/*
 * Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation
 * All rights reserved.
 *
 * This file is part of the Gnome Library.
 *
 * The Gnome 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.
 *
 * The Gnome 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 the Gnome Library; see the file COPYING.LIB.  If not,
 * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>
#include "gnome-vfs-i18n.h"

#include "gnome-vfs-private-utils.h"
#include <errno.h>
#include <fcntl.h>
#include <glib/ghash.h>
#include <glib/gmessages.h>
#include <glib/gstrfuncs.h>
#include <glib/gutils.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <unistd.h>

static GHashTable *alias_table = NULL;
static GHashTable *category_table = NULL;

/*read an alias file for the locales*/
static void
read_aliases (char *file)
{
  FILE *fp;
  char buf[256];
  
  if (!alias_table)
    alias_table = g_hash_table_new (g_str_hash, g_str_equal);
  fp = fopen (file,"r");
  if (!fp)
    return;
  while (fgets (buf, 256, fp))
    {
      char *p, *q;

      g_strstrip (buf);

      /* Line is a comment */
      if ((buf[0] == '#') || (buf[0] == '\0'))
	continue;

      /* Reads first column */
      for (p = buf, q = NULL; *p; p++) {
	if ((*p == '\t') || (*p == ' ') || (*p == ':')) {
	  *p = '\0';
	  q = p+1;
	  while ((*q == '\t') || (*q == ' ')) {
	    q++;
	  }
	  break;
	}
      }
      /* The line only had one column */
      if (!q || *q == '\0')
	continue;
      
      /* Read second column */
      for (p = q; *p; p++) {
	if ((*p == '\t') || (*p == ' ')) {
	  *p = '\0';
	  break;
	}
      }

      /* Add to alias table if necessary */
      if (!g_hash_table_lookup (alias_table, buf)) {
	g_hash_table_insert (alias_table, g_strdup (buf), g_strdup (q));
      }
    }
  fclose (fp);
}

static char *
unalias_lang (char *lang)
{
  char *p;
  int i;

  if (!alias_table)
    {
      read_aliases ("/usr/share/locale/locale.alias");
      read_aliases ("/usr/local/share/locale/locale.alias");
      read_aliases ("/usr/lib/X11/locale/locale.alias");
      read_aliases ("/usr/openwin/lib/locale/locale.alias");
    }
  i = 0;
  while ((p = g_hash_table_lookup (alias_table, lang)) && (strcmp (p, lang) != 0))
    {
      lang = p;
      if (i++ == 30)
        {
          static gboolean said_before = FALSE;
	  if (!said_before)
            g_warning ("Too many alias levels for a locale, "
		       "may indicate a loop");
	  said_before = TRUE;
	  return lang;
	}
    }
  return lang;
}

/* Mask for components of locale spec. The ordering here is from
 * least significant to most significant
 */
enum
{
  COMPONENT_CODESET =   1 << 0,
  COMPONENT_TERRITORY = 1 << 1,
  COMPONENT_MODIFIER =  1 << 2
};

/* Break an X/Open style locale specification into components
 */
static guint
explode_locale (const gchar *locale,
		gchar **language, 
		gchar **territory, 
		gchar **codeset, 
		gchar **modifier)
{
  const gchar *uscore_pos;
  const gchar *at_pos;
  const gchar *dot_pos;

  guint mask = 0;

  uscore_pos = strchr (locale, '_');
  dot_pos = strchr (uscore_pos ? uscore_pos : locale, '.');
  at_pos = strchr (dot_pos ? dot_pos : (uscore_pos ? uscore_pos : locale), '@');

  if (at_pos)
    {
      mask |= COMPONENT_MODIFIER;
      *modifier = g_strdup (at_pos);
    }
  else
    at_pos = locale + strlen (locale);

  if (dot_pos)
    {
      mask |= COMPONENT_CODESET;
      *codeset = g_strndup (dot_pos, at_pos - dot_pos);
    }
  else
    dot_pos = at_pos;

  if (uscore_pos)
    {
      mask |= COMPONENT_TERRITORY;
      *territory = g_strndup (uscore_pos, dot_pos - uscore_pos);
    }
  else
    uscore_pos = dot_pos;

  *language = g_strndup (locale, uscore_pos - locale);

  return mask;
}

/*
 * Compute all interesting variants for a given locale name -
 * by stripping off different components of the value.
 *
 * For simplicity, we assume that the locale is in
 * X/Open format: language[_territory][.codeset][@modifier]
 *
 * TODO: Extend this to handle the CEN format (see the GNUlibc docs)
 *       as well. We could just copy the code from glibc wholesale
 *       but it is big, ugly, and complicated, so I'm reluctant
 *       to do so when this should handle 99% of the time...
 */
static GList *
compute_locale_variants (const gchar *locale)
{
  GList *retval = NULL;

  gchar *language;
  gchar *territory;
  gchar *codeset;
  gchar *modifier;

  guint mask;
  guint i;

  g_return_val_if_fail (locale != NULL, NULL);

  mask = explode_locale (locale, &language, &territory, &codeset, &modifier);

  /* Iterate through all possible combinations, from least attractive
   * to most attractive.
   */
  for (i = 0; i <= mask; i++)
    if ((i & ~mask) == 0)
      {
	gchar *val = g_strconcat (language,
				  (i & COMPONENT_TERRITORY) ? territory : "",
				  (i & COMPONENT_CODESET) ? codeset : "",
				  (i & COMPONENT_MODIFIER) ? modifier : "",
				  NULL);
	retval = g_list_prepend (retval, val);
      }

  g_free (language);
  if (mask & COMPONENT_CODESET)
    g_free (codeset);
  if (mask & COMPONENT_TERRITORY)
    g_free (territory);
  if (mask & COMPONENT_MODIFIER)
    g_free (modifier);

  return retval;
}

/* The following is (partly) taken from the gettext package.
   Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.  */

static const gchar *
guess_category_value (const gchar *categoryname)
{
  const gchar *retval;

  /* The highest priority value is the `LANGUAGE' environment
     variable.  This is a GNU extension.  */
  retval = g_getenv ("LANGUAGE");
  if ((retval != NULL) && (retval[0] != '\0'))
    return retval;

  /* `LANGUAGE' is not set.  So we have to proceed with the POSIX
     methods of looking to `LC_ALL', `LC_xxx', and `LANG'.  On some
     systems this can be done by the `setlocale' function itself.  */

  /* Setting of LC_ALL overwrites all other.  */
  retval = g_getenv ("LC_ALL");  
  if ((retval != NULL) && (retval[0] != '\0'))
    return retval;

  /* Next comes the name of the desired category.  */
  retval = g_getenv (categoryname);
  if ((retval != NULL) && (retval[0] != '\0'))
    return retval;

  /* Last possibility is the LANG environment variable.  */
  retval = g_getenv ("LANG");
  if ((retval != NULL) && (retval[0] != '\0'))
    return retval;

  return NULL;
}

/**
 * gnome_vfs_i18n_get_language_list:
 * @category_name: Name of category to look up, e.g. "LC_MESSAGES".
 * 
 * This computes a list of language strings.  It searches in the
 * standard environment variables to find the list, which is sorted
 * in order from most desirable to least desirable.  The `C' locale
 * is appended to the list if it does not already appear (other
 * routines depend on this behaviour).
 * If @category_name is %NULL, then LC_ALL is assumed.
 * 
 * Return value: a copy of the list of languages (which you need to free).
 **/
GList *
gnome_vfs_i18n_get_language_list (const gchar *category_name)
{
  GList *list;

  if (!category_name)
    category_name = "LC_ALL";

  if (category_table)
    {
      list = g_hash_table_lookup (category_table, (const gpointer) category_name);
    }
  else
    {
      category_table = g_hash_table_new (g_str_hash, g_str_equal);
      list = NULL;
    }

  if (!list)
    {
      gint c_locale_defined = FALSE;
  
      const gchar *category_value;
      gchar *category_memory, *orig_category_memory;

      category_value = guess_category_value (category_name);
      if (!category_value)
	category_value = "C";
      orig_category_memory = category_memory =
	g_malloc (strlen (category_value)+1);
      
      while (category_value[0] != '\0')
	{
	  while ((category_value[0] != '\0') && (category_value[0] == ':'))
	    ++category_value;
	  
	  if (category_value[0] != '\0')
	    {
	      char *cp = category_memory;
	      
	      while ((category_value[0] != '\0') && (category_value[0] != ':'))
		*category_memory++ = *category_value++;
	      
	      category_memory[0] = '\0'; 
	      category_memory++;
	      
	      cp = unalias_lang (cp);
	      
	      if (strcmp (cp, "C") == 0)
		c_locale_defined = TRUE;
	      
	      list = g_list_concat (list, compute_locale_variants (cp));
	    }
	}

      g_free (orig_category_memory);
      
      if (!c_locale_defined)
	list= g_list_append (list, "C");

      g_hash_table_insert (category_table, (gpointer) category_name, list);
    }

  return g_list_copy (list);
}