/* gettext.c - gettext module */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2009 Free Software Foundation, Inc.
 *
 *  GRUB 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/types.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/err.h>
#include <grub/dl.h>
#include <grub/normal.h>
#include <grub/file.h>
#include <grub/kernel.h>

/* 
   .mo file information from: 
   http://www.gnu.org/software/autoconf/manual/gettext/MO-Files.html .
*/


static grub_file_t grub_mofile_open (const char *name);
static grub_file_t fd_mo;

static int grub_gettext_offsetoriginal;
static int grub_gettext_max;

static const char* (*grub_gettext_original) (const char *s);

#define GETTEXT_MAGIC_NUMBER 0
#define GETTEXT_FILE_FORMAT 4
#define GETTEXT_NUMBER_OF_STRINGS 8
#define GETTEXT_OFFSET_ORIGINAL 12
#define GETTEXT_OFFSET_TRANSLATION 16

#define MO_MAGIC_NUMBER 0x950412de

static grub_uint32_t
grub_gettext_get_info (int offset)
{
  grub_uint32_t value;

  grub_file_seek (fd_mo, offset);
  grub_file_read (fd_mo, (char*) &value, 4);
  value = grub_cpu_to_le32 (value);
  return value;
}

static void
grub_gettext_getstring_from_offset (grub_uint32_t offset, grub_uint32_t length, char *translation)
{
  grub_file_seek (fd_mo, offset);
  grub_file_read (fd_mo, translation, length);
  translation[length] = '\0';
}

static char*
grub_gettext_gettranslation_from_position (int position)
{
  int offsettranslation;
  int internal_position;
  grub_uint32_t length, offset;
  char *translation;

  offsettranslation = grub_gettext_get_info (GETTEXT_OFFSET_TRANSLATION);

  internal_position = offsettranslation + position * 8;

  grub_file_seek (fd_mo, internal_position);
  grub_file_read (fd_mo, (char*) &length, 4);
  length = grub_cpu_to_le32 (length);
  
  grub_file_seek (fd_mo, internal_position + 4),
  grub_file_read (fd_mo, (char*) &offset, 4);
  offset = grub_cpu_to_le32 (offset);

  translation = grub_malloc(length + 1);
  grub_gettext_getstring_from_offset (offset, length, translation);

  return translation;
}

static char*
grub_gettext_getstring_from_position (int position)
{
  int internal_position;
  int length, offset;
  char *original;

  /* Get position for string i.  */
  internal_position = grub_gettext_offsetoriginal + (position * 8);

  /* Get the length of the string i.  */
  grub_file_seek (fd_mo, internal_position);
  grub_file_read (fd_mo, (char *) &length, 4);

  /* Get the offset of the string i.  */
  grub_file_seek (fd_mo, internal_position + 4);
  grub_file_read (fd_mo, (char *) &offset, 4);

  /* Get the string i.  */
  original = grub_malloc (length + 1);
  grub_gettext_getstring_from_offset (offset, length, original);

  return original;
}

static const char*
grub_gettext_translate (const char *orig)
{
  char *current_string;
  char *ret;

  int min,max,current;

  if (fd_mo == 0)
    return orig;

  min = 0;
  max = grub_gettext_max;

  current = (max + min) / 2;

  while (current != min && current != max)
    {
      current_string = grub_gettext_getstring_from_position (current);

      /* Search by bisection.  */
      if (grub_strcmp (current_string, orig) < 0)
        {
          grub_free(current_string);
          min=current;
        }
      else if (grub_strcmp (current_string, orig) > 0)
        {
          grub_free(current_string);
          max=current;
        }
      else if (grub_strcmp (current_string, orig) == 0)
        {
          grub_free(current_string);
          return grub_gettext_gettranslation_from_position (current);
        }
    current = (max+min)/2;
    }

  ret = grub_malloc(grub_strlen(orig) + 1);
  grub_strcpy(ret,orig);
  return ret;
}

/* This is similar to grub_gzfile_open. */
static grub_file_t
grub_mofile_open (const char *filename)
{
  int unsigned magic;
  int version;

  /* Using fd_mo and not another variable because
     it's needed for grub_gettext_get_info.  */

  fd_mo = grub_file_open (filename);
  if (! fd_mo)
    {
      grub_error (GRUB_ERR_FILE_READ_ERROR, "Cannot read %s",filename);
      return 0;
    }

  magic = grub_gettext_get_info (GETTEXT_MAGIC_NUMBER);

  if (magic != MO_MAGIC_NUMBER)
    {
      grub_error (GRUB_ERR_BAD_FILE_TYPE, "mo: invalid mo file: %s", filename);
      grub_file_close (fd_mo);
      fd_mo = 0;
      return 0;
    }
  
  version = grub_gettext_get_info (GETTEXT_FILE_FORMAT);

  if (version != 0)
    {
      grub_error (GRUB_ERR_BAD_FILE_TYPE, "mo: invalid mo version in file: %s", filename);
      fd_mo = 0;
      return 0;
    }
  
  /*
  Do we want .mo.gz files? Then, the code:
  file = grub_gzio_open (io, 0); // 0: transparent
  if (! file)
    {
      grub_printf("Problems opening the file\n");
      grub_file_close (io);
      return 0;
    }
  */

  return fd_mo;
}

static void
grub_gettext_init_ext (const char *lang)
{
  char *mo_file;
  char *locale_dir;

  locale_dir = grub_env_get ("locale_dir");
  
  fd_mo = 0;
      
  // mo_file e.g.: /boot/grub/locale/ca.mo

  mo_file = grub_malloc (grub_strlen (locale_dir) + sizeof ("/") + grub_strlen (lang) + sizeof(".mo"));
 
  // Warning: if changing some paths in the below line, change the grub_malloc
  // contents below
 
  grub_sprintf (mo_file, "%s/%s.mo", locale_dir, lang);

  grub_dprintf("gettext", "Will try to open file: %s " ,mo_file);

  fd_mo = grub_mofile_open(mo_file);
  grub_free (mo_file);

  if (fd_mo)
    {
      grub_gettext_offsetoriginal = grub_gettext_get_info(GETTEXT_OFFSET_ORIGINAL);
      grub_gettext_max = grub_gettext_get_info(GETTEXT_NUMBER_OF_STRINGS);

      grub_gettext_original = grub_gettext;
      grub_gettext = grub_gettext_translate;
    }
}

static char*
grub_gettext_env_write_lang (struct grub_env_var *var __attribute__ ((unused)),
			     const char *val)
{
  grub_gettext_init_ext (val);

  return grub_strdup (val);
}

GRUB_MOD_INIT(gettext)
{
  (void)mod;			/* To stop warning.  */
 
  const char *lang;

  lang = grub_env_get ("lang"); 

  grub_gettext_init_ext (lang);

  /* Testing:
  grub_register_command ("_", grub_cmd_translate, GRUB_COMMAND_FLAG_BOTH,
			 "_", "internalization support trans", 0);
  */

  /* Reload .mo file information if lang changes.  */
  grub_register_variable_hook ("lang", NULL, grub_gettext_env_write_lang);

  /* Preserve hooks after context changes.  */
  grub_env_export ("lang");
}

GRUB_MOD_FINI(gettext)
{
  if (fd_mo != 0)
    grub_file_close(fd_mo);

  grub_gettext = grub_gettext_original;
}