//  This may look like C code, but it is really -*- C++ -*-

//  ------------------------------------------------------------------
//  The Goldware Library
//  Copyright (C) 1990-1999 Odinn Sorensen
//  Copyright (C) 1999-2000 Alexander S. Aganichev
//  ------------------------------------------------------------------
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Library General Public
//  License as published by the Free Software Foundation; either
//  version 2 of the License, or (at your option) any later version.
//
//  This library 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
//  Library General Public License for more details.
//
//  You should have received a copy of the GNU Library 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
//  ------------------------------------------------------------------
//  $Id: gtimutil.cpp,v 1.12 2011/02/21 13:09:11 stas_degteff Exp $
//  ------------------------------------------------------------------
//  Time utility functions.
//  ------------------------------------------------------------------

#include <cstdarg>
#include <cstdio>
#include <gmemall.h>
#include <gstrall.h>
#include <gtimall.h>
#include <gutlmisc.h>
#include <gutlmtsk.h>

#ifdef __OS2__
#define INCL_BASE
#include <os2.h>
#endif

#ifdef __WIN32__
#include <windows.h>
#endif


//  ------------------------------------------------------------------

const char* gmonths[] = {
  "ERR",
  "Jan", "Feb", "Mar",
  "Apr", "May", "Jun",
  "Jul", "Aug", "Sep",
  "Oct", "Nov", "Dec",
  "ERR"
};


//  ------------------------------------------------------------------
//  Returns current timezone offset based on TZ environment variable.

int tzoffset()
{
  time32_t t1 = gtime(NULL);
  struct tm tp; ggmtime(&tp, &t1);
  tp.tm_isdst = -1;
  time32_t t2 = gmktime(&tp);
  int dt = (int)(t1 - t2);
  return (dt / 3600) * 100 + (dt % 3600) / 60;
}


//  ------------------------------------------------------------------

char* __gampm[2] = {
  "AM", "PM"
};

char* __gsweekday[7] = {
  "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};

char* __glweekday[7] = {
  "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};

char* __gsmonth[12] = {
  "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

char* __glmonth[12] = {
  "January", "February", "March",     "April",   "May",      "June",
  "July",    "August",   "September", "October", "November", "December"
};

char* gampm[2] = {
  "AM", "PM"
};

char* gsweekday[7] = {
  NULL, NULL, NULL, NULL, NULL, NULL, NULL
};

char* glweekday[7] = {
  NULL, NULL, NULL, NULL, NULL, NULL, NULL
};

char* gsmonth[12] = {
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
};

char* glmonth[12] = {
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
};


//  ------------------------------------------------------------------
//  written 6 september 1989 by jim nutt
//  released into the public domain by jim nutt
//  modified 21-Oct-89 by Rob Duff

static char buf[26];
static char format[] = "%?";

static int pow[5] = { 1, 10, 100, 1000, 10000 };


//  ------------------------------------------------------------------
//  static void strfmt(char *str, char *fmt);
//  simple sprintf for strftime
//  each format descriptor is of the form %n
//  where n goes from zero to four
//  0    -- string %s
//  1..4 -- int %?.?d

static void strfmt(char *str, const char *fmt, ...) {

  int ival, ilen;
  char *sval;
  va_list vp;

  va_start(vp, fmt);
  while(*fmt) {
    if(*fmt++ == '%') {
      ilen = *fmt++ - '0';
      if(ilen == 0)                 // zero means string arg
      {
        sval = va_arg(vp, char*);
        while(*sval)
          *str++ = *sval++;
      }
      else {                        // always leading zeros
        if(ilen == ('-' - '0')) {
          ilen = *fmt++ - '0';
          ival = va_arg(vp, int);
          bool padding = true;
          while(ilen) {
            ival %= pow[ilen];
            int cval = ival / pow[ilen-1];
            if(cval)
              padding = false;
            if(--ilen and padding)
              cval = ' ' - '0';
            *str++ = (char)('0' + cval);
          }
        }
        else {
          ival = va_arg(vp, int);
          while(ilen) {
            ival %= pow[ilen--];
            *str++ = (char)('0' + ival / pow[ilen]);
          }
        }
      }
    }
    else  *str++ = fmt[-1];
  }
  *str = '\0';
  va_end(vp);
}


//  ------------------------------------------------------------------
//  In differ to ANSI C strftime this function supports reloading of
//  field names
//  Return NULL if output truncated, otherwize return s.

#define setvar(internal,external,field) \
  char **internal = external; \
  if(internal[field] == NULL) internal = __##external;

char *strftimei(char *s, size_t maxs, const char *f, const struct tm *t)
{
  char *p, *q, *r;

  setvar(aday, gsweekday, t->tm_wday);
  setvar(day, glweekday, t->tm_wday);
  setvar(amonth, gsmonth, t->tm_mon);
  setvar(month, glmonth, t->tm_mon);

  p = s;
  q = s + maxs - 1;
  while((*f != NUL)) {
    if(*f++ == '%') {
      r = buf;
      switch(*f++) {

        case '%':
          format[1] = NUL;
          r = format;
          break;

        case 'a':
          r = aday[t->tm_wday];
          break;

        case 'A':
          r = day[t->tm_wday];
          break;

        case 'b':
          r = amonth[t->tm_mon];
          break;

        case 'B':
          r = month[t->tm_mon];
          break;

        case 'C':
          strfmt(r, "%0 %0 %-2 %2:%2:%2 %4",
            aday[t->tm_wday], amonth[t->tm_mon],
            t->tm_mday,t->tm_hour, t->tm_min,
            t->tm_sec, t->tm_year+1900);
          break;

        case 'e':
          strfmt(r, "%-2", t->tm_mday);
          break;

        case 'E':
          sprintf(r, "%u", (uint)t->tm_mday);
          break;

        case 'p':
          r = gampm[(t->tm_hour>11)?1:0];
          break;

        default:
          format[1] = f[-1];
          if(strftime(r, 26, format, t) == 0) {
            buf[0] = '%';   // reconstruct the format
            buf[1] = f[-1];
            buf[2] = '\0';
            if(buf[1] == 0)
              f--;          // back up if at end of string
          }
          break;
      }
      while(*r) {
        if(p == q) {
          *q = '\0';
          return 0;
        }
        *p++ = *r++;
      }
    }
    else {
      if(p == q) {
        *q = '\0';
        return 0;
      }
      *p++ = f[-1];
    }
  }
  *p = '\0';
  return s;
}


//  ------------------------------------------------------------------
//  Convert string-month to integer

int str2mon(const char* ptr) {

  int mon;

  switch(g_toupper(*ptr)) {
    case 'A':
      if(g_toupper(ptr[1]) == 'P')
        mon = 4;
      else
        mon = 8;
      break;
    case 'D':
      mon = 12;
      break;
    case 'F':
      mon = 2;
      break;
    case 'J':
      if(g_toupper(ptr[1]) == 'A')
        mon = 1;
      else if(g_toupper(ptr[2]) == 'L')
        mon = 7;
      else
        mon = 6;
      break;
    case 'M':
      if(g_toupper(ptr[2]) == 'R')
        mon = 3;
      else
        mon = 5;
      break;
    case 'N':
      mon = 11;
      break;
    case 'O':
      mon = 10;
      break;
    case 'S':
      mon = 9;
      break;
    default:
      mon = 0;
  }

  return mon;
}


//  ------------------------------------------------------------------

time32_t FTimeToTime(FTime* __ftime, struct tm* __tm) {

  struct tm _tm;
  uint32_t _time = 0;

  if(__tm == NULL)
    __tm = &_tm;

  // Only try to convert a valid date
  if(__ftime->ft_year >= 5) {   // FidoNet standards didn't exist before 1985
    if((__ftime->ft_day >= 1) and (__ftime->ft_day <= 31)) {
      if((__ftime->ft_month >= 1) and (__ftime->ft_month <= 12)) {

        __tm->tm_year  = __ftime->ft_year + 80;
        __tm->tm_mon   = __ftime->ft_month - 1;
        __tm->tm_mday  = __ftime->ft_day;
        __tm->tm_hour  = __ftime->ft_hour;
        __tm->tm_min   = __ftime->ft_min;
        __tm->tm_sec   = __ftime->ft_tsec * 2;
        __tm->tm_isdst = -1;

        time32_t a  = gmktime(__tm);
        struct tm tp; ggmtime(&tp, &a);
        tp.tm_isdst = -1;
        time32_t b  = gmktime(&tp);
        _time = a + a - b;

        if(_time == (uint32_t)0xFFFFFFFFL)
          _time = 0;
      }
    }
  }

  return _time;
}


//  ------------------------------------------------------------------

FTime TimeToFTime(time32_t __time) {

  FTime _ft;
  memset(&_ft, 0, sizeof(FTime));

  if (__time)
  {
    struct tm _tmp; ggmtime(&_tmp, &__time);
    _ft.ft_year  = (word)(_tmp.tm_year - 80);
    _ft.ft_month = (word)(_tmp.tm_mon + 1);
    _ft.ft_day   = (word)(_tmp.tm_mday);
    _ft.ft_hour  = (word)(_tmp.tm_hour);
    _ft.ft_min   = (word)(_tmp.tm_min);
    _ft.ft_tsec  = (word)(_tmp.tm_sec / 2);
  }

  return _ft;
}


//  ------------------------------------------------------------------

time32_t FidoTimeToUnix(char* ptr) {

  bool date_ok = false;
  int year=0, month=0, day=0;
  int hour=0, minute=0, second=0;

  ptr = strskip_wht(ptr);
  if(not isdigit(*ptr)) {
    // Skip past weekday string (SEA format)
    ptr = strskip_wht(strskip_txt(ptr));
  }
  if(*ptr) {
    if(isdigit(*ptr)) {
      day = atoi(ptr);
      ptr = strskip_wht(strskip_txt(ptr));
      if(g_isalpha(*ptr)) {
        month = str2mon(ptr);
        if(month) {
          ptr = strskip_wht(strskip_txt(ptr));
          if(isdigit(*ptr)) {
            year = atoi(ptr);
            ptr = strskip_wht(strskip_txt(ptr));
            if(isdigit(*ptr)) {
              hour = atoi(ptr);
              ptr = strskip_digits(ptr);
              if(*ptr and isdigit(ptr[1])) {
                minute = atoi(++ptr);
                date_ok = true;
                // The seconds part is only in the FTS-1 format
                ptr = strskip_digits(ptr);
                if(*ptr and isdigit(ptr[1])) {
                  second = atoi(++ptr);
                }
              }
            }
          }
        }
      }
    }
  }

  // Convert datetime to UNIX timestamp
  if(date_ok) {
    struct tm t;
    t.tm_year  = (year < 80) ? (year+100) : year;
    t.tm_mon   = month - 1;
    t.tm_mday  = day;
    t.tm_hour  = hour;
    t.tm_min   = minute;
    t.tm_sec   = second;
    t.tm_isdst = -1;
    time32_t a  = gmktime(&t);
    struct tm tp; ggmtime(&tp, &a);
    tp.tm_isdst = -1;
    time32_t b  = gmktime(&tp);
    return a + a - b;
  }
  return (uint32_t)-1;
}


//  ------------------------------------------------------------------

char* TimeToStr(char* buf, time32_t t)
{
  struct tm tm; ggmtime(&tm, &t);
  return strftimei(buf, 20, "%Y-%m-%d %H:%M:%S", &tm);
}


//  ------------------------------------------------------------------

char* FTimeToStr(char* buf, FTime& t) {

  sprintf(buf, "%04u-%02u-%02u %02u:%02u:%02u",
    t.ft_year+1980, t.ft_month, t.ft_day,
    t.ft_hour, t.ft_min, t.ft_tsec*2
  );
  return buf;
}


//  ------------------------------------------------------------------

const char* gfiletime::c_str(char* buf) {

  sprintf(buf, "%04u-%02u-%02u %02u:%02u:%02u",
    ft_year+1980, ft_month, ft_day,
    ft_hour, ft_min, ft_tsec*2
  );
  return buf;
}


//  ------------------------------------------------------------------

const char* gopustime::c_str(char* buf) {

  sprintf(buf, "%04u-%02u-%02u %02u:%02u:%02u",
    ft_year+1980, ft_month, ft_day,
    ft_hour, ft_min, ft_tsec*2
  );
  return buf;
}


//  ------------------------------------------------------------------
