<?php

/**
 * @file
 * Internationalization (i18n) submodule: Menu translation.
 *
 * @author Jose A. Reyero, 2005
 *
 */

/**
 * Implements hook_menu()
 */
function i18n_menu_menu() {
  $items['admin/structure/menu/manage/translation'] = array(
    'title' => 'Translation sets',
    'page callback' => 'i18n_translation_set_list_manage',
    'page arguments' => array('menu_link'),
    'access arguments' => array('administer menu'),
    'type' => MENU_LOCAL_TASK,
    'weight' => 10,
  );
  $items['admin/structure/menu/manage/translation/add'] = array(
    'title' => 'Add translation',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('i18n_menu_translation_form'),
    'access arguments' => array('administer menu'),
    'type' => MENU_LOCAL_ACTION,
    'file' => 'i18n_menu.admin.inc',
  );
  $items['admin/structure/menu/manage/translation/edit/%i18n_menu_translation'] = array(
    'title' => 'Edit translation',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('i18n_menu_translation_form', 6),
    'access arguments' => array('administer menu'),
    'type' => MENU_CALLBACK,
    'file' => 'i18n_menu.admin.inc',
  );
  $items['admin/structure/menu/manage/translation/delete/%i18n_menu_translation'] = array(
    'title' => 'Delete translation',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('i18n_translation_set_delete_confirm', 6),
    'access arguments' => array('administer menu'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_menu_alter()
 */
function i18n_menu_menu_alter(&$items) {
  $items['admin/structure/menu/item/%menu_link'] = $items['admin/structure/menu/item/%menu_link/edit'];
  $items['admin/structure/menu/item/%menu_link']['type'] = MENU_CALLBACK;
  $items['admin/structure/menu/item/%menu_link/edit']['type'] = MENU_DEFAULT_LOCAL_TASK;
  $items['admin/structure/menu/manage/%menu']['title callback'] = 'i18n_menu_menu_overview_title';
}

/**
 * Preprocess theme_menu_admin_overview to translate menu name and description
 *
 * @param $variables
 */
function i18n_menu_preprocess_menu_admin_overview(&$variables) {
  $variables['title'] = i18n_string(array('menu', 'menu', $variables['name'], 'title'), $variables['title']);
  $variables['description'] = i18n_string(array('menu', 'menu', $variables['name'], 'description'), $variables['description']);
}

/**
 * Title callback for the menu overview page and links.
 */
function i18n_menu_menu_overview_title($menu) {
  return i18n_string(array('menu', 'menu', $menu['menu_name'], 'title'), $menu['title']);
}

/**
 * Implements hook_block_view().
 */
function i18n_menu_block_view_alter(&$data, $block) {
  if (($block->module == 'menu' || $block->module == 'system') && (i18n_menu_mode($block->delta) & I18N_MODE_MULTIPLE)) {
    $menus = menu_get_menus();
    if (isset($menus[$block->delta])) {
      if (empty($block->title)) {
        $data['subject'] = i18n_string_plain(
          array('menu', 'menu', $block->delta, 'title'),
          $menus[$block->delta]
        );
      }
      // Add contextual links for this block.
      if (!empty($data['content'])) {
        $data['content']['#contextual_links']['menu'] = array('admin/structure/menu/manage', array($block->delta));
      }
    }
  }
}

/**
 * Implements hook_i18n_translate_path()
 */
function i18n_menu_i18n_translate_path($path) {
  $item = i18n_menu_link_load($path, i18n_langcode());
  if ($item && ($set = i18n_translation_object('menu_link', $item))) {
    $links = array();
    foreach ($set->get_translations() as $lang => $link) {
      $links[$lang] = array(
        'href' => $link['link_path'],
        'title' => $link['link_title'],
        'i18n_type' => 'menu_link',
        'i18n_object' => $link,
      );
    }
    return $links;
  }
}

/**
 * Implements hook_menu_insert()
 */
function i18n_menu_menu_insert($menu) {
  i18n_menu_menu_update($menu);
}

/**
 * Implements hook_menu_update()
 */
function i18n_menu_menu_update($menu) {
  // Stores the fields of menu links which need an update.
  $update = array();

  if (!isset($menu['i18n_mode'])) {
    $menu['i18n_mode'] = I18N_MODE_NONE;
  }
  if (!($menu['i18n_mode'] & I18N_MODE_LANGUAGE)) {
    $menu['language'] = LANGUAGE_NONE;
  }
  db_update('menu_custom')
    ->fields(array('language' => $menu['language'], 'i18n_mode' => $menu['i18n_mode']))
    ->condition('menu_name', $menu['menu_name'])
    ->execute();
  if (!$menu['i18n_mode']) {
    $update['language'] = LANGUAGE_NONE;
  }
  elseif ($menu['i18n_mode'] & I18N_MODE_LANGUAGE) {
    $update['language'] = $menu['language'];
  }

  // Non translatable menu.
  if (!($menu['i18n_mode'] & I18N_MODE_TRANSLATE)) {
    $tsids = db_select('menu_links')
      ->fields('menu_links', array('i18n_tsid'))
      ->groupBy('i18n_tsid')
      ->condition('menu_name', $menu['menu_name'])
      ->condition('customized', 1)
      ->condition('i18n_tsid', 0, '<>')
      ->execute()
      ->fetchCol(0);
    if (!empty($tsids)) {
      foreach ($tsids as $tsid) {
        if ($translation_set = i18n_translation_set_load($tsid)) {
          $translation_set->delete();
        }
      }
    }
    $update['i18n_tsid'] = 0;
  }

  if (!empty($update)) {
    db_update('menu_links')
      ->fields($update)
      ->condition('menu_name', $menu['menu_name'])
      ->condition('customized', 1)
      ->execute();
  }

  // Update strings, always add translation if no language
  if (!i18n_object_langcode($menu)) {
    i18n_string_object_update('menu', $menu);
  }

  // Clear all menu caches.
  menu_cache_clear_all();
}

/**
 * Implements hook_menu_delete()
 */
function i18n_menu_menu_delete($menu) {
  i18n_string_object_remove('menu', $menu);
}

/**
 * Implements hook_menu_link_alter().
 *
 * This function is invoked from menu_link_save() before default
 * menu link options (menu_name, module, etc.. have been set)
 */
function i18n_menu_menu_link_alter(&$item) {
  // We just make sure every link has a valid language property.
  if (!i18n_object_langcode($item)) {
    $item['language'] = LANGUAGE_NONE;
  }
}

/**
 * Implements hook_menu_link_insert()
 */
function i18n_menu_menu_link_insert($link) {
  i18n_menu_menu_link_update($link);
}

/**
 * Implements hook_menu_link_update().
 */
function i18n_menu_menu_link_update($link) {
  // Stores the fields to update.
  $fields = array();
  $menu_mode = i18n_menu_mode($link['menu_name']);

  if ($menu_mode & I18N_MODE_TRANSLATE && isset($link['language'])) {
    // Multilingual menu links, translatable, it may be part of a
    // translation set.
    if (i18n_object_langcode($link)) {
      if (!empty($link['translation_set'])) {
        // Translation set comes as parameter, we may be creating a translation,
        // add link to the set.
        $translation_set = $link['translation_set'];
        $translation_set
          ->add_item($link)
          ->save(TRUE);
      }
    }
    elseif ($link['language'] === LANGUAGE_NONE && !empty($link['original_item']['i18n_tsid'])) {
      if ($translation_set = i18n_translation_set_load($link['original_item']['i18n_tsid'])) {
        $translation_set->remove_language($link['original_item']['language']);
        // If there are no links left in this translation set, delete the set.
        // Otherwise update the set.
        $translation_set->update_delete();
      }
      $fields['i18n_tsid'] = 0;
    }
  }
  // For multilingual menu items, always set a language and mark them for
  // 'alter' so they can be processed later by
  // hook_translated_link_menu_alter().
  if ($menu_mode) {
    if (!isset($link['language'])) {
      $link['language'] = LANGUAGE_NONE;
    }
    if (_i18n_menu_link_check_alter($link) && empty($link['options']['alter'])) {
      $fields['options'] = $link['options'];
      $fields['options']['alter'] = TRUE;
    }
    // We cannot unmark links for altering because we don't know what other
    // modules use it for.
  }
  // Update language field if the link has a language value.
  if (isset($link['language'])) {
    $fields['language'] = $link['language'];
  }

  if (!empty($fields)) {
    // If link options are to be updated, they need to be serialized.
    if (isset($fields['options'])) {
      $fields['options'] = serialize($fields['options']);
    }
    db_update('menu_links')
      ->fields($fields)
      ->condition('mlid', $link['mlid'])
      ->execute();
  }
  // Update translatable strings if any for customized links that belong to a
  // localizable menu.
  if (_i18n_menu_link_is_localizable($link)) {
    i18n_string_object_update('menu_link', $link);
  }
  else {
    i18n_string_object_remove('menu_link', $link);
  }
}

/**
 * Implements hook_menu_delete()
 */
function i18n_menu_menu_link_delete($link) {
  // If a translation set exists for this link, remove this link from the set.
  if (!empty($link['i18n_tsid'])) {
    if ($translation_set = i18n_translation_set_load($link['i18n_tsid'])) {
      $translation_set->get_translations();

      $translation_set->remove_language($link['language']);

      // If there are no links left in this translation set, delete the set.
      // Otherwise update the set.
      $translation_set->update_delete();
    }
  }

  i18n_string_object_remove('menu_link', $link);
}

/**
 * Get menu mode or compare with given one
 */
function i18n_menu_mode($name, $mode = NULL) {
  $menu = menu_load($name);
  if (!$menu || !isset($menu['i18n_mode'])) {
    return isset($mode) ? FALSE : I18N_MODE_NONE;
  }
  else {
    return isset($mode) ? $menu['i18n_mode'] & $mode : $menu['i18n_mode'];
  }
}

/**
 * Implements hook_translated_menu_link_alter().
 *
 * Translate localizable menu links on the fly.
 * Filter out items that have a different language from current interface.
 *
 * @see i18n_menu_menu_link_alter()
 */
function i18n_menu_translated_menu_link_alter(&$item) {
  // Only process links to be displayed not processed before by i18n_menu.
  if (_i18n_menu_link_process($item)) {
    if (!_i18n_menu_link_is_visible($item)) {
      $item['hidden'] = TRUE;
    }
    elseif (_i18n_menu_link_is_localizable($item)) {
      // Item has undefined language, it is a candidate for localization.
      _i18n_menu_link_localize($item);
    }
  }
}

/**
 * Implements hook_help().
 */
function i18n_menu_help($path, $arg) {
  switch ($path) {
    case 'admin/help#i18n_menu' :
      $output = '<p>' . t('This module adds support for multilingual menus. You can setup multilingual options for each menu:') . '</p>';
      $output .= '<ul>';
      $output .= '<li>' . t('Menus can be fully multilingual with translatable (or localized) menu items.') . '</li>';
      $output .= '<li>' . t('Menus can be configured to have a fixed language. All menu items share this language setting and the menu will be visible in that language only.') . '</li>';
      $output .= '<li>' . t('Menus can also be configured to have no translations.') . '</li>';
      $output .= '</ul>';
      $output .= '<p>' . t('The multilingual options of a menu must be configured before individual menu items can be translated. Go to the <a href="@menu-admin">Menus administration page</a> and follow the "edit menu" link to the menu in question.', array('@menu-admin' => url('admin/structure/menu') ) ) . '</p>';
      $output .= '<p>' . t('To search and translate strings, use the <a href="@translate-interface">translation interface</a> pages.', array('@translate-interface' => url('admin/config/regional/translate'))) . '</p>';
      return $output;

    case 'admin/config/regional/i18n':
      $output = '<p>' . t('Menus and menu items can be translated on the <a href="@configure_menus">Menu administration page</a>.', array('@configure_menus' => url('admin/structure/menu'))) . '</p>';
      return $output;
  }
}

/**
 * Implements hook_variable_info_alter()
 */
function i18n_menu_variable_info_alter(&$variables, $options) {
  // Make menu variables translatable
  $variables['menu_main_links_source']['localize'] = TRUE;
  $variables['menu_secondary_links_source']['localize'] = TRUE;
  $variables['menu_parent_[node_type]']['localize'] = TRUE;
  $variables['menu_options_[node_type]']['localize'] = TRUE;
}

/**
 * Get localized menu tree.
 *
 * @param string $menu_name
 *   The menu the translated tree has to be fetched from.
 * @param string $langcode
 *   Optional language code to get the menu in, defaults to request language.
 * @param bool $reset
 *   Whether to reset the internal i18n_menu_translated_tree cache.
 */
function i18n_menu_translated_tree($menu_name, $langcode = NULL, $reset = FALSE) {
  $menu_output = &drupal_static(__FUNCTION__);
  $langcode = $langcode ? $langcode : i18n_language_interface()->language;
  if (!isset($menu_output[$langcode][$menu_name]) || $reset) {
    $tree = menu_tree_page_data($menu_name);
    $tree = i18n_menu_localize_tree($tree, $langcode);
    $menu_output[$langcode][$menu_name] = menu_tree_output($tree);
  }
  return $menu_output[$langcode][$menu_name];
}

/**
 * Localize menu tree.
 */
function i18n_menu_localize_tree($tree, $langcode = NULL) {
  $langcode = $langcode ? $langcode : i18n_language_interface()->language;
  foreach ($tree as $index => &$item) {
    $link = $item['link'];
    // We only process links that are visible and not processed before.
    if (_i18n_menu_link_process($item['link'])) {
      if (!_i18n_menu_link_is_visible($item['link'], $langcode)) {
        // Remove links for other languages than current.
        // Links with language won't be localized.
        unset($tree[$index]);
        // @todo Research whether the above has any advantage over:
        // $item['hidden'] = TRUE;
      }
      else {
        if (_i18n_menu_link_is_localizable($item['link'])) {
          // Item has undefined language, it is a candidate for localization.
          _i18n_menu_link_localize($item['link'], $langcode);
        }
        // Localize subtree.
        if (!empty($item['below'])) {
          $item['below'] = i18n_menu_localize_tree($item['below'], $langcode);
        }
      }
    }
  }
  return $tree;
}

/**
 * Localize menu renderable array
 */
function i18n_menu_localize_elements(&$elements) {
  foreach (element_children($elements) as $mlid) {
    $elements[$mlid]['#title'] = i18n_string(array('menu', 'item', $mlid, 'title'), $elements[$mlid]['#title']);
    if (!empty($tree[$mlid]['#localized_options']['attributes']['title'])) {
      $elements[$mlid]['#localized_options']['attributes']['title'] = i18n_string(array('menu', 'item', $mlid, 'description'), $tree[$mlid]['#localized_options']['attributes']['title']);
    }
    i18n_menu_localize_elements($elements[$mlid]);
  }
}

/**
 * Return an array of localized links for a navigation menu.
 *
 * Localized version of menu_navigation_links()
 */
function i18n_menu_navigation_links($menu_name, $level = 0) {
  // Don't even bother querying the menu table if no menu is specified.
  if (empty($menu_name)) {
    return array();
  }

  // Get the menu hierarchy for the current page.
  $tree = menu_tree_page_data($menu_name, $level + 1);
  $tree = i18n_menu_localize_tree($tree);

  // Go down the active trail until the right level is reached.
  while ($level-- > 0 && $tree) {
    // Loop through the current level's items until we find one that is in trail.
    while ($item = array_shift($tree)) {
      if ($item['link']['in_active_trail']) {
        // If the item is in the active trail, we continue in the subtree.
        $tree = empty($item['below']) ? array() : $item['below'];
        break;
      }
    }
  }

  // Create a single level of links.
  $router_item = menu_get_item();
  $links = array();
  foreach ($tree as $item) {
    if (!$item['link']['hidden']) {
      $class = '';
      $l = $item['link']['localized_options'];
      $l['href'] = $item['link']['href'];
      $l['title'] = $item['link']['title'];
      if ($item['link']['in_active_trail']) {
        $class = ' active-trail';
        $l['attributes']['class'][] = 'active-trail';
      }
      // Normally, l() compares the href of every link with $_GET['q'] and sets
      // the active class accordingly. But local tasks do not appear in menu
      // trees, so if the current path is a local task, and this link is its
      // tab root, then we have to set the class manually.
      if ($item['link']['href'] == $router_item['tab_root_href'] && $item['link']['href'] != $_GET['q']) {
        $l['attributes']['class'][] = 'active';
      }
      // Keyed with the unique mlid to generate classes in theme_links().
      $links['menu-' . $item['link']['mlid'] . $class] = $l;
    }
  }
  return $links;
}

/**
 * Get localized menu title
 */
function _i18n_menu_link_title($link, $langcode = NULL) {
  $key = i18n_object_info('menu_link', 'key');
  return i18n_string_translate(array('menu', 'item', $link[$key], 'title'), $link['link_title'], array('langcode' => $langcode, 'sanitize' => FALSE));
}

/**
 * Localize menu item title and description.
 *
 * This will be invoked always after _menu_item_localize()
 *
 * Link properties to manage:
 * - title, menu router title
 * - link_title, menu link title
 * - options.attributes.title, menu link description.
 * - localized_options.attributes.title,
 *
 * @see _menu_item_localize()
 * @see _menu_link_translate()
 */
function _i18n_menu_link_localize(&$link, $langcode = NULL) {
  // Only translate title if it has no special callback.
  if (empty($link['title callback']) || $link['title callback'] === 't') {
    $link['title'] = _i18n_menu_link_title($link, $langcode);
  }
  if ($description = _i18n_menu_link_description($link, $langcode)) {
    $link['localized_options']['attributes']['title'] = $description;
  }
}

/**
 * Get localized menu description
 */
function _i18n_menu_link_description($link, $langcode = NULL) {
  if (!empty($link['options']['attributes']['title'])) {
    $key = i18n_object_info('menu_link', 'key');
    return i18n_string_translate(array('menu', 'item', $link[$key], 'description'), $link['options']['attributes']['title'], array('langcode' => $langcode));
  }
  else {
    return NULL;
  }
}

/**
 * Check whether this link is to be processed by i18n_menu and start processing.
 */
function _i18n_menu_link_process(&$link) {
  // Only links that have a language property and haven't been processed before.
  // We also translate links marked as hidden because core breadcrumbs ignore
  // that flag and excluding them would basically interfere with core behaviour.
  // We also check that they belong to a menu with language options.
  if (empty($link['i18n_menu']) && !empty($link['language']) && !empty($link['access']) && i18n_menu_mode($link['menu_name'])) {
    // Mark so it won't be processed twice.
    $link['i18n_menu'] = TRUE;
    // Skip if administering this menu or this menu item.
    if (arg(0) == 'admin' && arg(1) == 'structure' && arg(2) == 'menu') {
      if (arg(3) == 'manage' && $link['menu_name'] == arg(4)) {
        return FALSE;
      }
      elseif (arg(3) == 'item' && arg(4) == $link['mlid']) {
        return FALSE;
      }
    }
    // Skip if administering this menu item through the node edit form.
    elseif (arg(0) == 'node' && arg(2) == 'edit' && $link['link_path'] == arg(0) . '/' . arg(1)) {
      return FALSE;
    }
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Check whether this menu item should be marked for altering.
 *
 * Menu items that have a language or that have any localizable strings
 * will be marked to be run through hook_translated_menu_link_alter().
 *
 * @see i18n_menu_translated_menu_link_alter()
 */
function _i18n_menu_link_check_alter($link) {
  return i18n_menu_mode($link['menu_name']) && (i18n_object_langcode($link) || _i18n_menu_link_is_localizable($link, TRUE));
}

/**
 * Check whether this link should be localized by i18n_menu.
 *
 * @param array $link
 *   Menu link array.
 * @param bool $check_strings
 *   Whether to check if the link has actually localizable strings. Since this
 *   is a more expensive operation, it will be just checked when editing menu
 *   items.
 *
 * @return boolean
 *   Returns TRUE if link is localizable.
 */
function _i18n_menu_link_is_localizable($link, $check_strings = FALSE) {
  return !empty($link['customized']) && !i18n_object_langcode($link) && i18n_menu_mode($link['menu_name'], I18N_MODE_LOCALIZE) &&
  (!$check_strings || _i18n_menu_link_localizable_properties($link));
}

/**
 * Check whether this menu link is visible for current/given language.
 */
function _i18n_menu_link_is_visible($link, $langcode = NULL) {
  $langcode = $langcode ? $langcode : i18n_language_interface()->language;
  return $link['language'] == LANGUAGE_NONE || $link['language'] == $langcode;
}

/**
 * Get localizable properties for menu link checking against the router item.
 */
function _i18n_menu_link_localizable_properties($link) {
  $props = array();
  $router = !empty($link['router_path']) ? _i18n_menu_get_router($link['router_path']) : NULL;
  if (!empty($link['link_title'])) {
    // If the title callback is 't' and the link title matches the router title
    // it will be localized by core, not by i18n_menu.
    if (!$router ||
        (empty($router['title_callback']) || ($router['title_callback'] != 't' || !empty($link['customized']))) ||
        (empty($router['title']) || $router['title'] != $link['link_title'])
    ) {
      $props[] = 'title';
    }
  }
  if (!empty($link['options']['attributes']['title'])) {
    // If the description matches the router description, it will be localized
    // by core.
    if (!$router || empty($router['description']) || ($router['description'] != $link['options']['attributes']['title']) || !empty($link['customized'])) {
      $props[] = 'description';
    }
  }
  return $props;
}

/**
 * Get the menu router for this router path.
 *
 * We need the untranslated title to compare, and this will be fast.
 * There's no api function to do this?
 *
 * @param string $path
 *   The path to fetch from the router.
 */
function _i18n_menu_get_router($path) {
  $cache = &drupal_static(__FUNCTION__, array());
  if (!array_key_exists($path, $cache)) {
    $cache[$path] = db_select('menu_router', 'mr')
      ->fields('mr', array('title', 'title_callback', 'description'))
      ->condition('path', $path)
      ->execute()
      ->fetchAssoc();
  }
  return $cache[$path];
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function i18n_menu_form_menu_edit_menu_alter(&$form, &$form_state) {
  $menu = menu_load($form['old_name']['#value']);
  $i18n_mode = $menu && isset($menu['i18n_mode']) ? $menu['i18n_mode'] : I18N_MODE_NONE;
  $langcode = $menu && isset($menu['language']) ? $menu['language'] : LANGUAGE_NONE;

  $form += i18n_translation_mode_element('menu', $i18n_mode, $langcode);
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Add a language selector to the menu_edit_item form and register a submit
 * callback to process items.
 */
function i18n_menu_form_menu_edit_item_alter(&$form, &$form_state) {
  $item = &$form['original_item']['#value'];
  $item['language'] = i18n_menu_item_get_language($item);
  // Check whether this item belongs to a node object and it is a supported type.
  $node_item = ($node = i18n_menu_item_get_node($item)) && i18n_menu_node_supported_type($node->type);
  if (!$node_item && i18n_menu_mode($item['menu_name'], I18N_MODE_TRANSLATE)) {
    //$form['i18n'] = array('#type' => 'fieldset');
    $form['i18n']['language'] = array(
      '#description' => t('This item belongs to a multilingual menu. You can set a language for it.'),
    ) + i18n_element_language_select($item);

    // If the term to be added will be a translation of a source term,
    // set the default value of the option list to the target language and
    // create a form element for storing the translation set of the source term.
    if (isset($_GET['translation']) && isset($_GET['target']) && ($source_item = menu_link_load($_GET['translation']))) {
      if (!empty($source_item['i18n_tsid'])) {
        $translation_set = i18n_translation_set_load($source_item['i18n_tsid']);
      }
      else {
        // Create object and stick the source information in the translation set.
        $translation_set = i18n_translation_set_build('menu_link')
          ->add_item($source_item);
      }
      $form['link_path']['#default_value'] = $source_item['link_path'];

      // Maybe we should disable the 'link_path' and 'parent' form elements?
      // $form['link_path']['#disabled'] = TRUE;
      // $form['parent']['#disabled'] = TRUE;

      $form['i18n']['language']['#default_value'] = $_GET['target'];
      $form['i18n']['language']['#disabled'] = TRUE;

      drupal_set_title(t('%language translation of menu item %title', array('%language' => locale_language_name($_GET['target']), '%title' => $source_item['link_title'])), PASS_THROUGH);
    }
    elseif (!empty($item['i18n_tsid'])) {
      $translation_set = i18n_translation_set_load($item['i18n_tsid']);
    }

    // Add the translation set to the form so we know the new menu item
    // needs to be added to that set.
    if (!empty($translation_set)) {
      $form['translation_set'] = array(
        '#type' => 'value',
        '#value' => $translation_set,
      );

      // If the current term is part of a translation set,
      // remove all other languages of the option list.
      if ($translations = $translation_set->get_translations()) {
        unset($form['i18n']['language']['#options'][LANGUAGE_NONE]);
        foreach ($translations as $langcode => $translation) {
          if ($translation['mlid'] !== $item['mlid']) {
            unset($form['i18n']['language']['#options'][$langcode]);
          }
        }
      }
    }
  }
  else {
    $form['language'] = array(
      '#type' => 'value',
      '#value' => $item['language'],
    );
  }
  if ($node_item && i18n_langcode($item['language'])) {
    $form['i18n']['message'] = array(
      '#type' => 'item',
      '#title' => t('Language'),
      '#markup' => i18n_language_name($item['language']),
      '#description' => t('This menu item belongs to a node, so it will have the same language as the node and cannot be localized.'),
    );
  }
  array_unshift($form['#validate'], 'i18n_menu_menu_item_prepare_normal_path');
}

/**
 * Implements hook_form_FORM_ID_alter().
 * FORM_ID = menu-overview-form.
 * Add a "translate" link in operations column for each menu item.
 */
function i18n_menu_form_menu_overview_form_alter(&$form, &$form_state) {
  if (i18n_menu_mode($form['#menu']['menu_name'], I18N_MODE_MULTIPLE)) {
    foreach (element_children($form) as $element) {
      if (substr($element, 0, 5) == 'mlid:') {
        $item = $form[$element]["#item"];
        $mlid = $form[$element]['#item']['mlid'];
        if (i18n_get_object('menu', $mlid)->get_translate_access()) {
          $form[$element]['operations']['translate'] = array(
            '#type' => 'link',
            '#title' => t('translate'),
            '#href' => "admin/structure/menu/item/{$mlid}/translate",
          );
          $form[$element]['title']['#markup'] = l(_i18n_menu_link_title($item), $item['href'], $item['localized_options']);
        }
      }
    }
  }
}

/**
 * Normal path should be checked with menu item's language to avoid
 * troubles when a node and it's translation has the same url alias.
 */
function i18n_menu_menu_item_prepare_normal_path($form, &$form_state) {
  $item = &$form_state['values'];
  $item['link_path'] = i18n_prepare_normal_path($item['link_path'], $item['language']);
}

/**
 * Get language for menu item
 */
function i18n_menu_item_get_language($item) {
  if (isset($item['language'])) {
    return $item['language'];
  }
  else {
    $menu = menu_load($item['menu_name']);
    if (!isset($menu['i18n_mode'])) {
      return LANGUAGE_NONE;
    }
    switch ($menu['i18n_mode']) {
      case I18N_MODE_LANGUAGE:
        return $menu['language'];
      case I18N_MODE_NONE:
      case I18N_MODE_LOCALIZE:
        return LANGUAGE_NONE;
      default:
        if (!empty($item['mlid'])) {
          return db_select('menu_links', 'm')
            ->fields('m', array('language'))
            ->condition('mlid', $item['mlid'])
            ->execute()
            ->fetchField();
        }
        else {
          return LANGUAGE_NONE;
        }
    }
  }
}

/**
 * Implements hook_form_node_form_alter().
 *
 * Add language to menu settings of the node form, as well as setting defaults
 * to match the translated item's menu settings.
 */
function i18n_menu_form_node_form_alter(&$form, &$form_state, $form_id) {
  if (isset($form['menu'])) {
    $node = $form['#node'];
    $link = $node->menu;
    if (!empty($link['mlid'])) {
      // Preserve the menu item language whatever it is.
      $form['menu']['link']['language'] = array('#type' => 'value', '#value' => $link['language']);
    }
    elseif (i18n_menu_node_supported_type($node->type)) {
      // Set menu language to node language but only if it is a supported node type.
      $form['menu']['link']['language'] = array('#type' => 'value', '#value' => $node->language);
    }
    else {
      $form['menu']['link']['language'] = array('#type' => 'value', '#value' => LANGUAGE_NONE);
    }
    // Customized must be set to 1 to save language.
    $form['menu']['link']['customized'] = array('#type' => 'value', '#value' => 1);
  }
}

/**
 * Check whether a node type has multilingual support (but not entity translation).
 */
function i18n_menu_node_supported_type($type) {
  $supported = &drupal_static(__FUNCTION__);
  if (!isset($supported[$type])) {
    $mode = variable_get('language_content_type_' . $type, 0);
    $supported[$type] = $mode == 1 || $mode == 2; // 2 == TRANSLATION_ENABLED
  }
  return $supported[$type];
}

/**
 * Get the node object for a menu item.
 */
function i18n_menu_item_get_node($item) {
  return isset($item['router_path']) && $item['router_path'] == 'node/%' ? node_load(arg(1, $item['link_path'])) : NULL;
}

/**
 * Implements hook_node_presave()
 *
 * Set menu link language to node language
 */
function i18n_menu_node_presave($node) {
  if (!empty($node->menu) && isset($node->language) && i18n_menu_node_supported_type($node->type)) {
    $node->menu['language'] = i18n_object_langcode($node, LANGUAGE_NONE);
    // Store node type with menu item so we can quickly access it later.
    $node->menu['options']['node_type'] = $node->type;
  }
}

/**
 * Implements hook_node_prepare_translation().
 */
function i18n_menu_node_prepare_translation($node) {
  if (empty($node->menu['mlid']) && !empty($node->translation_source)) {
    $tnode = $node->translation_source;
    // Prepare the tnode so the menu item will be available.
    node_object_prepare($tnode);
    $node->menu['link_title'] = $tnode->menu['link_title'];
    $node->menu['weight'] = $tnode->menu['weight'];
  }
}

/**
 * Process menu and menu item add/edit form submissions.
 *
 * @todo See where this fits
 */
/*
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", array($form_state['values']['language'], $mid));
  return 'admin/build/menu';
}
*/

/**
 * Load translation set. Menu loading callback.
 */
function i18n_menu_translation_load($tsid) {
  return i18n_translation_set_load($tsid, 'menu_link');
}

/**
 * Load menu item by path, language
 */
function i18n_menu_link_load($path, $langcode) {
  $query = db_select('menu_links', 'ml');
  $query->leftJoin('menu_router', 'm', 'm.path = ml.router_path');
  $query->fields('ml');
  // Weight should be taken from {menu_links}, not {menu_router}.
  $query->addField('ml', 'weight', 'link_weight');
  $query->fields('m');
  $query->condition('ml.link_path', $path);
  $query->condition('ml.language', $langcode);
  if ($item = $query->execute()->fetchAssoc()) {
    $item['weight'] = $item['link_weight'];
    _menu_link_translate($item);
    return $item;
  }
}

/**
 * Implements hook_query_TAG_alter() for features_menu_links.
 * Add needed fields to properly serialize localization information.
 */
function i18n_menu_query_features_menu_link_alter($query) {
  $query->fields('menu_links', array('language', 'customized'));
}

/**
 * Implements hook_query_TAG_alter()
 *
 * Using tag 'preferred_menu_links' added in menu_link_get_preferred().
 * See http://drupal.org/node/1854134
 */
function i18n_menu_query_preferred_menu_links_alter(QueryAlterableInterface $query) {
  global $language;
  // Get queried tables.
  $tables = $query->getTables();

  foreach ($tables as $alias => $table) {
    if ($table['table'] == 'menu_links') {
      // Add language filter, ensuring that we don't have any collision when
      // determining the active menu trail when there are multiple menu items
      // with same link path but different languages.
      if ($language) {
        $query->condition('language', array($language->language, LANGUAGE_NONE), 'IN');
      }
      break;
    }
  }
}

