menu.module

<?php
/**
 * @file
 * Allows administrators to customize the site's menus.
 *
 * A menu (in this context) is a hierarchical collection of links, generally
 * used for navigation. This is not to be confused with the
 * @link menu Menu system @endlink of menu.inc and hook_menu(), which defines
 * page routing requests for Backdrop. The menu system also allows the defined
 * page routing URLs to be added to these menus.
 */

/**
 * Maximum length of menu name as entered by the user. Database length is 32
 * and we add a menu- prefix.
 */
define('MENU_MAX_MENU_NAME_LENGTH_UI', 27);

/**
 * Implements hook_permission().
 */
function menu_permission() {
  return array(
    'administer menu' => array(
      'title' => t('Administer menus and menu items'),
    ),
  );
}

/**
 * Implements hook_menu().
 */
function menu_menu() {
  $items['admin/structure/menu'] = array(
    'title' => 'Menus',
    'description' => 'Add new menus to your site, edit existing menus, and rename and reorganize menu links.',
    'page callback' => 'menu_overview_page',
    'access arguments' => array('administer menu'),
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/parents'] = array(
    'title' => 'Parent menu items',
    'page callback' => 'menu_parent_options_js',
    'delivery callback' => 'backdrop_json_deliver',
    'type' => MENU_CALLBACK,
    'access arguments' => array('administer menu'),
  );
  $items['admin/structure/menu/list'] = array(
    'title' => 'List menus',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/structure/menu/add'] = array(
    'title' => 'Add menu',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_edit_menu', 'add'),
    'access arguments' => array('administer menu'),
    'type' => MENU_LOCAL_ACTION,
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/manage/%menu'] = array(
    'title' => 'Edit links',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_overview_form', 4),
    'title callback' => 'menu_overview_title',
    'title arguments' => array(4),
    'access arguments' => array('administer menu'),
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/manage/%menu/list'] = array(
    'title' => 'Edit links',
    'weight' => -10,
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
  );
  $items['admin/structure/menu/manage/%menu/add'] = array(
    'title' => 'Add link',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_edit_item', 'add', NULL, 4),
    'access arguments' => array('administer menu'),
    'type' => MENU_LOCAL_ACTION,
    'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/manage/%menu/configure'] = array(
    'title' => 'Configure menu',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_edit_menu', 'configure', 4),
    'access arguments' => array('administer menu'),
    'type' => MENU_LOCAL_TASK,
    'context' => MENU_CONTEXT_PAGE,
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/manage/%menu/delete'] = array(
    'title' => 'Delete menu',
    'page callback' => 'menu_delete_menu_page',
    'page arguments' => array(4),
    'access arguments' => array('administer menu'),
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/item/%menu_link/edit'] = array(
    'title' => 'Edit link',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_edit_item', 'edit', 4, NULL),
    'access arguments' => array('administer menu'),
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/item/%menu_link/reset'] = array(
    'title' => 'Reset menu link',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_reset_item_confirm', 4),
    'access arguments' => array('administer menu'),
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/item/%menu_link/delete'] = array(
    'title' => 'Delete menu link',
    'page callback' => 'menu_item_delete_page',
    'page arguments' => array(4),
    'access arguments' => array('administer menu'),
    'file' => 'menu.admin.inc',
  );
  $items['admin/structure/menu/settings'] = array(
    'title' => 'Menu settings',
    'description' => 'Configure global settings for menus.',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('menu_settings_form'),
    'access arguments' => array('administer menu'),
    'type' => MENU_LOCAL_TASK,
    'file' => 'menu.admin.inc',
    'weight' => 99,
  );
  return $items;
}

/**
 * Implements hook_theme().
 */
function menu_theme() {
  $base = array(
    'file' => 'menu.theme.inc',
  );

  return array(
    'menu_overview_form' => array(
      'render element' => 'form',
    ) + $base,
    'menu_admin_overview' => array(
      'variables' => array('title' => NULL, 'name' => NULL, 'description' => NULL),
    ) + $base,
  );
}

/**
 * Implements hook_config_info().
 */
function menu_config_info() {
  $prefixes['menu.menu'] = array(
    'name_key' => 'menu_name',
    'label_key' => 'title',
    'group' => t('Menus'),
  );
  $prefixes['menu.settings'] = array(
    'label' => t('Menu settings'),
    'group' => t('Menus'),
  );
  return $prefixes;
}

/**
 * Implements hook_enable().
 *
 * Add a link for each custom menu.
 */
function menu_enable() {
  menu_rebuild();
  $base_link = db_query("SELECT mlid AS plid, menu_name FROM {menu_links} WHERE link_path = 'admin/structure/menu' AND module = 'system'")->fetchAssoc();
  $base_link['router_path'] = 'admin/structure/menu/manage/%';
  $base_link['module'] = 'menu';
  $menus = menu_load_all();
  foreach ($menus as $menu) {
    // $link is passed by reference to menu_link_save(), so we make a copy of $base_link.
    $link = $base_link;
    $link['mlid'] = 0;
    $link['link_title'] = $menu['title'];
    $link['link_path'] = 'admin/structure/menu/manage/' . $menu['menu_name'];
    $menu_link = db_query("SELECT mlid FROM {menu_links} WHERE link_path = :path AND plid = :plid", array(
      ':path' => $link['link_path'],
      ':plid' => $link['plid']
    ))
    ->fetchField();
    if (!$menu_link) {
      menu_link_save($link);
    }
  }
  menu_cache_clear_all();
}

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

/**
 * Load the data for a single custom menu.
 *
 * @param $menu_name
 *   The unique name of a custom menu to load.
 * @return
 *   Array defining the custom menu, or FALSE if the menu doesn't exist.
 */
function menu_load($menu_name) {
  $all_menus = menu_load_all();
  return isset($all_menus[$menu_name]) ? $all_menus[$menu_name] : FALSE;
}

/**
 * Load all custom menu data.
 *
 * @return
 *   Array of custom menu data.
 */
function menu_load_all() {
  $custom_menus = &backdrop_static(__FUNCTION__);
  if (!isset($custom_menus)) {
    if ($cached = cache('menu')->get('menu_configs')) {
      $custom_menus = $cached->data;
    }
    else {
      $config_names = config_get_names_with_prefix('menu.menu.');
      foreach ($config_names as $config_name) {
        $menu = config_get($config_name);
        $custom_menus[$menu['menu_name']] = $menu;
      }
      cache('menu')->set('menu_configs', $custom_menus);
    }
  }
  return $custom_menus;
}

/**
 * Save a custom menu.
 *
 * @param $menu
 *   An array representing a custom menu:
 *   - menu_name: The unique name of the custom menu (composed of lowercase
 *     letters, numbers, and hyphens).
 *   - title: The human readable menu title.
 *   - description: The custom menu description.
 *
 * Modules should always pass a fully populated $menu when saving a custom
 * menu, so other modules are able to output proper status or watchdog messages.
 *
 * @see menu_load()
 */
function menu_save($menu) {
  $menu_defaults = array(
    'menu_name' => '',
    'title' => '',
    'description' => '',
  );
  $menu += $menu_defaults;
  $menu = array_intersect_key($menu, $menu_defaults);

  $config = config('menu.menu.' . $menu['menu_name']);
  $status = $config->isNew() ? SAVED_NEW : SAVED_UPDATED;
  $config->setData($menu);
  $config->save();
  menu_cache_clear_all();

  switch ($status) {
    case SAVED_NEW:
      // Make sure the menu is present in the active menus variable so that its
      // items may appear in the menu active trail.
      // @see menu_set_active_menu_names()
      $config = config('system.core');

      $active_menus = $config->get('active_menus_default') ?: array_keys(menu_get_menus());
      if (!in_array($menu['menu_name'], $active_menus)) {
        $active_menus[] = $menu['menu_name'];
        $config->set('active_menus_default', $active_menus)->save();
      }

      module_invoke_all('menu_insert', $menu);
      break;

    case SAVED_UPDATED:
      module_invoke_all('menu_update', $menu);
      break;
  }
}

/**
 * Delete a custom menu and all contained links.
 *
 * Note that this function deletes all menu links in a custom menu. While menu
 * links derived from router paths may be restored by rebuilding the menu, all
 * customized and custom links will be irreversibly gone. Therefore, this
 * function should usually be called from a user interface (form submit) handler
 * only, which allows the user to confirm the action.
 *
 * @param $menu
 *   An array representing a custom menu:
 *   - menu_name: The unique name of the custom menu.
 *   - title: The human readable menu title.
 *   - description: The custom menu description.
 *
 * Modules should always pass a fully populated $menu when deleting a custom
 * menu, so other modules are able to output proper status or watchdog messages.
 *
 * @see menu_load()
 *
 * menu_delete_links() will take care of clearing the page cache. Other modules
 * should take care of their menu-related data by implementing
 * hook_menu_delete().
 */
function menu_delete($menu) {
  $config = config('system.core');

  // Delete all links from the menu.
  menu_delete_links($menu['menu_name']);

  // Remove menu from active menus variable.
  $active_menus = $config->get('active_menus_default') ?: array_keys(menu_get_menus());
  foreach ($active_menus as $i => $menu_name) {
    if ($menu['menu_name'] == $menu_name) {
      unset($active_menus[$i]);
      $config->set('active_menus_default', $active_menus)->save();
    }
  }

  // Delete the custom menu.
  config('menu.menu.' . $menu['menu_name'])->delete();

  menu_cache_clear_all();
  module_invoke_all('menu_delete', $menu);
}

/**
 * Return a list of menu items that are valid possible parents for the given menu item.
 *
 * @param $menus
 *   An array of menu names and titles, such as from menu_get_menus().
 * @param $item
 *   The menu item or the node type for which to generate a list of parents.
 *   If $item['mlid'] == 0 then the complete tree is returned.
 * @param $type
 *   The node type for which to generate a list of parents.
 *   If $item itself is a node type then $type is ignored.
 * @return
 *   An array of menu link titles keyed on the a string containing the menu name
 *   and mlid. The list excludes the given item and its children.
 */
function menu_parent_options($menus, $item, $type = '') {
  $available_menus = array();
  if (!is_array($item)) {
    // If $item is not an array then it is a node type.
    // Use it as $type and prepare a dummy menu item for _menu_get_options().
    $type = $item;
    $item = array('mlid' => 0);
  }
  if (empty($type)) {
    // If no node type is set, use all menus given to this function.
    $available_menus = $menus;
  }
  else {
    // If a node type is set, use all available menus for this type.
    $node_type = node_type_load($type);
    foreach ($node_type->settings['menu_options'] as $menu) {
      $available_menus[$menu] = $menu;
    }
  }

  return _menu_get_options($menus, $available_menus, $item);
}

/**
 * Page callback.
 * Get all the available menus and menu items as a JavaScript array.
 */
function menu_parent_options_js() {
  $available_menus = array();
  if (isset($_POST['menus']) && count($_POST['menus'])) {
    foreach ($_POST['menus'] as $menu) {
      $available_menus[$menu] = $menu;
    }
  }
  $options = _menu_get_options(menu_get_menus(), $available_menus, array('mlid' => 0));

  // Displayed as JSON by delivery callback backdrop_json_deliver().
  return $options;
}

/**
 * Ajax callback to replace the menu item parent options.
 *
 * Whenever the item language changes, the available parents also have to get
 * updated.
 *
 * @see menu_edit_item().
 * @see menu_form_node_form_alter().
 */
function menu_update_parent_options_ajax($form, $form_state) {
  if ($form['#form_id'] == 'menu_edit_item') {
    $item = $form['original_item']['#value'];
    if (isset($form_state['values']['langcode'])) {
      $item['langcode'] = $form_state['values']['langcode'];
      $form['parent']['#options'] = menu_parent_options(menu_get_menus(), $item);
    }
    return $form['parent'];
  }
  elseif (isset($form['#node'])) {
    $item = $form['#node']->menu;
    if (isset($form_state['values']['langcode'])) {
      $item['langcode'] = $form_state['values']['langcode'];
      $form['menu']['link']['parent']['#options'] = menu_parent_options(menu_get_menus(), $item, $form['#node']->type);
    }
    return $form['menu']['link']['parent'];
  }
}

/**
 * Helper function to get the items of the given menu.
 */
function _menu_get_options($menus, $available_menus, $item) {
  // If the item has children, there is an added limit to the depth of valid parents.
  if (isset($item['parent_depth_limit'])) {
    $limit = $item['parent_depth_limit'];
  }
  else {
    $limit = _menu_parent_depth_limit($item);
  }

  $options = array();
  $langcode = NULL;
  if (module_exists('language') && isset($item['langcode'])) {
    $langcode = $item['langcode'];
  }
  foreach ($menus as $menu_name => $title) {
    if (isset($available_menus[$menu_name])) {
      $tree = menu_tree_all_data($menu_name, NULL, NULL, $langcode);
      $options[$menu_name . ':0'] = $title;
      _menu_parents_recurse($tree, $menu_name, '· ', $options, $item['mlid'], $limit);
    }
  }
  return $options;
}

/**
 * Recursive helper function for menu_parent_options().
 */
function _menu_parents_recurse($tree, $menu_name, $indent, &$options, $exclude, $depth_limit) {
  foreach ($tree as $data) {
    if ($data['link']['depth'] > $depth_limit) {
      // Don't iterate through any links on this level.
      break;
    }
    if ($data['link']['mlid'] != $exclude && $data['link']['hidden'] >= 0) {
      $title = $indent . ' ' . truncate_utf8($data['link']['title'], 30, TRUE, FALSE);
      if ($data['link']['hidden']) {
        $title .= ' (' . t('disabled') . ')';
      }
      $options[$menu_name . ':' . $data['link']['mlid']] = $title;
      if ($data['below']) {
        _menu_parents_recurse($data['below'], $menu_name, $indent . '· ', $options, $exclude, $depth_limit);
      }
    }
  }
}

/**
 * Reset a system-defined menu link.
 */
function menu_reset_item($link) {
  // To reset the link to its original values, we need to retrieve its
  // definition from hook_menu(). Otherwise, for example, the link's menu would
  // not be reset, because properties like the original 'menu_name' are not
  // stored anywhere else. Since resetting a link happens rarely and this is a
  // one-time operation, retrieving the full menu router does no harm.
  $menu = menu_get_router();
  $router_item = $menu[$link['router_path']];
  $new_link = _menu_link_build($router_item);
  // Merge existing menu link's ID and 'has_children' property.
  foreach (array('mlid', 'has_children') as $key) {
    $new_link[$key] = $link[$key];
  }
  menu_link_save($new_link);
  return $new_link;
}

/**
 * Implements hook_block_info().
 */
function menu_block_info() {
  $menus = menu_get_menus(FALSE);

  $blocks = array();
  foreach ($menus as $name => $title) {
    $blocks[$name] = array(
      // No need to wrap $title in t(), since these menu titles are already
      // translated.
      'info' => check_plain($title),
      'description' => t('A list of links for the menu: %title.', array('%title' => $title)),
      // Menu blocks can't be cached because each menu item can have a custom
      // access callback. menu.inc manages its own caching.
      'cache' => BACKDROP_NO_CACHE,
    );
  }
  return $blocks;
}

/**
 * Implements hook_block_view().
 */
function menu_block_view($delta = '', $settings = array()) {
  module_load_include('inc', 'system', 'system.menu');
  $settings += system_menu_block_defaults($delta);
  $data = system_menu_block_build($settings);
  $block['subject'] = $data['subject'];
  $block['content'] = $data['content'];
  // Add contextual links for this block.
  if (!empty($block['content'])) {
    $block['content']['#contextual_links']['menu'] = array('admin/structure/menu/manage', array($delta));
  }
  return $block;
}

/**
 * Implements hook_block_configure().
 */
function menu_block_configure($delta, $settings) {
  foreach (menu_get_menus(FALSE) as $menu_name => $title) {
    if ($delta === $menu_name) {
      module_load_include('inc', 'system', 'system.menu');
      return _system_block_configure($delta, $settings);
    }
  }
}

/**
 * Implements hook_block_view_alter().
 */
function menu_block_view_alter(&$data, $block) {
  // Add contextual links for system menu blocks.
  if ($block->module == 'system' && !empty($data['content'])) {
    $system_menus = menu_list_system_menus();
    if (isset($system_menus[$block->delta])) {
      $data['content']['#contextual_links']['menu'] = array('admin/structure/menu/manage', array($block->delta));
    }
  }
}

/**
 * Implements hook_menu_local_tasks_alter().
 */
function menu_menu_local_tasks_alter(&$data, $router_item, $root_path) {
  // Add language code to the "Add link" action link under
  // admin/structure/menu/manage/[menu-name].
  if ($root_path == 'admin/structure/menu/manage/%') {
    foreach ($data['actions']['output'] as $key => $action_link) {
      if ($action_link['#link']['path'] === 'admin/structure/menu/manage/%/add') {
        $default_langcode = isset($_GET['langcode']) ? $_GET['langcode'] : LANGUAGE_NONE;
        $query['langcode'] = $default_langcode;
        $data['actions']['output'][$key]['#link']['localized_options'] = array('query' => $query);
      }
    }
  }
}

/**
 * Implements hook_node_insert().
 */
function menu_node_insert(Node $node) {
  menu_node_save($node);
}

/**
 * Implements hook_node_update().
 */
function menu_node_update(Node $node) {
  menu_node_save($node);
}

/**
 * Helper for hook_node_insert() and hook_node_update().
 */
function menu_node_save(Node $node) {
  if (isset($node->menu)) {
    $link = &$node->menu;
    if (isset($link['enabled']) && !$link['enabled']) {
      if (!empty($link['mlid'])) {
        menu_link_delete($link['mlid']);
      }
    }
    elseif (trim($link['link_title'])) {
      $link['link_title'] = trim($link['link_title']);
      $link['link_path'] = "node/$node->nid";
      $link['langcode'] = $node->langcode;
      if (trim($link['description'])) {
        $link['options']['attributes']['title'] = trim($link['description']);
      }
      else {
        // If the description field was left empty, remove the title attribute
        // from the menu link.
        unset($link['options']['attributes']['title']);
      }
      if (!menu_link_save($link)) {
        backdrop_set_message(t('There was an error saving the menu link.'), 'error');
      }
    }
  }
}

/**
 * Implements hook_node_predelete().
 */
function menu_node_predelete(Node $node) {
  // Delete all menu module links that point to this node.
  $result = db_query("SELECT mlid FROM {menu_links} WHERE link_path = :path AND module = 'menu'", array(':path' => 'node/' . $node->nid), array('fetch' => PDO::FETCH_ASSOC));
  foreach ($result as $m) {
    menu_link_delete($m['mlid']);
  }
}

/**
 * Implements hook_node_prepare().
 */
function menu_node_prepare(Node $node) {
  if (empty($node->menu)) {
    $node_type = node_type_load($node->type);

    // Prepare the node for the edit form so that $node->menu always exists.
    $menu_name = strtok($node_type->settings['menu_parent'], ':');
    $item = array();
    if (isset($node->nid)) {
      $mlid = FALSE;
      // Give priority to the default menu
      $type_menus = $node_type->settings['menu_options'];
      if (in_array($menu_name, $type_menus)) {
        $mlid = db_query_range("SELECT mlid FROM {menu_links} WHERE link_path = :path AND menu_name = :menu_name AND module = 'menu' ORDER BY mlid ASC", 0, 1, array(
          ':path' => 'node/' . $node->nid,
          ':menu_name' => $menu_name,
        ))->fetchField();
      }
      // Check all allowed menus if a link does not exist in the default menu.
      if (!$mlid && !empty($type_menus)) {
        $mlid = db_query_range("SELECT mlid FROM {menu_links} WHERE link_path = :path AND module = 'menu' AND menu_name IN (:type_menus) ORDER BY mlid ASC", 0, 1, array(
          ':path' => 'node/' . $node->nid,
          ':type_menus' => array_values($type_menus),
        ))->fetchField();
      }
      if ($mlid) {
        $item = menu_link_load($mlid);
      }
    }
    // Set the dummy item langcode to the same language as the node.
    if (module_exists('language') && empty($item)) {
      $item['langcode'] = $node->langcode;
    }
    // Set default values.
    $node->menu = $item + array(
      'link_title' => '',
      'mlid' => 0,
      'plid' => 0,
      'menu_name' => $menu_name,
      'weight' => 0,
      'options' => array(),
      'module' => 'menu',
      'expanded' => 0,
      'hidden' => 0,
      'has_children' => 0,
      'customized' => 0,
    );
  }
  // Find the depth limit for the parent select.
  if (!isset($node->menu['parent_depth_limit'])) {
    $node->menu['parent_depth_limit'] = _menu_parent_depth_limit($node->menu);
  }
}

/**
 * Find the depth limit for items in the parent select.
 */
function _menu_parent_depth_limit($item) {
  return MENU_MAX_DEPTH - 1 - (($item['mlid'] && $item['has_children']) ? menu_link_children_relative_depth($item) : 0);
}

/**
 * Calculate the delta for the weight element for a given set of menus.
 *
 * @param string|array $menu_names
 *   Menu name or an array of menu names.
 * @param int $max_delta
 *   Optional maximum value.
 *
 * @return int
 *   Delta value.
 */
function _menu_get_menu_weight_delta($menu_names, $max_delta = NULL) {
  if (is_string($menu_names)) {
    $menu_names = array($menu_names);
  }

  $weight_info = db_query("SELECT MAX(weight) AS max_weight, MIN(weight) as min_weight FROM {menu_links} WHERE menu_name IN (:menu_names)", array(':menu_names' => $menu_names))->fetchObject();

  $delta = max(abs((int) $weight_info->min_weight), abs((int) $weight_info->max_weight)) + 1;

  // Honor max param, if given.
  if (!is_null($max_delta) && $delta > $max_delta) {
    $delta = $max_delta;
  }

  // Provide a minimum.
  if ($delta < 50) {
    $delta = 50;
  }
  return $delta;
}

/**
 * Implements hook_form_BASE_FORM_ID_alter().
 *
 * Adds menu item fields to the node form.
 *
 * @see menu_node_submit()
 */
function menu_form_node_form_alter(&$form, $form_state) {
  // Generate a list of possible parents (not including this link or descendants).
  // @todo This must be handled in a #process handler.
  $link = $form['#node']->menu;
  $type = $form['#node']->type;
  $node_type = node_type_load($type);

  // Function menu_node_prepare() makes sure, that $node->menu always exists.
  $options = menu_parent_options(menu_get_menus(), $link, $type);
  // If no possible parent menu items were found, there is nothing to display.
  if (empty($options)) {
    return;
  }
  // Attach ajax to the node form language select list.
  if (module_exists('language')) {
    $form['langcode']['#ajax'] = array(
      'callback' => 'menu_update_parent_options_ajax',
      'wrapper' => 'menu-parent-select-wrapper',
    );
  }

  $form['menu'] = array(
    '#type' => 'fieldset',
    '#title' => t('Menu settings'),
    '#access' => user_access('administer menu'),
    '#collapsible' => TRUE,
    '#collapsed' => !$link['link_title'],
    '#group' => 'additional_settings',
    '#attached' => array(
      'js' => array(backdrop_get_path('module', 'menu') . '/js/menu.js'),
    ),
    '#tree' => TRUE,
    '#weight' => 40,
    '#attributes' => array('class' => array('menu-link-form')),
  );
  $form['menu']['enabled'] = array(
    '#type' => 'checkbox',
    '#title' => t('Provide a menu link'),
    '#default_value' => empty($form['#node']->nid) ? $node_type->settings['menu_default'] : (int) (bool) $link['mlid'],
  );
  $form['menu']['link'] = array(
    '#type' => 'container',
    '#parents' => array('menu'),
    '#states' => array(
      'invisible' => array(
        'input[name="menu[enabled]"]' => array('checked' => FALSE),
      ),
    ),
  );

  // Populate the element with the link data.
  foreach (array('mlid', 'module', 'hidden', 'has_children', 'customized', 'options', 'expanded', 'hidden', 'parent_depth_limit') as $key) {
    $form['menu']['link'][$key] = array('#type' => 'value', '#value' => $link[$key]);
  }

  $form['menu']['link']['link_title'] = array(
    '#type' => 'textfield',
    '#title' => t('Menu link title'),
    '#maxlength' => 255,
    '#default_value' => $link['mlid'] ? $link['link_title'] : '',
  );

  $form['menu']['link']['description'] = array(
    '#type' => 'textarea',
    '#title' => t('Description'),
    '#default_value' => isset($link['options']['attributes']['title']) ? $link['options']['attributes']['title'] : '',
    '#rows' => 1,
    '#description' => t('Shown when hovering over the menu link.'),
  );

  $default = ($link['mlid'] ? $link['menu_name'] . ':' . $link['plid'] : $node_type->settings['menu_parent']);
  // If the current parent menu item is not present in options, use the first
  // available option as default value.
  // @todo User should not be allowed to access menu link settings in such a
  // case.
  if (!isset($options[$default])) {
    $array = array_keys($options);
    $default = reset($array);
  }
  $form['menu']['link']['parent'] = array(
    '#type' => 'select',
    '#title' => t('Parent item'),
    '#default_value' => $default,
    '#options' => $options,
    '#attributes' => array('class' => array('menu-parent-select')),
    '#prefix' => '<div id="menu-parent-select-wrapper">',
    '#suffix' => '</div>',
  );
  // Get number of items in all possible parent menus, so the weight selector is
  // sized appropriately.
  $menu_names = array_keys(menu_get_menus());
  $menu_options = array();
  foreach ($menu_names as $menu_name) {
    if (isset($options[$menu_name . ':0'])) {
      $menu_options[] = $menu_name;
    }
  }
  // Make sure that we always have values in menu_options.
  $menu_options = !empty($menu_options) ? $menu_options : $menu_names;

  $form['menu']['link']['weight'] = array(
    '#type' => 'weight',
    '#title' => t('Weight'),
    '#delta' => _menu_get_menu_weight_delta($menu_options),
    '#default_value' => $link['weight'],
    '#description' => t('Menu links with smaller weights are displayed before links with larger weights.'),
  );
}

/**
 * Implements hook_node_submit().
 *
 * @see menu_form_node_form_alter()
 */
function menu_node_submit(Node $node, $form, $form_state) {
  // Decompose the selected menu parent option into 'menu_name' and 'plid', if
  // the form used the default parent selection widget.
  if (!empty($form_state['values']['menu']['parent'])) {
    list($node->menu['menu_name'], $node->menu['plid']) = explode(':', $form_state['values']['menu']['parent']);
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Adds menu options to the node type form.
 */
function menu_form_node_type_form_alter(&$form, $form_state) {
  $menu_options = menu_get_menus();
  $node_type = $form['#node_type'];
  $form['menu'] = array(
    '#type' => 'fieldset',
    '#title' => t('Menu settings'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
    '#attached' => array(
      'js' => array(backdrop_get_path('module', 'menu') . '/js/menu.admin.js'),
    ),
    '#group' => 'additional_settings',
    '#weight' => 15,
  );
  $form['menu']['menu_default'] = array(
    '#type' => 'checkbox',
    '#title' => t('Add a link into the menu for new content of this type'),
    '#default_value' => $node_type->settings['menu_default'],
  );
  $form['menu']['menu_options'] = array(
    '#type' => 'checkboxes',
    '#title' => t('Menus where this content may be placed'),
    '#default_value' => $node_type->settings['menu_options'],
    '#options' => $menu_options,
  );
  // To avoid an 'illegal option' error after saving the form we have to load
  // all available menu items.
  // Otherwise it is not possible to dynamically add options to the list.
  // @todo Convert menu_parent_options() into a #process callback.
  $options = menu_parent_options(menu_get_menus(), array('mlid' => 0));
  $form['menu']['menu_parent'] = array(
    '#type' => 'select',
    '#title' => t('Default parent item'),
    '#default_value' => $node_type->settings['menu_parent'],
    '#options' => $options,
    '#description' => t('Links to content will be placed below this item in the menu.'),
    '#attributes' => array('class' => array('menu-title-select')),
  );

  // Call Backdrop.menu_update_parent_list() to filter the list of
  // available default parent menu items based on the selected menus.
  backdrop_add_js(
    '(function ($) { Backdrop.menu_update_parent_list(); })(jQuery);',
    array('scope' => 'footer', 'type' => 'inline')
  );
}

/**
 * Implements hook_node_type_load()
 */
function menu_node_type_load(&$types) {
  foreach ($types as $type_name => $type) {
    $types[$type_name]->settings += array(
      'menu_default' => FALSE,
      'menu_options' => array(),
      'menu_parent' => 'main-menu:0',
    );
  }
}

/**
 * Return an associative array of the custom menus names.
 *
 * @param $all
 *   If FALSE return only user-added menus, or if TRUE also include
 *   the menus defined by the system.
 * @return
 *   An array with the machine-readable names as the keys, and human-readable
 *   titles as the values.
 */
function menu_get_menus($all = TRUE) {
  if ($custom_menus = menu_load_all()) {
    if (!$all) {
      $custom_menus = array_diff_key($custom_menus, menu_list_system_menus());
    }
    foreach ($custom_menus as $menu_name => $menu) {
      $custom_menus[$menu_name] = t($menu['title']);
    }
    asort($custom_menus);
  }
  return $custom_menus;
}

/**
 * Implements hook_preprocess_block().
 */
function menu_preprocess_block(&$variables) {
  if ($variables['block']->module == 'menu') {
    $variables['attributes']['role'] = 'navigation';
  }
}