i18n.module

<?php

/**
 * @file
 * Internationalization (i18n) module.
 *
 * This module extends multilingual support being the base module for the i18n package.
 * - Multilingual variables
 * - Extended languages for nodes
 * - Extended language API
 *
 * @author Jose A. Reyero, 2004
 */

// Some constants. Language support modes for content
define('LANGUAGE_SUPPORT_NONE', 0);
define('LANGUAGE_SUPPORT_NORMAL', 1);
define('LANGUAGE_SUPPORT_EXTENDED', 2);
define('LANGUAGE_SUPPORT_EXTENDED_NOT_DISPLAYED', 3);

/**
 * Implementation of hook_boot()
 * 
 * Initialize variables, that will be used to decide on site_frontpage
 */
function i18n_boot() {
  drupal_bootstrap(DRUPAL_BOOTSTRAP_LANGUAGE);
  _i18n_init();  
}

/**
 * Implementation of hook_init().
 *
 * Special fix for site_frontpage, that may have been used before the language variables are loaded.
 */
function i18n_init() {
  // If not in bootstrap, variable init. Otherwise we are serving a cached page so we don't need anything else.
  if (!_i18n_is_bootstrap()) {
    _i18n_init(TRUE);
    _i18n_init_mode();
  }
}

/**
 * Initialize multilingual variables and use them for site_frontpage
 * 
 * Special fix for site_frontpage, that may have been used before the language variables are loaded.
 */
function _i18n_init($check_frontpage = FALSE) {
  static $done, $default_frontpage;
  
  // Prevent this function from running twice;
  if (!isset($done)) {
    $done = TRUE;
    $default_frontpage = variable_get('site_frontpage', 'node');
    i18n_variable_init();
  }
  // We do aditional frontpage check if this has run after first bootstrap phase.
  // But if this runs in hook_boot we should be ok
  if ($check_frontpage && $default_frontpage != variable_get('site_frontpage', 'node') && $_GET['q'] == drupal_get_normal_path($default_frontpage)) {
    $_GET['q'] = drupal_get_normal_path(variable_get('site_frontpage', 'node'));
  }
}

/**
 * Initialize selection mode
 */
function _i18n_init_mode() {
  if (i18n_selection_mode() != 'off') {
    // Node language when loading specific nodes or creating translations.
    if (arg(0) == 'node' ) {
      // We shouldn't call menu_get_object() because it may end up calling i18n_selection_mode(), see #614548
      // Also we better don't do the full node loading here because there may be missing modules (init)
      if (is_numeric(arg(1)) && (arg(2) == 'edit') && ($lang = i18n_node_get_lang(arg(1)))) {
        i18n_selection_mode('node', $lang);
      }
      elseif (arg(1) == 'add' && !empty($_GET['translation']) && !empty($_GET['language'])) {
        i18n_selection_mode('translation', db_escape_string($_GET['language']));
      }
    }
    elseif (arg(0) == 'admin') {
      // There are some exceptions for admin pages.
      if (arg(1) == 'content' && user_access('administer all languages')) {
        // No restrictions for administration pages.
        i18n_selection_mode('off');
      }
      elseif (arg(1) == 'build' && (arg(2) == 'menu-customize' || arg(2) == 'menu')) {
        // All nodes available when editing custom menu items.
        i18n_selection_mode('off');
      }
    }
  }  
}
/**
 * Implementation of hook_help().
 */
function i18n_help($path = 'admin/help#i18n', $arg) {
  switch ($path) {
    case 'admin/help#i18n' :
      $output = '<p>'. t('This module improves support for multilingual content in Drupal sites:') .'</p>';
      $output .= '<ul>';
      $output .= '<li>'. t('Shows content depending on page language.') .'</li>';
      $output .= '<li>'. t('Handles multilingual variables.') .'</li>';
      $output .= '<li>'. t('Extended language option for chosen content types. For these content types transations will be allowed for all defined languages, not only for enabled ones.') .'</li>';
      $output .= '<li>'. t('Provides a block for language selection and two theme functions: <em>i18n_flags</em> and <em>i18n_links</em>.') .'</li>';
      $output .= '</ul>';
      $output .= '<p>'. t('This is the base module for several others adding different features:') .'</p>';
      $output .= '<ul>';
      $output .= '<li>'. t('Multilingual menu items.') .'</li>';
      $output .= '<li>'. t('Multilingual taxonomy adds a language field for taxonomy vocabularies and terms.') .'</li>';
      $output .= '</ul>';
      $output .= '<p>'. t('For more information, see the online handbook entry for <a href="@i18n">Internationalization module</a>.', array('@i18n' => 'http://drupal.org/node/133977')) .'</p>';
      return $output;

    case 'admin/settings/language/i18n':
      $output = '<ul>';
      $output .= '<li>'. t('To enable multilingual support for specific content types go to <a href="@configure_content_types">configure content types</a>.', array('@configure_content_types' => url('admin/content/types'))) .'</li>';
      $output .= '</ul>';
      return $output;
  }
}

/**
 * Implementation of hook_menu().
 */
function i18n_menu() {
  $items['admin/settings/language/i18n'] = array(
    'title' => 'Multilingual system',
    'description' => 'Configure extended options for multilingual content and translations.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('i18n_admin_settings'),
    'access arguments' => array('administer site configuration'),
    'file' => 'i18n.admin.inc',
    'type' => MENU_LOCAL_TASK,
    'weight' => 10,
  );
  $items['admin/settings/language/i18n/configure'] = array(
    'title' => 'Options',
    'description' => 'Configure extended options for multilingual content and translations.',
    //'page callback' => 'drupal_get_form',
    //'page arguments' => array('i18n_admin_settings'),
    //'access arguments' => array('administer site configuration'),
    'file' => 'i18n.admin.inc',
    'type' => MENU_DEFAULT_LOCAL_TASK,
  );
  $items['admin/settings/language/i18n/variables'] = array(
    'title' => 'Variables',
    'description' => 'Multilingual variables.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('i18n_admin_variables_form'),
    'access arguments' => array('administer site configuration'),
    'file' => 'i18n.admin.inc',
    'type' => MENU_LOCAL_TASK,
  );
  // Autocomplete callback for nodes
  $items['i18n/node/autocomplete'] = array(
    'title' => 'Node title autocomplete',
    'page callback' => 'i18n_node_autocomplete',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
    'file' => 'i18n.pages.inc',
  );
  return $items;
}

/**
 * Implementation of hook_menu_alter().
 *
 * Take over the node translation page.
 */
function i18n_menu_alter(&$items) {
  $items['node/%node/translate']['page callback'] = 'i18n_translation_node_overview';
  $items['node/%node/translate']['file'] = 'i18n.pages.inc';
  $items['node/%node/translate']['module'] = 'i18n';
}

/**
 * Implementation of hook_nodeapi().
 */
function i18n_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  global $language;

  if (variable_get('language_content_type_' . $node->type, 0)) {
    // Set current language for new nodes if option enabled
    if ($op == 'prepare' && empty($node->nid) && empty($node->language) && variable_get('i18n_newnode_current_' . $node->type, 0)) {
      $node->language = $language->language;
    }
  }
}

/**
 * Implementation of hook_alter_translation_link().
 *
 * Handles links for extended language. The links will have current language.
 */
function i18n_translation_link_alter(&$links, $path) {
  global $language;

  // Check for a node related path, and for its translations.
  if ((preg_match("!^node/([0-9]+)(/.+|)$!", $path, $matches)) && ($node = node_load((int)$matches[1])) && !empty($node->tnid)) {
    // make sure language support is set to LANGUAGE_SUPPORT_EXTENDED, so links
    // dont get added for LANGUAGE_SUPPORT_EXTENDED_NOT_DISPLAYED
    if (variable_get('i18n_node_'. $node->type, LANGUAGE_SUPPORT_NORMAL) == LANGUAGE_SUPPORT_EXTENDED) {
      $languages = language_list();
      $extended = array();
      foreach (translation_node_get_translations($node->tnid) as $langcode => $translation_node) {
        if (!isset($links[$langcode]) && isset($languages[$langcode])) {
          $extended[$langcode] = array(
            'href' => 'node/'. $translation_node->nid . $matches[2],
            'language' => $language,
            'language_icon' => $languages[$langcode],
            'title' => $languages[$langcode]->native,
            'attributes' => array('class' => 'language-link'),
          );
        }
      }
      // This will run after languageicon module, so we add icon in case that one is enabled.
      if ($extended && function_exists('languageicons_translation_link_alter')) {
        languageicons_translation_link_alter($extended, $path);
      }
      $links = array_merge($links, $extended);
    }
  }
}

/**
 * Implementation of hook_link_alter().
 *
 * Handles links for extended languages. Sets current interface language.
 */
function i18n_link_alter(&$links, $node) {
  global $language;

  $language_support = variable_get('i18n_node_'. $node->type, LANGUAGE_SUPPORT_NORMAL);

  // Hide node translation links.
  if (variable_get('i18n_hide_translation_links', 0) == 1) {
    foreach ($links as $module => $link) {
      if (strpos($module, 'node_translation') === 0) {
        unset($links[$module]);
      }
    }
  }

  if (!empty($node->tnid)) {
    foreach (array_keys(i18n_language_list('extended')) as $langcode) {
      $index = 'node_translation_'. $langcode;
      if (!empty($links[$index])) {
        if ($language_support != LANGUAGE_SUPPORT_EXTENDED && $links[$index]['language']->enabled == 0) {
          unset($links[$index]);
        }
        else {
          $links[$index]['language'] = $language;
        }
      }
    }
  }
}

/**
 * Implementation of hook_user().
 *
 * Switch to user's language after login.
 */
function i18n_user($op, &$edit, &$account, $category = NULL) {
  if ($op == 'login' && $account->language) {
    i18n_get_lang($account->language);
  }
}

/**
 * Implementation of hook_elements().
 *
 * Add a process callback for textfields.
 */
function i18n_elements() {
  $type = array();
  $type['textfield'] = array('#process' => array('i18n_textfield_process'));
  return $type;
}

/**
 * Process callback for textfield elements.
 *
 * When editing or translating a node, set Javascript to rewrite autocomplete
 * paths to use the node language prefix rather than the current content one.
 */
function i18n_textfield_process($element) {
  global $language;
  static $sent = FALSE;

  // Ensure we send the Javascript only once.
  if (!$sent && isset($element['#autocomplete_path']) && !empty($element['#autocomplete_path']) && variable_get('language_negotiation', LANGUAGE_NEGOTIATION_NONE) != LANGUAGE_NEGOTIATION_NONE) {
    // Add a JS file for node forms.
    // Determine if we are either editing or translating an existing node.
    // We can't act on regular node creation because we don't have a specified
    // node language.
    $node_edit = $node = menu_get_object() && arg(2) == 'edit' && isset($node->language) && !empty($node->language);
    $node_translate = arg(0) == 'node' && arg(1) == 'add' && !empty($_GET['translation']) && !empty($_GET['language']);
    if ($node_edit || $node_translate) {
      $node_language = $node_edit ? $node->language : $_GET['language'];
      // Only needed if the node language is different from the interface one.
      if ($node_language != $language->language) {
        $languages = language_list();
        if (isset($languages[$node_language])) {
          drupal_add_js(drupal_get_path('module', 'i18n') . '/i18n.js');
          // Pass the interface and content language base paths.
          // Remove any trailing forward slash. Doing so prevents a mismatch
          // that occurs when a language has no prefix and hence gets a path
          // with a trailing forward slash.
          $interface = rtrim(url('', array('absolute' => TRUE)), '/');
          $content = rtrim(url('', array('absolute' => TRUE, 'language' => $languages[$node_language])), '/');
          $data = array('interface_path' => $interface, 'content_path' => $content);
          drupal_add_js(array('i18n' => $data), 'setting');
        }
      }
    }
    $sent = TRUE;
  }
  return $element;
}

/**
 * Simple i18n API
 */

/**
 * Get language properties.
 *
 * @param $code
 *   Language code.
 * @param $property
 *   It may be 'name', 'native', 'ltr'...
 */
function i18n_language_property($code, $property) {
  $languages = language_list();
  return isset($languages[$code]->$property) ? $languages[$code]->$property : NULL;
}

/**
 * Get node language.
 */
function i18n_node_get_lang($nid, $default = '') {
  $lang = db_result(db_query('SELECT language FROM {node} WHERE nid = %d', $nid));
  return $lang ? $lang : $default ;
}

/**
 * Get allowed languages for node.
 *
 * This allows node types to define its own language list implementing hook 'language_list'.
 *
 * @param $node
 *   Node to retrieve language list for.
 * @param $translate
 *   Only languages available for translation. Filter out existing translations.
 */
function i18n_node_language_list($node, $translate = FALSE) {
  // Check if the node module manages its own language list.
  $languages = node_invoke($node, 'language_list', $translate);

  if (!$languages) {
    if (variable_get('i18n_node_'. $node->type, 0) >= LANGUAGE_SUPPORT_EXTENDED) {
      $languages = locale_language_list('name', TRUE); // All defined languages
    }
    else {
      $languages = locale_language_list(); // All enabled languages
    }
    if ($translate && isset($node->tnid) && $node->tnid && ($translations = translation_node_get_translations($node->tnid))) {
      unset($translations[$node->language]);
      foreach (array_keys($translations) as $langcode) {
        unset($languages[$langcode]);
      }
    }
    // Language may be locked for this node type, restrict options to current one
    if (variable_get('i18n_lock_node_' . $node->type, 0) && !empty($node->language) && !empty($languages[$node->language])) {
      $languages = array($node->language => $languages[$node->language]);
    }
    // Check language required for this type (no language neutral)
    elseif (!variable_get('i18n_required_node_' . $node->type, 0)) {
      $languages = array('' => t('Language neutral')) + $languages;
    }
  }

  return $languages;
}

/**
 * Selection mode for content.
 *
 * Warning: when used with params they need to be escaped, as some values are thrown directly in queries.
 *
 * Allows several modes for query rewriting and to change them programatically.
 *  off = No language conditions inserted.
 *  simple = Only current language and no language.
 *  mixed = Only current and default languages.
 *  strict = Only current language.
 *  default = Only default language.
 *  user = User defined, in the module's settings page.
 *  params = Gets the stored params.
 *  reset = Returns to previous.
 *  custom = add custom where clause, like "%alias.language = 'en'".
 */
function i18n_selection_mode($mode = NULL, $params = NULL) {
  static $current_mode;
  static $current_value = '';
  static $store = array();

  // Initialization, first time this runs
  if (!isset($current_mode)) {
    $current_mode = variable_get('i18n_selection_mode', 'simple');
  }

  if (!$mode) {
    return $current_mode;
  }
  elseif ($mode == 'params') {
    return $current_value;
  }
  elseif ($mode == 'reset') {
    list($current_mode, $current_value) = array_pop($store);
  }
  else {
    array_push($store, array($current_mode, $current_value));
    $current_mode = $mode;
    $current_value = $params;
  }
}

/**
 * Implementation of hook_db_rewrite_sql().
 *
 * Rewrite node queries so language selection options are enforced.
 */
function i18n_db_rewrite_sql($query, $primary_table, $primary_key, $args = array()) {
  // If mode is 'off' = no rewrite, we cannot return any empty 'where' string so check here.
  $mode = i18n_selection_mode();
  if ($mode == 'off') return;

  // Disable language conditions for views.
  if (array_key_exists('view', $args)) return;

  switch ($primary_table) {
    case 'n':
    case 'node':
      // No rewrite for queries with subselect ? (views count queries).
      // @ TO DO Actually these queries look un-rewrittable, check with other developers.
      if (preg_match("/FROM \(SELECT/", $query)) return;
      // No rewrite for translation module queries.
      if (preg_match("/.*FROM {node} $primary_table WHERE.*$primary_table\.tnid/", $query)) return;
      // When loading specific nodes, language conditions shouldn't apply.
      if (preg_match("/WHERE.*\s$primary_table.nid\s*=\s*(\d|%d)/", $query)) return;
      // If language conditions already there, get out.
      if (preg_match("/i18n/", $query)) return;


      // Mixed mode is a bit more complex, we need to join in one more table
      // and add some more conditions, but only if language is not default.
      if ($mode == 'mixed') {
        $result['where'] = i18n_db_rewrite_where($primary_table, 'node', 'simple');
        if (i18n_get_lang() != i18n_default_language()) {
          $result['join'] = "LEFT JOIN {node} i18n ON $primary_table.tnid > 0 AND $primary_table.tnid = i18n.tnid AND i18n.language = '". i18n_get_lang() ."'";
          // So we show also nodes that have default language.
          $result['where'] .= " OR $primary_table.language = '". i18n_default_language() ."' AND i18n.nid IS NULL";
        }
      }
      else {
        $result['where'] = i18n_db_rewrite_where($primary_table, 'node', $mode);
      }
      return $result;
  }
}

/**
 * Rewrites queries depending on rewriting mode.
 */
function i18n_db_rewrite_where($alias, $type, $mode = NULL) {
  if (!$mode) {
    // Some exceptions for query rewrites.
    $mode = i18n_selection_mode();
  }

  // Get languages to simplify query building.
  $current = i18n_get_lang();
  $default = i18n_default_language();

  if ($mode == 'strict' && $type != 'node') {
    // Special case. Selection mode is 'strict' but this should be only for node queries.
    $mode = 'simple';
  }
  elseif ($mode == 'mixed' && $current == $default) {
    // If mode is mixed but current = default, is the same as 'simple'.
    $mode = 'simple';
  }

  switch ($mode) {
    case 'off':
      return '';

    case 'simple':
      return "$alias.language ='$current' OR $alias.language ='' OR $alias.language IS NULL" ;

    case 'mixed':
      return "$alias.language ='$current' OR $alias.language ='$default' OR $alias.language ='' OR $alias.language IS NULL" ;

    case 'strict':
      return "$alias.language ='$current'" ;

    case 'node':
    case 'translation':
      return "$alias.language ='". i18n_selection_mode('params') ."' OR $alias.language ='' OR $alias.language IS NULL" ;

    case 'default':
      return "$alias.language ='$default' OR $alias.language ='' OR $alias.language IS NULL" ;

    case 'custom':
      return str_replace('%alias', $alias, i18n_selection_mode('params'));
  }
}

/**
 * Implementation of hook_preprocess_page().
 *
 * Add the language code to the classes for the <body> tag. Unfortunately, some
 * themes will not respect the variable we're modifying to achieve this - in
 * particular, Garland and Minelli do not.
 */
function i18n_preprocess_page(&$variables) {
  if (isset($variables['body_classes'])) {
    global $language;
    $variables['body_classes'] .= ' i18n-' . $language->language;
  }
}

/**
 * Implementation of hook_exit().
 */
function i18n_exit() {
  _i18n_variable_exit();
}

/**
 * Implementation of hook_form_alter();
 *
 * This is the place to add language fields to all forms.
 */
function i18n_form_alter(&$form, $form_state, $form_id) {
  global $language;

  switch ($form_id) {
    case 'node_type_form':
      $disabled = !variable_get('language_content_type_'. $form['#node_type']->type, 0);
      $form['i18n'] = array(
        '#type' => 'fieldset',
        '#title' => t('Multilanguage options'),
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
        '#description' => t('Extended multilingual options provided by Internationalization module.'),
        '#disabled' => $disabled,
      );
      // Add disabled message
      if ($disabled) {
        $form['i18n']['#description'] .= ' <em>' . t('These will be available only when you enable Multilingual support in Workflow settings above.') . '</em>';
      }
      // Some settings about node languages
      $form['i18n']['options'] = array(
        '#title' => t('Options for node language'),
        '#type' => 'fieldset',
        '#disabled' => $disabled,
      );
      $form['i18n']['options']['i18n_newnode_current'] = array(
        '#type' => 'checkbox',
        '#title' => t('Set current language as default for new content.'),
        '#default_value' => variable_get('i18n_newnode_current_' . $form['#node_type']->type, 0),
        '#disabled' => $disabled,
      );
      $form['i18n']['options']['i18n_required_node'] = array(
        '#type' => 'checkbox',
        '#title' => t('Require language (Do not allow Language Neutral).'),
        '#default_value' => variable_get('i18n_required_node_' . $form['#node_type']->type, 0),
        '#disabled' => $disabled,
      );
      $form['i18n']['options']['i18n_lock_node'] = array(
        '#type' => 'checkbox',
        '#title' => t('Lock language (Cannot be changed).'),
        '#default_value' => variable_get('i18n_lock_node_' . $form['#node_type']->type, 0),
        '#disabled' => $disabled,
      );
      // Add extended language support option to content type form.
      $form['i18n']['i18n_node'] = array(
        '#type' => 'radios',
        '#title' => t('Extended language support'),
        '#default_value' => variable_get('i18n_node_'. $form['#node_type']->type, LANGUAGE_SUPPORT_NORMAL),
        '#options' => _i18n_content_language_options(),
        '#description' => t('If enabled, all defined languages will be allowed for this content type in addition to only enabled ones. This is useful to have more languages for content than for the interface.'),
        '#disabled' => $disabled,
      );
      break;

    default:
      // Extensions for node edit forms
      if (isset($form['#id']) && $form['#id'] == 'node-form') {
        if (isset($form['#node']->type)) {
          if (variable_get('language_content_type_'. $form['#node']->type, 0)) {
            if (!empty($form['language']['#options'])) {
              $form['language']['#options'] = i18n_node_language_list($form['#node'], TRUE);
            }
          }
          elseif (!isset($form['#node']->nid)) {
            // Set language to empty for not multilingual nodes when creating
            $form['language'] = array('#type' => 'value', '#value' => '');
          }
        }
      }

      // Multilingual variables in settings form.
      if (isset($form['#theme']) && $form['#theme'] == 'system_settings_form' && $variables = i18n_variable()) {
        if ($i18n_variables = i18n_form_alter_settings($form, $variables)) {
          array_unshift($form['#submit'], 'i18n_variable_form_submit');
          $form['#i18n_variables'] = $i18n_variables;
        }
      }
  }
}

/**
 * Implementation of hook_perm().
 *
 * Permissions defined
 * - administer all languages
 *   Disables language conditions for administration pages, so the user can view objects for all languages at the same time.
 *   This applies for: menu items, taxonomy
 * - administer translations
 *   Will allow to add/remove existing nodes to/from translation sets.
 */
function i18n_perm() {
  return array('administer all languages', 'administer translations');
}

/**
 * Implementation of hook_theme().
 */
function i18n_theme() {
  return array(
    'i18n_node_select_translation' => array(
      'arguments' => array('element' => NULL),
      'file' => 'i18n.pages.inc',
    ),
  );
}

/**
 * Process menu and menu item add/edit form submissions.
 */
function i18n_menu_edit_item_form_submit($form, &$form_state) {
  $mid = menu_edit_item_save($form_state['values']);
  db_query("UPDATE {menu} SET language = '%s' WHERE mid = %d", $form_state['values']['language'], $mid);
  return 'admin/build/menu';
}

/**
 * Check for multilingual variables in form.
 */
function i18n_form_alter_settings(&$form, &$variables) {
  $result = array();
  foreach (element_children($form) as $field) {
    if (count(element_children($form[$field])) && empty($form[$field]['#tree'])) {
      $result += i18n_form_alter_settings($form[$field], $variables);
    }
    elseif (in_array($field, $variables)) {
      // Add form field class: i18n-variable
      $form[$field]['#attributes']['class'] = !empty($form[$field]['#attributes']['class']) ? $form[$field]['#attributes']['class'] . ' i18n-variable' : 'i18n-variable';
      $form[$field]['#description'] = !empty($form[$field]['#description']) ? $form[$field]['#description'] : '';
      $form[$field]['#description'] .= ' <strong>'. t('This is a multilingual variable.') .'</strong>';
      // Addd field => name to result
      $result[$field] = !empty($form[$field]['#title']) ? $form[$field]['#title'] : $field;
    }
  }
  return $result;
}

/**
 * Save multilingual variables and remove them from form.
 */
function i18n_variable_form_submit($form, &$form_state) {
  $op = isset($form_state['values']['op']) ? $form_state['values']['op'] : '';
  $variables = i18n_variable();
  $language = i18n_get_lang();
  $is_default = $language == language_default('language');
  foreach ($form_state['values'] as $key => $value) {
    if (i18n_variable($key)) {
      if ($op == t('Reset to defaults')) {
        i18n_variable_del($key, $language);
      }
      else {
        if (is_array($value) && isset($form_state['values']['array_filter'])) {
          $value = array_keys(array_filter($value));
        }
        i18n_variable_set($key, $value, $language);
      }
      // If current is default language, we allow global (without language) variables to be set too
      if (!$is_default) {
        unset($form_state['values'][$key]);
      }
    }
  }
  // The form will go now through system_settings_form_submit()
}

/**
 * Initialization of multilingual variables.
 *
 * @param $langcode
 *   Language to retrieve variables. Defaults to current language.
 */
function i18n_variable_init($langcode = NULL) {
  global $conf;

  $langcode = $langcode ? $langcode : i18n_get_lang();
  if ($variables = _i18n_variable_init($langcode)) {
    $conf = array_merge($conf, $variables);
  }
}

/**
 * Get language from context.
 */
function _i18n_get_context_lang() {
  // Node language when loading specific nodes or creating translations.
  if (arg(0) == 'node' ) {
    if (($node = menu_get_object('node')) && $node->language) {
      return $node->language;
    }
    elseif (arg(1) == 'add' && !empty($_GET['translation']) && !empty($_GET['language'])) {
      return $_GET['language'];
    }
  }
}

/**
 * Helper function to create language selector.
 */
function _i18n_language_select($value ='', $description ='', $weight = -20, $languages = NULL) {
  $languages = $languages ? $languages : locale_language_list();
  return array(
    '#type' => 'select',
    '#title' => t('Language'),
    '#default_value' => $value,
    '#options' => array_merge(array('' => ''), $languages),
    '#description' => $description,
    '#weight' => $weight,
  );
}

/**
 * Load language variables into array.
 */
function _i18n_variable_init($langcode) {
  global $i18n_conf;

  if (!isset($i18n_conf[$langcode])) {
    $cacheid = 'variables:'. $langcode;
    if ($cached = cache_get($cacheid)) {
      $i18n_conf[$langcode] = $cached->data;
    }
    else {
      $result = db_query("SELECT * FROM {i18n_variable} WHERE language = '%s'", $langcode);
      $i18n_conf[$langcode] = array();
      while ($variable = db_fetch_object($result)) {
        $i18n_conf[$langcode][$variable->name] = unserialize($variable->value);
      }
      cache_set($cacheid, $i18n_conf[$langcode]);
    }
  }

  return $i18n_conf[$langcode];
}

/**
 * Save multilingual variables that may have been changed by other methods than settings pages.
 */
function _i18n_variable_exit() {
  global $conf, $i18n_conf;

  $langcode = i18n_get_lang();
  if (isset($i18n_conf[$langcode])) {  
    $refresh = FALSE;
    // Rewritten because array_diff_assoc may fail with array variables.
    foreach (i18n_variable() as $name) {
      if (isset($conf[$name]) && isset($i18n_conf[$langcode][$name]) && $conf[$name] != $i18n_conf[$langcode][$name]) {  
        $refresh = TRUE;
        $i18n_conf[$langcode][$name] = $conf[$name];
        db_query("DELETE FROM {i18n_variable} WHERE name='%s' AND language='%s'", $name, $langcode);
        db_query("INSERT INTO {i18n_variable} (language, name, value) VALUES('%s', '%s', '%s')", $langcode, $name, serialize($conf[$name]));
      }
    }
    if ($refresh) {
      cache_set('variables:'. $langcode, $i18n_conf[$langcode]);
    }
  }
}

/**
 * Check whether we are in bootstrap mode.
 */
function _i18n_is_bootstrap() {
  return !function_exists('drupal_get_headers');
}

/**
 * Drupal 6, backwards compatibility layer.
 *
 * @ TO DO Fully upgrade all the modules and remove
 */

/**
 * This one expects to be called first from common.inc
 */
function i18n_get_lang() {
  global $language;
  return $language->language;
}

/**
 * @defgroup i18n_api Extended language API
 * @{
 * This is an extended language API to be used by modules in i18n package.
 */

/**
 * Returns language lists.
 */
function i18n_language_list($type = 'enabled', $field = 'name') {
  switch ($type) {
    case 'enabled':
      return locale_language_list($field);

    case 'extended':
      $enabled = locale_language_list($field);
      $defined = locale_language_list($field, TRUE);
      return array_diff_assoc($defined, $enabled);
  }
}

/**
 * Returns default language code.
 */
function i18n_default_language() {
  return language_default('language');
}

/**
 * Get list of supported languages, native name.
 *
 * @param $all
 *   TRUE to get all defined languages.
 */
function i18n_supported_languages($all = FALSE) {
  return locale_language_list('native', $all);
}

/**
 * Get list of multilingual variables or check whether a variable is multilingual
 */
function i18n_variable($name = NULL) {
  $variables = variable_get('i18n_variables', array());
  return $name ? in_array($name, $variables) : $variables;
}

/**
 * Set a persistent language dependent variable.
 *
 * @param $name
 *   The name of the variable to set.
 * @param $value
 *   The value to set. This can be any PHP data type; these functions take care
 *   of serialization as necessary.
 * @param $langcode
 *   Language code.
 */
function i18n_variable_set($name, $value, $langcode) {
  global $conf, $i18n_conf;

  $serialized_value = serialize($value);
  db_query("UPDATE {i18n_variable} SET value = '%s' WHERE name = '%s' AND language = '%s'", $serialized_value, $name, $langcode);
  if (!db_affected_rows()) {
    @db_query("INSERT INTO {i18n_variable} (name, language, value) VALUES ('%s', '%s', '%s')", $name, $langcode, $serialized_value);
  }
  cache_clear_all('variables:'. $langcode, 'cache');
  $i18n_conf[$langcode][$name] = $value;
  if ($langcode == i18n_get_lang()) {
    $conf[$name] = $value;
  }
}

/**
 * Get single multilingual variable
 */
function i18n_variable_get($name, $langcode, $default = NULL) {
  if ($variables = _i18n_variable_init($langcode)) {
    return isset($variables[$name]) ? $variables[$name] : $default;
  }
  else {
    return $default;
  }
}

/**
 * Unset a persistent multilingual variable.
 *
 * @param $name
 *   The name of the variable to undefine.
 * @param $langcode
 *   Optional language code. If not set it will delete the variable for all languages.
 */
function i18n_variable_del($name, $langcode = NULL) {
  global $conf, $i18n_conf;

  if ($langcode) {
    db_query("DELETE FROM {i18n_variable} WHERE name = '%s' AND language='%s'", $name, $langcode);
    cache_clear_all('variables:'. $langcode, 'cache');
    unset($i18n_conf[$langcode][$name]);
    // If current language, unset also global conf
    if ($langcode == i18n_get_lang()) {
      unset($conf[$name]);
    }
  }
  else {
    db_query("DELETE FROM {i18n_variable} WHERE name = '%s'", $name);
    if (db_affected_rows()) {
      cache_clear_all('variables:', 'cache', TRUE);
      if (is_array($i18n_conf)) {
        foreach (array_keys($i18n_conf) as $lang) {
          unset($i18n_conf[$lang][$name]);
        }
      }
    }
  }
}

/**
 * Utility. Get part of array variable.
 */
function i18n_array_variable_get($name, $element, $default = NULL) {
  if (($values = variable_get($name, array())) && isset($values[$element])) {
    return $values[$element];
  }
  else {
    return $default;
  }
}

/**
 * Utility. Set part of array variable.
 */
function i18n_array_variable_set($name, $element, $value) {
  $values = variable_get($name, array());
  $values[$element] = $value;
  variable_set($name, $values);
}

/**
 * @} End of "defgroup i18n_api".
 */

/**
 * List of language support modes for content.
 */
function _i18n_content_language_options() {
  return array(
    LANGUAGE_SUPPORT_NORMAL => t('Normal - All enabled languages will be allowed.'),
    LANGUAGE_SUPPORT_EXTENDED => t('Extended - All defined languages will be allowed.'),
    LANGUAGE_SUPPORT_EXTENDED_NOT_DISPLAYED => t('Extended, but not displayed - All defined languages will be allowed for input, but not displayed in links.'),
  );
}