<?php
/**
 * @file
 * Provides configurable blocks of menu items.
 */

/**
 * Denotes that the tree should use the menu picked by the curent page.
 */
define('MENU_TREE__CURRENT_PAGE_MENU', '_active');

// Off-load the following infrequently called hooks to another file.
function menu_block_theme(&$existing, $type, $theme, $path) {
  module_load_include('inc', 'menu_block', 'menu_block.admin');
  return _menu_block_theme($existing, $type, $theme, $path);
}
function menu_block_block_info() {
  module_load_include('inc', 'menu_block', 'menu_block.admin');
  return _menu_block_block_info();
}
function menu_block_block_configure($delta = '') {
  module_load_include('inc', 'menu_block', 'menu_block.admin');
  return _menu_block_block_configure($delta);
}
function menu_block_block_save($delta = '', $edit = array()) {
  module_load_include('inc', 'menu_block', 'menu_block.admin');
  return _menu_block_block_save($delta, $edit);
}
function menu_block_form_block_admin_display_form_alter(&$form, $form_state) {
  module_load_include('inc', 'menu_block', 'menu_block.admin');
  return _menu_block_form_block_admin_display_form_alter($form, $form_state);
}
function menu_block_ctools_plugin_directory($module, $plugin) {
  module_load_include('inc', 'menu_block', 'menu_block.admin');
  return _menu_block_ctools_plugin_directory($module, $plugin);
}

/**
 * Implements hook_menu().
 */
function menu_block_menu() {
  // @todo Remove this check if block module is re-added as a dependency.
  if (module_exists('block')) {
    $items['admin/structure/block/add-menu-block'] = array(
      'title' => 'Add menu block',
      'description' => 'Add a new menu block.',
      'page callback' => 'drupal_get_form',
      'page arguments' => array('menu_block_add_block_form'),
      'access arguments' => array('administer blocks'),
      'type' => MENU_LOCAL_ACTION,
      'file' => 'menu_block.admin.inc',
    );
    $default_theme = variable_get('theme_default', 'bartik');
    foreach (list_themes() as $key => $theme) {
      if ($key != $default_theme) {
        $items['admin/structure/block/list/' . $key . '/add-menu-block'] = array(
          'title' => 'Add menu block',
          'description' => 'Add a new menu block.',
          'page callback' => 'drupal_get_form',
          'page arguments' => array('menu_block_add_block_form'),
          'access arguments' => array('administer blocks'),
          'type' => MENU_LOCAL_ACTION,
          'file' => 'menu_block.admin.inc',
        );
      }
    }
    $items['admin/structure/block/delete-menu-block'] = array(
      'title' => 'Delete menu block',
      'page callback' => 'drupal_get_form',
      'page arguments' => array('menu_block_delete'),
      'access arguments' => array('administer blocks'),
      'type' => MENU_CALLBACK,
      'file' => 'menu_block.admin.inc',
    );
  }

  $items['admin/config/user-interface/menu-block'] = array(
    'title' => 'Menu block',
    'description' => 'Configure menu block.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('menu_block_admin_settings_form'),
    'access arguments' => array('administer blocks'),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'menu_block.admin.inc',
  );
  return $items;
}

/**
 * Implements hook_menu_alter().
 */
function menu_block_menu_alter(&$items) {
  // Fake the necessary menu attributes necessary for a contextual link.
  $items['admin/content/book/%node']['title'] = 'Edit book outline';
  $items['admin/content/book/%node']['type'] = MENU_LOCAL_TASK;
  $items['admin/content/book/%node']['context'] = (MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE);
  $items['admin/content/book/%node']['tab_root'] = 'admin/content/book';
}

/**
 * Implements hook_help().
 */
function menu_block_help($path, $arg) {
  switch ($path) {
    case 'admin/structure/block/manage/%/%':
      if ($arg[4] != 'menu_block') {
        break;
      }
    case 'admin/help#menu_block':
    case 'admin/structure/block/add-menu-block':
      module_load_include('inc', 'menu_block', 'menu_block.pages');
      return _menu_block_help($path, $arg);
  }
}

/**
 * Implements hook_block_view().
 */
function menu_block_block_view($delta = '') {
  $config = menu_block_get_config($delta);
  $data = menu_tree_build($config);
  // Add contextual links for this block.
  if (!empty($data['content'])) {
    if (in_array($config['menu_name'], array_keys(menu_get_menus()))) {
      $data['content']['#contextual_links']['menu_block'] = array('admin/structure/menu/manage', array($config['menu_name']));
    }
    elseif (strpos($config['menu_name'], 'book-toc-') === 0) {
      $node = str_replace('book-toc-', '', $config['menu_name']);
      $data['content']['#contextual_links']['menu_block'] = array('admin/content/book', array($node));
    }
  }
  return $data;
}

/**
 * Process variables for menu-block-wrapper.tpl.php.
 *
 * @see menu-block-wrapper.tpl.php
 */
function template_preprocess_menu_block_wrapper(&$variables) {
  $variables['classes_array'][] = 'menu-block-' . $variables['delta'];
  $variables['classes_array'][] = 'menu-name-' . $variables['config']['menu_name'];
  $variables['classes_array'][] = 'parent-mlid-' . $variables['config']['parent_mlid'];
  $variables['classes_array'][] = 'menu-level-' . $variables['config']['level'];
}

/**
 * Returns a list of menu names implemented by all modules.
 *
 * @return
 *   array A list of menu names and titles.
 */
function menu_block_get_all_menus() {
  $all_menus = &drupal_static(__FUNCTION__);

  if (!$all_menus) {
    if ($cached = cache_get('menu_block_menus', 'cache_menu')) {
      $all_menus = $cached->data;
    }
    else {
      // Retrieve core's menus.
      $all_menus = menu_get_menus();
      // Retrieve all the menu names provided by hook_menu_block_get_menus().
      $all_menus = array_merge($all_menus, module_invoke_all('menu_block_get_menus'));
      // Add an option to use the menu for the active menu item.
      $all_menus[MENU_TREE__CURRENT_PAGE_MENU] = '<' . t('the menu selected by the page') . '>';
      asort($all_menus);
      cache_set('menu_block_menus', $all_menus, 'cache_menu');
    }
  }
  return $all_menus;
}

/**
 * Returns the configuration for the requested block delta.
 *
 * @param $delta
 *   string The delta that uniquely identifies the block in the block system. If
 *   not specified, the default configuration will be returned.
 * @return
 *   array An associated array of configuration options.
 */
function menu_block_get_config($delta = NULL) {
  $config = array(
    'delta'       => $delta,
    'menu_name'   => 'main-menu',
    'parent_mlid' => 0,
    'title_link'  => 0,
    'admin_title' => '',
    'level'       => 1,
    'follow'      => 0,
    'depth'       => 0,
    'expanded'    => 0,
    'sort'        => 0,
  );

  // Get the block configuration options.
  if ($delta) {
    static $blocks;
    if (!isset($blocks)) {
      $blocks = module_invoke_all('menu_block_blocks');
    }
    if (!empty($blocks[$delta])) {
      // Merge the default values.
      $config = $blocks[$delta] + $config;
      // Set the delta.
      $config['delta'] = $delta;
      // Flag the block as exported.
      $config['exported_to_code'] = TRUE;
    }

    $config['title_link']  = variable_get("menu_block_{$delta}_title_link",  $config['title_link']);
    $config['admin_title'] = variable_get("menu_block_{$delta}_admin_title", $config['admin_title']);
    $config['level']       = variable_get("menu_block_{$delta}_level",       $config['level']);
    $config['follow']      = variable_get("menu_block_{$delta}_follow",      $config['follow']);
    $config['depth']       = variable_get("menu_block_{$delta}_depth",       $config['depth']);
    $config['expanded']    = variable_get("menu_block_{$delta}_expanded",    $config['expanded']);
    $config['sort']        = variable_get("menu_block_{$delta}_sort",        $config['sort']);
    list($config['menu_name'], $config['parent_mlid']) = explode(':', variable_get("menu_block_{$delta}_parent", $config['menu_name'] . ':' . $config['parent_mlid']));
  }

  return $config;
}

/**
 * Build a menu tree based on the provided configuration.
 *
 * @param $config
 *   array An array of configuration options that specifies how to build the
 *   menu tree and its title.
 *   - delta: (string) The menu_block's block delta.
 *   - menu_name: (string) The machine name of the requested menu. Can also be
 *     set to MENU_TREE__CURRENT_PAGE_MENU to use the menu selected by the page.
 *   - parent_mlid: (int) The mlid of the item that should root the tree. Use 0
 *     to use the menu's root.
 *   - title_link: (boolean) Specifies if the title should be rendered as a link
 *     or a simple string.
 *   - admin_title: (string) An optional title to uniquely identify the block on
 *     the administer blocks page.
 *   - level: (int) The starting level of the tree.
 *   - follow: (string) Specifies if the starting level should follow the
 *     active menu item. Should be set to 0, 'active' or 'child'.
 *   - depth: (int) The maximum depth the tree should contain, relative to the
 *     starting level.
 *   - expanded: (boolean) Specifies if the entire tree be expanded or not.
 *   - sort: (boolean) Specifies if the tree should be sorted with the active
 *     trail at the top of the tree.
 * @return
 *   array An associative array containing several pieces of data.
 *   - content: The tree as a renderable array.
 *   - subject: The title rendered as HTML.
 *   - subject_array: The title as a renderable array.
 */
function menu_tree_build($config) {
  // Retrieve the active menu item from the database.
  if ($config['menu_name'] == MENU_TREE__CURRENT_PAGE_MENU) {
    // Retrieve the list of available menus.
    $menu_order = variable_get('menu_block_menu_order', array('main-menu' => '', 'user-menu' => ''));

    // Check for regular expressions as menu keys.
    $patterns = array();
    foreach (array_keys($menu_order) as $pattern) {
      if ($pattern[0] == '/') {
        $patterns[$pattern] = NULL;
      }
    }

    // Extract the "current" path from the request, or from the active menu
    // trail if applicable.
    $link_path = $_GET['q'] ? $_GET['q'] : '<front>';
    $trail = menu_get_active_trail();
    $last_item = end($trail);
    if (!empty($last_item['link_path'])) {
      $link_path = $last_item['link_path'];
    }

    // Retrieve all the menus containing a link to the current page.
    $result = db_query("SELECT menu_name FROM {menu_links} WHERE link_path = :link_path", array(':link_path' => $link_path));
    foreach ($result as $item) {
      // Check if the menu is in the list of available menus.
      if (isset($menu_order[$item->menu_name])) {
        // Mark the menu.
        $menu_order[$item->menu_name] = MENU_TREE__CURRENT_PAGE_MENU;
      }
      else {
        // Check if the menu matches one of the available patterns.
        foreach (array_keys($patterns) as $pattern) {
          if (preg_match($pattern, $item->menu_name)) {
            // Mark the menu.
            $menu_order[$pattern] = MENU_TREE__CURRENT_PAGE_MENU;
            // Store the actual menu name.
            $patterns[$pattern] = $item->menu_name;
          }
        }
      }
    }
    // Find the first marked menu.
    $config['menu_name'] = array_search(MENU_TREE__CURRENT_PAGE_MENU, $menu_order);
    // If a pattern was matched, use the actual menu name instead of the pattern.
    if (!empty($patterns[$config['menu_name']])) {
      $config['menu_name'] = $patterns[$config['menu_name']];
    }
    $config['parent_mlid'] = 0;

    // If no menu link was found, don't display the block.
    if (empty($config['menu_name'])) {
      return array(
        'subject' => t('The menu selected by the page'),
        'subject_array' => array(),
        'content' => array(),
      );
    }
  }

  // Get the default block name.
  $menu_names = menu_block_get_all_menus();
  menu_block_set_title(t($menu_names[$config['menu_name']]));

  if ($config['expanded'] || $config['parent_mlid']) {
    // Get the full, un-pruned tree.
    $tree = menu_tree_all_data($config['menu_name']);
    // And add the active trail data back to the full tree.
    menu_tree_add_active_path($tree);
  }
  else {
    // Get the tree pruned for just the active trail.
    $tree = menu_tree_page_data($config['menu_name']);
  }

  // Allow alteration of the tree and config before we begin operations on it.
  drupal_alter('menu_block_tree', $tree, $config);

  // Localize the tree.
  if (module_exists('i18n_menu')) {
    $tree = i18n_menu_localize_tree($tree);
  }

  // Prune the tree along the active trail to the specified level.
  if ($config['level'] > 1 || $config['parent_mlid']) {
    if ($config['parent_mlid']) {
      $parent_item = menu_link_load($config['parent_mlid']);
      menu_tree_prune_tree($tree, $config['level'], $parent_item);
    }
    else {
      menu_tree_prune_tree($tree, $config['level']);
    }
  }

  // Prune the tree to the active menu item.
  if ($config['follow']) {
    menu_tree_prune_active_tree($tree, $config['follow']);
  }

  // If the menu-item-based tree is not "expanded", trim the tree to the active path.
  if ($config['parent_mlid'] && !$config['expanded']) {
    menu_tree_trim_active_path($tree);
  }

  // Trim the branches that extend beyond the specified depth.
  if ($config['depth'] > 0) {
    menu_tree_depth_trim($tree, $config['depth']);
  }

  // Sort the active path to the top of the tree.
  if ($config['sort']) {
    menu_tree_sort_active_path($tree);
  }

  // Render the tree.
  $data = array();
  $title = menu_block_get_title($config['title_link'], $config);
  $data['subject_array'] = $title;
  $data['subject'] = drupal_render($title);
  $data['content']['#content'] = menu_block_tree_output($tree, $config);
  if (!empty($data['content']['#content'])) {
    $data['content']['#theme'] = array(
      'menu_block_wrapper__' . str_replace('-', '_', $config['delta']),
      'menu_block_wrapper__' . str_replace('-', '_', $config['menu_name']),
      'menu_block_wrapper'
    );
    $data['content']['#config'] = $config;
    $data['content']['#delta'] = $config['delta'];
  }
  else {
    $data['content'] = '';
  }

  return $data;
}

/**
 * Retrieves the menu item to use for the tree's title.
 *
 * @param $render_title_as_link
 *   boolean A boolean that says whether to render the title as a link or a
 *   simple string.
 * @return
 *   array A renderable array containing the tree's title.
 */
function menu_block_get_title($render_title_as_link = TRUE) {
  $menu_item = menu_block_set_title();

  // The tree's title is a menu title, a normal string.
  if (is_string($menu_item)) {
    $title = array('#markup' => check_plain($menu_item));
  }
  // The tree's title is a menu item with a link.
  elseif ($render_title_as_link) {
    if (!empty($menu_item['in_active_trail'])) {
      if (!empty($menu_item['localized_options']['attributes']['class'])) {
        $menu_item['localized_options']['attributes']['class'][] = 'active-trail';
      }
      else {
        $menu_item['localized_options']['attributes']['class'][] = 'active-trail';
      }
    }
    $title = array(
      '#type' => 'link',
      '#title' => $menu_item['title'],
      '#href' => $menu_item['href'],
      '#options' => $menu_item['localized_options'],
    );
  }
  // The tree's title is a menu item.
  else {
    $title = array('#markup' => check_plain($menu_item['title']));
  }
  return $title;
}

/**
 * Sets the menu item to use for the tree's title.
 *
 * @param $item
 *   array The menu item (an array) or the menu item's title as a string.
 */
function menu_block_set_title($item = NULL) {
  $menu_item = &drupal_static(__FUNCTION__);

  // Save the menu item.
  if (!is_null($item)) {
    $menu_item = $item;
  }

  return $menu_item;
}

/**
 * Add the active trail indicators into the tree.
 *
 * The data returned by menu_tree_page_data() has link['in_active_trail'] set to
 * TRUE for each menu item in the active trail. The data returned from
 * menu_tree_all_data() does not contain the active trail indicators. This is a
 * helper function that adds it back in.
 *
 * @param $tree
 *   array The menu tree.
 * @return
 *   void
 */
function menu_tree_add_active_path(&$tree) {
  // Grab any menu item to find the menu_name for this tree.
  $menu_item = current($tree);
  $tree_with_trail = menu_tree_page_data($menu_item['link']['menu_name']);

  // To traverse the original tree down the active trail, we use a pointer.
  $subtree_pointer =& $tree;

  // Find each key in the active trail.
  while ($tree_with_trail) {
    foreach ($tree_with_trail AS $key => &$value) {
      if ($tree_with_trail[$key]['link']['in_active_trail']) {
        // Set the active trail info in the original tree.
        $subtree_pointer[$key]['link']['in_active_trail'] = TRUE;
        // Continue in the subtree, if it exists.
        $tree_with_trail =& $tree_with_trail[$key]['below'];
        $subtree_pointer =& $subtree_pointer[$key]['below'];
        break;
      }
      else {
        unset($tree_with_trail[$key]);
      }
    }
  }
}

/**
 * Trim everything but the active trail in the tree.
 *
 * @param $tree
 *   array The menu tree to trim.
 * @return
 *   void
 */
function menu_tree_trim_active_path(&$tree) {
  foreach ($tree AS $key => &$value) {
    if (($tree[$key]['link']['in_active_trail'] || $tree[$key]['link']['expanded']) && $tree[$key]['below']) {
      // Continue in the subtree, if it exists.
      menu_tree_trim_active_path($tree[$key]['below']);
    }
    else {
      // Trim anything not expanded or along the active trail.
      $tree[$key]['below'] = FALSE;
    }
  }
}

/**
 * Sort the active trail to the top of the tree.
 *
 * @param $tree
 *   array The menu tree to sort.
 * @return
 *   void
 */
function menu_tree_sort_active_path(&$tree) {
  module_load_include('inc', 'menu_block', 'menu_block.sort');
  _menu_tree_sort_active_path($tree);
}

/**
 * Prune a tree so that it begins at the specified level.
 *
 * This function will follow the active menu trail to the specified level.
 *
 * @param $tree
 *   array The menu tree to prune.
 * @param $level
 *   int The level of the original tree that will start the pruned tree.
 * @param $parent_item
 *   array The menu item that should be used as the root of the tree.
 * @return
 *   void
 */
function menu_tree_prune_tree(&$tree, $level, $parent_item = FALSE) {
  if (!empty($parent_item)) {
    // Prune the tree along the path to the menu item.
    for ($i = 1; $i <= MENU_MAX_DEPTH && $parent_item["p$i"] != '0'; $i++) {
      $plid = $parent_item["p$i"];
      $found_active_trail = FALSE;
      // Examine each element at this level for the ancestor.
      foreach ($tree AS $key => &$value) {
        if ($tree[$key]['link']['mlid'] == $plid) {
          menu_block_set_title($tree[$key]['link']);
          // Prune the tree to the children of this ancestor.
          $tree = $tree[$key]['below'] ? $tree[$key]['below'] : array();
          $found_active_trail = TRUE;
          break;
        }
      }
      // If we don't find the ancestor, bail out.
      if (!$found_active_trail) {
        $tree = array();
        break;
      }
    }
  }

  // Trim the upper levels down to the one desired.
  for ($i = 1; $i < $level; $i++) {
    $found_active_trail = FALSE;
    // Examine each element at this level for the active trail.
    foreach ($tree AS $key => &$value) {
      if ($tree[$key]['link']['in_active_trail']) {
        // Get the title for the pruned tree.
        menu_block_set_title($tree[$key]['link']);
        // Prune the tree to the children of the item in the active trail.
        $tree = $tree[$key]['below'] ? $tree[$key]['below'] : array();
        $found_active_trail = TRUE;
        break;
      }
    }
    // If we don't find the active trail, the active item isn't in the tree we want.
    if (!$found_active_trail) {
      $tree = array();
      break;
    }
  }
}

/**
 * Prune a tree so that it begins at the active menu item.
 *
 * @param $tree
 *   array The menu tree to prune.
 * @param $level
 *   string The level which the tree will be pruned to: 'active' or 'child'.
 * @return
 *   void
 */
function menu_tree_prune_active_tree(&$tree, $level) {
  module_load_include('inc', 'menu_block', 'menu_block.follow');
  _menu_tree_prune_active_tree($tree, $level);
}

/**
 * Prune a tree so it does not extend beyond the specified depth limit.
 *
 * @param $tree
 *   array The menu tree to prune.
 * @param $depth_limit
 *   int The maximum depth of the returned tree; must be a positive integer.
 * @return
 *   void
 */
function menu_tree_depth_trim(&$tree, $depth_limit) {
  // Prevent invalid input from returning a trimmed tree.
  if ($depth_limit < 1) {
    return;
  }

  // Examine each element at this level to find any possible children.
  foreach ($tree AS $key => &$value) {
    if ($tree[$key]['below']) {
      if ($depth_limit > 1) {
        menu_tree_depth_trim($tree[$key]['below'], $depth_limit-1);
      }
      else {
        // Remove the children items.
        $tree[$key]['below'] = FALSE;
      }
    }
    if ($depth_limit == 1 && $tree[$key]['link']['has_children']) {
      // Turn off the menu styling that shows there were children.
      $tree[$key]['link']['has_children'] = FALSE;
      $tree[$key]['link']['leaf_has_children'] = TRUE;
    }
  }
}

/**
 * Returns a rendered menu tree.
 *
 * This is a copy of menu_tree_output() with additional classes added to the
 * output.
 *
 * @param $tree
 *   array A data structure representing the tree as returned from menu_tree_data.
 * @return
 *   string The rendered HTML of that data structure.
 */
function menu_block_tree_output(&$tree, $config = array()) {
  $build = array();
  $items = array();

  // Create context if no config was provided.
  if (empty($config)) {
    $config['delta'] = 0;
    // Grab any menu item to find the menu_name for this tree.
    $menu_item = current($tree);
    $config['menu_name'] = $menu_item['link']['menu_name'];
  }
  $hook_delta = str_replace('-', '_', $config['delta']);
  $hook_menu_name = str_replace('-', '_', $config['menu_name']);

  // Pull out just the menu items we are going to render so that we
  // get an accurate count for the first/last classes.
  foreach ($tree as $key => &$value) {
    if (!$tree[$key]['link']['hidden']) {
      $items[] = $tree[$key];
    }
  }

  $num_items = count($items);
  foreach ($items as $i => &$data) {
    $class = array();
    if ($i == 0) {
      $class[] = 'first';
    }
    if ($i == $num_items - 1) {
      $class[] = 'last';
    }
    // Set a class if the link has children.
    if ($data['below']) {
      $class[] = 'expanded';
    }
    elseif ($data['link']['has_children']) {
      $class[] = 'collapsed';
    }
    else {
      $class[] = 'leaf';
    }
    if (!empty($data['link']['leaf_has_children'])) {
      $class[] = 'has-children';
    }
    // Set a class if the link is in the active trail.
    if ($data['link']['in_active_trail']) {
      $class[] = 'active-trail';
      $data['link']['localized_options']['attributes']['class'][] = 'active-trail';
    }
    if ($data['link']['href'] == $_GET['q'] || ($data['link']['href'] == '<front>' && drupal_is_front_page())) {
      $class[] = 'active';
    }
    // Set a menu link ID class.
    $class[] = 'menu-mlid-' . $data['link']['mlid'];

    // Allow menu-specific theme overrides.
    $element['#theme'] = array(
      'menu_link__menu_block__' . $hook_delta,
      'menu_link__menu_block__' . $hook_menu_name,
      'menu_link__menu_block',
      'menu_link__' . $hook_menu_name,
      'menu_link',
    );
    $element['#attributes']['class'] = $class;
    $element['#title'] = $data['link']['title'];
    $element['#href'] = $data['link']['href'];
    $element['#localized_options'] = !empty($data['link']['localized_options']) ? $data['link']['localized_options'] : array();
    $element['#below'] = $data['below'] ? menu_block_tree_output($data['below'], $config) : $data['below'];
    $element['#original_link'] = $data['link'];
    $element['#bid'] = array('module' => 'menu_block', 'delta' => $config['delta']);
    // Index using the link's unique mlid.
    $build[$data['link']['mlid']] = $element;
  }
  if ($build) {
    // Make sure drupal_render() does not re-order the links.
    $build['#sorted'] = TRUE;
    // Add the theme wrapper for outer markup.
    // Allow menu-specific theme overrides.
    $build['#theme_wrappers'][] = array(
      'menu_tree__menu_block__' . $hook_delta,
      'menu_tree__menu_block__' . $hook_menu_name,
      'menu_tree__menu_block',
      'menu_tree__' . $hook_menu_name,
      'menu_tree',
    );
  }

  return $build;
}

/**
 * Implements hook_menu_block_get_menus() on behalf of book.module.
 */
function book_menu_block_get_menus() {
  $menus = array();
  foreach (book_get_books() AS $book) {
    $menus[$book['menu_name']] = $book['title'];
  }
  return $menus;
}

/**
 * Implements hook_menu_block_get_sort_menus() on behalf of book.module.
 */
function book_menu_block_get_sort_menus() {
  return array(
    '/^book\-toc\-.+/' => t('Book navigation'),
  );
}