/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- 
 *  gtksourceiter.h
 *
 *  Copyright (C) 2000 - 2005 Paolo Maggi 
 *  Copyright (C) 2002, 2003 Jeroen Zwartepoorte
 *
 *  This program 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 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 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.
 */

/*
 * Parts of this file are copied from the gedit and glimmer project.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include "gtksourceiter.h"

#define GTK_TEXT_UNKNOWN_CHAR 0xFFFC

/* this function acts like g_utf8_offset_to_pointer() except that if it finds a
 * decomposable character it consumes the decomposition length from the given
 * offset.  So it's useful when the offset was calculated for the normalized
 * version of str, but we need a pointer to str itself. */
static const gchar *
pointer_from_offset_skipping_decomp (const gchar *str, gint offset)
{
	gchar *casefold, *normal;
	const gchar *p, *q;

	p = str;
	while (offset > 0)
	{
		q = g_utf8_next_char (p);
		casefold = g_utf8_casefold (p, q - p);
		normal = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
		offset -= g_utf8_strlen (normal, -1);
		g_free (casefold);
		g_free (normal);
		p = q;
	}
	return p;
}

static gboolean
exact_prefix_cmp (const gchar *string,
		  const gchar *prefix,
		  guint        prefix_len)
{
	GUnicodeType type;

	if (strncmp (string, prefix, prefix_len) != 0)
		return FALSE;
	if (string[prefix_len] == '\0')
		return TRUE;

	type = g_unichar_type (g_utf8_get_char (string + prefix_len));

	/* If string contains prefix, check that prefix is not followed
	 * by a unicode mark symbol, e.g. that trailing 'a' in prefix
	 * is not part of two-char a-with-hat symbol in string. */
	return type != G_UNICODE_NON_SPACING_MARK &&
		type != G_UNICODE_ENCLOSING_MARK &&
		type != G_UNICODE_NON_SPACING_MARK;
}

static const gchar *
utf8_strcasestr (const gchar *haystack, const gchar *needle)
{
	gsize needle_len;
	gsize haystack_len;
	const gchar *ret = NULL;
	gchar *p;
	gchar *casefold;
	gchar *caseless_haystack;
	gint i;

	g_return_val_if_fail (haystack != NULL, NULL);
	g_return_val_if_fail (needle != NULL, NULL);

	casefold = g_utf8_casefold (haystack, -1);
	caseless_haystack = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
	g_free (casefold);

	needle_len = g_utf8_strlen (needle, -1);
	haystack_len = g_utf8_strlen (caseless_haystack, -1);

	if (needle_len == 0)
	{
		ret = (gchar *)haystack;
		goto finally_1;
	}

	if (haystack_len < needle_len)
	{
		ret = NULL;
		goto finally_1;
	}

	p = (gchar*)caseless_haystack;
	needle_len = strlen (needle);
	i = 0;

	while (*p)
	{
		if (exact_prefix_cmp (p, needle, needle_len))
		{
			ret = pointer_from_offset_skipping_decomp (haystack, i);
			goto finally_1;
		}

		p = g_utf8_next_char (p);
		i++;
	}

finally_1:
	g_free (caseless_haystack);

	return ret;
}

static const gchar *
utf8_strrcasestr (const gchar *haystack, const gchar *needle)
{
	gsize needle_len;
	gsize haystack_len;
	const gchar *ret = NULL;
	gchar *p;
	gchar *casefold;
	gchar *caseless_haystack;
	gint i;

	g_return_val_if_fail (haystack != NULL, NULL);
	g_return_val_if_fail (needle != NULL, NULL);

	casefold = g_utf8_casefold (haystack, -1);
	caseless_haystack = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
	g_free (casefold);

	needle_len = g_utf8_strlen (needle, -1);
	haystack_len = g_utf8_strlen (caseless_haystack, -1);

	if (needle_len == 0)
	{
		ret = (gchar *)haystack;
		goto finally_1;
	}

	if (haystack_len < needle_len)
	{
		ret = NULL;
		goto finally_1;
	}

	i = haystack_len - needle_len;
	p = g_utf8_offset_to_pointer (caseless_haystack, i);
	needle_len = strlen (needle);

	while (p >= caseless_haystack)
	{
		if (exact_prefix_cmp (p, needle, needle_len))
		{
			ret = pointer_from_offset_skipping_decomp (haystack, i);
			goto finally_1;
		}

		p = g_utf8_prev_char (p);
		i--;
	}

finally_1:
	g_free (caseless_haystack);

	return ret;
}

static gboolean
utf8_caselessnmatch (const char *s1, const char *s2,
		     gssize n1, gssize n2)
{
	gchar *casefold;
	gchar *normalized_s1;
	gchar *normalized_s2;
	gint len_s1;
	gint len_s2;
	gboolean ret = FALSE;

	g_return_val_if_fail (s1 != NULL, FALSE);
	g_return_val_if_fail (s2 != NULL, FALSE);
	g_return_val_if_fail (n1 > 0, FALSE);
	g_return_val_if_fail (n2 > 0, FALSE);

	casefold = g_utf8_casefold (s1, n1);
	normalized_s1 = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
	g_free (casefold);

	casefold = g_utf8_casefold (s2, n2);
	normalized_s2 = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
	g_free (casefold);

	len_s1 = strlen (normalized_s1);
	len_s2 = strlen (normalized_s2);

	if (len_s1 < len_s2)
		goto finally_2;

	ret = (strncmp (normalized_s1, normalized_s2, len_s2) == 0);

finally_2:
	g_free (normalized_s1);
	g_free (normalized_s2); 

	return ret;
}

static void
forward_chars_with_skipping (GtkTextIter *iter,
			     gint         count,
			     gboolean     skip_invisible,
			     gboolean     skip_nontext,
			     gboolean     skip_decomp)
{
	gint i;

	g_return_if_fail (count >= 0);

	i = count;

	while (i > 0)
	{
		gboolean ignored = FALSE;

		/* minimal workaround to avoid the infinite loop of bug #168247.
		 * It doesn't fix the problemjust the symptom...
		 */
		if (gtk_text_iter_is_end (iter))
			return;

		if (skip_nontext && gtk_text_iter_get_char (iter) == GTK_TEXT_UNKNOWN_CHAR)
			ignored = TRUE;

		if (!ignored && skip_invisible &&
		    /* _gtk_text_btree_char_is_invisible (iter)*/ FALSE)
			ignored = TRUE;

		if (!ignored && skip_decomp)
		{
			/* being UTF8 correct sucks; this accounts for extra
			   offsets coming from canonical decompositions of
			   UTF8 characters (e.g. accented characters) which 
			   g_utf8_normalize() performs */
			gchar *normal;
			gchar buffer[6];
			gint buffer_len;

			buffer_len = g_unichar_to_utf8 (gtk_text_iter_get_char (iter), buffer);
			normal = g_utf8_normalize (buffer, buffer_len, G_NORMALIZE_NFD);
			i -= (g_utf8_strlen (normal, -1) - 1);
			g_free (normal);
		}

		gtk_text_iter_forward_char (iter);

		if (!ignored)
			--i;
	}
}

static gboolean
lines_match (const GtkTextIter *start,
	     const gchar      **lines,
	     gboolean           visible_only,
	     gboolean           slice,
	     GtkTextIter       *match_start,
	     GtkTextIter       *match_end)
{
	GtkTextIter next;
	gchar *line_text;
	const gchar *found;
	gint offset;

	if (*lines == NULL || **lines == '\0')
	{
		if (match_start)
			*match_start = *start;
		if (match_end)
			*match_end = *start;
		return TRUE;
	}

	next = *start;
	gtk_text_iter_forward_line (&next);

	/* No more text in buffer, but *lines is nonempty */
	if (gtk_text_iter_equal (start, &next))
		return FALSE;

	if (slice)
	{
		if (visible_only)
			line_text = gtk_text_iter_get_visible_slice (start, &next);
		else
			line_text = gtk_text_iter_get_slice (start, &next);
	}
	else
	{
		if (visible_only)
			line_text = gtk_text_iter_get_visible_text (start, &next);
		else
			line_text = gtk_text_iter_get_text (start, &next);
	}

	if (match_start) /* if this is the first line we're matching */
	{
		found = utf8_strcasestr (line_text, *lines);
	}
	else
	{
		/* If it's not the first line, we have to match from the
		 * start of the line.
		 */
		if (utf8_caselessnmatch (line_text, *lines, strlen (line_text),
					 strlen (*lines)))
			found = line_text;
		else
			found = NULL;
	}

	if (found == NULL)
	{
		g_free (line_text);
		return FALSE;
	}

	/* Get offset to start of search string */
	offset = g_utf8_strlen (line_text, found - line_text);

	next = *start;

	/* If match start needs to be returned, set it to the
	 * start of the search string.
	 */
	forward_chars_with_skipping (&next, offset, visible_only, !slice, FALSE);
	if (match_start)
	{
		*match_start = next;
	}

	/* Go to end of search string */
	forward_chars_with_skipping (&next, g_utf8_strlen (*lines, -1), visible_only, !slice, TRUE);

	g_free (line_text);

	++lines;

	if (match_end)
		*match_end = next;

	/* pass NULL for match_start, since we don't need to find the
	 * start again.
	 */
	return lines_match (&next, lines, visible_only, slice, NULL, match_end);
}

static gboolean
backward_lines_match (const GtkTextIter *start,
		      const gchar      **lines,
		      gboolean           visible_only,
		      gboolean           slice,
		      GtkTextIter       *match_start,
		      GtkTextIter       *match_end)
{
	GtkTextIter line, next;
	gchar *line_text;
	const gchar *found;
	gint offset;

	if (*lines == NULL || **lines == '\0')
	{
		if (match_start)
			*match_start = *start;
		if (match_end)
			*match_end = *start;
		return TRUE;
	}

	line = next = *start;
	if (gtk_text_iter_get_line_offset (&next) == 0)
	{
		if (!gtk_text_iter_backward_line (&next))
			return FALSE;
	}
	else
		gtk_text_iter_set_line_offset (&next, 0);

	if (slice)
	{
		if (visible_only)
			line_text = gtk_text_iter_get_visible_slice (&next, &line);
		else
			line_text = gtk_text_iter_get_slice (&next, &line);
	}
	else
	{
		if (visible_only)
			line_text = gtk_text_iter_get_visible_text (&next, &line);
		else
			line_text = gtk_text_iter_get_text (&next, &line);
	}

	if (match_start) /* if this is the first line we're matching */
	{
		found = utf8_strrcasestr (line_text, *lines);
	}
	else
	{
		/* If it's not the first line, we have to match from the
		 * start of the line.
		 */
		if (utf8_caselessnmatch (line_text, *lines, strlen (line_text),
					 strlen (*lines)))
			found = line_text;
		else
			found = NULL;
	}

	if (found == NULL)
	{
		g_free (line_text);
		return FALSE;
	}

	/* Get offset to start of search string */
	offset = g_utf8_strlen (line_text, found - line_text);

	forward_chars_with_skipping (&next, offset, visible_only, !slice, FALSE);

	/* If match start needs to be returned, set it to the
	 * start of the search string.
	 */
	if (match_start)
	{
		*match_start = next;
	}

	/* Go to end of search string */
	forward_chars_with_skipping (&next, g_utf8_strlen (*lines, -1), visible_only, !slice, TRUE);

	g_free (line_text);

	++lines;

	if (match_end)
		*match_end = next;

	/* try to match the rest of the lines forward, passing NULL
	 * for match_start so lines_match will try to match the entire
	 * line */
	return lines_match (&next, lines, visible_only,
			    slice, NULL, match_end);
}

/* strsplit () that retains the delimiter as part of the string. */
static gchar **
strbreakup (const char *string,
	    const char *delimiter,
	    gint        max_tokens)
{
	GSList *string_list = NULL, *slist;
	gchar **str_array, *s, *casefold, *new_string;
	guint i, n = 1;

	g_return_val_if_fail (string != NULL, NULL);
	g_return_val_if_fail (delimiter != NULL, NULL);

	if (max_tokens < 1)
		max_tokens = G_MAXINT;

	s = strstr (string, delimiter);
	if (s)
	{
		guint delimiter_len = strlen (delimiter);

		do
		{
			guint len;

			len = s - string + delimiter_len;
			new_string = g_new (gchar, len + 1);
			strncpy (new_string, string, len);
			new_string[len] = 0;
			casefold = g_utf8_casefold (new_string, -1);
			g_free (new_string);
			new_string = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
			g_free (casefold);
			string_list = g_slist_prepend (string_list, new_string);
			n++;
			string = s + delimiter_len;
			s = strstr (string, delimiter);
		} while (--max_tokens && s);
	}

	if (*string)
	{
		n++;
		casefold = g_utf8_casefold (string, -1);
		new_string = g_utf8_normalize (casefold, -1, G_NORMALIZE_NFD);
		g_free (casefold);
		string_list = g_slist_prepend (string_list, new_string);
	}

	str_array = g_new (gchar*, n);

	i = n - 1;

	str_array[i--] = NULL;
	for (slist = string_list; slist; slist = slist->next)
		str_array[i--] = slist->data;

	g_slist_free (string_list);

	return str_array;
}

/**
 * gtk_source_iter_forward_search:
 * @iter: start of search.
 * @str: a search string.
 * @flags: flags affecting how the search is done.
 * @match_start: return location for start of match, or %%NULL.
 * @match_end: return location for end of match, or %%NULL.
 * @limit: bound for the search, or %%NULL for the end of the buffer.
 * 
 * Searches forward for @str. Any match is returned by setting 
 * @match_start to the first character of the match and @match_end to the 
 * first character after the match. The search will not continue past
 * @limit. Note that a search is a linear or O(n) operation, so you
 * may wish to use @limit to avoid locking up your UI on large
 * buffers.
 * 
 * If the #GTK_SOURCE_SEARCH_VISIBLE_ONLY flag is present, the match may
 * have invisible text interspersed in @str. i.e. @str will be a
 * possibly-noncontiguous subsequence of the matched range. similarly,
 * if you specify #GTK_SOURCE_SEARCH_TEXT_ONLY, the match may have
 * pixbufs or child widgets mixed inside the matched range. If these
 * flags are not given, the match must be exact; the special 0xFFFC
 * character in @str will match embedded pixbufs or child widgets.
 * If you specify the #GTK_SOURCE_SEARCH_CASE_INSENSITIVE flag, the text will
 * be matched regardless of what case it is in.
 *
 * Same as gtk_text_iter_forward_search(), but supports case insensitive
 * searching.
 * 
 * Return value: whether a match was found.
 **/
gboolean
gtk_source_iter_forward_search (const GtkTextIter   *iter,
				const gchar         *str,
				GtkSourceSearchFlags flags,
				GtkTextIter         *match_start,
				GtkTextIter         *match_end,
				const GtkTextIter   *limit)
{
	gchar **lines = NULL;
	GtkTextIter match;
	gboolean retval = FALSE;
	GtkTextIter search;
	gboolean visible_only;
	gboolean slice;

	g_return_val_if_fail (iter != NULL, FALSE);
	g_return_val_if_fail (str != NULL, FALSE);

	if ((flags & GTK_SOURCE_SEARCH_CASE_INSENSITIVE) == 0)
		return gtk_text_iter_forward_search (iter, str, flags,
						     match_start, match_end,
						     limit); 

	if (limit && gtk_text_iter_compare (iter, limit) >= 0)
		return FALSE;

	if (*str == '\0')
	{
		/* If we can move one char, return the empty string there */
		match = *iter;

		if (gtk_text_iter_forward_char (&match))
		{
			if (limit && gtk_text_iter_equal (&match, limit))
				return FALSE;

			if (match_start)
				*match_start = match;
			if (match_end)
				*match_end = match;
			return TRUE;
		}
		else
		{
			return FALSE;
		}
	}

	visible_only = (flags & GTK_SOURCE_SEARCH_VISIBLE_ONLY) != 0;
	slice = (flags & GTK_SOURCE_SEARCH_TEXT_ONLY) == 0;

	/* locate all lines */
	lines = strbreakup (str, "\n", -1);

	search = *iter;

	do
	{
		/* This loop has an inefficient worst-case, where
		 * gtk_text_iter_get_text () is called repeatedly on
		 * a single line.
		 */
		GtkTextIter end;

		if (limit && gtk_text_iter_compare (&search, limit) >= 0)
			break;

		if (lines_match (&search, (const gchar**)lines,
				 visible_only, slice, &match, &end))
		{
			if (limit == NULL ||
			    (limit && gtk_text_iter_compare (&end, limit) <= 0))
			{
				retval = TRUE;

				if (match_start)
					*match_start = match;
				if (match_end)
					*match_end = end;
			}
			break;
		}
	} while (gtk_text_iter_forward_line (&search));

	g_strfreev ((gchar**)lines);

	return retval;
}

/**
 * gtk_source_iter_backward_search:
 * @iter: a #GtkTextIter where the search begins.
 * @str: search string.
 * @flags: bitmask of flags affecting the search.
 * @match_start: return location for start of match, or %%NULL.
 * @match_end: return location for end of match, or %%NULL.
 * @limit: location of last possible @match_start, or %%NULL for start of buffer.
 * 
 * Same as gtk_text_iter_backward_search(), but supports case insensitive
 * searching.
 * 
 * Return value: whether a match was found.
 **/
gboolean
gtk_source_iter_backward_search (const GtkTextIter   *iter,
				 const gchar         *str,
				 GtkSourceSearchFlags flags,
				 GtkTextIter         *match_start,
				 GtkTextIter         *match_end,
				 const GtkTextIter   *limit)
{
	gchar **lines = NULL;
	GtkTextIter match;
	gboolean retval = FALSE;
	GtkTextIter search;
	gboolean visible_only;
	gboolean slice;

	g_return_val_if_fail (iter != NULL, FALSE);
	g_return_val_if_fail (str != NULL, FALSE);

	if ((flags & GTK_SOURCE_SEARCH_CASE_INSENSITIVE) == 0)
		return gtk_text_iter_backward_search (iter, str, flags,
						      match_start, match_end,
						      limit); 

	if (limit && gtk_text_iter_compare (iter, limit) <= 0)
		return FALSE;

	if (*str == '\0')
	{
		/* If we can move one char, return the empty string there */
		match = *iter;

		if (gtk_text_iter_backward_char (&match))
		{
			if (limit && gtk_text_iter_equal (&match, limit))
				return FALSE;

			if (match_start)
				*match_start = match;
			if (match_end)
				*match_end = match;
			return TRUE;
		}
		else
		{
			return FALSE;
		}
	}

	visible_only = (flags & GTK_SOURCE_SEARCH_VISIBLE_ONLY) != 0;
	slice = (flags & GTK_SOURCE_SEARCH_TEXT_ONLY) == 0;

	/* locate all lines */
	lines = strbreakup (str, "\n", -1);

	search = *iter;

	while (TRUE)
	{
		/* This loop has an inefficient worst-case, where
		 * gtk_text_iter_get_text () is called repeatedly on
		 * a single line.
		 */
		GtkTextIter end;

		if (limit && gtk_text_iter_compare (&search, limit) <= 0)
			break;

		if (backward_lines_match (&search, (const gchar**)lines,
					  visible_only, slice, &match, &end))
		{
			if (limit == NULL || (limit &&
					      gtk_text_iter_compare (&end, limit) > 0))
			{
				retval = TRUE;

				if (match_start)
					*match_start = match;
				if (match_end)
					*match_end = end;
			}
			break;
		}

		if (gtk_text_iter_get_line_offset (&search) == 0)
		{
			if (!gtk_text_iter_backward_line (&search))
				break;
		}
		else
		{
			gtk_text_iter_set_line_offset (&search, 0);
		}
	}

	g_strfreev ((gchar**)lines);

	return retval;
}

/*
 * gtk_source_iter_find_matching_bracket is implemented in gtksourcebuffer.c
 */
