<?php
// $Id$

/**
 * @file
 * API for the Drupal menu system.
 */

/**
 * @defgroup menu Menu system
 * @{
 * Define the navigation menus, and route page requests to code based on URLs.
 *
 * The Drupal menu system drives both the navigation system from a user
 * perspective and the callback system that Drupal uses to respond to URLs
 * passed from the browser. For this reason, a good understanding of the
 * menu system is fundamental to the creation of complex modules.
 *
 * Drupal's menu system follows a simple hierarchy defined by paths.
 * Implementations of hook_menu() define menu items and assign them to
 * paths (which should be unique). The menu system aggregates these items
 * and determines the menu hierarchy from the paths. For example, if the
 * paths defined were a, a/b, e, a/b/c/d, f/g, and a/b/h, the menu system
 * would form the structure:
 * - a
 *   - a/b
 *     - a/b/c/d
 *     - a/b/h
 * - e
 * - f/g
 * Note that the number of elements in the path does not necessarily
 * determine the depth of the menu item in the tree.
 *
 * When responding to a page request, the menu system looks to see if the
 * path requested by the browser is registered as a menu item with a
 * callback. If not, the system searches up the menu tree for the most
 * complete match with a callback it can find. If the path a/b/i is
 * requested in the tree above, the callback for a/b would be used.
 *
 * The found callback function is called with any arguments specified
 * in the "callback arguments" attribute of its menu item. The
 * attribute must be an array. After these arguments, any remaining
 * components of the path are appended as further arguments. In this
 * way, the callback for a/b above could respond to a request for
 * a/b/i differently than a request for a/b/j.
 *
 * For an illustration of this process, see page_example.module.
 *
 * Access to the callback functions is also protected by the menu system.
 * The "access" attribute of each menu item is checked as the search for a
 * callback proceeds. If this attribute is TRUE, then access is granted; if
 * FALSE, then access is denied. The first found "access" attribute
 * determines the accessibility of the target. Menu items may omit this
 * attribute to use the value provided by an ancestor item.
 *
 * In the default Drupal interface, you will notice many links rendered as
 * tabs. These are known in the menu system as "local tasks", and they are
 * rendered as tabs by default, though other presentations are possible.
 * Local tasks function just as other menu items in most respects. It is
 * convention that the names of these tasks should be short verbs if
 * possible. In addition, a "default" local task should be provided for
 * each set. When visiting a local task's parent menu item, the default
 * local task will be rendered as if it is selected; this provides for a
 * normal tab user experience. This default task is special in that it
 * links not to its provided path, but to its parent item's path instead.
 * The default task's path is only used to place it appropriately in the
 * menu hierarchy.
 */

/**
 * @name Menu flags
 * @{
 * Flags for use in the "type" attribute of menu items.
 */

define('MENU_IS_ROOT', 0x0001);
define('MENU_VISIBLE_IN_TREE', 0x0002);
define('MENU_VISIBLE_IN_BREADCRUMB', 0x0004);
define('MENU_VISIBLE_IF_HAS_CHILDREN', 0x0008);
define('MENU_MODIFIABLE_BY_ADMIN', 0x0010);
define('MENU_MODIFIED_BY_ADMIN', 0x0020);
define('MENU_CREATED_BY_ADMIN', 0x0040);
define('MENU_IS_LOCAL_TASK', 0x0080);
define('MENU_EXPANDED', 0x0100);
define('MENU_LINKS_TO_PARENT', 0x0200);

/**
 * @} End of "Menu flags".
 */

/**
 * @name Menu item types
 * @{
 * Menu item definitions provide one of these constants, which are shortcuts for
 * combinations of the above flags.
 */

/**
 * Normal menu items show up in the menu tree and can be moved/hidden by
 * the administrator. Use this for most menu items. It is the default value if
 * no menu item type is specified.
 */
define('MENU_NORMAL_ITEM', MENU_VISIBLE_IN_TREE | MENU_VISIBLE_IN_BREADCRUMB | MENU_MODIFIABLE_BY_ADMIN);

/**
 * Item groupings are used for pages like "node/add" that simply list
 * subpages to visit. They are distinguished from other pages in that they will
 * disappear from the menu if no subpages exist.
 */
define('MENU_ITEM_GROUPING', MENU_VISIBLE_IF_HAS_CHILDREN | MENU_VISIBLE_IN_BREADCRUMB | MENU_MODIFIABLE_BY_ADMIN);

/**
 * Callbacks simply register a path so that the correct function is fired
 * when the URL is accessed. They are not shown in the menu.
 */
define('MENU_CALLBACK', MENU_VISIBLE_IN_BREADCRUMB);

/**
 * Dynamic menu items change frequently, and so should not be stored in the
 * database for administrative customization.
 */
define('MENU_DYNAMIC_ITEM', MENU_VISIBLE_IN_TREE | MENU_VISIBLE_IN_BREADCRUMB);

/**
 * Modules may "suggest" menu items that the administrator may enable. They act
 * just as callbacks do until enabled, at which time they act like normal items.
 */
define('MENU_SUGGESTED_ITEM', MENU_MODIFIABLE_BY_ADMIN | MENU_VISIBLE_IN_BREADCRUMB);

/**
 * Local tasks are rendered as tabs by default. Use this for menu items that
 * describe actions to be performed on their parent item. An example is the path
 * "node/52/edit", which performs the "edit" task on "node/52".
 */
define('MENU_LOCAL_TASK', MENU_IS_LOCAL_TASK);

/**
 * Every set of local tasks should provide one "default" task, that links to the
 * same path as its parent when clicked.
 */
define('MENU_DEFAULT_LOCAL_TASK', MENU_IS_LOCAL_TASK | MENU_LINKS_TO_PARENT);

/**
 * Custom items are those defined by the administrator. Reserved for internal
 * use; do not return from hook_menu() implementations.
 */
define('MENU_CUSTOM_ITEM', MENU_VISIBLE_IN_TREE | MENU_VISIBLE_IN_BREADCRUMB | MENU_CREATED_BY_ADMIN | MENU_MODIFIABLE_BY_ADMIN);

/**
 * Custom menus are those defined by the administrator. Reserved for internal
 * use; do not return from hook_menu() implementations.
 */
define('MENU_CUSTOM_MENU', MENU_IS_ROOT | MENU_VISIBLE_IN_TREE | MENU_CREATED_BY_ADMIN | MENU_MODIFIABLE_BY_ADMIN);

/**
 * @} End of "Menu item types".
 */

/**
 * @name Menu status codes
 * @{
 * Status codes for menu callbacks.
 */

define('MENU_FOUND', 1);
define('MENU_NOT_FOUND', 2);
define('MENU_ACCESS_DENIED', 3);
define('MENU_SITE_OFFLINE', 4);

/**
 * @} End of "Menu status codes".
 */

/**
 * Returns the ancestors (and relevant placeholders) for any given path.
 *
 * For example, the ancestors of node/12345/edit are:
 *
 * node/12345/edit
 * node/12345/%
 * node/%/edit
 * node/%/%
 * node/12345
 * node/%
 * node
 *
 * To generate these, we will use binary numbers. Each bit represents a
 * part of the path. If the bit is 1, then it represents the original
 * value while 0 means wildcard. If the path is node/12/edit/foo
 * then the 1011 bitstring represents node/%/edit/foo where % means that
 * any argument matches that part.
 *
 * @param $parts
 *   An array of path parts, for the above example
 *   array('node', '12345', 'edit').
 * @return
 *   An array which contains the ancestors and placeholders. Placeholders
 *   simply contain as many %s as the ancestors.
 */
function menu_get_ancestors($parts) {
  $n1 = count($parts);
  $placeholders = array();
  $ancestors = array();
  $end = (1 << $n1) - 1;
  $length = $n1 - 1;
  for ($i = $end; $i > 0; $i--) {
    $current = '';
    $count = 0;
    for ($j = $length; $j >= 0; $j--) {
      if ($i & (1 << $j)) {
        $count++;
        $current .= $parts[$length - $j];
      }
      else {
        $current .= '%';
      }
      if ($j) {
        $current .= '/';
      }
    }
    // If the number was like 10...0 then the next number will be 11...11,
    // one bit less wide.
    if ($count == 1) {
      $length--;
    }
    $placeholders[] = "'%s'";
    $ancestors[] = $current;
  }
  return array($ancestors, $placeholders);
}

/**
 * The menu system uses serialized arrays stored in the database for
 * arguments. However, often these need to change according to the
 * current path. This function unserializes such an array and does the
 * necessary change.
 *
 * Integer values are mapped according to the $map parameter. For
 * example, if unserialize($data) is array('node_load', 1) and $map is
 * array('node', '12345') then 'node_load' will not be changed
 * because it is not an integer, but 1 will as it is an integer. As
 * $map[1] is '12345', 1 will be replaced with '12345'. So the result
 * will be array('node_load', '12345').
 *
 * @param @data
 *   A serialized array.
 * @param @map
 *   An array of potential replacements.
 * @return
 *   The $data array unserialized and mapped.
 */
function menu_unserialize($data, $map) {
  if ($data = unserialize($data)) {
    foreach ($data as $k => $v) {
      if (is_int($v)) {
        $data[$k] = isset($map[$v]) ? $map[$v] : '';
      }
    }
    return $data;
  }
  else {
    return array();
  }
}

/**
 * Replaces the statically cached item for a given path.
 *
 * @param $path
 *   The path
 * @param $item
 *   The menu item. This is a menu entry, an associative array,
 *   with keys like title, access callback, access arguments etc.
 */
function menu_set_item($path, $item) {
  menu_get_item($path, TRUE, $item);
}

function menu_get_item($path = NULL, $execute = TRUE, $item = NULL) {
  static $items;
  if (!isset($path)) {
    $path = $_GET['q'];
  }
  if (isset($item)) {
    $items[$path] = $item;
  }
  if (!isset($items[$path])) {
    $map = arg(NULL, $path);
    $parts = array_slice($map, 0, 6);
    list($ancestors, $placeholders) = menu_get_ancestors($parts);
    if ($item = db_fetch_object(db_query_range('SELECT * FROM {menu} WHERE path IN ('. implode (',', $placeholders) .') ORDER BY fit DESC', $ancestors, 0, 1))) {
      $item->access = _menu_access($item, $map);
      if ($map === FALSE) {
        $items[$path] = FALSE;
        return FALSE;
      }
      if ($execute) {
        $item->page_arguments = array_merge(menu_unserialize($item->page_arguments, $map), array_slice($parts, $item->number_parts));
      }
    }
    $items[$path] = $item;
  }
  return $items[$path];
}

/**
 * Execute the handler associated with the active menu item.
 */
function menu_execute_active_handler() {
  if ($item = menu_get_item()) {
    return $item->access ? call_user_func_array($item->page_callback, $item->page_arguments) : MENU_ACCESS_DENIED;
  }
  return MENU_NOT_FOUND;
}

function _menu_access($item, &$map) {
  if ($item->map_callback) {
    $map = call_user_func_array($item->map_callback, array_merge(array($map), unserialize($item->map_arguments)));
    if ($map === FALSE) {
      return FALSE;
    }
  }
  $callback = $item->access_callback;
  if (is_numeric($callback)) {
    return $callback;
  }
  $arguments = menu_unserialize($item->access_arguments, $map);
  // As call_user_func_array is quite slow and user_access is a very common
  // callback, it is worth making a special case for it.
  if ($callback == 'user_access') {
    return (count($arguments) == 1) ? user_access($arguments[0]) : user_access($arguments[0], $arguments[1]);
  }
  return call_user_func_array($callback, $arguments);
}

/**
 * Returns a rendered menu tree.
 */
function menu_tree() {
  $item = menu_get_item();
  list(, $menu) = _menu_tree(db_query('SELECT * FROM {menu} WHERE pid IN ('. $item->parents .') AND visible = 1 ORDER BY vancode'));
  return $menu;
}

function _menu_tree($result = NULL, $depth = 0, $link = array('link' => '', 'has_children' => FALSE)) {
  static $original_map;
  $remnant = array('link' => '', 'has_children' => FALSE);
  $tree = '';
  while ($item = db_fetch_object($result)) {
    $map = arg(NULL, $item->path);
    if (!_menu_access($item, $map)) {
      continue;
    }
    $menu_link = array('link' => $item->menu_link, 'has_children' => $item->has_children);
    if ($item->depth > $depth) {
      list($remnant, $menu) = _menu_tree($result, $item->depth, $menu_link);
      $tree .= theme('menu_tree', $link, $menu);
      $link = $remnant;
      $remnant = '';
    }
    elseif ($item->depth == $depth) {
      $tree .= theme('menu_link', $link);
      $link = $menu_link;
    }
    else {
      $remnant = $menu_link;
      break;
    }
  }
  if ($link['link']) {
    $tree .= theme('menu_link', $link);
  }
  return array($remnant, $tree);
}

/**
 * Generate the HTML for a menu tree.
 */
function theme_menu_tree($link, $tree) {
  $tree = '<ul class="menu">'. $tree .'</ul>';
  return $link['link'] ? theme('menu_link', $link, $tree) : $tree;
}

/**
 * Generate the HTML for a menu link.
 */
function theme_menu_link($link, $menu = '') {
  return '<li class="'. ($menu ? 'expanded' : ($link['has_children'] ? 'collapsed' : 'leaf')) .'">'. $link['link'] . $menu .'</li>' . "\n";
}

/**
 * Returns the help associated with the active menu item.
 */
function menu_get_active_help() {
  $path = $_GET['q'];
  $output = '';
  $item = menu_get_item();

  if (!$item->access) {
    // Don't return help text for areas the user cannot access.
    return;
  }

  foreach (module_list() as $name) {
    if (module_hook($name, 'help')) {
      if ($temp = module_invoke($name, 'help', $path)) {
        $output .= $temp ."\n";
      }
      if (module_hook('help', 'page')) {
        if (arg(0) == "admin") {
          if (module_invoke($name, 'help', 'admin/help#'. arg(2)) && !empty($output)) {
            $output .= theme("more_help_link", url('admin/help/'. arg(2)));
          }
        }
      }
    }
  }
  return $output;
}

/**
 * Populate the database representation of the menu.
 */
function menu_rebuild() {
  $next = array();
  db_query('DELETE FROM {menu}');
  $menu = module_invoke_all('menu');
  foreach (module_implements('menu_alter') as $module) {
    $function = $module .'_menu_alter';
    $function($menu);
  }
  $mid = 1;
  // First pass.
  foreach ($menu as $path => $item) {
    $item = &$menu[$path];
    $parts = explode('/', $path, 6);
    $number_parts = count($parts);
    // We store the highest index of parts here to save some work in the weight
    // calculation loop.
    $slashes = $number_parts - 1;
    // If there is no %, it fits maximally.
    if (strpos($path, '%') === FALSE) {
      $fit = (1 << $number_parts) - 1;
    }
    else {
      // We need to calculate the fitness.
      $fit = 0;
      foreach ($parts as $k => $part) {
        // ($part != '%') is the bit we want and we shift it to its place
        // by shifting to left by ($slashes - $k) bits.
        $fit |=  ($part != '%') << ($slashes - $k);
      }
    }
    if (!isset($item['_visible'])) {
      $item['_visible'] = (!isset($item['type']) || ($item['type'] & MENU_VISIBLE_IN_TREE)) ? 1 : 0;
    }
    $depth = 1;
    if (!isset($item['_mid'])) {
      $item['_mid'] = $mid++;
    }
    $parents = array($item['_mid']);
    for ($i = $slashes; $i; $i--) {
      $parent_path = implode('/', array_slice($parts, 0, $i));
      // We need to calculate depth to be able to sort. depth needs visibility.
      if (isset($menu[$parent_path])) {
        $parent = &$menu[$parent_path];
        // It's possible that the parent was not processed yet.
        if (!isset($parent['_mid'])) {
          $parent['_mid'] = $mid++;
        }
        if (!isset($parent['_visible'])) {
          $parent['_visible'] = (!isset($parent['type']) || ($parent['type'] & MENU_VISIBLE_IN_TREE)) ? 1 : 0;
        }
        if ($item['_visible'] && $parent['_visible']) {
          $parent['_has_children'] = 1;
          $depth++;
          $parents[] = $parent['_mid'];
          if (!isset($item['_pid'])) {
            $item['_pid'] = $parent['_mid'];
            $item['_visible_parent_path'] = $parent_path;
          }
        }
        unset($parent);
      }
    }
    $parents[] = 0;
    $parents = implode(',', array_reverse($parents));
    // Store variables and set defaults.
    $item += array(
      '_fit' => $fit,
      '_number_parts' => $number_parts,
      '_parts' => $parts,
      '_pid' => 0,
      '_depth' => $depth,
      '_parents' => $parents,
      '_has_children' => 0,
      'title' => '',
      'weight' => 0,
    );
    $sort[$path] = ($item['_visible'] ? $depth : $number_parts) . sprintf('%05d', $item['weight']) . $item['title'];
    unset($item);
  }
  array_multisort($sort, $menu);
  // Second pass: calculate ancestors, vancode and store into the database.
  foreach ($menu as $path => $item) {
    $item = &$menu[$path];
    for ($i = $item['_number_parts'] - 1; $i; $i--) {
      $parent_path = implode('/', array_slice($item['_parts'], 0, $i));
      if (isset($menu[$parent_path])) {
        $parent = $menu[$parent_path];
        // If a callback is not found, we try to find the first parent that
        // has this callback. When found, its callback argument will also be
        // copied but only if there is none in the current item.
        foreach (array('access', 'map', 'page') as $type) {
          if (!isset($item["$type callback"]) && isset($parent["$type callback"])) {
            $item["$type callback"] = $parent["$type callback"];
            if (!isset($item["$type arguments"]) && isset($parent["$type arguments"])) {
              $item["$type arguments"] = $parent["$type arguments"];
            }
          }
        }
      }
    }
    if (!isset($item['access callback'])) {
      $menu[$path]['access callback'] = isset($item['access arguments']) ? 'user_access' : 0;
    }
    if (!isset($item['map callback']) && isset($item['map arguments'])) {
      $item['map callback'] = 'menu_map';
    }
    foreach (array('access', 'map', 'page') as $type) {
      if (isset($item["$type callback"]) && !isset($item["$type arguments"])) {
        $item["$type arguments"] = array();
      }
    }
    if (is_bool($item['access callback'])) {
      $item['access callback'] = intval($item['access callback']);
    }
    if ($item['_visible']) {
      $prefix = isset($item['_visible_parent_path']) ? $menu[$item['_visible_parent_path']]['_prefix'] : '';
      if (!isset($next[$prefix])) {
        $next[$prefix] = 0;
      }
      $vancode = $prefix . int2vancode($next[$prefix]++);
      $menu[$path]['_prefix'] = $vancode .'.';
      $link = l($item['title'], $path, isset($item['attributes']) ? $item['attributes'] : array(), isset($item['query']) ? $item['query'] : NULL, isset($item['fragment']) ? $item['fragment'] : NULL);
    }
    else {
      $vancode = '';
      $link = '';
    }
    db_query("INSERT INTO {menu} (mid, pid, path, access_callback, access_arguments, page_callback, page_arguments, map_callback, map_arguments, fit, number_parts, vancode, menu_link, visible, parents, depth, has_children) VALUES (%d, %d, '%s', '%s', '%s', '%s', '%s', '%s', '%s', %d, %d, '%s', '%s', %d, '%s', %d, %d)", $item['_mid'], $item['_pid'], $path, $item['access callback'], serialize($item['access arguments']), $item['page callback'], serialize($item['page arguments']), $item['map callback'], serialize($item['map arguments']), $item['_fit'], $item['_number_parts'], $vancode .'+', $link, $item['_visible'], $item['_parents'], $item['_depth'], $item['_has_children']);
    // $item needs to be unset because of the reference above.
    unset($item);
  }
}

function menu_map($arg, $function, $index, $default = FALSE) {
  $arg[$index] = is_numeric($arg[$index]) ? $function($arg[$index]) : $default;
  return $arg[$index] ? $arg : FALSE;
}

// Placeholders.
function menu_primary_links() {
}

function menu_secondary_links() {
}

function menu_primary_local_tasks() {
}

function menu_secondary_local_tasks() {
}

function menu_set_active_item() {
}

function menu_set_location() {
}

function menu_get_active_breadcrumb() {
  return array(l(t('Home'), ''));
}