/*
 * Copyright (C) 2010 Collabora Ltd.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Authors: Xavier Claessens <xclaesse@gmail.com>
 */

#include "config.h"
#include "tpaw-string-parser.h"

#include <string.h>

#include "tpaw-utils.h"

#define SCHEMES           "([a-zA-Z\\+]+)"
#define INVALID_CHARS     "\\s\"<>"
#define INVALID_CHARS_EXT INVALID_CHARS "\\[\\](){},;:"
#define INVALID_CHARS_FULL INVALID_CHARS_EXT "?'"
#define BODY              "([^"INVALID_CHARS_FULL"])([^"INVALID_CHARS_EXT"]*)"
#define BODY_END          "([^"INVALID_CHARS"]*)[^"INVALID_CHARS_FULL".]"
#define URI_REGEX         "("SCHEMES"://"BODY_END")" \
                          "|((www|ftp)\\."BODY_END")" \
                          "|((mailto:)?"BODY"@"BODY"\\."BODY_END")"

static GRegex *
uri_regex_dup_singleton (void)
{
  static GRegex *uri_regex = NULL;

  /* We intentionally leak the regex so it's not recomputed */
  if (!uri_regex)
    {
      GError *error = NULL;

      uri_regex = g_regex_new (URI_REGEX, 0, 0, &error);
      if (uri_regex == NULL)
        {
          g_warning ("Failed to create reg exp: %s", error->message);
          g_error_free (error);
          return NULL;
        }
    }

  return g_regex_ref (uri_regex);
}

void
tpaw_string_parser_substr (const gchar *text,
    gssize len,
    TpawStringParser *parsers,
    gpointer user_data)
{
  if (parsers != NULL && parsers[0].match_func != NULL)
    {
      parsers[0].match_func (text, len,
          parsers[0].replace_func, parsers + 1,
          user_data);
    }
}

void
tpaw_string_match_link (const gchar *text,
    gssize len,
    TpawStringReplace replace_func,
    TpawStringParser *sub_parsers,
    gpointer user_data)
{
  GRegex *uri_regex;
  GMatchInfo *match_info;
  gboolean match;
  gint last = 0;

  uri_regex = uri_regex_dup_singleton ();
  if (uri_regex == NULL)
    {
      tpaw_string_parser_substr (text, len, sub_parsers, user_data);
      return;
    }

  match = g_regex_match_full (uri_regex, text, len, 0, 0, &match_info, NULL);
  if (match)
    {
      gint s = 0, e = 0;

      do
        {
          g_match_info_fetch_pos (match_info, 0, &s, &e);

          if (s > last)
            {
              /* Append the text between last link (or the
               * start of the message) and this link */
              tpaw_string_parser_substr (text + last,
                  s - last,
                  sub_parsers,
                  user_data);
            }

          replace_func (text + s, e - s, NULL, user_data);

          last = e;
        } while (g_match_info_next (match_info, NULL));
    }

  tpaw_string_parser_substr (text + last, len - last, sub_parsers, user_data);

  g_match_info_free (match_info);
  g_regex_unref (uri_regex);
}

void
tpaw_string_match_all (const gchar *text,
    gssize len,
    TpawStringReplace replace_func,
    TpawStringParser *sub_parsers,
    gpointer user_data)
{
  replace_func (text, len, NULL, user_data);
}

void
tpaw_string_replace_link (const gchar *text,
    gssize len,
    gpointer match_data,
    gpointer user_data)
{
  GString *string = user_data;
  gchar *real_url;
  gchar *title;
  gchar *markup;

  real_url = tpaw_make_absolute_url_len (text, len);

  /* Need to copy manually, because g_markup_printf_escaped does not work
   * with string precision pitfalls. */
  title = g_strndup (text, len);

  /* Append the link inside <a href=""></a> tag */
  markup = g_markup_printf_escaped ("<a href=\"%s\">%s</a>", real_url, title);

  g_string_append (string, markup);

  g_free (real_url);
  g_free (title);
  g_free (markup);
}

void
tpaw_string_replace_escaped (const gchar *text,
    gssize len,
    gpointer match_data,
    gpointer user_data)
{
  GString *string = user_data;
  gchar *escaped;
  guint i;
  gsize escaped_len, old_len;

  escaped = g_markup_escape_text (text, len);
  escaped_len = strlen (escaped);

  /* Allocate more space to string (we really need a g_string_extend...) */
  old_len = string->len;
  g_string_set_size (string, old_len + escaped_len);
  g_string_truncate (string, old_len);

  /* Remove '\r' */
  for (i = 0; i < escaped_len; i++)
    {
      if (escaped[i] != '\r')
        g_string_append_c (string, escaped[i]);
    }

  g_free (escaped);
}

gchar *
tpaw_add_link_markup (const gchar *text)
{
  TpawStringParser parsers[] = {
        {tpaw_string_match_link, tpaw_string_replace_link},
        {tpaw_string_match_all, tpaw_string_replace_escaped},
        {NULL, NULL}};
  GString *string;

  g_return_val_if_fail (text != NULL, NULL);

  string = g_string_sized_new (strlen (text));
  tpaw_string_parser_substr (text, -1, parsers, string);

  return g_string_free (string, FALSE);
}
