/* The GIMP -- an image manipulation program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * String substitution utilities for config files
 * Copyright (C) 2001  Sven Neumann <sven@gimp.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU 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 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.
 */

#include "config.h"

#include <stdio.h>
#include <string.h>

#include <glib-object.h>

#include "libgimpbase/gimpbase.h"

#include "gimpconfig-path.h"

#include "gimp-intl.h"


#define SUBSTS_ALLOC 4

static gchar        * gimp_config_path_expand_only (const gchar  *path,
                                                    GError      **error);
static inline gchar * extract_token                (const gchar **str);


/**
 * gimp_config_path_expand:
 * @path: a %NUL-terminated string in UTF-8 encoding
 * @recode: whether to convert to the filesystem's encoding
 * @error: return location for errors
 *
 * Paths as stored in the gimprc have to be treated special.  The
 * string may contain special identifiers such as for example
 * ${gimp_dir} that have to be substituted before use. Also the user's
 * filesystem may be in a different encoding than UTF-8 (which is what
 * is used for the gimprc). This function does the variable
 * substitution for you and can also attempt to convert to the
 * filesystem encoding.
 *
 * Return value: a newly allocated %NUL-terminated string
 **/
gchar *
gimp_config_path_expand (const gchar  *path,
                         gboolean      recode,
                         GError      **error)
{
  g_return_val_if_fail (path != NULL, NULL);
  g_return_val_if_fail (error == NULL || *error == NULL, NULL);

  if (recode)
    {
      gchar *retval;
      gchar *expanded = gimp_config_path_expand_only (path, error);

      if (! expanded)
        return NULL;

      retval = g_filename_from_utf8 (expanded, -1, NULL, NULL, error);

      g_free (expanded);

      return retval;
    }

  return gimp_config_path_expand_only (path, error);
}

static gchar *
gimp_config_path_expand_only (const gchar  *path,
                              GError      **error)
{
  const gchar *p;
  const gchar *s;
  gchar       *n;
  gchar       *token;
  gchar       *filename = NULL;
  gchar       *expanded = NULL;
  gchar      **substs   = NULL;
  guint        n_substs = 0;
  gint         length   = 0;
  gint         i;

  p = path;

  while (*p)
    {

#ifndef G_OS_WIN32
      if (*p == '~')
	{
	  length += strlen (gimp_filename_to_utf8 (g_get_home_dir ()));
	  p += 1;
	}
      else
#endif  /* G_OS_WIN32 */

      if ((token = extract_token (&p)) != NULL)
        {
          for (i = 0; i < n_substs; i++)
            if (strcmp (substs[2*i], token) == 0)
              break;

          if (i < n_substs)
            {
              s = substs[2*i+1];
            }
          else
            {
              s = NULL;

              if (strcmp (token, "gimp_dir") == 0)
                s = gimp_directory ();
              else if (strcmp (token, "gimp_data_dir") == 0)
                s = gimp_data_directory ();
              else if (strcmp (token, "gimp_plug_in_dir") == 0 ||
		       strcmp (token, "gimp_plugin_dir") == 0)
                s = gimp_plug_in_directory ();
              else if (strcmp (token, "gimp_sysconf_dir") == 0)
                s = gimp_sysconf_directory ();

              if (!s)
                s = g_getenv (token);

#ifdef G_OS_WIN32
              /* The default user gimprc on Windows references
               * ${TEMP}, but not all Windows installations have that
               * environment variable, even if it should be kinda
               * standard. So special-case it.
               */
              if (!s && strcmp (token, "TEMP") == 0)
                s = g_get_tmp_dir ();
#endif  /* G_OS_WIN32 */
            }

          if (!s)
            {
              g_set_error (error, 0, 0, _("Cannot expand ${%s}"), token);
              g_free (token);
              goto cleanup;
            }

          if (n_substs % SUBSTS_ALLOC == 0)
            substs = g_renew (gchar *, substs, 2 * (n_substs + SUBSTS_ALLOC));

          substs[2*n_substs]     = token;
          substs[2*n_substs + 1] = (gchar *) gimp_filename_to_utf8 (s);

          length += strlen (substs[2*n_substs + 1]);

          n_substs++;
        }
      else
	{
          length += g_utf8_skip[(const guchar) *p];
          p = g_utf8_next_char (p);
	}
    }

  if (n_substs == 0)
    return g_strdup (path);

  expanded = g_new (gchar, length + 1);

  p = path;
  n = expanded;

  while (*p)
    {

#ifndef G_OS_WIN32
      if (*p == '~')
	{
	  *n = '\0';
	  strcat (n, gimp_filename_to_utf8 (g_get_home_dir ()));
	  n += strlen (gimp_filename_to_utf8 (g_get_home_dir ()));
	  p += 1;
	}
      else
#endif  /* G_OS_WIN32 */

      if ((token = extract_token (&p)) != NULL)
        {
          for (i = 0; i < n_substs; i++)
            {
              if (strcmp (substs[2*i], token) == 0)
                {
                  s = substs[2*i+1];

                  *n = '\0';
                  strcat (n, s);
                  n += strlen (s);

                  break;
                }
            }

          g_free (token);
	}
      else
	{
	  *n++ = *p++;
	}
    }

  *n = '\0';

 cleanup:
  for (i = 0; i < n_substs; i++)
    g_free (substs[2*i]);

  g_free (substs);
  g_free (filename);

  return expanded;
}

static inline gchar *
extract_token (const gchar **str)
{
  const gchar *p;
  gchar       *token;

  if (strncmp (*str, "${", 2))
    return NULL;

  p = *str + 2;

  while (*p && (*p != '}'))
    p = g_utf8_next_char (p);

  if (!p)
    return NULL;

  token = g_strndup (*str + 2, g_utf8_pointer_to_offset (*str + 2, p));

  *str = p + 1; /* after the closing bracket */

  return token;
}