (game));
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, ".\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_object_too_heavy()
 *
 * Return TRUE if the given object is too heavy for the player to carry.
 */
static sc_bool
lib_object_too_heavy (sc_gameref_t game, sc_int object, sc_bool *is_portable)
{
  sc_int player_limit, index_, weight, object_weight;

  /* Get the player limit and the given object weight. */
  player_limit = obj_get_player_weight_limit (game);
  object_weight = obj_get_weight (game, object);

  /* Sum weights for objects currently held or worn by player. */
  weight = 0;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (gs_object_position (game, index_) == OBJ_HELD_PLAYER
          || gs_object_position (game, index_) == OBJ_WORN_PLAYER)
        weight += obj_get_weight (game, index_);
    }

  /* If requested, return object portability. */
  if (is_portable)
    *is_portable = !(object_weight > player_limit);

  /* Return TRUE if the new object exceeds limit. */
  return weight + object_weight > player_limit;
}


/*
 * lib_object_too_large()
 *
 * Return TRUE if the given object is too large for the player to carry.
 */
static sc_bool
lib_object_too_large (sc_gameref_t game, sc_int object, sc_bool *is_portable)
{
  sc_int player_limit, index_, size, object_size;

  /* Get the player limit and the given object size. */
  player_limit = obj_get_player_size_limit (game);
  object_size = obj_get_size (game, object);

  /* Sum sizes for objects currently held or worn by player. */
  size = 0;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (gs_object_position (game, index_) == OBJ_HELD_PLAYER
          || gs_object_position (game, index_) == OBJ_WORN_PLAYER)
        size += obj_get_size (game, index_);
    }

  /* If requested, return object portability. */
  if (is_portable)
    *is_portable = !(object_size > player_limit);

  /* Return TRUE if the new object exceeds limit. */
  return size + object_size > player_limit;
}


/*
 * lib_cmd_take_npc()
 *
 * Reject attempts to take an npc.
 */
sc_bool
lib_cmd_take_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int npc;
  sc_bool is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "take", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  pf_buffer_string (filter, "I don't think ");
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter, " would appreciate being handled.\n");
  return TRUE;
}


/*
 * lib_take_backend_common()
 *
 * Common backend handler for taking objects.  Takes all objects currently
 * referenced in the game, trying game commands first, and then moving other
 * unhandled objects to the player inventory.
 *
 * Objects to action are flagged in object_references; objects requested but
 * deemed not actionable are flagged in multiple_references.
 */
static void
lib_take_backend_common (sc_gameref_t game, sc_int associate,
                         sc_bool is_associate_object, sc_bool is_associate_npc)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object_count, object, count, trail, total, npc;
  sc_int too_heavy, too_large;
  sc_bool too_heavy_portable, too_large_portable, has_printed;
  assert (!is_associate_object || !is_associate_npc);

  /* Initialize our notions of anything exceeding player capacity. */
  too_heavy_portable = too_large_portable = FALSE;
  too_large = too_heavy = -1;

  /*
   * Try game commands for all referenced objects first.  If any succeed,
   * remove that reference from the list.  At the same time, filter out and
   * flag any object that takes us over the player's capacity.  We report
   * only the first.
   */
  has_printed = FALSE;
  object_count = gs_object_count (game);
  for (object = 0; object < object_count; object++)
    {
      sc_bool status;

      if (!game->object_references[object])
        continue;

      /*
       * If the object is inside or on something already held by the player,
       * capacity checks are meaningless.
       */
      if (!((gs_object_position (game, object) == OBJ_IN_OBJECT
            || gs_object_position (game, object) == OBJ_ON_OBJECT)
            && obj_indirectly_held_by_player (game,
                                              gs_object_parent (game, object))))
        {
          sc_bool is_portable;

          /*
           * See if the object takes us beyond capacity.  If it does and it's
           * the first of its kind, note it and continue.
           */
          if (lib_object_too_heavy (game, object, &is_portable))
            {
              if (too_heavy == -1)
                {
                  too_heavy = object;
                  too_heavy_portable = is_portable;
                }
              game->object_references[object] = FALSE;
              continue;
            }
          if (lib_object_too_large (game, object, &is_portable))
            {
              if (too_large == -1)
                {
                  too_large = object;
                  too_large_portable = is_portable;
                }
              game->object_references[object] = FALSE;
              continue;
            }
        }

      /* Now try for a game command, using the associate if supplied. */
      if (is_associate_object)
        status = lib_try_game_command_with_object (game, "get",
                                                   object, "from", associate);
      else if (is_associate_npc)
        status = lib_try_game_command_with_npc (game, "get",
                                                object, "from", associate);
      else
        status = lib_try_game_command_short (game, "get", object);
      if (status)
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
        }
    }

  /*
   * We attempt acquisition of get-able objects here only for cases where
   * there is either no associate, or where the associate is an object.  If
   * the associate is an NPC, we're going to refuse all acquisitions later
   * on, by forcing object references.
   */
  total = 0;
  if (!is_associate_npc)
    {
      sc_int parent, start, limit;

      /*
       * Attempt to acquire each remaining get-able object in turn, looping 
       * on each possible parent object in turn, with an initial parent of
       * -1 for objects not contained or supported.
       *
       * If we're dealing with only objects from a known container or
       * supporter, eliminate all but one iteration of the parent search.
       */
      start = is_associate_object ? associate : -1;
      limit = is_associate_object ? associate : object_count - 1;

      for (parent = start; parent <= limit; parent++)
        {
          count = 0;
          trail = -1;
          for (object = 0; object < object_count; object++)
            {
              sc_bool is_portable;

              if (!game->object_references[object])
                continue;

              /*
               * If parent is -1, ignore contained objects, otherwise ignore
               * objects not contained, or if contained, not contained by the
               * current parent.
               */
              if (parent == -1)
                {
                  if (gs_object_position (game, object) == OBJ_IN_OBJECT
                      || gs_object_position (game, object) == OBJ_ON_OBJECT)
                    continue;
                }
              else
                {
                  if (!(gs_object_position (game, object) == OBJ_IN_OBJECT
                        || gs_object_position (game, object) == OBJ_ON_OBJECT))
                    continue;
                  if (gs_object_parent (game, object) != parent)
                    continue;
                }

              /*
               * Here we have to repeat capacity checks.  As objects are
               * acquired more and more of the player's capacity gets used up.
               * This means a check directly before each acquisition.
               */
               if (parent == -1
                   || !obj_indirectly_held_by_player (game, parent))
                {
                  if (lib_object_too_heavy (game, object, &is_portable))
                    {
                      if (too_heavy == -1)
                        {
                          too_heavy = object;
                          too_heavy_portable = is_portable;
                        }
                      continue;
                    }
                  if (lib_object_too_large (game, object, &is_portable))
                    {
                      if (too_large == -1)
                        {
                          too_large = object;
                          too_large_portable = is_portable;
                        }
                      continue;
                    }
                }

              if (count > 0)
                {
                  if (count == 1)
                    {
                      if (has_printed)
                        pf_buffer_string (filter, total == 0 ? "\n" : "  ");
                      if (parent == -1)
                        pf_buffer_string (filter,
                                          lib_select_response (game,
                                                         "You pick up ",
                                                         "I pick up ",
                                                         "%player% picks up "));
                      else
                        pf_buffer_string (filter,
                                          lib_select_response (game,
                                                           "You take ",
                                                           "I take ",
                                                           "%player% takes "));
                    }
                  else
                    pf_buffer_string (filter, ", ");
                  lib_print_object_np (game, trail);
                }
              trail = object;
              count++;

              gs_object_player_get (game, object);
            }

          if (count >= 1)
            {
              if (count == 1)
                {
                  if (has_printed)
                    pf_buffer_string (filter, total == 0 ? "\n" : "  ");
                  if (parent == -1)
                    pf_buffer_string (filter,
                                      lib_select_response (game,
                                                         "You pick up ",
                                                         "I pick up ",
                                                         "%player% picks up "));
                  else
                    pf_buffer_string (filter,
                                      lib_select_response (game,
                                                           "You take ",
                                                           "I take ",
                                                           "%player% takes "));
                }
              else
                pf_buffer_string (filter, " and ");
              lib_print_object_np (game, trail);
              if (parent != -1)
                {
                  pf_buffer_string (filter, " from ");
                  lib_print_object_np (game, parent);
                }
              pf_buffer_character (filter, '.');
            }
          total += count;
          has_printed |= count > 0;
        }
    }

  /*
   * If we ran out of capacity, either in weight or in size, print the
   * details.  Note that we currently only report the first object of any
   * type to go over capacity.
   */
  if (too_heavy != -1)
    {
      if (has_printed)
        pf_buffer_string (filter, "  ");
      pf_new_sentence (filter);
      lib_print_object_np (game, too_heavy);
      pf_buffer_string (filter,
                        lib_select_plurality (game, too_heavy, " is", " are"));
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           " too heavy for you to carry",
                                           " too heavy for me to carry",
                                           " too heavy for %player% to carry"));
      if (too_heavy_portable)
        pf_buffer_string (filter, " at the moment");
      pf_buffer_character (filter, '.');
      has_printed |= TRUE;
    }
  else if (too_large != -1)
    {
      if (has_printed)
        pf_buffer_string (filter, "  ");
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "Your hands are full",
                                             "My hands are full",
                                             "%player%'s hands are full"));
      if (too_large_portable)
        pf_buffer_string (filter, " at the moment");
      pf_buffer_character (filter, '.');
      has_printed |= TRUE;
    }

  /*
   * Note any remaining multiple references left out of the take operation.
   * This is some workload...
   *
   * First, deal with the case where we have an associated object.
   */
  if (is_associate_object)
    {
      count = 0;
      trail = -1;
      for (object = 0; object < object_count; object++)
        {
          if (!game->multiple_references[object])
            continue;

          if (gs_object_position (game, object) == OBJ_HELD_PLAYER
              || gs_object_position (game, object) == OBJ_WORN_PLAYER)
            continue;

          if (count > 0)
            {
              if (count == 1)
                {
                  if (has_printed)
                    pf_buffer_string (filter, "  ");
                  pf_new_sentence (filter);
                  lib_print_object_np (game, trail);
                }
              else
                pf_buffer_string (filter, ", ");
            }
          trail = object;
          count++;

          game->multiple_references[object] = FALSE;
        }

      if (count >= 1)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_new_sentence (filter);
              lib_print_object_np (game, trail);
              pf_buffer_string (filter,
                                lib_select_plurality (game, trail,
                                                      " is not ",
                                                      " are not "));
            }
          else
            {
              pf_buffer_string (filter, " and ");
              lib_print_object_np (game, trail);
              pf_buffer_string (filter, " are not ");
            }
          if (obj_is_container (game, associate))
            {
              pf_buffer_string (filter, "in ");
              if (obj_is_surface (game, associate))
                pf_buffer_string (filter, "or on ");
            }
          else
            pf_buffer_string (filter, "on ");
          lib_print_object_np (game, associate);
          pf_buffer_character (filter, '.');
        }
      has_printed |= count > 0;
    }

  /*
   * Now, deal with the case where we have an associated NPC.  Once this
   * case is handled, we can force the object references so that the code
   * that follows on from here will report errors taking all objects.
   *
   * Note that this means that we can never successfully take an object
   * from an NPC; that'll have to happen via a game's own commands.
   */
  if (is_associate_npc)
    {
      count = 0;
      trail = -1;
      for (object = 0; object < object_count; object++)
        {
          if (!game->multiple_references[object])
            continue;

          if (gs_object_position (game, object) == OBJ_PART_NPC)
            continue;

          if (count > 0)
            {
              if (count == 1)
                {
                  if (has_printed)
                    pf_buffer_string (filter, "  ");
                  pf_new_sentence (filter);
                  lib_print_npc_np (game, associate);
                  pf_buffer_string (filter, " is not carrying ");
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object_np (game, trail);
            }
          trail = object;
          count++;

          game->multiple_references[object] = FALSE;
        }

      if (count >= 1)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_new_sentence (filter);
              lib_print_npc_np (game, associate);
              pf_buffer_string (filter, " is not carrying ");
              lib_print_object_np (game, trail);
            }
          else
            {
              pf_buffer_string (filter, " or ");
              lib_print_object_np (game, trail);
            }
          pf_buffer_character (filter, '!');
        }
      has_printed |= count > 0;

      /*
       * Merge any remaining object references into multiple references,
       * so that succeeding code complains about the inability to acquire
       * these objects.
       */
      for (object = 0; object < object_count; object++)
        {
          game->multiple_references[object] |= game->object_references[object];
          game->object_references[object] = FALSE;
        }
    }

  /*
   * The remainder of this routine is common error reporting for both object
   * and NPC associates (and also for no associates).
   */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (gs_object_position (game, object) != OBJ_HELD_PLAYER)
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You've already got ",
                                                     "I've already got ",
                                                     "%player% already has "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You've already got ",
                                                 "I've already got ",
                                                 "%player% already has "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '!');
    }
  has_printed |= count > 0;

  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (gs_object_position (game, object) != OBJ_WORN_PLAYER)
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                               "You're already wearing ",
                                               "I'm already wearing ",
                                               "%player% is already wearing "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                               "You're already wearing ",
                                               "I'm already wearing ",
                                               "%player% is already wearing "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '!');
    }
  has_printed |= count > 0;

  for (npc = 0; npc < gs_npc_count (game); npc++)
    {
      count = 0;
      trail = -1;
      for (object = 0; object < object_count; object++)
        {
          if (!game->multiple_references[object])
            continue;

          if (gs_object_position (game, object) != OBJ_HELD_NPC
              && gs_object_position (game, object) != OBJ_WORN_NPC)
            continue;
          if (gs_object_parent (game, object) != npc)
            continue;

          if (count > 0)
            {
              if (count == 1)
                {
                  if (has_printed)
                    pf_buffer_string (filter, "  ");
                  pf_new_sentence (filter);
                  lib_print_npc_np (game, gs_object_parent (game, trail));
                  pf_buffer_string (filter,
                                    lib_select_response (game,
                                                 " refuses to give you ",
                                                 " refuses to give me ",
                                                 " refuses to give %player% "));
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object_np (game, trail);
            }
          trail = object;
          count++;

          game->multiple_references[object] = FALSE;
        }

      if (count >= 1)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_new_sentence (filter);
              lib_print_npc_np (game, gs_object_parent (game, trail));
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                 " refuses to give you ",
                                                 " refuses to give me ",
                                                 " refuses to give %player% "));
            }
          else
            pf_buffer_string (filter, " and ");
          lib_print_object_np (game, trail);
          pf_buffer_character (filter, '!');
        }
      has_printed |= count > 0;
    }

  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You can't take ",
                                                     "I can't take ",
                                                     "%player% can't take "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You can't take ",
                                                 "I can't take ",
                                                 "%player% can't take "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '!');
    }
}


/*
 * lib_take_backend()
 * lib_take_from_object_backend()
 * lib_take_from_npc_backend()
 *
 * Facets of lib_take_backend_common().  Provide backend handling for either
 * the plain "take" handlers, or the "take from <something>" handlers.
 */
static void
lib_take_backend (sc_gameref_t game)
{
  lib_take_backend_common (game, -1, FALSE, FALSE);
}

static void
lib_take_from_object_backend (sc_gameref_t game, sc_int associate)
{
  lib_take_backend_common (game, associate, TRUE, FALSE);
}

static void
lib_take_from_npc_backend (sc_gameref_t game, sc_int associate)
{
  lib_take_backend_common (game, associate, FALSE, TRUE);
}


/*
 * lib_take_filter()
 * lib_take_not_associated_filter()
 *
 * Helper functions for deciding if an object may be acquired in this context.
 * Returns TRUE if an object may be acquired, FALSE otherwise.
 */
static sc_bool
lib_take_filter (sc_gameref_t game, sc_int object, sc_int unused)
{
  assert (unused == -1);

  /*
   * To be take-able, an object must be visible in the room, not static,
   * and not already held or worn by the player or an NPC.
   */
  return obj_indirectly_in_room (game, object, gs_playerroom (game))
         && !obj_is_static (game, object)
         && !(gs_object_position (game, object) == OBJ_HELD_PLAYER
              || gs_object_position (game, object) == OBJ_WORN_PLAYER)
         && !(gs_object_position (game, object) == OBJ_HELD_NPC
              || gs_object_position (game, object) == OBJ_WORN_NPC);
}

static sc_bool
lib_take_not_associated_filter (sc_gameref_t game,
                                sc_int object, sc_int unused)
{
  assert (unused == -1);

  /* In addition to other checks, the object may not be in or on an object. */
  return lib_take_filter (game, object, -1)
         && !(gs_object_position (game, object) == OBJ_ON_OBJECT
              || gs_object_position (game, object) == OBJ_IN_OBJECT);
}


/*
 * lib_cmd_take_all()
 *
 * Attempt to take all objects currently visible to the player.
 */
sc_bool
lib_cmd_take_all (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_take_not_associated_filter, -1,
                                       NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_take_backend (game);
  else
    pf_buffer_string (filter, "There is nothing to pick up here.");

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_take_except_multiple()
 *
 * Take all objects currently available to the player, excepting those listed
 * in %text%.
 */
sc_bool
lib_cmd_take_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find leave target objects. */
  if (!lib_parse_multiple_objects (game, "leave",
                                   lib_take_not_associated_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_take_not_associated_filter, -1,
                                     &references);
  if (objects > 0 || references > 0)
    lib_take_backend (game);
  else
    {
      if (objects == 0)
        pf_buffer_string (filter, "There is nothing else to pick up here.");
      else
        pf_buffer_string (filter, "There is nothing to pick up here.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_take_multiple()
 *
 * Take all objects currently available to the player and listed in %text%.
 */
sc_bool
lib_cmd_take_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find take target objects. */
  if (!lib_parse_multiple_objects (game, "take",
                                   lib_take_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_take_filter, -1,
                                       &references);
  if (objects > 0 || references > 0)
    lib_take_backend (game);
  else
    pf_buffer_string (filter, "There is nothing to pick up here.");

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_take_from_filter()
 *
 * Helper function for deciding if an object may be acquired in this context.
 * Returns TRUE if an object may be acquired, FALSE otherwise.
 */
static sc_bool
lib_take_from_filter (sc_gameref_t game, sc_int object, sc_int associate)
{
  /*
   * To be take-able, an object must be either inside or on the specified
   * object.
   */
  return (gs_object_position (game, object) == OBJ_IN_OBJECT
          || gs_object_position (game, object) == OBJ_ON_OBJECT)
         && !obj_is_static (game, object)
         && gs_object_parent (game, object) == associate;
}


/*
 * lib_take_from_empty()
 *
 * Common error handling for when nothing is taken from a container or
 * supporter object.
 */
static void
lib_take_from_empty (sc_gameref_t game, sc_int associate, sc_bool is_except)
{
  const sc_filterref_t filter = gs_get_filter (game);

  if (obj_is_container (game, associate) && obj_is_surface (game, associate))
    {
      if (gs_object_openness (game, associate) <= OBJ_OPEN)
        {
          if (is_except)
            pf_buffer_string (filter, "There is nothing else in or on ");
          else
            pf_buffer_string (filter, "There is nothing in or on ");
          lib_print_object_np (game, associate);
          pf_buffer_character (filter, '.');
        }
      else
        {
          if (is_except)
            pf_buffer_string (filter, "There is nothing else on ");
          else
            pf_buffer_string (filter, "There is nothing on ");
          lib_print_object_np (game, associate);
          if (gs_object_openness (game, associate) == OBJ_LOCKED)
            pf_buffer_string (filter, " and it is locked.");
          else
            pf_buffer_string (filter, " and it is closed.");
        }
    }
  else
    {
      if (obj_is_container (game, associate))
        {
          if (gs_object_openness (game, associate) <= OBJ_OPEN)
            {
              if (is_except)
                pf_buffer_string (filter, "There is nothing else inside ");
              else
                pf_buffer_string (filter, "There is nothing inside ");
              lib_print_object_np (game, associate);
              pf_buffer_character (filter, '.');
            }
          else
            {
              pf_new_sentence (filter);
              lib_print_object_np (game, associate);
              if (gs_object_openness (game, associate) == OBJ_LOCKED)
                pf_buffer_string (filter, " is locked.");
              else
                pf_buffer_string (filter, " is closed.");
            }
        }
      else
        {
          if (is_except)
            pf_buffer_string (filter, "There is nothing else on ");
          else
            pf_buffer_string (filter, "There is nothing on ");
          lib_print_object_np (game, associate);
          pf_buffer_character (filter, '.');
        }
    }
}


/*
 * lib_take_from_is_valid()
 *
 * Validate the supporter requested in "take from" commands.
 */
static sc_bool
lib_take_from_is_valid (sc_gameref_t game, sc_int associate)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Disallow emptying non-container/non-surface objects. */
  if (!(obj_is_container (game, associate)
        || obj_is_surface (game, associate)))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                         "You can't take anything from ",
                                         "I can't take anything from ",
                                         "%player% can't take anything from "));
      lib_print_object_np (game, associate);
      pf_buffer_string (filter, ".\n");
      return FALSE;
    }

  /* If object is a container, and is closed, reject now. */
  if (obj_is_container (game, associate)
      && gs_object_openness (game, associate) > OBJ_OPEN)
    {
      pf_new_sentence (filter);
      lib_print_object_np (game, associate);
      pf_buffer_string (filter,
                        lib_select_plurality (game, associate,
                                             " is closed.\n",
                                             " are closed.\n"));
      return FALSE;
    }

  /* Associate is a valid target for "take from". */
  return TRUE;
}


/*
 * lib_cmd_take_all_from()
 *
 * Attempt to take all objects contained in or supported by a given object.
 */
sc_bool
lib_cmd_take_all_from (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int associate, objects;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  associate = lib_disambiguate_object (game, "take from", &is_ambiguous);
  if (associate == -1)
    return is_ambiguous;

  /* Validate the associate object to take from. */
  if (!lib_take_from_is_valid (game, associate))
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_take_from_filter, associate,
                                       NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_take_from_object_backend (game, associate);
  else
    lib_take_from_empty (game, associate, FALSE);

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_take_from_except_multiple()
 *
 * Take all objects contained in or supported by a given object, excepting
 * those listed in %text%.
 */
sc_bool
lib_cmd_take_from_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int associate, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  associate = lib_disambiguate_object (game, "take from", &is_ambiguous);
  if (associate == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find leave target objects. */
  if (!lib_parse_multiple_objects (game, "leave",
                                   lib_take_from_filter, associate,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Validate the associate object to take from. */
  if (!lib_take_from_is_valid (game, associate))
    return TRUE;

  /* As a special case, complain about requests to retain the associate. */
  if (game->multiple_references[associate])
    {
      pf_buffer_string (filter,
                        "I only understood you as far as wanting to leave ");
      lib_print_object_np (game, associate);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_take_from_filter, associate,
                                     &references);
  if (objects > 0 || references > 0)
    lib_take_from_object_backend (game, associate);
  else
    lib_take_from_empty (game, associate, TRUE);

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_take_from_multiple()
 *
 * Take the objects currently inside an object and listed in %text%.  This
 * function isn't mandatory -- plain "take <object>" works fine with contain-
 * ers and surfaces, but it's a standard in Adrift so here it is.
 */
sc_bool
lib_cmd_take_from_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int associate, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  associate = lib_disambiguate_object (game, "take from", &is_ambiguous);
  if (associate == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find take target objects. */
  if (!lib_parse_multiple_objects (game, "take",
                                   lib_take_from_filter, associate,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Validate the associate object to take from. */
  if (!lib_take_from_is_valid (game, associate))
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_take_from_filter, associate,
                                       &references);
  if (objects > 0 || references > 0)
    lib_take_from_object_backend (game, associate);
  else
    lib_take_from_empty (game, associate, FALSE);

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_take_from_npc_filter()
 *
 * Helper function for deciding if an object may be acquired in this context.
 * Returns TRUE if an object may be acquired, FALSE otherwise.
 */
static sc_bool
lib_take_from_npc_filter (sc_gameref_t game, sc_int object, sc_int associate)
{
  /*
   * To be take-able, an object must be either held or worn by the specified
   * NPC.
   */
  return (gs_object_position (game, object) == OBJ_HELD_NPC
          || gs_object_position (game, object) == OBJ_WORN_NPC)
         && !obj_is_static (game, object)
         && gs_object_parent (game, object) == associate;
}


/*
 * lib_cmd_take_all_from_npc()
 *
 * Attempt to take all objects held or worn by a given NPC.
 */
sc_bool
lib_cmd_take_all_from_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int associate, objects;
  sc_bool is_ambiguous;

  /* Get the referenced NPC, and if none, consider complete. */
  associate = lib_disambiguate_npc (game, "take from", &is_ambiguous);
  if (associate == -1)
    return is_ambiguous;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_take_from_npc_filter, associate,
                                       NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_take_from_npc_backend (game, associate);
  else
    {
      pf_new_sentence (filter);
      lib_print_npc_np (game, associate);
      pf_buffer_string (filter, " is not carrying anything!");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_take_from_npc_except_multiple()
 *
 * Attempt to take all objects held or worn by a given NPC, excepting those
 * listed in %text%.
 */
sc_bool
lib_cmd_take_from_npc_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int associate, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced NPC, and if none, consider complete. */
  associate = lib_disambiguate_npc (game, "take from", &is_ambiguous);
  if (associate == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find leave target objects. */
  if (!lib_parse_multiple_objects (game, "leave",
                                   lib_take_from_npc_filter, associate,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_take_from_npc_filter, associate,
                                     &references);
  if (objects > 0 || references > 0)
    lib_take_from_npc_backend (game, associate);
  else
    {
      pf_new_sentence (filter);
      lib_print_npc_np (game, associate);
      pf_buffer_string (filter, " is not carrying anything else!");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_take_from_npc_multiple()
 *
 * Attempt to take the objects currently held or worn by an NPC and listed
 * in %text%.
 */
sc_bool
lib_cmd_take_from_npc_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int associate, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced NPC, and if none, consider complete. */
  associate = lib_disambiguate_npc (game, "take from", &is_ambiguous);
  if (associate == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find take target objects. */
  if (!lib_parse_multiple_objects (game, "take",
                                   lib_take_from_npc_filter, associate,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_take_from_npc_filter, associate,
                                       &references);
  if (objects > 0 || references > 0)
    lib_take_from_npc_backend (game, associate);
  else
    {
      pf_new_sentence (filter);
      lib_print_npc_np (game, associate);
      pf_buffer_string (filter, " is not carrying anything!");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_drop_backend()
 *
 * Common backend handler for dropping objects.  Drops all objects currently
 * referenced in the game, trying game commands first, and then moving other
 * unhandled objects to the player room floor.
 *
 * Objects to action are flagged in object_references; objects requested but
 * deemed not actionable are flagged in multiple_references.
 */
static void
lib_drop_backend (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object_count, object, count, trail;
  sc_bool has_printed;

  /*
   * Try game commands for all referenced objects first.  If any succeed,
   * remove that reference from the list.
   */
  has_printed = FALSE;
  object_count = gs_object_count (game);
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (lib_try_game_command_short (game, "drop", object))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
        }
    }

  /* Drop every object that remains referenced. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You drop ",
                                                     "I drop ",
                                                     "%player% drops "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      gs_object_to_room (game, object, gs_playerroom (game));
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You drop ",
                                                 "I drop ",
                                                 "%player% drops "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  /* Note any remaining multiple references left out of the drop operation. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                   "You are not holding ",
                                                   "I am not holding ",
                                                   "%player% is not holding "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You are not holding ",
                                                 "I am not holding ",
                                                 "%player% is not holding "));
        }
      else
        pf_buffer_string (filter, " or ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
}


/*
 * lib_drop_filter()
 *
 * Helper function for deciding if an object may be dropped in this context.
 * Returns TRUE if an object may be dropped, FALSE otherwise.
 */
static sc_bool
lib_drop_filter (sc_gameref_t game, sc_int object, sc_int unused)
{
  assert (unused == -1);

  return !obj_is_static (game, object)
         && gs_object_position (game, object) == OBJ_HELD_PLAYER;
}


/*
 * lib_cmd_drop_all()
 *
 * Drop all objects currently held by the player.
 */
sc_bool
lib_cmd_drop_all (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_drop_filter, -1,
                                       NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_drop_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                          "You're not carrying anything.",
                                          "I'm not carrying anything.",
                                          "%player%'s not carrying anything."));
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_drop_except_multiple()
 *
 * Drop all objects currently held by the player, excepting those listed in
 * %text%.
 */
sc_bool
lib_cmd_drop_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "retain",
                                   lib_drop_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_drop_filter, -1,
                                     &references);
  if (objects > 0 || references > 0)
    lib_drop_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not holding anything",
                                           "I am not holding anything",
                                           "%player% is not holding anything"));
      if (objects == 0)
        pf_buffer_string (filter, " else");
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_drop_multiple()
 *
 * Drop all objects currently held by the player and listed in %text%.
 */
sc_bool
lib_cmd_drop_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find drop target objects. */
  if (!lib_parse_multiple_objects (game, "drop",
                                   lib_drop_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_drop_filter, -1,
                                       &references);
  if (objects > 0 || references > 0)
    lib_drop_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                          "You are not holding anything.",
                                          "I am not holding anything.",
                                          "%player% is not holding anything."));
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_give_object_npc()
 * lib_cmd_give_object()
 *
 * Attempt to give an object to an NPC.
 */
sc_bool
lib_cmd_give_object_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, npc;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "give", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "give to", NULL);
  if (npc == -1)
    return TRUE;

  /* Reject if not holding the object offered. */
  if (gs_object_position (game, object) != OBJ_HELD_PLAYER)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You don't have ",
                                             "I don't have ",
                                             "%player% doesn't have "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, "!\n");
      return TRUE;
    }

  /* After all that, the npc is disinterested. */
  pf_new_sentence (filter);
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter, " doesn't seem interested in ");
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

sc_bool
lib_cmd_give_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "give", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject if not holding the object offered. */
  if (gs_object_position (game, object) != OBJ_HELD_PLAYER)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You don't have ",
                                             "I don't have ",
                                             "%player% doesn't have "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, "!\n");
      return TRUE;
    }

  /* After all that, we have to ask (and shouldn't this be "to whom?"). */
  pf_buffer_string (filter, "Give ");
  lib_print_object_np (game, object);
  pf_buffer_string (filter, " to who?\n");
  return TRUE;
}


/*
 * lib_wear_backend()
 *
 * Common backend handler for wearing objects.  Puts on all objects currently
 * referenced in the game, moving objects to worn by player.
 *
 * Objects to action are flagged in object_references; objects requested but
 * deemed not actionable are flagged in multiple_references.
 */
static void
lib_wear_backend (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object_count, object, count, trail;
  sc_bool has_printed;

  /*
   * Try game commands for all referenced objects first.  If any succeed,
   * remove that reference from the list.
   */
  has_printed = FALSE;
  object_count = gs_object_count (game);
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (lib_try_game_command_short (game, "wear", object))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
        }
    }

  /* Wear every object referenced. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You put on ",
                                                     "I put on ",
                                                     "%player% puts on "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      gs_object_player_wear (game, object);
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You put on ",
                                                 "I put on ",
                                                 "%player% puts on "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  /* Note any remaining multiple references left out of the wear operation. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (gs_object_position (game, object) != OBJ_WORN_PLAYER)
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                               "You are already wearing ",
                                               "I am already wearing ",
                                               "%player% is already wearing "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                               "You are already wearing ",
                                               "I am already wearing ",
                                               "%player% is already wearing "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (gs_object_position (game, object) == OBJ_HELD_PLAYER)
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                   "You are not holding ",
                                                   "I am not holding ",
                                                   "%player% is not holding "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You are not holding ",
                                                 "I am not holding ",
                                                 "%player% is not holding "));
        }
      else
        pf_buffer_string (filter, " or ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You can't wear ",
                                                     "I can't wear ",
                                                     "%player% can't wear "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You can't wear ",
                                                 "I can't wear ",
                                                 "%player% can't wear "));
        }
      else
        pf_buffer_string (filter, " or ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
}


/*
 * lib_wear_filter()
 *
 * Helper function for deciding if an object may be worn in this context.
 * Returns TRUE if an object may be worn, FALSE otherwise.
 */
static sc_bool
lib_wear_filter (sc_gameref_t game, sc_int object, sc_int unused)
{
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  assert (unused == -1);

  /*
   * The object is wearable if the player is holding it, and it's not static
   * (static moved to player inventory by event), and if it's marked wearable
   * in properties.
   */
  if (gs_object_position (game, object) == OBJ_HELD_PLAYER
      && !obj_is_static (game, object))
    {
      sc_vartype_t vt_key[3];

      /* Return wearability from the object properties. */
      vt_key[0].string = "Objects";
      vt_key[1].integer = object;
      vt_key[2].string = "Wearable";
      return prop_get_boolean (bundle, "B<-sis", vt_key);
    }

  return FALSE;
}


/*
 * lib_cmd_wear_all()
 *
 * Wear all wearable objects currently held by the player.
 */
sc_bool
lib_cmd_wear_all (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_wear_filter, -1,
                                       NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_wear_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You're not carrying anything",
                                           "I'm not carrying anything",
                                           "%player%'s not carrying anything"));
      pf_buffer_string (filter, " that can be worn.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_wear_except_multiple()
 *
 * Wear all wearable objects currently held by the player, excepting those
 * listed in %text%.
 */
sc_bool
lib_cmd_wear_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "retain",
                                   lib_wear_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_wear_filter, -1,
                                     &references);
  if (objects > 0 || references > 0)
    lib_wear_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not holding anything",
                                           "I am not holding anything",
                                           "%player% is not holding anything"));
      if (objects == 0)
        pf_buffer_string (filter, " else");
      pf_buffer_string (filter, " that can be worn.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_wear_multiple()
 *
 * Wear all objects currently held by the player, wearable, and listed
 * in %text%.
 */
sc_bool
lib_cmd_wear_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find wear target objects. */
  if (!lib_parse_multiple_objects (game, "wear",
                                   lib_wear_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_wear_filter, -1,
                                       &references);
  if (objects > 0 || references > 0)
    lib_wear_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not holding anything",
                                           "I am not holding anything",
                                           "%player% is not holding anything"));
      pf_buffer_string (filter, " that can be worn.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_remove_backend()
 *
 * Common backend handler for removing objects.  Takes off on all objects
 * currently referenced in the game, moving objects to held by player.
 *
 * Objects to action are flagged in object_references; objects requested but
 * deemed not actionable are flagged in multiple_references.
 */
static void
lib_remove_backend (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object_count, object, count, trail;
  sc_bool has_printed;

  /*
   * Try game commands for all referenced objects first.  If any succeed,
   * remove that reference from the list.
   */
  has_printed = FALSE;
  object_count = gs_object_count (game);
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (lib_try_game_command_short (game, "remove", object))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
        }
    }

  /* Remove every object referenced. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You remove ",
                                                     "I remove ",
                                                     "%player% removes "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      gs_object_player_get (game, object);
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You remove ",
                                                 "I remove ",
                                                 "%player% removes "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  /* Note any remaining multiple references left out of the remove operation. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                   "You are not wearing ",
                                                   "I am not wearing ",
                                                   "%player% is not wearing "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You are not wearing ",
                                                 "I am not wearing ",
                                                 "%player% is not wearing "));
        }
      else
        pf_buffer_string (filter, " or ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '!');
    }
}


/*
 * lib_remove_filter()
 *
 * Helper function for deciding if an object may be removed in this context.
 * Returns TRUE if an object is currently being worn, FALSE otherwise.
 */
static sc_bool
lib_remove_filter (sc_gameref_t game, sc_int object, sc_int unused)
{
  assert (unused == -1);

  return !obj_is_static (game, object)
         && gs_object_position (game, object) == OBJ_WORN_PLAYER;
}


/*
 * lib_cmd_remove_all()
 *
 * Remove all objects currently held by the player.
 */
sc_bool
lib_cmd_remove_all (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_remove_filter, -1,
                                       NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_remove_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You're not wearing anything",
                                           "I'm not wearing anything",
                                           "%player%'s not wearing anything"));
      pf_buffer_string (filter, " that can be removed.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_remove_except_multiple()
 *
 * Remove all objects currently worn by the player, excepting those listed
 * in %text%.
 */
sc_bool
lib_cmd_remove_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "retain",
                                   lib_remove_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_remove_filter, -1,
                                     &references);
  if (objects > 0 || references > 0)
    lib_remove_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not wearing anything",
                                           "I am not wearing anything",
                                           "%player% is not wearing anything"));
      if (objects == 0)
        pf_buffer_string (filter, " else");
      pf_buffer_string (filter, " that can be removed.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_remove_multiple()
 *
 * Remove all objects currently worn by the player, and listed in %text%.
 */
sc_bool
lib_cmd_remove_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int objects, references;

  /* Parse the multiple objects list to find remove target objects. */
  if (!lib_parse_multiple_objects (game, "remove",
                                   lib_remove_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_remove_filter, -1,
                                       &references);
  if (objects > 0 || references > 0)
    lib_remove_backend (game);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not holding anything",
                                           "I am not holding anything",
                                           "%player% is not holding anything"));
      pf_buffer_string (filter, " that can be removed.");
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_inventory()
 *
 * List objects carried and worn by the player.
 */
sc_bool
lib_cmd_inventory (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, count, trail;
  sc_bool wearing;

  /* Find and list each object worn by the player. */
  count = 0;
  trail = -1;
  wearing = FALSE;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (gs_object_position (game, object) == OBJ_WORN_PLAYER)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  pf_buffer_string (filter,
                                    lib_select_response (game,
                                                       "You are wearing ",
                                                       "I am wearing ",
                                                       "%player% is wearing "));
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You are wearing ",
                                                 "I am wearing ",
                                                 "%player% is wearing "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object (game, trail);
      wearing = TRUE;
    }

  /* Find and list each object owned by the player. */
  count = 0;
  for (object = 0; object < gs_object_count (game); object++)
    {
      if (gs_object_position (game, object) == OBJ_HELD_PLAYER)
        {
          if (count > 0)
            {
              if (count == 1)
                {
                  if (wearing)
                    {
                      pf_buffer_string (filter,
                                        lib_select_response (game,
                                                ", and you are carrying ",
                                                ", and I am carrying ",
                                                ", and %player% is carrying "));
                    }
                  else
                    {
                      pf_buffer_string (filter,
                                        lib_select_response (game,
                                                      "You are carrying ",
                                                      "I am carrying ",
                                                      "%player% is carrying "));
                    }
                }
              else
                pf_buffer_string (filter, ", ");
              lib_print_object (game, trail);
            }
          trail = object;
          count++;
        }
    }
  if (count >= 1)
    {
      /* Print out final listed object. */
      if (count == 1)
        {
          if (wearing)
            {
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                ", and you are carrying ",
                                                ", and I am carrying ",
                                                ", and %player% is carrying "));
            }
          else
            {
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You are carrying ",
                                                     "I am carrying ",
                                                     "%player% is carrying "));
            }
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object (game, trail);
      pf_buffer_character (filter, '.');

      /* Print contents of every container and surface carried. */
      for (object = 0; object < gs_object_count (game); object++)
        {
          if (gs_object_position (game, object) == OBJ_HELD_PLAYER)
            {
              if (obj_is_container (game, object)
                  && gs_object_openness (game, object) <= OBJ_OPEN)
                {
                  lib_list_in_object (game, object, TRUE);
                }
              if (obj_is_surface (game, object))
                {
                  lib_list_on_object (game, object, TRUE);
                }
            }
        }
      pf_buffer_character (filter, '\n');
    }
  else
    {
      if (wearing)
        {
          pf_buffer_string (filter, ", and ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                            "you are carrying nothing.\n",
                                            "I am carrying nothing.\n",
                                            "%player% is carrying nothing.\n"));
        }
      else
        {
          pf_buffer_string (filter,
                            lib_select_response (game,
                                            "You are carrying nothing.\n",
                                            "I am carrying nothing.\n",
                                            "%player% is carrying nothing.\n"));
        }
    }

  /* Successful command. */
  return TRUE;
}


/*
 * lib_cmd_open_object()
 *
 * Attempt to open the referenced object.
 */
sc_bool
lib_cmd_open_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, openness;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "open", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Get the current object openness. */
  openness = gs_object_openness (game, object);

  /* React to the request based on openness state. */
  switch (openness)
    {
    case OBJ_OPEN:
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is already open!\n",
                                              " are already open!\n"));
      return TRUE;

    case OBJ_CLOSED:
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You open ",
                                             "I open ",
                                             "%player% opens "));
      lib_print_object_np (game, object);
      pf_buffer_character (filter, '.');

      /* Set open state, and list contents. */
      gs_set_object_openness (game, object, OBJ_OPEN);
      lib_list_in_object (game, object, TRUE);
      pf_buffer_character (filter, '\n');
      return TRUE;

    case OBJ_LOCKED:
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't open ",
                                             "I can't open ",
                                             "%player% can't open "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, " as it is locked!\n");
      return TRUE;

    default:
      break;
    }

  /* The object isn't openable. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't open ",
                                         "I can't open ",
                                         "%player% can't open "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, "!\n");
  return TRUE;
}


/*
 * lib_cmd_close_object()
 *
 * Attempt to close the referenced object.
 */
sc_bool
lib_cmd_close_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object, openness;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "close", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Get the current object openness. */
  openness = gs_object_openness (game, object);

  /* React to the request based on openness state. */
  switch (openness)
    {
    case OBJ_OPEN:
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You close ",
                                             "I close ",
                                             "%player% closes "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, ".\n");

      /* Set closed state. */
      gs_set_object_openness (game, object, OBJ_CLOSED);
      return TRUE;

    case OBJ_CLOSED:
    case OBJ_LOCKED:
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is already closed!\n",
                                              " are already closed!\n"));
      return TRUE;

    default:
      break;
    }

  /* The object isn't closeable. */
  pf_buffer_string (filter,
                        lib_select_response (game,
                                         "You can't close ",
                                         "I can't close ",
                                         "%player% can't close "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, "!\n");
  return TRUE;
}


/*
 * lib_attempt_key_acquisition()
 *
 * Automatically get an object being used as a key, if possible.
 */
static void
lib_attempt_key_acquisition (sc_gameref_t game, sc_int object)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Disallow getting static objects. */
  if (obj_is_static (game, object))
    return;

  /* If the object is not seen or available, reject the attempt. */
  if (!(gs_object_seen (game, object)
        && obj_indirectly_in_room (game, object, gs_playerroom (game))))
    return;

  /*
   * Check if we already have it, or are wearing it, or if a NPC has or is
   * wearing it.
   */
  if (gs_object_position (game, object) == OBJ_HELD_PLAYER
      || gs_object_position (game, object) == OBJ_WORN_PLAYER
      || gs_object_position (game, object) == OBJ_HELD_NPC
      || gs_object_position (game, object) == OBJ_WORN_NPC)
    return;

  /*
   * If the object is contained in or on something we're already holding,
   * capacity checks are meaningless.
   */
  if (!obj_indirectly_held_by_player (game, object))
    {
      if (lib_object_too_heavy (game, object, NULL)
          || lib_object_too_large (game, object, NULL))
        return;
    }

  /* Retry game commands for the object with a standard "get". */
  if (lib_try_game_command_short (game, "get", object))
    return;

  /* Note what we're doing. */
  if (gs_object_position (game, object) == OBJ_IN_OBJECT
      || gs_object_position (game, object) == OBJ_ON_OBJECT)
    {
      pf_buffer_string (filter, "(Taking ");
      lib_print_object_np (game, object);

      pf_buffer_string (filter, " from ");
      lib_print_object_np (game, gs_object_parent (game, object));
      pf_buffer_string (filter, " first)\n");
    }
  else
    {
      pf_buffer_string (filter, "(Picking up ");
      lib_print_object_np (game, object);
      pf_buffer_string (filter, " first)\n");
    }

  /* Take possession of the object. */
  gs_object_player_get (game, object);
}


/*
 * lib_cmd_unlock_object_with()
 *
 * Attempt to unlock the referenced object.
 */
sc_bool
lib_cmd_unlock_object_with (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_int object, key, openness;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "unlock", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /*
   * Now try to get the key from referenced text, and disambiguate as usual.
   */
  if (!uip_match ("%object%", var_get_ref_text (vars), game))
    {
      pf_buffer_string (filter, "What do you want to unlock that with?\n");
      return TRUE;
    }
  key = lib_disambiguate_object (game, "unlock that with", NULL);
  if (key == -1)
    return TRUE;

  /* React to the request based on openness state. */
  openness = gs_object_openness (game, object);
  switch (openness)
    {
    case OBJ_OPEN:
    case OBJ_CLOSED:
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is not locked!\n",
                                              " are not locked!\n"));
      return TRUE;

    case OBJ_LOCKED:
      {
        sc_vartype_t vt_key[3];
        sc_int key_index, the_key;

        vt_key[0].string = "Objects";
        vt_key[1].integer = object;
        vt_key[2].string = "Key";
        key_index = prop_get_integer (bundle, "I<-sis", vt_key);
        if (key_index == -1)
          break;

        the_key = obj_dynamic_object (game, key_index);
        if (the_key != key)
          {
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You can't unlock ",
                                                   "I can't unlock ",
                                                   "%player% can't unlock "));
            lib_print_object_np (game, object);
            pf_buffer_string (filter, " with ");
            lib_print_object_np (game, key);
            pf_buffer_string (filter, ".\n");
            return TRUE;
          }

        if (gs_object_position (game, key) != OBJ_HELD_PLAYER)
          {
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You are not holding ",
                                                   "I am not holding ",
                                                   "%player% is not holding "));
            lib_print_object_np (game, key);
            pf_buffer_string (filter, ".\n");
            return TRUE;
          }

        gs_set_object_openness (game, object, OBJ_CLOSED);
        pf_buffer_string (filter,
                          lib_select_response (game,
                                               "You unlock ",
                                               "I unlock ",
                                               "%player% unlocks "));
        lib_print_object_np (game, object);
        pf_buffer_string (filter, " with ");
        lib_print_object_np (game, key);
        pf_buffer_string (filter, ".\n");
        return TRUE;
      }

    default:
      break;
    }

  /* The object isn't lockable. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't unlock ",
                                         "I can't unlock ",
                                         "%player% can't unlock "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}


/*
 * lib_cmd_unlock_object()
 *
 * Attempt to unlock the referenced object, automatically selecting key.
 */
sc_bool
lib_cmd_unlock_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_int object, openness;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "unlock", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* React to the request based on openness state. */
  openness = gs_object_openness (game, object);
  switch (openness)
    {
    case OBJ_OPEN:
    case OBJ_CLOSED:
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is not locked!\n",
                                              " are not locked!\n"));
      return TRUE;

    case OBJ_LOCKED:
      {
        sc_vartype_t vt_key[3];
        sc_int key_index, key;

        vt_key[0].string = "Objects";
        vt_key[1].integer = object;
        vt_key[2].string = "Key";
        key_index = prop_get_integer (bundle, "I<-sis", vt_key);
        if (key_index == -1)
          break;

        key = obj_dynamic_object (game, key_index);
        lib_attempt_key_acquisition (game, key);
        if (gs_object_position (game, key) != OBJ_HELD_PLAYER)
          {
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You don't have",
                                                   "I don't have",
                                                   "%player% doesn't have"));
            pf_buffer_string (filter, " anything to unlock ");
            lib_print_object_np (game, object);
            pf_buffer_string (filter, " with!\n");
            return TRUE;
          }

        gs_set_object_openness (game, object, OBJ_CLOSED);
        pf_buffer_string (filter,
                          lib_select_response (game,
                                               "You unlock ",
                                               "I unlock ",
                                               "%player% unlocks "));
        lib_print_object_np (game, object);
        pf_buffer_string (filter, " with ");
        lib_print_object_np (game, key);
        pf_buffer_string (filter, ".\n");
        return TRUE;
      }

    default:
      break;
    }

  /* The object isn't lockable. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't unlock ",
                                         "I can't unlock ",
                                         "%player% can't unlock "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}


/*
 * lib_cmd_lock_object_with()
 *
 * Attempt to lock the referenced object.
 */
sc_bool
lib_cmd_lock_object_with (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_int object, key, openness;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "lock", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /*
   * Now try to get the key from referenced text, and disambiguate as usual.
   */
  if (!uip_match ("%object%", var_get_ref_text (vars), game))
    {
      pf_buffer_string (filter, "What do you want to lock that with?\n");
      return TRUE;
    }
  key = lib_disambiguate_object (game, "lock that with", NULL);
  if (key == -1)
    return TRUE;

  /* React to the request based on openness state. */
  openness = gs_object_openness (game, object);
  switch (openness)
    {
    case OBJ_OPEN:
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't lock ",
                                             "I can't lock ",
                                             "%player% can't lock "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, " as it is open.\n");
      return TRUE;

    case OBJ_CLOSED:
      {
        sc_vartype_t vt_key[3];
        sc_int key_index, the_key;

        vt_key[0].string = "Objects";
        vt_key[1].integer = object;
        vt_key[2].string = "Key";
        key_index = prop_get_integer (bundle, "I<-sis", vt_key);
        if (key_index == -1)
          break;

        the_key = obj_dynamic_object (game, key_index);
        if (the_key != key)
          {
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You can't lock ",
                                                   "I can't lock ",
                                                   "%player% can't lock "));
            lib_print_object_np (game, object);
            pf_buffer_string (filter, " with ");
            lib_print_object_np (game, key);
            pf_buffer_string (filter, ".\n");
            return TRUE;
          }

        if (gs_object_position (game, key) != OBJ_HELD_PLAYER)
          {
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You are not holding ",
                                                   "I am not holding ",
                                                   "%player% is not holding "));
            lib_print_object_np (game, key);
            pf_buffer_string (filter, ".\n");
            return TRUE;
          }

        gs_set_object_openness (game, object, OBJ_LOCKED);
        pf_buffer_string (filter, lib_select_response (game,
                                                       "You lock ",
                                                       "I lock ",
                                                       "%player% locks "));
        lib_print_object_np (game, object);
        pf_buffer_string (filter, " with ");
        lib_print_object_np (game, key);
        pf_buffer_string (filter, ".\n");
        return TRUE;
      }

    case OBJ_LOCKED:
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is already locked!\n",
                                              " are already locked!\n"));
      return TRUE;

    default:
      break;
    }

  /* The object isn't lockable. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't lock ",
                                         "I can't lock ",
                                         "%player% can't lock "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}


/*
 * lib_cmd_lock_object()
 *
 * Attempt to lock the referenced object, automatically selecting key.
 */
sc_bool
lib_cmd_lock_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_int object, openness;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "lock", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* React to the request based on openness state. */
  openness = gs_object_openness (game, object);
  switch (openness)
    {
    case OBJ_OPEN:
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't lock ",
                                             "I can't lock ",
                                             "%player% can't lock "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, " as it is open.\n");
      return TRUE;

    case OBJ_CLOSED:
      {
        sc_vartype_t vt_key[3];
        sc_int key_index, key;

        vt_key[0].string = "Objects";
        vt_key[1].integer = object;
        vt_key[2].string = "Key";
        key_index = prop_get_integer (bundle, "I<-sis", vt_key);
        if (key_index == -1)
          break;

        key = obj_dynamic_object (game, key_index);
        lib_attempt_key_acquisition (game, key);
        if (gs_object_position (game, key) != OBJ_HELD_PLAYER)
          {
            pf_buffer_string (filter,
                              lib_select_response (game,
                                                   "You don't have",
                                                   "I don't have",
                                                   "%player% doesn't have"));
            pf_buffer_string (filter, " anything to lock ");
            lib_print_object_np (game, object);
            pf_buffer_string (filter, " with!\n");
            return TRUE;
          }

        gs_set_object_openness (game, object, OBJ_LOCKED);
        pf_buffer_string (filter,
                          lib_select_response (game,
                                               "You lock ",
                                               "I lock ",
                                               "%player% locks "));
        lib_print_object_np (game, object);
        pf_buffer_string (filter, " with ");
        lib_print_object_np (game, key);
        pf_buffer_string (filter, ".\n");
        return TRUE;
      }

    case OBJ_LOCKED:
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object,
                                              " is already locked!\n",
                                              " are already locked!\n"));
      return TRUE;

    default:
      break;
    }

  /* The object isn't lockable. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't lock ",
                                         "I can't lock ",
                                         "%player% can't lock "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}


/*
 * lib_compare_subject()
 *
 * Compare a subject, comma or NUL terminated.  Helper for ask.
 */
static sc_bool
lib_compare_subject (const sc_char *subject, sc_int posn,
                     const sc_char *string)
{
  sc_int word_posn, string_posn;

  /* Skip any leading subject spaces. */
  for (word_posn = posn;
       subject[word_posn] != NUL && isspace (subject[word_posn]);)
    word_posn++;
  for (string_posn = 0;
       string[string_posn] != NUL && isspace (string[string_posn]);)
    string_posn++;

  /* Match characters from words with the string at position. */
  while (TRUE)
    {
      /* Any character mismatch means no match. */
      if (tolower (subject[word_posn]) != tolower (string[string_posn]))
        return FALSE;

      /* Move to next character in each. */
      word_posn++;
      string_posn++;

      /*
       * If at space, advance over whitespace in subjects list.  Stop when we
       * hit the end of the element or list.
       */
      while (isspace (subject[word_posn])
             && subject[word_posn] != COMMA && subject[word_posn] != NUL)
        subject++;

      /* Advance over whitespace in the current string too. */
      while (isspace (string[string_posn]) && string[string_posn] != NUL)
        string_posn++;

      /*
       * If we found the end of the subject, and the end of the current string,
       * we've matched.  If not at the end of the current string, though, only
       * a partial match.
       */
      if (subject[word_posn] == NUL || subject[word_posn] == COMMA)
        {
          if (string[string_posn] == NUL)
            break;
          else
            return FALSE;
        }
    }

  /* Matched in the loop; return TRUE. */
  return TRUE;
}


/*
 * lib_npc_reply_to()
 *
 * Reply for an NPC on a given topic.  Helper for ask.
 */
static sc_bool
lib_npc_reply_to (sc_gameref_t game, sc_int npc, sc_int topic)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_int task;
  const sc_char *response;

  /* Find any associated task to control response. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Topics";
  vt_key[3].integer = topic;
  vt_key[4].string = "Task";
  task = prop_get_integer (bundle, "I<-sisis", vt_key);

  /* Get the response, and print if anything there. */
  if (task > 0 && gs_task_done (game, task - 1))
    vt_key[4].string = "AltReply";
  else
    vt_key[4].string = "Reply";
  response = prop_get_string (bundle, "S<-sisis", vt_key);
  if (!sc_strempty (response))
    {
      pf_buffer_string (filter, response);
      pf_buffer_character (filter, '\n');
      return TRUE;
    }

  /* No response to this combination. */
  return FALSE;
}


/*
 * lib_cmd_ask_npc_about()
 *
 * Converse with NPC.
 */
sc_bool
lib_cmd_ask_npc_about (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[5];
  sc_int npc, topic_count, topic, topic_match, default_topic;
  sc_bool found, default_found, is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "ask", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  if (lib_trace)
    sc_trace ("Library: asking NPC %ld\n", npc);

  /* Get the topics the NPC converses about. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Topics";
  topic_count = prop_get_child_count (bundle, "I<-sis", vt_key);
  topic_match = default_topic = -1;
  found = default_found = FALSE;
  for (topic = 0; topic < topic_count; topic++)
    {
      const sc_char *subjects;
      sc_int posn;

      /* Get subject list for this topic. */
      vt_key[3].integer = topic;
      vt_key[4].string = "Subject";
      subjects = prop_get_string (bundle, "S<-sisis", vt_key);

      /* If this is the special "*" topic, note and continue. */
      if (!sc_strcasecmp (subjects, "*"))
        {
          if (lib_trace)
            sc_trace ("Library:_ \"*\" is %ld\n", topic);

          default_topic = topic;
          default_found = TRUE;
          continue;
        }

      /* Split into subjects by comma delimiter. */
      for (posn = 0; subjects[posn] != NUL;)
        {
          if (lib_trace)
            sc_trace ("Library:_ subject %s[%ld]\n", subjects, posn);

          /* See if this subject matches. */
          if (lib_compare_subject (subjects, posn, var_get_ref_text (vars)))
            {
              if (lib_trace)
                sc_trace ("Library:_ matched\n");

              topic_match = topic;
              found = TRUE;
              break;
            }

          /* Move to next subject, or end of list. */
          while (subjects[posn] != COMMA && subjects[posn] != NUL)
            posn++;
          if (subjects[posn] == COMMA)
            posn++;
        }
    }

  /* Handle any matched subject first, and "*" second. */
  if (found && lib_npc_reply_to (game, npc, topic_match))
    return TRUE;
  else if (default_found && lib_npc_reply_to (game, npc, default_topic))
    return TRUE;

  /* NPC has no response. */
  pf_new_sentence (filter);
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter,
                    lib_select_response (game,
                                " does not respond to your question.\n",
                                " does not respond to my question.\n",
                                " does not respond to %player%'s question.\n"));
  return TRUE;
}


/*
 * lib_check_put_in_recursion()
 *
 * Checks for infinite recursion when placing an object in an object.  Returns
 * TRUE if no recursion detected.
 */
static sc_bool
lib_check_put_in_recursion (sc_gameref_t game,
                            sc_int object, sc_int container, sc_bool report)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int check;

  /* Avoid the obvious possibility of infinite recursion. */
  if (container == object)
    {
      if (report)
        {
          pf_buffer_string (filter,
                            lib_select_response (game,
                                "You can't put an object inside itself!",
                                "I can't put an object inside itself!",
                                "%player% can't put an object inside itself!"));
        }
      return FALSE;
    }

  /* Avoid the subtle possibility of infinite recursion. */
  check = container;
  while (gs_object_position (game, check) == OBJ_ON_OBJECT
         || gs_object_position (game, check) == OBJ_IN_OBJECT)
    {
      check = gs_object_parent (game, check);
      if (check == object)
        {
          if (report)
            {
              pf_buffer_string (filter,
                                lib_select_response (game,
                                    "You can't put an object inside one",
                                    "I can't put an object inside one",
                                    "%player% can't put an object inside one"));
              pf_buffer_string (filter, " it's on or in!");
            }
          return FALSE;
        }
    }

  /* No infinite recursion detected. */
  return TRUE;
}


/*
 * lib_put_in_backend()
 *
 * Common backend handler for placing objects in containers.  Places all
 * objects currently referenced in the game into a container, trying game
 * commands first, and then moving other unhandled objects into the container.
 *
 * Objects to action are flagged in object_references; objects requested but
 * deemed not actionable are flagged in multiple_references.
 */
static void
lib_put_in_backend (sc_gameref_t game, sc_int container)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object_count, object, count, trail, capacity, maxsize;
  sc_bool has_printed;

  /*
   * Try game commands for all referenced objects first.  If any succeed,
   * remove that reference from the list.  At the same time, check for and
   * weed out any moves that result in infinite recursion.
   */
  has_printed = FALSE;
  object_count = gs_object_count (game);
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      /* Reject and remove attempts to place objects in themselves. */
      if (!lib_check_put_in_recursion (game, object, container, !has_printed))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
          continue;
        }

      if (lib_try_game_command_with_object (game,
                                            "put", object, "in", container))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
        }
    }

  /* Retrieve the container's limits. */
  maxsize = obj_get_container_maxsize (game, container);
  capacity = obj_get_container_capacity (game, container);

  /* Put in every object that remains referenced. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      /* If too big, or exceeds container limits, ignore for now. */
      if (obj_get_size (game, object) > maxsize)
        continue;
      else
        {
          sc_int other, contains;

          contains = 0;
          for (other = 0; other < gs_object_count (game); other++)
            {
              if (gs_object_position (game, other) == OBJ_IN_OBJECT
                  && gs_object_parent (game, other) == container)
                contains++;
            }
          if (contains >= capacity)
            continue;
        }

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You put ",
                                                     "I put ",
                                                     "%player% puts "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      gs_object_move_into (game, object, container);
      game->object_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You put ",
                                                 "I put ",
                                                 "%player% puts "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_string (filter, " inside ");
      lib_print_object_np (game, container);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  /*
   * Report objects not put in because of their size.  These objects remain in
   * standard references, as do objects rejected because of capacity limits.
   * By removing too large objects in this loop, we're left later on with just
   * the objects rejected by capacity limits.
   */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (!(obj_get_size (game, object) > maxsize))
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_new_sentence (filter);
              lib_print_object_np (game, trail);
            }
          else
            pf_buffer_string (filter, ", ");
        }
      trail = object;
      count++;

      game->object_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_new_sentence (filter);
          lib_print_object_np (game, trail);
          pf_buffer_string (filter,
                            lib_select_plurality (game, trail,
                                                  " is too big",
                                                  " are too big"));
        }
      else
        {
          pf_buffer_string (filter, " and ");
          lib_print_object_np (game, trail);
          pf_buffer_string (filter, " are too big");
        }
      pf_buffer_string (filter, " to fit inside ");
      lib_print_object_np (game, container);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  /*
   * Report objects not put in because the container is too full.  This should
   * be all remaining objects in standard references.
   */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_new_sentence (filter);
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->object_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_new_sentence (filter);
          lib_print_object_np (game, trail);
        }
      else
        {
          pf_buffer_string (filter, " and ");
          lib_print_object_np (game, trail);
        }
      pf_buffer_string (filter, " can't fit inside ");
      lib_print_object_np (game, container);
      pf_buffer_string (filter, " at the moment.");
    }
  has_printed |= count > 0;

  /* Note any remaining multiple references left out of the operation. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                   "You are not holding ",
                                                   "I am not holding ",
                                                   "%player% is not holding "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You are not holding ",
                                                 "I am not holding ",
                                                 "%player% is not holding "));
        }
      else
        pf_buffer_string (filter, " or ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
}


/*
 * lib_put_in_filter()
 * lib_put_in_not_container_filter()
 *
 * Helper functions for deciding if an object may be put in another this
 * context.  Returns TRUE if an object may be manipulated, FALSE otherwise.
 */
static sc_bool
lib_put_in_filter (sc_gameref_t game, sc_int object, sc_int unused)
{
  assert (unused == -1);

  return !obj_is_static (game, object)
         && gs_object_position (game, object) == OBJ_HELD_PLAYER;
}

static sc_bool
lib_put_in_not_container_filter (sc_gameref_t game,
                                 sc_int object, sc_int container)
{
  return lib_put_in_filter (game, object, -1) && object != container;
}


/*
 * lib_put_in_is_valid()
 *
 * Validate the container requested in "put in" commands.
 */
static sc_bool
lib_put_in_is_valid (sc_gameref_t game, sc_int container)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Verify that the container object is a container. */
  if (!obj_is_container (game, container))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                        "You can't put anything inside ",
                                        "I can't put anything inside ",
                                        "%player% can't put anything inside "));
      lib_print_object_np (game, container);
      pf_buffer_string (filter, "!\n");
      return FALSE;
    }

  /* If the container is closed, reject now. */
  if (gs_object_openness (game, container) > OBJ_OPEN)
    {
      pf_new_sentence (filter);
      lib_print_object_np (game, container);
      pf_buffer_string (filter,
                        lib_select_plurality (game, container, " is", " are"));
      if (gs_object_openness (game, container) == OBJ_LOCKED)
        pf_buffer_string (filter, " locked!\n");
      else
        pf_buffer_string (filter, " closed!\n");
      return FALSE;
    }

  /* Container is a valid target for "put in". */
  return TRUE;
}


/*
 * lib_cmd_put_all_in()
 *
 * Put all objects currently held by the player into a container.
 */
sc_bool
lib_cmd_put_all_in (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int container, objects;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  container = lib_disambiguate_object (game, "put that into", &is_ambiguous);
  if (container == -1)
    return is_ambiguous;

  /* Validate the container object to take from. */
  if (!lib_put_in_is_valid (game, container))
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_put_in_not_container_filter,
                                       container, NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_put_in_backend (game, container);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You're not carrying anything",
                                           "I'm not carrying anything",
                                           "%player%'s not carrying anything"));
      if (obj_indirectly_held_by_player (game, container))
        pf_buffer_string (filter, " else");
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_put_in_except_multiple()
 *
 * Put all objects currently held by the player into an object, excepting
 * those listed in %text%.
 */
sc_bool
lib_cmd_put_in_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int container, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  container = lib_disambiguate_object (game, "put that into", &is_ambiguous);
  if (container == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "retain",
                                   lib_put_in_not_container_filter,
                                   container, &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Validate the container object to put into. */
  if (!lib_put_in_is_valid (game, container))
    return TRUE;

  /* As a special case, complain about requests to retain the container. */
  if (game->multiple_references[container])
    {
      pf_buffer_string (filter,
                        "I only understood you as far as wanting to retain ");
      lib_print_object_np (game, container);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_put_in_not_container_filter,
                                     container, &references);
  if (objects > 0 || references > 0)
    lib_put_in_backend (game, container);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not holding anything",
                                           "I am not holding anything",
                                           "%player% is not holding anything"));
      if (objects == 0)
        pf_buffer_string (filter, " else");
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_put_in_multiple()
 *
 * Put all objects currently held by the player and listed in %text% into an
 * object.
 */
sc_bool
lib_cmd_put_in_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int container, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  container = lib_disambiguate_object (game, "put that into", &is_ambiguous);
  if (container == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "move",
                                   lib_put_in_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Validate the container object to put into. */
  if (!lib_put_in_is_valid (game, container))
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_put_in_filter, -1,
                                       &references);
  if (objects > 0 || references > 0)
    lib_put_in_backend (game, container);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                          "You are not holding anything.",
                                          "I am not holding anything.",
                                          "%player% is not holding anything."));
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_check_put_on_recursion()
 *
 * Checks for infinite recursion when placing an object on an object.  Returns
 * TRUE if no recursion detected.
 */
static sc_bool
lib_check_put_on_recursion (sc_gameref_t game,
                            sc_int object, sc_int supporter, sc_bool report)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int check;

  /* Avoid the obvious possibility of infinite recursion. */
  if (supporter == object)
    {
      if (report)
        {
          pf_buffer_string (filter,
                            lib_select_response (game,
                                  "You can't put an object onto itself!",
                                  "I can't put an object onto itself!",
                                  "%player% can't put an object onto itself!"));
        }
      return FALSE;
    }

  /* Avoid the subtle possibility of infinite recursion. */
  check = supporter;
  while (gs_object_position (game, check) == OBJ_ON_OBJECT
         || gs_object_position (game, check) == OBJ_IN_OBJECT)
    {
      check = gs_object_parent (game, check);
      if (check == object)
        {
          if (report)
            {
              pf_buffer_string (filter,
                                lib_select_response (game,
                                      "You can't put an object onto one",
                                      "I can't put an object onto one",
                                      "%player% can't put an object onto one"));
              pf_buffer_string (filter, " it's on or in!");
            }
          return FALSE;
        }
    }

  /* No infinite recursion detected. */
  return TRUE;
}


/*
 * lib_put_on_backend()
 *
 * Common backend handler for placing objects on supporters.  Places all
 * objects currently referenced in the game onto a supporter, trying game
 * commands first, and then moving other unhandled objects onto the supporter.
 *
 * Objects to action are flagged in object_references; objects requested but
 * deemed not actionable are flagged in multiple_references.
 */
static void
lib_put_on_backend (sc_gameref_t game, sc_int supporter)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object_count, object, count, trail;
  sc_bool has_printed;

  /*
   * Try game commands for all referenced objects first.  If any succeed,
   * remove that reference from the list.  At the same time, check for and
   * weed out any moves that result in infinite recursion.
   */
  has_printed = FALSE;
  object_count = gs_object_count (game);
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      /* Reject and remove attempts to place objects on themselves. */
      if (!lib_check_put_on_recursion (game, object, supporter, !has_printed))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
          continue;
        }

      if (lib_try_game_command_with_object (game,
                                            "put", object, "on", supporter))
        {
          game->object_references[object] = FALSE;
          has_printed = TRUE;
        }
    }

  /* Put on every object that remains referenced. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->object_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                     "You put ",
                                                     "I put ",
                                                     "%player% puts "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      gs_object_move_onto (game, object, supporter);
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You put ",
                                                 "I put ",
                                                 "%player% puts "));
        }
      else
        pf_buffer_string (filter, " and ");
      lib_print_object_np (game, trail);
      pf_buffer_string (filter, " onto ");
      lib_print_object_np (game, supporter);
      pf_buffer_character (filter, '.');
    }
  has_printed |= count > 0;

  /* Note any remaining multiple references left out of the operation. */
  count = 0;
  trail = -1;
  for (object = 0; object < object_count; object++)
    {
      if (!game->multiple_references[object])
        continue;

      if (count > 0)
        {
          if (count == 1)
            {
              if (has_printed)
                pf_buffer_string (filter, "  ");
              pf_buffer_string (filter,
                                lib_select_response (game,
                                                   "You are not holding ",
                                                   "I am not holding ",
                                                   "%player% is not holding "));
            }
          else
            pf_buffer_string (filter, ", ");
          lib_print_object_np (game, trail);
        }
      trail = object;
      count++;

      game->multiple_references[object] = FALSE;
    }

  if (count >= 1)
    {
      if (count == 1)
        {
          if (has_printed)
            pf_buffer_string (filter, "  ");
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 "You are not holding ",
                                                 "I am not holding ",
                                                 "%player% is not holding "));
        }
      else
        pf_buffer_string (filter, " or ");
      lib_print_object_np (game, trail);
      pf_buffer_character (filter, '.');
    }
}


/*
 * lib_put_on_filter()
 * lib_put_on_not_supporter_filter()
 *
 * Helper functions for deciding if an object may be put on another this
 * context.  Returns TRUE if an object may be manipulated, FALSE otherwise.
 */
static sc_bool
lib_put_on_filter (sc_gameref_t game, sc_int object, sc_int unused)
{
  assert (unused == -1);

  return !obj_is_static (game, object)
         && gs_object_position (game, object) == OBJ_HELD_PLAYER;
}

static sc_bool
lib_put_on_not_supporter_filter (sc_gameref_t game,
                                 sc_int object, sc_int supporter)
{
  return lib_put_on_filter (game, object, -1) && object != supporter;
}


/*
 * lib_put_on_is_valid()
 *
 * Validate the supporter requested in "put on" commands.
 */
static sc_bool
lib_put_on_is_valid (sc_gameref_t game, sc_int supporter)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Verify that the supporter object is a supporter. */
  if (!obj_is_surface (game, supporter))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                            "You can't put anything on ",
                                            "I can't put anything on ",
                                            "%player% can't put anything on "));
      lib_print_object_np (game, supporter);
      pf_buffer_string (filter, "!\n");
      return FALSE;
    }

  /* Surface is a valid target for "put on". */
  return TRUE;
}


/*
 * lib_cmd_put_all_on()
 *
 * Put all objects currently held by the player onto a supporter.
 */
sc_bool
lib_cmd_put_all_on (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int supporter, objects;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  supporter = lib_disambiguate_object (game, "put that onto", &is_ambiguous);
  if (supporter == -1)
    return is_ambiguous;

  /* Validate the supporter object to take from. */
  if (!lib_put_on_is_valid (game, supporter))
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  gs_set_multiple_references (game);
  objects = lib_apply_multiple_filter (game,
                                       lib_put_on_not_supporter_filter,
                                       supporter, NULL);
  gs_clear_multiple_references (game);
  if (objects > 0)
    lib_put_on_backend (game, supporter);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You're not carrying anything",
                                           "I'm not carrying anything",
                                           "%player%'s not carrying anything"));
      if (obj_indirectly_held_by_player (game, supporter))
        pf_buffer_string (filter, " else");
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_put_on_except_multiple()
 *
 * Put all objects currently held by the player onto an object, excepting
 * those listed in %text%.
 */
sc_bool
lib_cmd_put_on_except_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int supporter, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  supporter = lib_disambiguate_object (game, "put that onto", &is_ambiguous);
  if (supporter == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "retain",
                                   lib_put_on_not_supporter_filter,
                                   supporter, &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Validate the supporter object to put into. */
  if (!lib_put_on_is_valid (game, supporter))
    return TRUE;

  /* As a special case, complain about requests to retain the supporter. */
  if (game->multiple_references[supporter])
    {
      pf_buffer_string (filter,
                        "I only understood you as far as wanting to retain ");
      lib_print_object_np (game, supporter);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_except_filter (game,
                                     lib_put_on_not_supporter_filter,
                                     supporter, &references);
  if (objects > 0 || references > 0)
    lib_put_on_backend (game, supporter);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                           "You are not holding anything",
                                           "I am not holding anything",
                                           "%player% is not holding anything"));
      if (objects == 0)
        pf_buffer_string (filter, " else");
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_put_on_multiple()
 *
 * Put all objects currently held by the player and listed in %text% onto an
 * object.
 */
sc_bool
lib_cmd_put_on_multiple (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int supporter, objects, references;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  supporter = lib_disambiguate_object (game, "put that onto", &is_ambiguous);
  if (supporter == -1)
    return is_ambiguous;

  /* Parse the multiple objects list to find retain target objects. */
  if (!lib_parse_multiple_objects (game, "move",
                                   lib_put_on_filter, -1,
                                   &references))
    return FALSE;
  else if (references == 0)
    return TRUE;

  /* Validate the supporter object to put into. */
  if (!lib_put_on_is_valid (game, supporter))
    return TRUE;

  /* Filter objects into references, then handle with the backend. */
  objects = lib_apply_multiple_filter (game,
                                       lib_put_on_filter, -1,
                                       &references);
  if (objects > 0 || references > 0)
    lib_put_on_backend (game, supporter);
  else
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                          "You are not holding anything.",
                                          "I am not holding anything.",
                                          "%player% is not holding anything."));
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}


/*
 * lib_cmd_read_object()
 * lib_cmd_read_other()
 *
 * Attempt to read the referenced object, or something else.
 */
sc_bool
lib_cmd_read_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  sc_int object, task;
  sc_bool is_readable, is_ambiguous;
  const sc_char *readtext, *description;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "read", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Verify that the object is readable. */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Readable";
  is_readable = prop_get_boolean (bundle, "B<-sis", vt_key);
  if (!is_readable)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't read ",
                                             "I can't read ",
                                             "%player% can't read "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, "!\n");
      return TRUE;
    }

  /* Get and print the object's read text, if any. */
  vt_key[2].string = "ReadText";
  readtext = prop_get_string (bundle, "S<-sis", vt_key);
  if (!sc_strempty (readtext))
    {
      pf_buffer_string (filter, readtext);
      pf_buffer_character (filter, '\n');
      return TRUE;
    }

  /* Degrade to a shortened object examine. */
  vt_key[2].string = "Task";
  task = prop_get_integer (bundle, "I<-sis", vt_key) - 1;

  /* Select either the main or the alternate description. */
  if (task >= 0 && gs_task_done (game, task))
    vt_key[2].string = "AltDesc";
  else
    vt_key[2].string = "Description";

  /* Print the description, or a "nothing special" default. */
  description = prop_get_string (bundle, "S<-sis", vt_key);
  if (!sc_strempty (description))
    pf_buffer_string (filter, description);
  else
    {
      pf_buffer_string (filter, "There is nothing special about ");
      lib_print_object_np (game, object);
      pf_buffer_character (filter, '.');
    }

  pf_buffer_character (filter, '\n');
  return TRUE;
}

sc_bool
lib_cmd_read_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Reject the attempt. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You see no such thing.\n",
                                         "I see no such thing.\n",
                                         "%player% sees no such thing.\n"));
  return TRUE;
}


/*
 * lib_cmd_attack_npc()
 * lib_cmd_attack_npc_with()
 *
 * Attempt to attack an NPC, with and without weaponry.
 */
sc_bool
lib_cmd_attack_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int npc;
  sc_bool is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "attack", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  /* Print a standard response. */
  pf_new_sentence (filter);
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter,
                    lib_select_response (game,
                                      " avoids your feeble attempts.\n",
                                      " avoids my feeble attempts.\n",
                                      " avoids %player%'s feeble attempts.\n"));
  return TRUE;
}

sc_bool
lib_cmd_attack_npc_with (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_int object, npc;
  sc_vartype_t vt_key[3];
  sc_bool weapon, is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "attack", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "attack with", NULL);
  if (object == -1)
    return TRUE;

  /* Ensure the referenced object is held. */
  if (gs_object_position (game, object) != OBJ_HELD_PLAYER)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You are not holding ",
                                             "I am not holding ",
                                             "%player% is not holding "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Check for static object moved to player by event. */
  if (obj_is_static (game, object))
    {
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object, " is", " are"));
      pf_buffer_string (filter, " not a weapon.\n");
      return TRUE;
    }

  /* Print standard response depending on if the object is a weapon. */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Weapon";
  weapon = prop_get_boolean (bundle, "B<-sis", vt_key);
  if (weapon)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You swing at ",
                                             "I swing at ",
                                             "%player% swings at "));
      lib_print_npc_np (game, npc);
      pf_buffer_string (filter, " with ");
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             " but you miss.\n",
                                             " but I miss.\n",
                                             " but misses.\n"));
    }
  else
    {
      /*
       * TODO Adrift uses "affective" [sic] here.  Should SCARE be right, or
       * bug-compatible?
       */
      pf_buffer_string (filter, "I don't think ");
      lib_print_object_np (game, object);
      pf_buffer_string (filter, " would be a very effective weapon.\n");
    }
  return TRUE;
}


/*
 * lib_cmd_kiss_npc()
 * lib_cmd_kiss_object()
 * lib_cmd_kiss_other()
 *
 * Reject romantic advances in all cases.
 */
sc_bool
lib_cmd_kiss_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  sc_int npc, gender;
  sc_bool is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "kiss", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  vt_key[0].string = "NPCs";
  vt_key[1].integer = npc;
  vt_key[2].string = "Gender";
  gender = prop_get_integer (bundle, "I<-sis", vt_key);

  switch (gender)
    {
    case NPC_MALE:
      pf_buffer_string (filter, "I'm not sure he would appreciate that!\n");
      break;

    case NPC_FEMALE:
      pf_buffer_string (filter, "I'm not sure she would appreciate that!\n");
      break;

    case NPC_NEUTER:
      pf_buffer_string (filter, "I'm not sure it would appreciate that!\n");
      break;

    default:
      sc_error ("lib_cmd_kiss_npc: unknown gender, %ld\n", gender);
    }
  return TRUE;
}

sc_bool
lib_cmd_kiss_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "kiss", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  pf_buffer_string (filter, "I'm not sure ");
  lib_print_object_np (game, object);
  pf_buffer_string (filter, " would appreciate that.\n");
  return TRUE;
}

sc_bool
lib_cmd_kiss_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Reject this attempt. */
  pf_buffer_string (filter, "I'm not sure it would appreciate that.\n");
  return TRUE;
}


/*
 * lib_cmd_buy_object()
 * lib_cmd_buy_other()
 *
 * Standard responses to attempts to buy something.
 */
sc_bool
lib_cmd_buy_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "buy", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  pf_buffer_string (filter, "I don't think ");
  lib_print_object_np (game, object);
  pf_buffer_string (filter,
                    lib_select_plurality (game, object, " is", " are"));
  pf_buffer_string (filter, " for sale.\n");
  return TRUE;
}

sc_bool
lib_cmd_buy_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Reject this attempt. */
  pf_buffer_string (filter, "I don't think that is for sale.\n");
  return TRUE;
}


/*
 * lib_cmd_break_object()
 * lib_cmd_break_other()
 *
 * Standard responses to attempts to break something.
 */
sc_bool
lib_cmd_break_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "break", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You might need ",
                                         "I might need ",
                                         "%player% might need "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

sc_bool
lib_cmd_break_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Reject this attempt. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You might need that.\n",
                                         "I might need that.\n",
                                         "%player% might need that.\n"));
  return TRUE;
}


/*
 * lib_cmd_smell_object()
 * lib_cmd_smell_other()
 *
 * Standard responses to attempts to smell something.
 */
sc_bool
lib_cmd_smell_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "smell", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  pf_new_sentence (filter);
  lib_print_object_np (game, object);
  pf_buffer_string (filter, " smells normal.\n");
  return TRUE;
}

sc_bool
lib_cmd_smell_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Reject this attempt. */
  pf_buffer_string (filter, "That smells normal.\n");
  return TRUE;
}


/*
 * lib_cmd_sell_object()
 * lib_cmd_sell_other()
 *
 * Standard responses to attempts to sell something.
 */
sc_bool
lib_cmd_sell_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "sell", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject this attempt. */
  pf_buffer_string (filter, "No-one is interested in buying ");
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

sc_bool
lib_cmd_sell_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "No-one is interested in buying that.\n");
  return TRUE;
}


/*
 * lib_cmd_eat_object()
 *
 * Consume edible objects.
 */
sc_bool
lib_cmd_eat_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[3];
  sc_int object;
  sc_bool edible, is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "eat", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Check that we have the object to eat. */
  if (gs_object_position (game, object) != OBJ_HELD_PLAYER)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You are not holding ",
                                             "I am not holding ",
                                             "%player% is not holding "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Check for static object moved to player by event. */
  if (obj_is_static (game, object))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't eat ",
                                             "I can't eat ",
                                             "%player% can't eat "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Is this object inedible? */
  vt_key[0].string = "Objects";
  vt_key[1].integer = object;
  vt_key[2].string = "Edible";
  edible = prop_get_boolean (bundle, "B<-sis", vt_key);
  if (!edible)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't eat ",
                                             "I can't eat ",
                                             "%player% can't eat "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, ".\n");
      return TRUE;
    }

  /* Confirm, and hide the object. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You eat ",
                                         "I eat ", "%player% eats "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter,
                    ".  Not bad, but it could do with a pinch of salt!\n");
  gs_object_make_hidden (game, object);
  return TRUE;
}


/* Enumerated sit/stand/lie types. */
enum
{ OBJ_STANDABLE_MASK = 1 << 0,
  OBJ_LIEABLE_MASK = 1 << 1
};
typedef enum
{ MOVE_SIT, MOVE_SIT_FLOOR,
  MOVE_STAND, MOVE_STAND_FLOOR,
  MOVE_LIE, MOVE_LIE_FLOOR
} sc_movement_t;

/*
 * lib_stand_sit_lie()
 *
 * Central handler for stand, sit, and lie commands.
 */
static sc_bool
lib_stand_sit_lie (sc_gameref_t game, sc_movement_t movement)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_int object, position;
  const sc_char *already_doing_that, *success_message;

  /* Initialize variables to avoid gcc warnings. */
  object = -1;
  already_doing_that = FALSE;
  success_message = FALSE;
  position = 0;

  /* Get a target object for movement, -1 if floor. */
  switch (movement)
    {
    case MOVE_STAND:
    case MOVE_SIT:
    case MOVE_LIE:
      {
        const sc_char *disambiguate, *cant_do_that;
        sc_int sit_lie_flags, movement_mask;
        sc_vartype_t vt_key[3];
        sc_bool is_ambiguous;

        /* Initialize variables to avoid gcc warnings. */
        disambiguate = NULL;
        cant_do_that = NULL;
        movement_mask = 0;

        /* Set disambiguation and not amenable messages. */
        switch (movement)
          {
          case MOVE_STAND:
            disambiguate = "stand on";
            cant_do_that = lib_select_response (game,
                                                "You can't stand on ",
                                                "I can't stand on ",
                                                "%player% can't stand on ");
            movement_mask = OBJ_STANDABLE_MASK;
            break;
          case MOVE_SIT:
            disambiguate = "sit on";
            cant_do_that = lib_select_response (game,
                                                "You can't sit on ",
                                                "I can't sit on ",
                                                "%player% can't sit on ");
            movement_mask = OBJ_STANDABLE_MASK;
            break;
          case MOVE_LIE:
            disambiguate = "lie on";
            cant_do_that = lib_select_response (game,
                                                "You can't lie on ",
                                                "I can't lie on ",
                                                "%player% can't lie on ");
            movement_mask = OBJ_LIEABLE_MASK;
            break;
          default:
            sc_fatal ("lib_sit_stand_lie:"
                      " movement error, %ld\n", (sc_int) movement);
          }

        /* Get the referenced object; if none, consider complete. */
        object = lib_disambiguate_object (game, disambiguate, &is_ambiguous);
        if (object == -1)
          return is_ambiguous;

        /* Verify the referenced object is amenable. */
        vt_key[0].string = "Objects";
        vt_key[1].integer = object;
        vt_key[2].string = "SitLie";
        sit_lie_flags = prop_get_integer (bundle, "I<-sis", vt_key);
        if (!(sit_lie_flags & movement_mask))
          {
            pf_buffer_string (filter, cant_do_that);
            lib_print_object_np (game, object);
            pf_buffer_string (filter, ".\n");
            return TRUE;
          }
        break;
      }

    case MOVE_STAND_FLOOR:
    case MOVE_SIT_FLOOR:
    case MOVE_LIE_FLOOR:
      object = -1;
      break;

    default:
      sc_fatal ("lib_sit_stand_lie:"
                " movement error, %ld\n", (sc_int) movement);
    }

  /* Set up confirmation messages and position. */
  switch (movement)
    {
    case MOVE_STAND:
      already_doing_that = lib_select_response (game,
                                            "You are already standing on ",
                                            "I am already standing on ",
                                            "%player% is already standing on ");
      success_message = lib_select_response (game,
                                             "You stand on ",
                                             "I stand on ",
                                             "%player% stands on ");
      position = 0;
      break;

    case MOVE_STAND_FLOOR:
      already_doing_that = lib_select_response (game,
                                             "You are already standing!\n",
                                             "I am already standing!\n",
                                             "%player% is already standing!\n");
      success_message = lib_select_response (game,
                                             "You stand up",
                                             "I stand up",
                                             "%player% stands up");
      position = 0;
      break;

    case MOVE_SIT:
      already_doing_that = lib_select_response (game,
                                             "You are already sitting on ",
                                             "I am already sitting on ",
                                             "%player% is already sitting on ");
      if (gs_playerposition (game) == 2)
        success_message = lib_select_response (game,
                                               "You sit up on ",
                                               "I sit up on ",
                                               "%player% sits up on ");
      else
        success_message = lib_select_response (game,
                                               "You sit down on ",
                                               "I sit down on ",
                                               "%player% sits down on ");
      position = 1;
      break;

    case MOVE_SIT_FLOOR:
      already_doing_that = lib_select_response (game,
                                         "You are already sitting down.\n",
                                         "I am already sitting down.\n",
                                         "%player% is already sitting down.\n");
      if (gs_playerposition (game) == 2)
        success_message = lib_select_response (game,
                                           "You sit up on the ground.\n",
                                           "I sit up on the ground.\n",
                                           "%player% sits up on the ground.\n");
      else
        success_message = lib_select_response (game,
                                         "You sit down on the ground.\n",
                                         "I sit down on the ground.\n",
                                         "%player% sits down on the ground.\n");
      position = 1;
      break;

    case MOVE_LIE:
      already_doing_that = lib_select_response (game,
                                               "You are already lying on ",
                                               "I am already lying on ",
                                               "%player% is already lying on ");
      success_message = lib_select_response (game,
                                             "You lie down on ",
                                             "I lie down on ",
                                             "%player% lies down on ");
      position = 2;
      break;

    case MOVE_LIE_FLOOR:
      already_doing_that = lib_select_response (game,
                                           "You are already lying down.\n",
                                           "I am already lying down.\n",
                                           "%player% is already lying down.\n");
      success_message = lib_select_response (game,
                                         "You lie down on the ground.\n",
                                         "I lie down on the ground.\n",
                                         "%player% lies down on the ground.\n");
      position = 2;
      break;

    default:
      sc_fatal ("lib_sit_stand_lie:"
                " movement error, %ld\n", (sc_int) movement);
    }

  /* See if already doing this. */
  if (gs_playerposition (game) == position && gs_playerparent (game) == object)
    {
      pf_buffer_string (filter, already_doing_that);
      if (object != -1)
        {
          lib_print_object_np (game, object);
          pf_buffer_string (filter, ".\n");
        }
      return TRUE;
    }

  /* Confirm movement, with special case for getting off an object. */
  pf_buffer_string (filter, success_message);
  if (movement == MOVE_STAND_FLOOR)
    {
      if (gs_playerparent (game) != -1)
        {
          pf_buffer_string (filter, " from ");
          lib_print_object_np (game, gs_playerparent (game));
        }
      pf_buffer_string (filter, ".\n");
    }
  else if (object != -1)
    {
      lib_print_object_np (game, object);
      pf_buffer_string (filter, ".\n");
    }

  /* Adjust player position and parent. */
  gs_set_playerposition (game, position);
  gs_set_playerparent (game, object);
  return TRUE;
}


/*
 * lib_cmd_stand_*
 * lib_cmd_sit_*
 * lib_cmd_lie_*
 *
 * Stand, sit, or lie on an object, or on the floor.
 */
sc_bool
lib_cmd_stand_on_object (sc_gameref_t game)
{
  return lib_stand_sit_lie (game, MOVE_STAND);
}

sc_bool
lib_cmd_stand_on_floor (sc_gameref_t game)
{
  return lib_stand_sit_lie (game, MOVE_STAND_FLOOR);
}

sc_bool
lib_cmd_sit_on_object (sc_gameref_t game)
{
  return lib_stand_sit_lie (game, MOVE_SIT);
}

sc_bool
lib_cmd_sit_on_floor (sc_gameref_t game)
{
  return lib_stand_sit_lie (game, MOVE_SIT_FLOOR);
}

sc_bool
lib_cmd_lie_on_object (sc_gameref_t game)
{
  return lib_stand_sit_lie (game, MOVE_LIE);
}

sc_bool
lib_cmd_lie_on_floor (sc_gameref_t game)
{
  return lib_stand_sit_lie (game, MOVE_LIE_FLOOR);
}


/*
 * lib_cmd_get_off_object()
 * lib_cmd_get_off()
 *
 * Get off whatever supporter the player rests on.
 */
sc_bool
lib_cmd_get_off_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object; if none, consider complete. */
  object = lib_disambiguate_object (game, "get off", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Reject the attempt if the player is not on the given object. */
  if (gs_playerparent (game) != object)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You are not on ",
                                             "I am not on ",
                                             "%player% is not on "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, "!\n");
      return TRUE;
    }

  /* Confirm movement. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You get off ", "I get off ",
                                         "%player% gets off "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");

  /* Adjust player position and parent. */
  gs_set_playerposition (game, 0);
  gs_set_playerparent (game, -1);
  return TRUE;
}

sc_bool
lib_cmd_get_off (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Reject the attempt if the player is not on anything. */
  if (gs_playerparent (game) == -1)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You are not on anything!\n",
                                             "I am not on anything!\n",
                                             "%player% is not on anything!\n"));
      return TRUE;
    }

  /* Confirm movement. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You get off ", "I get off ",
                                         "%player% gets off "));
  lib_print_object_np (game, gs_playerparent (game));
  pf_buffer_string (filter, ".\n");

  /* Adjust player position and parent. */
  gs_set_playerposition (game, 0);
  gs_set_playerparent (game, -1);
  return TRUE;
}


/*
 * lib_cmd_save()
 * lib_cmd_restore()
 *
 * Save/restore a game.
 */
sc_bool
lib_cmd_save (sc_gameref_t game)
{
  if (if_confirm (SC_CONF_SAVE))
    {
      if (ser_save_game_prompted (game))
        if_print_string ("Ok.\n");
      else
        if_print_string ("Save failed.\n");
    }

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_restore (sc_gameref_t game)
{
  if (if_confirm (SC_CONF_RESTORE))
    {
      if (ser_load_game_prompted (game))
        {
          if_print_string ("Ok.\n");
          game->is_running = FALSE;
          game->do_restore = TRUE;
        }
      else
        if_print_string ("Restore failed.\n");
    }

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_locate_object()
 * lib_cmd_locate_npc()
 *
 * Display the location of a selected object, and selected NPC.
 */
sc_bool
lib_cmd_locate_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int index_, count, object, room, position, parent;

  game->is_admin = TRUE;

  /*
   * Filter to remove unseen object references.  Note that this is different
   * from NPCs, who we acknowledge even when unseen.
   */
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (!gs_object_seen (game, index_))
        game->object_references[index_] = FALSE;
    }

  /* Count the number of objects referenced by the last command. */
  count = 0;
  object = -1;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (game->object_references[index_])
        {
          count++;
          object = index_;
        }
    }

  /*
   * If no objects identified, be coy about revealing anything; if more than
   * one, be vague.
   */
  if (count == 0)
    {
      pf_buffer_string (filter, "I don't know where that is.\n");
      return TRUE;
    }
  else if (count > 1)
    {
      pf_buffer_string (filter,
                        "Please be more clear about what you want to"
                        " locate.\n");
      return TRUE;
    }

  /*
   * The reference is unambiguous, so we're responsible for noting it in
   * variables.  Disambiguation would normally do this for us, but we just
   * bypassed it.
   */
  var_set_ref_object (vars, object);

  /* See if we can print a message based on position and parent. */
  position = gs_object_position (game, object);
  parent = gs_object_parent (game, object);
  switch (position)
    {
    case OBJ_HIDDEN:
      if (!obj_is_static (game, object))
        {
          pf_buffer_string (filter, "I don't know where that is.\n");
          return TRUE;
        }
      break;

    case OBJ_HELD_PLAYER:
      pf_new_sentence (filter);
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You are carrying ",
                                             "I am carrying ",
                                             "%player% is carrying "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, "!\n");
      return TRUE;

    case OBJ_WORN_PLAYER:
      pf_new_sentence (filter);
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You are wearing ",
                                             "I am wearing ",
                                             "%player% is wearing "));
      lib_print_object_np (game, object);
      pf_buffer_string (filter, "!\n");
      return TRUE;

    case OBJ_HELD_NPC:
    case OBJ_WORN_NPC:
      if (gs_npc_seen (game, parent))
        {
          pf_new_sentence (filter);
          lib_print_npc_np (game, parent);
          pf_buffer_string (filter,
                            (position == OBJ_HELD_NPC)
                              ? " is holding " : " is wearing ");
          lib_print_object_np (game, object);
          pf_buffer_string (filter, ".\n");
        }
      else
        {
          pf_buffer_string (filter, "I don't know where that is.\n");
        }
      return TRUE;

    case OBJ_PART_NPC:
      if (parent == -1)
        {
          pf_new_sentence (filter);
          lib_print_object_np (game, object);
          pf_buffer_string (filter,
                            lib_select_plurality (game, object, " is", " are"));
          pf_buffer_string (filter,
                            lib_select_response (game,
                                                 " a part of you!\n",
                                                 " a part of me!\n",
                                                 " a part of %player%!\n"));
        }
      else
        {
          if (gs_npc_seen (game, parent))
            {
              pf_new_sentence (filter);
              lib_print_object_np (game, object);
              pf_buffer_string (filter,
                                lib_select_plurality (game, object,
                                                      " is", " are"));
              pf_buffer_string (filter, " a part of ");
              lib_print_npc_np (game, parent);
              pf_buffer_string (filter, ".\n");
            }
          else
            {
              pf_buffer_string (filter, "I don't know where that is.\n");
            }
        }
      return TRUE;

    case OBJ_ON_OBJECT:
    case OBJ_IN_OBJECT:
      if (gs_object_seen (game, parent))
        {
          pf_new_sentence (filter);
          lib_print_object_np (game, object);
          pf_buffer_string (filter,
                            lib_select_plurality (game, object, " is", " are"));
          pf_buffer_string (filter,
                            (position == OBJ_ON_OBJECT) ? " on " : " inside ");
          lib_print_object_np (game, parent);
          pf_buffer_string (filter, ".\n");
        }
      else
        {
          pf_buffer_string (filter, "I don't know where that is.\n");
        }
      return TRUE;
    }

  /*
   * Object is either static unmoved, or dynamic and on the floor of a room.
   * Check each room for the object, stopping on first found.
   */
  for (room = 0; room < gs_room_count (game); room++)
    {
      if (obj_indirectly_in_room (game, object, room))
        break;
    }
  if (room == gs_room_count (game))
    {
      pf_buffer_string (filter, "I don't know where that is.\n");
      return TRUE;
    }

  /* Check that this room's been visited by the player. */
  if (!gs_room_seen (game, room))
    {
      pf_new_sentence (filter);
      lib_print_object_np (game, object);
      pf_buffer_string (filter,
                        lib_select_plurality (game, object, " is", " are"));
      pf_buffer_string (filter,
                        lib_select_response (game,
                             " somewhere that you haven't been yet.\n",
                             " somewhere that I haven't been yet.\n",
                             " somewhere that %player% hasn't been yet.\n"));
      return TRUE;
    }

  /* Print the details of the object's room. */
  pf_new_sentence (filter);
  lib_print_object_np (game, object);
  pf_buffer_string (filter, " -- ");
  pf_buffer_string (filter, lib_get_room_name (game, room));
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

sc_bool
lib_cmd_locate_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int index_, count, npc, room;

  game->is_admin = TRUE;

  /* Count the number of NPCs referenced by the last command. */
  count = 0;
  npc = -1;
  for (index_ = 0; index_ < gs_npc_count (game); index_++)
    {
      if (game->npc_references[index_])
        {
          count++;
          npc = index_;
        }
    }

  /*
   * If no NPCs identified, be coy about revealing anything; if more than one,
   * be vague.  The "... where that is..." is the correct message even for
   * NPCs -- it's the same response as for lib_locate_other().
   */
  if (count == 0)
    {
      pf_buffer_string (filter, "I don't know where that is.\n");
      return TRUE;
    }
  else if (count > 1)
    {
      pf_buffer_string (filter,
                        "Please be more clear about who you want to locate.\n");
      return TRUE;
    }

  /*
   * The reference is unambiguous, so we're responsible for noting it in
   * variables.  Disambiguation would normally do this for us, but we just
   * bypassed it.
   */
  var_set_ref_character (vars, npc);

  /* See if this NPC has been seen yet. */
  if (!gs_npc_seen (game, npc))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You haven't seen ",
                                             "I haven't seen ",
                                             "%player% hasn't seen "));
      lib_print_npc_np (game, npc);
      pf_buffer_string (filter, " yet!\n");
      return TRUE;
    }

  /* Check each room for the NPC, stopping on first found. */
  for (room = 0; room < gs_room_count (game); room++)
    {
      if (npc_in_room (game, npc, room))
        break;
    }
  if (room == gs_room_count (game))
    {
      pf_buffer_string (filter, "I don't know where ");
      lib_print_npc_np (game, npc);
      pf_buffer_string (filter, " is.\n");
      return TRUE;
    }

  /* Check that this room's been visited by the player. */
  if (!gs_room_seen (game, room))
    {
      lib_print_npc_np (game, npc);
      pf_buffer_string (filter,
                        lib_select_response (game,
                             " is somewhere that you haven't been yet.\n",
                             " is somewhere that I haven't been yet.\n",
                             " is somewhere that %player% hasn't been yet.\n"));
      return TRUE;
    }

  /* Print the location, and smart-alec response. */
  pf_new_sentence (filter);
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter, " -- ");
  pf_buffer_string (filter, lib_get_room_name (game, room));
#if 0
  if (room == gs_playerroom (game))
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                         "  (Right next to you, silly!)",
                                         "  (Right next to me, silly!)",
                                         "  (Right next to %player%, silly!)"));
    }
#endif
  pf_buffer_string (filter, ".\n");
  return TRUE;
}


/*
 * lib_cmd_turns()
 * lib_cmd_score()
 *
 * Display turns taken and score so far.
 */
sc_bool
lib_cmd_turns (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_char buffer[32];

  pf_buffer_string (filter, "You have taken ");
  sprintf (buffer, "%ld", game->turns);
  pf_buffer_string (filter, buffer);
  if (game->turns == 1)
    pf_buffer_string (filter, " turn so far.\n");
  else
    pf_buffer_string (filter, " turns so far.\n");

  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_score (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[2];
  sc_int max_score, percent;
  sc_char buffer[32];

  /* Get max score, and calculate score as a percentage. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "MaxScore";
  max_score = prop_get_integer (bundle, "I<-ss", vt_key);
  if (game->score > 0 && max_score > 0)
    percent = (game->score * 100) / max_score;
  else
    percent = 0;

  /* Output carefully formatted response. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "Your score is ",
                                         "My score is ",
                                         "%player%'s score is "));
  sprintf (buffer, "%ld", game->score);
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, " out of a maximum of ");
  sprintf (buffer, "%ld", max_score);
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, ".  (");
  sprintf (buffer, "%ld", percent);
  pf_buffer_string (filter, buffer);
  pf_buffer_string (filter, "%)\n");

  game->is_admin = TRUE;
  return TRUE;
}


/*
 * lib_cmd_*()
 *
 * Standard response commands.  These are uninteresting catch-all cases,
 * but it's good to make then right as game ALRs may look for them.
 */
sc_bool
lib_cmd_profanity (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    "I really don't think there's any need for language like"
                    " that!\n");
  return TRUE;
}

sc_bool
lib_cmd_examine_all (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Please examine one object at a time.\n");
  return TRUE;
}

sc_bool
lib_cmd_examine_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You see no such thing.\n",
                                         "I see no such thing.\n",
                                         "%player% sees no such thing.\n"));
  return TRUE;
}

sc_bool
lib_cmd_locate_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "I don't know where that is!\n");
  game->is_admin = TRUE;
  return TRUE;
}

sc_bool
lib_cmd_unix_like (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "This isn't Unix you know!\n");
  return TRUE;
}

sc_bool
lib_cmd_dos_like (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "This isn't Dos you know!\n");
  return TRUE;
}

sc_bool
lib_cmd_cry (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "There's no need for that!\n");
  return TRUE;
}

sc_bool
lib_cmd_dance (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You do a little dance.\n",
                                         "I do a little dance.\n",
                                         "%player% does a little dance.\n"));
  return TRUE;
}

sc_bool
lib_cmd_eat_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "I don't understand what you are trying to eat.\n");
  return TRUE;
}

sc_bool
lib_cmd_fight (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "There is nothing worth fighting here.\n");
  return TRUE;
}

sc_bool
lib_cmd_feed (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "There is nothing worth feeding here.\n");
  return TRUE;
}

sc_bool
lib_cmd_feel (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                              "You feel nothing out of the ordinary.\n",
                              "I feel nothing out of the ordinary.\n",
                              "%player% feels nothing out of the ordinary.\n"));
  return TRUE;
}

sc_bool
lib_cmd_fly (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't fly.\n",
                                         "I can't fly.\n",
                                         "%player% can't fly.\n"));
  return TRUE;
}

sc_bool
lib_cmd_hint (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    "You're just going to have to work it out for"
                    " yourself...\n");
  return TRUE;
}

sc_bool
lib_cmd_hum (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You hum a little tune.\n",
                                         "I hum a little tune.\n",
                                         "%player% hums a little tune.\n"));
  return TRUE;
}

sc_bool
lib_cmd_jump (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Wheee-boinng.\n");
  return TRUE;
}

sc_bool
lib_cmd_listen (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                              "You hear nothing out of the ordinary.\n",
                              "I hear nothing out of the ordinary.\n",
                              "%player% hears nothing out of the ordinary.\n"));
  return TRUE;
}

sc_bool
lib_cmd_please (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                        "Your kindness gets you nowhere.\n",
                                        "My kindness gets me nowhere.\n",
                                        "%player%'s kindness gets nowhere.\n"));
  return TRUE;
}

sc_bool
lib_cmd_punch (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Who do you think you are, Mike Tyson?\n");
  return TRUE;
}

sc_bool
lib_cmd_run (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "Why would you want to run?\n",
                                         "Why would I want to run?\n",
                                         "Why would %player% want to run?\n"));
  return TRUE;
}

sc_bool
lib_cmd_shout (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Aaarrrrgggghhhhhh!\n");
  return TRUE;
}

sc_bool
lib_cmd_say (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_char *string = NULL;

  switch (sc_randomint (1, 5))
    {
    case 1:
      string = "Gosh, that was very impressive.\n";
      break;
    case 2:
      string = lib_select_response (game,
                                    "Not surprisingly, no-one takes any notice"
                                    " of you.\n",
                                    "Not surprisingly, no-one takes any notice"
                                    " of me.\n",
                                    "Not surprisingly, no-one takes any notice"
                                    " of %player%.\n");
      break;
    case 3:
      string = "Wow!  That achieved a lot.\n";
      break;
    case 4:
      string = "Uh huh, yes, very interesting.\n";
      break;
    default:
      string = "That's the most interesting thing I've ever heard!\n";
      break;
    }

  pf_buffer_string (filter, string);
  return TRUE;
}

sc_bool
lib_cmd_sing (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You sing a little song.\n",
                                         "I sing a little song.\n",
                                         "%player% sings a little song.\n"));
  return TRUE;
}

sc_bool
lib_cmd_sleep (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Zzzzz.  Bored are you?\n");
  return TRUE;
}

sc_bool
lib_cmd_talk (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                  "No-one listens to your rabblings.\n",
                                  "No-one listens to my rabblings.\n",
                                  "No-one listens to %player%'s rabblings.\n"));
  return TRUE;
}

sc_bool
lib_cmd_thank (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "You're welcome.\n");
  return TRUE;
}

sc_bool
lib_cmd_whistle (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You whistle a little tune.\n",
                                         "I whistle a little tune.\n",
                                         "%player% whistles a little tune.\n"));
  return TRUE;
}

sc_bool
lib_cmd_interrogation (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_char *string = NULL;

  switch (sc_randomint (1, 17))
    {
    case 1:
      string = "Why do you want to know?\n";
      break;
    case 2:
      string = "Interesting question.\n";
      break;
    case 3:
      string = "Let me think about that one...\n";
      break;
    case 4:
      string = "I haven't a clue!\n";
      break;
    case 5:
      string = "All these questions are hurting my head.\n";
      break;
    case 6:
      string = "I'm not going to tell you.\n";
      break;
    case 7:
      string = "Someday I'll know the answer to that one.\n";
      break;
    case 8:
      string = "I could tell you, but then I'd have to kill you.\n";
      break;
    case 9:
      string = "Ha, as if I'd tell you!\n";
      break;
    case 10:
      string = "Ask me again later.\n";
      break;
    case 11:
      string = "I don't know - could you ask anyone else?\n";
      break;
    case 12:
      string = "Err, yes?!?\n";
      break;
    case 13:
      string = "Let me just check my memory banks...\n";
      break;
    case 14:
      string = "Because that's just the way it is.\n";
      break;
    case 15:
      string = "Do I ask you all sorts of awkward questions?\n";
      break;
    case 16:
      string = "Questions, questions...\n";
      break;
    default:
      string = "Who cares.\n";
      break;
    }

  pf_buffer_string (filter, string);
  return TRUE;
}

sc_bool
lib_cmd_xyzzy (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    "I'm sorry, but XYZZY doesn't do anything special in"
                    " this game!\n");
  return TRUE;
}

sc_bool
lib_cmd_egotistic (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

#if 0
  pf_buffer_string (filter,
                    "Campbell wrote this Adrift Runner.  It's pretty"
                    " good huh!\n");
#else
  pf_buffer_string (filter, "No comment.\n");
#endif

  return TRUE;
}

sc_bool
lib_cmd_yes_or_no (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter,
                    "That's interesting, but it doesn't mean much.\n");
  return TRUE;
}


/*
 * lib_cmd_ask_npc()
 * lib_cmd_ask_object()
 * lib_cmd_ask_other()
 *
 * Malformed and rhetorical question responses.
 */
sc_bool
lib_cmd_ask_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int npc;
  sc_bool is_ambiguous;

  /* Get the referenced npc, and if none, consider complete. */
  npc = lib_disambiguate_npc (game, "ask", &is_ambiguous);
  if (npc == -1)
    return is_ambiguous;

  /* Incomplete ask command, so offer help and return. */
  pf_buffer_string (filter, "Use the format \"ask ");
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter, " about [subject]\".\n");
  return TRUE;
}

sc_bool
lib_cmd_ask_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* Get the referenced object, and if none, consider complete. */
  object = lib_disambiguate_object (game, "ask", &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* No reply. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You get no reply from ",
                                         "I get no reply from ",
                                         "%player% gets no reply from "));
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

sc_bool
lib_cmd_ask_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  /* Incomplete ask command, so offer help and return. */
  pf_buffer_string (filter,
                    "Use the format \"ask [character] about [subject]\".\n");
  return TRUE;
}


/*
 * lib_cmd_kill_other()
 *
 * Uninteresting kill message when no weaponry is involved.
 */
sc_bool
lib_cmd_kill_other (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, "Now that isn't very nice.\n");
  return TRUE;
}


/*
 * lib_nothing_happens_common()
 * lib_nothing_happens_object()
 * lib_nothing_happens_other()
 *
 * Central handler for a range of nothing-happens messages.  More
 * uninteresting responses.
 */
static sc_bool
lib_nothing_happens_common (sc_gameref_t game,
                            const sc_char *verb_general,
                            const sc_char *verb_third_person,
                            sc_bool is_object)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_prop_setref_t bundle = gs_get_bundle (game);
  sc_vartype_t vt_key[2];
  sc_int perspective, object;
  const sc_char *person, *verb;
  sc_bool is_ambiguous;

  /* Use person and verb tense according to perspective. */
  vt_key[0].string = "Globals";
  vt_key[1].string = "Perspective";
  perspective = prop_get_integer (bundle, "I<-ss", vt_key);
  switch (perspective)
    {
    case FIRST_PERSON:
      person = "I ";
      verb = verb_general;
      break;
    case SECOND_PERSON:
      person = "You ";
      verb = verb_general;
      break;
    case THIRD_PERSON:
      person = "%player% ";
      verb = verb_third_person;
      break;
    default:
      sc_error ("lib_nothing_happens: unknown perspective, %ld\n", perspective);
      person = "You ";
      verb = verb_general;
      break;
    }

  /* If the command target was not an object, end it here. */
  if (!is_object)
    {
      pf_buffer_string (filter, person);
      pf_buffer_string (filter, verb);
      pf_buffer_string (filter, ", but nothing happens.\n");
      return TRUE;
    }

  /* Get the referenced object.  If none, return immediately. */
  object = lib_disambiguate_object (game, verb_general, &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Nothing happens. */
  pf_buffer_string (filter, person);
  pf_buffer_string (filter, verb);
  pf_buffer_character (filter, ' ');
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ", but nothing happens.\n");
  return TRUE;
}

static sc_bool
lib_nothing_happens_object (sc_gameref_t game,
                            const sc_char *verb_general,
                            const sc_char *verb_third_person)
{
  return lib_nothing_happens_common (game,
                                     verb_general, verb_third_person, TRUE);
}

static sc_bool
lib_nothing_happens_other (sc_gameref_t game,
                           const sc_char *verb_general,
                           const sc_char *verb_third_person)
{
  return lib_nothing_happens_common (game,
                                     verb_general, verb_third_person, FALSE);
}


/*
 * lib_cmd_*()
 *
 * Shake, rattle and roll, and assorted nothing-happens handlers.
 */
sc_bool
lib_cmd_hit_object (sc_gameref_t game)
{
  return lib_nothing_happens_object (game, "hit", "hits");
}

sc_bool
lib_cmd_kick_object (sc_gameref_t game)
{
  return lib_nothing_happens_object (game, "kick", "kicks");
}

sc_bool
lib_cmd_press_object (sc_gameref_t game)
{
  return lib_nothing_happens_object (game, "press", "presses");
}

sc_bool
lib_cmd_push_object (sc_gameref_t game)
{
  return lib_nothing_happens_object (game, "push", "pushes");
}

sc_bool
lib_cmd_pull_object (sc_gameref_t game)
{
  return lib_nothing_happens_object (game, "pull", "pulls");
}

sc_bool
lib_cmd_shake_object (sc_gameref_t game)
{
  return lib_nothing_happens_object (game, "shake", "shakes");
}

sc_bool
lib_cmd_hit_other (sc_gameref_t game)
{
  return lib_nothing_happens_other (game, "hit", "hits");
}

sc_bool
lib_cmd_kick_other (sc_gameref_t game)
{
  return lib_nothing_happens_other (game, "kick", "kicks");
}

sc_bool
lib_cmd_press_other (sc_gameref_t game)
{
  return lib_nothing_happens_other (game, "press", "presses");
}

sc_bool
lib_cmd_push_other (sc_gameref_t game)
{
  return lib_nothing_happens_other (game, "push", "pushes");
}

sc_bool
lib_cmd_pull_other (sc_gameref_t game)
{
  return lib_nothing_happens_other (game, "pull", "pulls");
}

sc_bool
lib_cmd_shake_other (sc_gameref_t game)
{
  return lib_nothing_happens_other (game, "shake", "shakes");
}


/*
 * lib_cant_do_common()
 * lib_cant_do_object()
 * lib_cant_do_other()
 *
 * Central handler for a range of can't-do messages.  Yet more uninterest-
 * ing responses.
 */
static sc_bool
lib_cant_do_common (sc_gameref_t game,
                    const sc_char *verb, sc_bool is_object)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* If the target is not an object, end it here. */
  if (!is_object)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "You can't ",
                                             "I can't ", "%player% can't "));
      pf_buffer_string (filter, verb);
      pf_buffer_string (filter, " that.\n");
      return TRUE;
    }

  /* Get the referenced object.  If none, return immediately. */
  object = lib_disambiguate_object (game, verb, &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Whatever it is, don't do it. */
  pf_buffer_string (filter,
                    lib_select_response (game,
                                         "You can't ",
                                         "I can't ", "%player% can't "));
  pf_buffer_string (filter, verb);
  pf_buffer_character (filter, ' ');
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

static sc_bool
lib_cant_do_object (sc_gameref_t game, const sc_char *verb)
{
  return lib_cant_do_common (game, verb, TRUE);
}

static sc_bool
lib_cant_do_other (sc_gameref_t game, const sc_char *verb)
{
  return lib_cant_do_common (game, verb, FALSE);
}


/*
 * lib_cmd_*()
 *
 * Assorted can't-do messages.
 */
sc_bool
lib_cmd_block_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "block");
}

sc_bool
lib_cmd_climb_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "climb");
}

sc_bool
lib_cmd_clean_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "clean");
}

sc_bool
lib_cmd_cut_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "cut");
}

sc_bool
lib_cmd_drink_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "drink");
}

sc_bool
lib_cmd_light_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "light");
}

sc_bool
lib_cmd_lift_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "lift");
}

sc_bool
lib_cmd_move_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "move");
}

sc_bool
lib_cmd_rub_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "rub");
}

sc_bool
lib_cmd_stop_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "stop");
}

sc_bool
lib_cmd_suck_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "suck");
}

sc_bool
lib_cmd_touch_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "touch");
}

sc_bool
lib_cmd_turn_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "turn");
}

sc_bool
lib_cmd_unblock_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "unblock");
}

sc_bool
lib_cmd_wash_object (sc_gameref_t game)
{
  return lib_cant_do_object (game, "wash");
}

sc_bool
lib_cmd_block_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "block");
}

sc_bool
lib_cmd_climb_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "climb");
}

sc_bool
lib_cmd_clean_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "clean");
}

sc_bool
lib_cmd_close_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "close");
}

sc_bool
lib_cmd_lock_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "lock");
}

sc_bool
lib_cmd_unlock_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "unlock");
}

sc_bool
lib_cmd_stand_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "stand on");
}

sc_bool
lib_cmd_sit_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "sit on");
}

sc_bool
lib_cmd_lie_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "lie on");
}

sc_bool
lib_cmd_cut_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "cut");
}

sc_bool
lib_cmd_drink_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "drink");
}

sc_bool
lib_cmd_lift_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "lift");
}

sc_bool
lib_cmd_light_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "light");
}

sc_bool
lib_cmd_move_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "move");
}

sc_bool
lib_cmd_stop_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "stop");
}

sc_bool
lib_cmd_rub_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "rub");
}

sc_bool
lib_cmd_suck_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "suck");
}

sc_bool
lib_cmd_turn_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "turn");
}

sc_bool
lib_cmd_touch_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "touch");
}

sc_bool
lib_cmd_unblock_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "unblock");
}

sc_bool
lib_cmd_wash_other (sc_gameref_t game)
{
  return lib_cant_do_other (game, "wash");
}


/*
 * lib_dont_think_common()
 * lib_dont_think_object()
 * lib_dont_think_other()
 *
 * Central handler for a range of don't_think messages.  Still more
 * uninteresting responses.
 */
static sc_bool
lib_dont_think_common (sc_gameref_t game,
                       const sc_char *verb, sc_bool is_object)
{
  const sc_filterref_t filter = gs_get_filter (game);
  sc_int object;
  sc_bool is_ambiguous;

  /* If the target is not an object, end it here. */
  if (!is_object)
    {
      pf_buffer_string (filter,
                        lib_select_response (game,
                                             "I don't think you can ",
                                             "I don't think I can ",
                                             "I don't think %player% can "));
      pf_buffer_string (filter, verb);
      pf_buffer_string (filter, " that.\n");
      return TRUE;
    }

  /* Get the referenced object.  If none, return immediately. */
  object = lib_disambiguate_object (game, verb, &is_ambiguous);
  if (object == -1)
    return is_ambiguous;

  /* Whatever it is, don't do it. */
  pf_buffer_string (filter, "I don't think you can ");
  pf_buffer_string (filter, verb);
  pf_buffer_character (filter, ' ');
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

static sc_bool
lib_dont_think_object (sc_gameref_t game, const sc_char *verb)
{
  return lib_dont_think_common (game, verb, TRUE);
}

static sc_bool
lib_dont_think_other (sc_gameref_t game, const sc_char *verb)
{
  return lib_dont_think_common (game, verb, FALSE);
}


/*
 * lib_cmd_*()
 *
 * Assorted don't-think messages.
 */
sc_bool
lib_cmd_fix_object (sc_gameref_t game)
{
  return lib_dont_think_object (game, "fix");
}

sc_bool
lib_cmd_mend_object (sc_gameref_t game)
{
  return lib_dont_think_object (game, "mend");
}

sc_bool
lib_cmd_repair_object (sc_gameref_t game)
{
  return lib_dont_think_object (game, "repair");
}

sc_bool
lib_cmd_fix_other (sc_gameref_t game)
{
  return lib_dont_think_other (game, "fix");
}

sc_bool
lib_cmd_mend_other (sc_gameref_t game)
{
  return lib_dont_think_other (game, "mend");
}

sc_bool
lib_cmd_repair_other (sc_gameref_t game)
{
  return lib_dont_think_other (game, "repair");
}


/*
 * lib_what()
 *
 * Central handler for doing something, but unsure to what.
 */
static sc_bool
lib_what (sc_gameref_t game, const sc_char *verb)
{
  const sc_filterref_t filter = gs_get_filter (game);

  pf_buffer_string (filter, verb);
  pf_buffer_string (filter, " what?\n");
  return TRUE;
}


/*
 * lib_cmd_*()
 *
 * Assorted "what?" messages.
 */
sc_bool
lib_cmd_block_what (sc_gameref_t game)
{
  return lib_what (game, "Block");
}

sc_bool
lib_cmd_break_what (sc_gameref_t game)
{
  return lib_what (game, "Break");
}

sc_bool
lib_cmd_destroy_what (sc_gameref_t game)
{
  return lib_what (game, "Destroy");
}

sc_bool
lib_cmd_smash_what (sc_gameref_t game)
{
  return lib_what (game, "Smash");
}

sc_bool
lib_cmd_buy_what (sc_gameref_t game)
{
  return lib_what (game, "Buy");
}

sc_bool
lib_cmd_clean_what (sc_gameref_t game)
{
  return lib_what (game, "Clean");
}

sc_bool
lib_cmd_climb_what (sc_gameref_t game)
{
  return lib_what (game, "Climb");
}

sc_bool
lib_cmd_cut_what (sc_gameref_t game)
{
  return lib_what (game, "Cut");
}

sc_bool
lib_cmd_drink_what (sc_gameref_t game)
{
  return lib_what (game, "Drink");
}

sc_bool
lib_cmd_fix_what (sc_gameref_t game)
{
  return lib_what (game, "Fix");
}

sc_bool
lib_cmd_hit_what (sc_gameref_t game)
{
  return lib_what (game, "Hit");
}

sc_bool
lib_cmd_kick_what (sc_gameref_t game)
{
  return lib_what (game, "Kick");
}

sc_bool
lib_cmd_light_what (sc_gameref_t game)
{
  return lib_what (game, "Light");
}

sc_bool
lib_cmd_lift_what (sc_gameref_t game)
{
  return lib_what (game, "Lift");
}

sc_bool
lib_cmd_mend_what (sc_gameref_t game)
{
  return lib_what (game, "Mend");
}

sc_bool
lib_cmd_move_what (sc_gameref_t game)
{
  return lib_what (game, "Move");
}

sc_bool
lib_cmd_press_what (sc_gameref_t game)
{
  return lib_what (game, "Press");
}

sc_bool
lib_cmd_pull_what (sc_gameref_t game)
{
  return lib_what (game, "Pull");
}

sc_bool
lib_cmd_push_what (sc_gameref_t game)
{
  return lib_what (game, "Push");
}

sc_bool
lib_cmd_repair_what (sc_gameref_t game)
{
  return lib_what (game, "Repair");
}

sc_bool
lib_cmd_sell_what (sc_gameref_t game)
{
  return lib_what (game, "Sell");
}

sc_bool
lib_cmd_shake_what (sc_gameref_t game)
{
  return lib_what (game, "Shake");
}

sc_bool
lib_cmd_rub_what (sc_gameref_t game)
{
  return lib_what (game, "Rub");
}

sc_bool
lib_cmd_stop_what (sc_gameref_t game)
{
  return lib_what (game, "Stop");
}

sc_bool
lib_cmd_suck_what (sc_gameref_t game)
{
  return lib_what (game, "Suck");
}

sc_bool
lib_cmd_touch_what (sc_gameref_t game)
{
  return lib_what (game, "Touch");
}

sc_bool
lib_cmd_turn_what (sc_gameref_t game)
{
  return lib_what (game, "Turn");
}

sc_bool
lib_cmd_unblock_what (sc_gameref_t game)
{
  return lib_what (game, "Unblock");
}

sc_bool
lib_cmd_wash_what (sc_gameref_t game)
{
  return lib_what (game, "Wash");
}

sc_bool
lib_cmd_drop_what (sc_gameref_t game)
{
  return lib_what (game, "Drop");
}

sc_bool
lib_cmd_get_what (sc_gameref_t game)
{
  return lib_what (game, "Take");
}

sc_bool
lib_cmd_give_what (sc_gameref_t game)
{
  return lib_what (game, "Give");
}

sc_bool
lib_cmd_open_what (sc_gameref_t game)
{
  return lib_what (game, "Open");
}

sc_bool
lib_cmd_remove_what (sc_gameref_t game)
{
  return lib_what (game, "Remove");
}

sc_bool
lib_cmd_wear_what (sc_gameref_t game)
{
  return lib_what (game, "Wear");
}

sc_bool
lib_cmd_lock_what (sc_gameref_t game)
{
  return lib_what (game, "Lock");
}

sc_bool
lib_cmd_unlock_what (sc_gameref_t game)
{
  return lib_what (game, "Unlock");
}


/*
 * lib_cmd_verb_object()
 * lib_cmd_verb_character()
 *
 * Handlers for unrecognized verbs with known object/NPC.
 */
sc_bool
lib_cmd_verb_object (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int count, object, index_;

  /* Ensure the reference is unambiguous. */
  count = 0;
  object = -1;
  for (index_ = 0; index_ < gs_object_count (game); index_++)
    {
      if (game->object_references[index_]
          && gs_object_seen (game, index_)
          && obj_indirectly_in_room (game, index_, gs_playerroom (game)))
        {
          count++;
          object = index_;
        }
    }
  if (count != 1)
    return FALSE;

  /* Save in variables. */
  var_set_ref_object (vars, object);

  /* Print don't understand message. */
  pf_buffer_string (filter, "I don't understand what you want me to do with ");
  lib_print_object_np (game, object);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}

sc_bool
lib_cmd_verb_npc (sc_gameref_t game)
{
  const sc_filterref_t filter = gs_get_filter (game);
  const sc_var_setref_t vars = gs_get_vars (game);
  sc_int count, npc, index_;

  /* Ensure the reference is unambiguous. */
  count = 0;
  npc = -1;
  for (index_ = 0; index_ < gs_npc_count (game); index_++)
    {
      if (game->npc_references[index_]
          && gs_npc_seen (game, index_)
          && npc_in_room (game, index_, gs_playerroom (game)))
        {
          count++;
          npc = index_;
        }
    }
  if (count != 1)
    return FALSE;

  /* Save in variables. */
  var_set_ref_character (vars, npc);

  /* Print don't understand message; unlike objects, there's no "me" here. */
  pf_buffer_string (filter, "I don't understand what you want to do with ");
  lib_print_npc_np (game, npc);
  pf_buffer_string (filter, ".\n");
  return TRUE;
}


/*
 * lib_debug_trace()
 *
 * Set library tracing on/off.
 */
void
lib_debug_trace (sc_bool flag)
{
  lib_trace = flag;
}
