<?php

/**
 * @file
 * The page manager module provides a UI and API to manage pages.
 *
 * It defines pages, both for system pages, overrides of system pages, and
 * custom pages using Drupal's normal menu system. It allows complex
 * manipulations of these pages, their content, and their hierarchy within
 * the site. These pages can be exported to code for superior revision
 * control.
 */

/**
 * Bit flag on the 'changed' value to tell us if an item was moved.
 */
define('PAGE_MANAGER_CHANGED_MOVED', 0x01);

/**
 * Bit flag on the 'changed' value to tell us if an item edited or added.
 */
define('PAGE_MANAGER_CHANGED_CACHED', 0x02);

/**
 * Bit flag on the 'changed' value to tell us if an item deleted.
 */
define('PAGE_MANAGER_CHANGED_DELETED', 0x04);

/**
 * Bit flag on the 'changed' value to tell us if an item has had its disabled status changed.
 */
define('PAGE_MANAGER_CHANGED_STATUS', 0x08);

// --------------------------------------------------------------------------
// Drupal hooks

/**
 * Implements hook_permission().
 */
function page_manager_permission() {
  return array(
    'use page manager' => array(
      'title' => t('Use Page Manager'),
      'description' => t("Allows users to use most of Page Manager's features, though restricts some of the most powerful, potentially site-damaging features. Note that even the reduced featureset still allows for enormous control over your website."),
      'restrict access' => TRUE,
    ),
    'administer page manager' => array(
      'title' => t('Administer Page Manager'),
      'description' => t('Allows complete control over Page Manager, i.e., complete control over your site. Grant with extreme caution.'),
      'restrict access' => TRUE,
    ),
  );

}

/**
 * Implements hook_ctools_plugin_directory() to let the system know
 * where our task and task_handler plugins are.
 */
function page_manager_ctools_plugin_directory($owner, $plugin_type) {
  if ($owner == 'page_manager') {
    return 'plugins/' . $plugin_type;
  }
  if ($owner == 'ctools' && $plugin_type == 'cache') {
    return 'plugins/' . $plugin_type;
  }
}

/**
 * Implements hook_ctools_plugin_type() to inform the plugin system that Page
 * Manager owns task, task_handler, and page_wizard plugin types.
 *
 * All of these are empty because the defaults all work.
 */
function page_manager_ctools_plugin_type() {
  return array(
    'tasks' => array(),
    'task_handlers' => array(),
    'page_wizards' => array(),
  );
}

/**
 * Delegated implementation of hook_menu().
 */
function page_manager_menu() {
  // For some reason, some things can activate modules without satisfying
  // dependencies. I don't know how, but this helps prevent things from
  // whitescreening when this happens.
  if (!module_exists('ctools')) {
    return;
  }

  $items = array();
  $base = array(
    'access arguments' => array('use page manager'),
    'file' => 'page_manager.admin.inc',
    'theme callback' => 'ajax_base_page_theme',
  );

  $items['admin/structure/pages'] = array(
    'title' => 'Pages',
    'description' => 'Add, edit and remove overridden system pages and user defined pages from the system.',
    'page callback' => 'page_manager_list_page',
  ) + $base;

  $items['admin/structure/pages/list'] = array(
    'title' => 'List',
    'page callback' => 'page_manager_list_page',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  ) + $base;

  $items['admin/structure/pages/edit/%page_manager_cache'] = array(
    'title' => 'Edit',
    'page callback' => 'page_manager_edit_page',
    'page arguments' => array(4),
    'type' => MENU_NORMAL_ITEM,
  ) + $base;

  $items['admin/structure/pages/%ctools_js/operation/%page_manager_cache'] = array(
    'page callback' => 'page_manager_edit_page_operation',
    'page arguments' => array(3, 5),
    'type' => MENU_NORMAL_ITEM,
  ) + $base;

  $items['admin/structure/pages/%ctools_js/enable/%page_manager_cache'] = array(
    'page callback' => 'page_manager_enable_page',
    'page arguments' => array(FALSE, 3, 5),
    'type' => MENU_CALLBACK,
  ) + $base;

  $items['admin/structure/pages/%ctools_js/disable/%page_manager_cache'] = array(
    'page callback' => 'page_manager_enable_page',
    'page arguments' => array(TRUE, 3, 5),
    'type' => MENU_CALLBACK,
  ) + $base;

  $tasks = page_manager_get_tasks();

  // Provide menu items for each task.
  foreach ($tasks as $task_id => $task) {
    // Allow the task to add its own menu items.
    if ($function = ctools_plugin_get_function($task, 'hook menu')) {
      $function($items, $task);
    }

    // And for those that provide subtasks, provide menu items for them, as well.
    foreach (page_manager_get_task_subtasks($task) as $subtask_id => $subtask) {
      // Allow the task to add its own menu items.
      if ($function = ctools_plugin_get_function($task, 'hook menu')) {
        $function($items, $subtask);
      }
    }
  }

  return $items;
}

function page_manager_admin_paths() {
  /* @todo FIX ME this is a major resource suck. */
  return;

  $items = array();
  ctools_include('page', 'page_manager', 'plugins/tasks');
  $pages = page_manager_page_load_all();
  foreach ($pages as $page) {
    // Make sure the page we're on is set to be an administrative path and that
    // it is not set to be a frontpage path.
    if ((isset($page->conf['admin_paths']) && $page->conf['admin_paths']) && (!isset($page->make_frontpage) || !$page->make_frontpage)) {
      $path_parts = explode('/', $page->path);
      foreach ($path_parts as $key => $part) {
        if (strpos($part, '%') !== FALSE || strpos($part, '!') !== FALSE) {
          $path_parts[$key] = '*';
        }
      }
      $path = implode('/', $path_parts);
      if ($page->menu['type'] == 'default tab') {
        array_pop($path_parts);
        $parent_path = implode('/', $path_parts);
        $items[$parent_path] = TRUE;
      }
      $items[$path] = TRUE;
    }
  }
  return $items;
}

/**
 * Implements hook_menu_alter.
 *
 * Get a list of all tasks and delegate to them.
 */
function page_manager_menu_alter(&$items) {
  // For some reason, some things can activate modules without satisfying
  // dependencies. I don't know how, but this helps prevent things from
  // whitescreening when this happens.
  if (!module_exists('ctools')) {
    return;
  }

  $tasks = page_manager_get_tasks();

  foreach ($tasks as $task) {
    if ($function = ctools_plugin_get_function($task, 'hook menu alter')) {
      $function($items, $task);
    }
    // let the subtasks alter the menu items too.
    foreach (page_manager_get_task_subtasks($task) as $subtask_id => $subtask) {
      if ($function = ctools_plugin_get_function($subtask, 'hook menu alter')) {
        $function($items, $subtask);
      }
    }
  }

  return $items;
}

/*
 * Implements hook_theme()
 */
function page_manager_theme() {
  // For some reason, some things can activate modules without satisfying
  // dependencies. I don't know how, but this helps prevent things from
  // whitescreening when this happens.
  if (!module_exists('ctools')) {
    return;
  }

  $base = array(
    'path' => drupal_get_path('module', 'page_manager') . '/theme',
    'file' => 'page_manager.theme.inc',
  );

  $items = array(
    'page_manager_handler_rearrange' => array(
      'render element' => 'form',
    ) + $base,
    'page_manager_edit_page' => array(
      'template' => 'page-manager-edit-page',
      'variables' => array('page' => NULL, 'save' => NULL, 'operations' => array(), 'content' => array()),
    ) + $base,
    'page_manager_lock' => array(
      'variables' => array('page' => array()),
    ) + $base,
    'page_manager_changed' => array(
      'variables' => array('text' => NULL, 'description' => NULL),
    ) + $base,
  );

  // Allow task plugins to have theme registrations by passing through:
  $tasks = page_manager_get_tasks();

  // Provide menu items for each task.
  foreach ($tasks as $task_id => $task) {
    if ($function = ctools_plugin_get_function($task, 'hook theme')) {
      $function($items, $task);
    }
  }

  return $items;
}

// --------------------------------------------------------------------------
// Page caching
//
// The page cache is used to store a page temporarily, using the ctools object
// cache. When loading from the page cache, it will either load the cached
// version, or if there is not one, load the real thing and create a cache
// object which can then be easily stored.

/**
 * Get the cached changes to a given task handler.
 */
function page_manager_get_page_cache($task_name) {
  $caches = drupal_static(__FUNCTION__, array());
  if (!isset($caches[$task_name])) {
    ctools_include('object-cache');
    $cache = ctools_object_cache_get('page_manager_page', $task_name);
    if (!$cache) {
      $cache = new stdClass();
      $cache->task_name = $task_name;
      list($cache->task_id, $cache->subtask_id) = page_manager_get_task_id($cache->task_name);

      $cache->task = page_manager_get_task($cache->task_id);
      if (empty($cache->task)) {
        return FALSE;
      }

      if ($cache->subtask_id) {
        $cache->subtask = page_manager_get_task_subtask($cache->task, $cache->subtask_id);
        if (empty($cache->subtask)) {
          return FALSE;
        }
      }
      else {
        $cache->subtask = $cache->task;
        $cache->subtask['name'] = '';
      }

      $cache->handlers = page_manager_load_sorted_handlers($cache->task, $cache->subtask_id);
      $cache->handler_info = array();
      foreach ($cache->handlers as $id => $handler) {
        $cache->handler_info[$id] = array(
          'weight' => $handler->weight,
          'changed' => FALSE,
          'name' => $id,
        );
      }
    }
    else {
      // ensure the task is loaded.
      page_manager_get_task($cache->task_id);
    }

    if ($task_name != '::new') {
      $cache->locked = ctools_object_cache_test('page_manager_page', $task_name);
    }
    else {
      $cache->locked = FALSE;
    }

    $caches[$task_name] = $cache;
  }

  return $caches[$task_name];
}

/**
 * Store changes to a task handler in the object cache.
 */
function page_manager_set_page_cache($page) {
  if (!empty($page->locked)) {
    return;
  }

  if (empty($page->task_name)) {
    return;
  }

  ctools_include('object-cache');
  $page->changed = TRUE;
  $cache = ctools_object_cache_set('page_manager_page', $page->task_name, $page);
}

/**
 * Remove an item from the object cache.
 */
function page_manager_clear_page_cache($name) {
  ctools_include('object-cache');
  ctools_object_cache_clear('page_manager_page', $name);
}

/**
 * Write all changes from the page cache and clear it out.
 */
function page_manager_save_page_cache($cache) {
  // Save the subtask:
  if ($function = ctools_plugin_get_function($cache->task, 'save subtask callback')) {
    $function($cache->subtask, $cache);
  }

  // Iterate through handlers and save/delete/update as necessary.
  // Go through each of the task handlers, check to see if it needs updating,
  // and update it if so.
  foreach ($cache->handler_info as $id => $info) {
    $handler = &$cache->handlers[$id];
    // If it has been marked for deletion, delete it.

    if ($info['changed'] & PAGE_MANAGER_CHANGED_DELETED) {
      page_manager_delete_task_handler($handler);
    }
    // If it has been somehow edited (or added), write the cached version
    elseif ($info['changed'] & PAGE_MANAGER_CHANGED_CACHED) {
      // Make sure we get updated weight from the form for this.
      $handler->weight = $info['weight'];
      page_manager_save_task_handler($handler);
    }
    // Otherwise, check to see if it has moved and, if so, update the weight.
    elseif ($info['weight'] != $handler->weight) {
      // Theoretically we could only do this for in code objects, but since our
      // load mechanism checks for all, this is less database work.
      page_manager_update_task_handler_weight($handler, $info['weight']);
    }

    // Set enable/disabled status.
    if ($info['changed'] & PAGE_MANAGER_CHANGED_STATUS) {
      ctools_include('export');
      ctools_export_set_object_status($cache->handlers[$id], $info['disabled']);
    }
  }

  page_manager_clear_page_cache($cache->task_name);

  if (!empty($cache->path_changed) || !empty($cache->new)) {
    // Force a menu rebuild to make sure the menu entries are set.
    menu_rebuild();
  }
  cache_clear_all();
}

/**
 * Menu callback to load a page manager cache object for menu callbacks.
 */
function page_manager_cache_load($task_name) {
  // load context plugin as there may be contexts cached here.
  ctools_include('context');
  return page_manager_get_page_cache($task_name);
}

/**
 * Generate a unique name for a task handler.
 *
 * Task handlers need to be named but they aren't allowed to set their own
 * names. Instead, they are named based upon their parent task and type.
 */
function page_manager_handler_get_name($task_name, $handlers, $handler) {
  $base = str_replace('-', '_', $task_name);
  // Generate a unique name. Unlike most named objects, we don't let people choose
  // names for task handlers because they mostly don't make sense.
  $base .= '_' . $handler->handler;

  // Once we have a base, check to see if it is used. If it is, start counting up.
  $name = $base;
  $count = 1;
  // If taken
  while (isset($handlers[$name])) {
    $name = $base . '_' . ++$count;
  }

  return $name;
}

/**
 * Import a handler into a page.
 *
 * This is used by both import and clone, since clone just exports the
 * handler and immediately imports it.
 */
function page_manager_handler_add_to_page(&$page, &$handler, $title = NULL) {
  $last = end($page->handler_info);
  $handler->weight = $last ? $last['weight'] + 1 : 0;
  $handler->task = $page->task_id;
  $handler->subtask = $page->subtask_id;
  $handler->export_type = EXPORT_IN_DATABASE;
  $handler->type = t('Normal');

  if ($title) {
    $handler->conf['title'] = $title;
  }

  $name = page_manager_handler_get_name($page->task_name, $page->handlers, $handler);

  $handler->name = $name;

  $page->handlers[$name] = $handler;
  $page->handler_info[$name] = array(
    'weight' => $handler->weight,
    'name' => $handler->name,
    'changed' => PAGE_MANAGER_CHANGED_CACHED,
  );
}

// --------------------------------------------------------------------------
// Database routines
//
// This includes fetching plugins and plugin info as well as specialized
// fetch methods to get groups of task handlers per task.

/**
 * Load a single task handler by name.
 *
 * Handlers can come from multiple sources; either the database or by normal
 * export method, which is handled by the ctools library, but handlers can
 * also be bundled with task/subtask. We have to check there and perform
 * overrides as appropriate.
 *
 * Handlers bundled with the task are of a higher priority than default
 * handlers provided by normal code, and are of a lower priority than
 * the database, so we have to check the source of handlers when we have
 * multiple to choose from.
 */
function page_manager_load_task_handler($task, $subtask_id, $name) {
  ctools_include('export');
  $result = ctools_export_load_object('page_manager_handlers', 'names', array($name));
  $handlers = page_manager_get_default_task_handlers($task, $subtask_id);
  return page_manager_compare_task_handlers($result, $handlers, $name);
}

/**
 * Load all task handlers for a given task/subtask.
 */
function page_manager_load_task_handlers($task, $subtask_id = NULL, $default_handlers = NULL) {
  ctools_include('export');
  $conditions = array(
    'task' => $task['name'],
  );

  if (isset($subtask_id)) {
    $conditions['subtask'] = $subtask_id;
  }

  $handlers = ctools_export_load_object('page_manager_handlers', 'conditions', $conditions);
  $defaults = isset($default_handlers) ? $default_handlers : page_manager_get_default_task_handlers($task, $subtask_id);
  foreach ($defaults as $name => $default) {
    $result = page_manager_compare_task_handlers($handlers, $defaults, $name);

    if ($result) {
      $handlers[$name] = $result;
      // Ensure task and subtask are correct, because it's easy to change task
      // names when editing a default and fail to do it on the associated handlers.
      $result->task = $task['name'];
      $result->subtask = $subtask_id;
    }
  }

  // Override weights from the weight table.
  if ($handlers) {
    $names = array();
    $placeholders = array();
    foreach ($handlers as $handler) {
      $names[] = $handler->name;
      $placeholders[] = "'%s'";
    }

    $result = db_query('SELECT name, weight FROM {page_manager_weights} WHERE name IN (:names)', array(':names' => $names));
    foreach ($result as $weight) {
      $handlers[$weight->name]->weight = $weight->weight;
    }
  }

  return $handlers;
}

/**
 * Get the default task handlers from a task, if they exist.
 *
 * Tasks can contain 'default' task handlers which are provided by the
 * default task. Because these can come from either the task or the
 * subtask, the logic is abstracted to reduce code duplication.
 */
function page_manager_get_default_task_handlers($task, $subtask_id) {
  // Load default handlers that are provied by the task/subtask itself.
  $handlers = array();
  if ($subtask_id) {
    $subtask = page_manager_get_task_subtask($task, $subtask_id);
    if (isset($subtask['default handlers'])) {
      $handlers = $subtask['default handlers'];
    }
  }
  else if (isset($task['default handlers'])) {
    $handlers = $task['default handlers'];
  }

  return $handlers;
}

/**
 * Compare a single task handler from two lists and provide the correct one.
 *
 * Task handlers can be gotten from multiple sources. As exportable objects,
 * they can be provided by default hooks and the database. But also, because
 * they are tightly bound to tasks, they can also be provided by default
 * tasks. This function reconciles where to pick up a task handler between
 * the exportables list and the defaults provided by the task itself.
 *
 * @param $result
 *   A list of handlers provided by export.inc
 * @param $handlers
 *   A list of handlers provided by the default task.
 * @param $name
 *   Which handler to compare.
 * @return
 *   Which handler to use, if any. May be NULL.
 */
function page_manager_compare_task_handlers($result, $handlers, $name) {
  // Compare our special default handler against the actual result, if
  // any, and do the right thing.
  if (!isset($result[$name]) && isset($handlers[$name])) {
    $handlers[$name]->type = t('Default');
    $handlers[$name]->export_type = EXPORT_IN_CODE;
    return $handlers[$name];
  }
  else if (isset($result[$name]) && !isset($handlers[$name])) {
    return $result[$name];
  }
  else if (isset($result[$name]) && isset($handlers[$name])) {
    if ($result[$name]->export_type & EXPORT_IN_DATABASE) {
      $result[$name]->type = t('Overridden');
      $result[$name]->export_type = $result[$name]->export_type | EXPORT_IN_CODE;
      return $result[$name];
    }
    else {
      // In this case, our default is a higher priority than the standard default.
      $handlers[$name]->type = t('Default');
      $handlers[$name]->export_type = EXPORT_IN_CODE;
      return $handlers[$name];
    }
  }
}

/**
 * Load all task handlers for a given task and subtask and sort them.
 */
function page_manager_load_sorted_handlers($task, $subtask_id = NULL, $enabled = FALSE) {
  $handlers = page_manager_load_task_handlers($task, $subtask_id);
  if ($enabled) {
    foreach ($handlers as $id => $handler) {
      if (!empty($handler->disabled)) {
        unset($handlers[$id]);
      }
    }
  }
  uasort($handlers, 'page_manager_sort_task_handlers');
  return $handlers;
}

/**
 * Callback for uasort to sort task handlers.
 *
 * Task handlers are sorted by weight then by name.
 */
function page_manager_sort_task_handlers($a, $b) {
  if ($a->weight < $b->weight) {
    return -1;
  }
  elseif ($a->weight > $b->weight) {
    return 1;
  }
  elseif ($a->name < $b->name) {
    return -1;
  }
  elseif ($a->name > $b->name) {
    return 1;
  }

  return 0;
}

/**
 * Write a task handler to the database.
 */
function page_manager_save_task_handler(&$handler) {
  $update = (isset($handler->did)) ? array('did') : array();
  // Let the task handler respond to saves:
  if ($function = ctools_plugin_load_function('page_manager', 'task_handlers', $handler->handler, 'save')) {
    $function($handler, $update);
  }

  drupal_write_record('page_manager_handlers', $handler, $update);
  db_delete('page_manager_weights')
    ->condition('name', $handler->name)
    ->execute();

  // If this was previously a default handler, we may have to write task handlers.
  if (!$update) {
    // @todo wtf was I going to do here?
  }
  return $handler;
}

/**
 * Remove a task handler.
 */
function page_manager_delete_task_handler($handler) {
  // Let the task handler respond to saves:
  if ($function = ctools_plugin_load_function('page_manager', 'task_handlers', $handler->handler, 'delete')) {
    $function($handler);
  }
  db_delete('page_manager_handlers')
    ->condition('name', $handler->name)
    ->execute();
  db_delete('page_manager_weights')
    ->condition('name', $handler->name)
    ->execute();
}

/**
 * Export a task handler into code suitable for import or use as a default
 * task handler.
 */
function page_manager_export_task_handler($handler, $indent = '') {
  ctools_include('export');
  ctools_include('plugins');
  $handler = clone $handler;

  $append = '';
  if ($function = ctools_plugin_load_function('page_manager', 'task_handlers', $handler->handler, 'export')) {
    $append = $function($handler, $indent);
  }

  $output = ctools_export_object('page_manager_handlers', $handler, $indent);
  $output .= $append;

  return $output;
}

/**
 * Loads page manager handler for export.
 *
 * Callback to load page manager handler within ctools_export_crud_load().
 *
 * @param string $name
 *   The name of the handler to load.
 *
 * @return
 *   Loaded page manager handler object, extended with external properties.
 */
function page_manager_export_task_handler_load($name) {
  $table = 'page_manager_handlers';
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  $result = ctools_export_load_object($table, 'names', array($name));
  if (isset($result[$name])) {
    $handler = $result[$name];

    // Weight is stored in additional table so that in-code task handlers
    // don't need to get written to the database just because they have their
    // weight changed. Therefore, handler could have no correspondent database
    // entry. Revert will not be performed for this handler and the weight
    // will not be reverted. To make possible revert of the weight field
    // export_type must simulate that the handler is stored in the database.
    $handler->export_type = EXPORT_IN_DATABASE;

    // Also, page manager handler weight should be overriden with correspondent
    // weight from page_manager_weights table, if there is one.
    $result = db_query('SELECT weight FROM {page_manager_weights} WHERE name = (:names)', array(':names' => $handler->name))->fetchField();
    if (is_numeric($result)) {
      $handler->weight = $result;
    }
    return $handler;
  }
}

/**
 * Create a new task handler object.
 *
 * @param $plugin
 *   The plugin this task handler is created from.
 */
function page_manager_new_task_handler($plugin) {
  // Generate a unique name. Unlike most named objects, we don't let people choose
  // names for task handlers because they mostly don't make sense.

  // Create a new, empty handler object.
  $handler          = new stdClass;
  $handler->title   = $plugin['title'];
  $handler->task    = NULL;
  $handler->subtask = NULL;
  $handler->name    = NULL;
  $handler->handler = $plugin['name'];
  $handler->weight  = 0;
  $handler->conf    = array();

  // These are provided by the core export API provided by ctools and we
  // set defaults here so that we don't cause notices. Perhaps ctools should
  // provide a way to do this for us so we don't have to muck with it.
  $handler->export_type = EXPORT_IN_DATABASE;
  $handler->type = t('Local');

  if (isset($plugin['default conf'])) {
    if (is_array($plugin['default conf'])) {
      $handler->conf = $plugin['default conf'];
    }
    else if (function_exists($plugin['default conf'])) {
      $handler->conf = $plugin['default conf']($handler);
    }
  }

  return $handler;
}

/**
 * Set an overidden weight for a task handler.
 *
 * We do this so that in-code task handlers don't need to get written
 * to the database just because they have their weight changed.
 */
function page_manager_update_task_handler_weight($handler, $weight) {
  db_delete('page_manager_weights')
    ->condition('name', $handler->name)
    ->execute();
  db_insert('page_manager_weights')
    ->fields(array(
      'name' => $handler->name,
      'weight' => $weight,
    ))
    ->execute();
}


/**
 * Shortcut function to get task plugins.
 */
function page_manager_get_tasks() {
  ctools_include('plugins');
  return ctools_get_plugins('page_manager', 'tasks');
}

/**
 * Shortcut function to get a task plugin.
 */
function page_manager_get_task($id) {
  ctools_include('plugins');
  return ctools_get_plugins('page_manager', 'tasks', $id);
}

/**
 * Get all tasks for a given type.
 */
function page_manager_get_tasks_by_type($type) {
  ctools_include('plugins');
  $all_tasks = ctools_get_plugins('page_manager', 'tasks');
  $tasks = array();
  foreach ($all_tasks as $id => $task) {
    if (isset($task['task type']) && $task['task type'] == $type) {
      $tasks[$id] = $task;
    }
  }

  return $tasks;
}

/**
 * Fetch all subtasks for a page managertask.
 *
 * @param $task
 *   A loaded $task plugin object.
 */
function page_manager_get_task_subtasks($task) {
  if (empty($task['subtasks'])) {
    return array();
  }

  if ($function = ctools_plugin_get_function($task, 'subtasks callback')) {
    $retval = $function($task);
    if (is_array($retval)) {
      return $retval;
    }
    else {
      dsm($retval);
    }
  }

  return array();
}

/**
 * Fetch all subtasks for a page managertask.
 *
 * @param $task
 *   A loaded $task plugin object.
 * @param $subtask_id
 *   The subtask ID to load.
 */
function page_manager_get_task_subtask($task, $subtask_id) {
  if (empty($task['subtasks'])) {
    return;
  }

  if ($function = ctools_plugin_get_function($task, 'subtask callback')) {
    return $function($task, $subtask_id);
  }
}

/**
 * Shortcut function to get task handler plugins.
 */
function page_manager_get_task_handlers() {
  ctools_include('plugins');
  return ctools_get_plugins('page_manager', 'task_handlers');
}

/**
 * Shortcut function to get a task handler plugin.
 */
function page_manager_get_task_handler($id) {
  ctools_include('plugins');
  return ctools_get_plugins('page_manager', 'task_handlers', $id);
}

/**
 * Retrieve a list of all applicable task handlers for a given task.
 *
 * This looks at the $task['handler type'] and compares that to $task_handler['handler type'].
 * If the task has no type, the id of the task is used instead.
 */
function page_manager_get_task_handler_plugins($task, $all = FALSE) {
  $type = isset($task['handler type']) ? $task['handler type'] : $task['name'];
  $name = $task['name'];

  $handlers = array();
  $task_handlers = page_manager_get_task_handlers();
  foreach ($task_handlers as $id => $handler) {
    $task_type = is_array($handler['handler type']) ? $handler['handler type'] : array($handler['handler type']);
    if (in_array($type, $task_type) || in_array($name, $task_type)) {
      if ($all || !empty($handler['visible'])) {
        $handlers[$id] = $handler;
      }
    }
  }

  return $handlers;
}

/**
 * Get the title for a given handler.
 *
 * If the plugin has no 'admin title' function, the generic title of the
 * plugin is used instead.
 */
function page_manager_get_handler_title($plugin, $handler, $task, $subtask_id) {
  $function = ctools_plugin_get_function($plugin, 'admin title');
  if ($function) {
    return $function($handler, $task, $subtask_id);
  }
  else {
    return $plugin['title'];
  }
}

/**
 * Get the admin summary (additional info) for a given handler.
 */
function page_manager_get_handler_summary($plugin, $handler, $page, $title = TRUE) {
  if ($function = ctools_plugin_get_function($plugin, 'admin summary')) {
    return $function($handler, $page->task, $page->subtask, $page, $title);
  }
}

/**
 * Get the admin summary (additional info) for a given page.
 */
function page_manager_get_page_summary($task, $subtask) {
  if ($function = ctools_plugin_get_function($subtask, 'admin summary')) {
    return $function($task, $subtask);
  }
}

/**
 * Split a task name into a task id and subtask id, if applicable.
 */
function page_manager_get_task_id($task_name) {
  if (strpos($task_name, '-') !== FALSE) {
    return explode('-', $task_name, 2);
  }
  else {
    return array($task_name, NULL);
  }
}

/**
 * Turn a task id + subtask_id into a task name.
 */
function page_manager_make_task_name($task_id, $subtask_id) {
  if ($subtask_id) {
    return $task_id . '-' . $subtask_id;
  }
  else {
    return $task_id;
  }
}

/**
 * Get the render function for a handler.
 */
function page_manager_get_renderer($handler) {
  return ctools_plugin_load_function('page_manager', 'task_handlers', $handler->handler, 'render');
}

// --------------------------------------------------------------------------
// Functions existing on behalf of tasks and task handlers


/**
 * Page manager arg load function because menu system will not load extra
 * files for these; they must be in a .module.
 */
function pm_arg_load($value, $subtask, $argument) {
  page_manager_get_task('page');
  return _pm_arg_load($value, $subtask, $argument);
}

/**
 * Special arg_load function to use %menu_tail like functionality to
 * get everything after the arg together as a single value.
 */
function pm_arg_tail_load($value, $subtask, $argument, $map) {
  $value = implode('/', array_slice($map, $argument));
  page_manager_get_task('page');
  return _pm_arg_load($value, $subtask, $argument);
}

/**
 * Special menu _load() function for the user:uid argument.
 *
 * This is just the normal page manager argument. It only exists so that
 * the to_arg can exist.
 */
function pm_uid_arg_load($value, $subtask, $argument) {
  page_manager_get_task('page');
  return _pm_arg_load($value, $subtask, $argument);
}

/**
 * to_arg function for the user:uid argument to provide the arg for the
 * current global user.
 */
function pm_uid_arg_to_arg($arg) {
  return user_uid_optional_to_arg($arg);
}

/**
 * Callback for access control ajax form on behalf of page.inc task.
 *
 * Returns the cached access config and contexts used.
 */
function page_manager_page_ctools_access_get($argument) {
  $page = page_manager_get_page_cache($argument);

  $contexts = array();

  // Load contexts based on argument data:
  if ($arguments = _page_manager_page_get_arguments($page->subtask['subtask'])) {
    $contexts = ctools_context_get_placeholders_from_argument($arguments);
  }

  return array($page->subtask['subtask']->access, $contexts);
}

/**
 * Callback for access control ajax form on behalf of page.inc task.
 *
 * Writes the changed access to the cache.
 */
function page_manager_page_ctools_access_set($argument, $access) {
  $page = page_manager_get_page_cache($argument);
  $page->subtask['subtask']->access = $access;
  page_manager_set_page_cache($page);
}

/**
 * Callback for access control ajax form on behalf of context task handler.
 *
 * Returns the cached access config and contexts used.
 */
function page_manager_task_handler_ctools_access_get($argument) {
  list($task_name, $name) = explode('*', $argument);
  $page = page_manager_get_page_cache($task_name);
  if (empty($name)) {
    $handler = &$page->new_handler;
  }
  else {
    $handler = &$page->handlers[$name];
  }

  if (!isset($handler->conf['access'])) {
    $handler->conf['access'] = array();
  }

  ctools_include('context-task-handler');

  $contexts = ctools_context_handler_get_all_contexts($page->task, $page->subtask, $handler);

  return array($handler->conf['access'], $contexts);
}

/**
 * Callback for access control ajax form on behalf of context task handler.
 *
 * Writes the changed access to the cache.
 */
function page_manager_task_handler_ctools_access_set($argument, $access) {
  list($task_name, $name) = explode('*', $argument);
  $page = page_manager_get_page_cache($task_name);
  if (empty($name)) {
    $handler = &$page->new_handler;
  }
  else {
    $handler = &$page->handlers[$name];
  }

  $handler->conf['access'] = $access;
  page_manager_set_page_cache($page);
}

/**
 * Form a URL to edit a given page given the trail.
 */
function page_manager_edit_url($task_name, $trail = array()) {
  if (!is_array($trail)) {
    $trail = array($trail);
  }

  if (empty($trail) || $trail == array('summary')) {
    return "admin/structure/pages/edit/$task_name";
  }

  return 'admin/structure/pages/nojs/operation/' . $task_name . '/' . implode('/', $trail);
}

/**
 * Watch menu links during the menu rebuild, and re-parent things if we need to.
 */
function page_manager_menu_link_alter(&$item) {
  return;
/** -- disabled, concept code --
  static $mlids = array();
  // Keep an array of mlids as links are saved that we can use later.
  if (isset($item['mlid'])) {
    $mlids[$item['path']] = $item['mlid'];
  }

  if (isset($item['parent_path'])) {
    if (isset($mlids[$item['parent_path']])) {
      $item['plid'] = $mlids[$item['parent_path']];
    }
    else {
      // Since we didn't already see an mlid, let's check the database for one.
      $mlid = db_query('SELECT mlid FROM {menu_links} WHERE router_path = :path', array('path' => $item['parent_path']))->fetchField();
      if ($mlid) {
        $item['plid'] = $mlid;
      }
    }
  }
 */
}

/**
 * Callback to list handlers available for export.
 */
function page_manager_page_manager_handlers_list() {
  $list = $types = array();
  $tasks = page_manager_get_tasks();
  foreach ($tasks as $type => $info) {
    if (empty($info['non-exportable'])) {
      $types[] = $type;
    }
  }

  $handlers = ctools_export_load_object('page_manager_handlers');
  foreach ($handlers as $handler) {
    if (in_array($handler->task, $types)) {
      $plugin = page_manager_get_task_handler($handler->handler);
      $title = page_manager_get_handler_title($plugin, $handler, $tasks[$handler->task], $handler->subtask);

      if ($title) {
        $list[$handler->name] = check_plain("$handler->task: $title ($handler->name)");
      }
      else {
        $list[$handler->name] = check_plain("$handler->task: ($handler->name)");
      }
    }
  }
  return $list;
}

/**
 * Callback to bulk export page manager pages.
 */
function page_manager_page_manager_pages_to_hook_code($names = array(), $name = 'foo') {
  $schema = ctools_export_get_schema('page_manager_pages');
  $export = $schema['export'];
  $objects = ctools_export_load_object('page_manager_pages', 'names', array_values($names));
  if ($objects) {
    $code = "/**\n";
    $code .= " * Implements hook_{$export['default hook']}()\n";
    $code .= " */\n";
    $code .= "function " . $name . "_{$export['default hook']}() {\n";
    foreach ($objects as $object) {
      // Have to implement our own because this export func sig requires it
      $code .= $export['export callback']($object, TRUE, '  ');
      $code .= "  \${$export['identifier']}s['" . check_plain($object->$export['key']) . "'] = \${$export['identifier']};\n\n";
    }
    $code .= "  return \${$export['identifier']}s;\n";
    $code .= "}\n";
    return $code;
  }
}

/**
 * Get the current page information.
 *
 * @return $page
 *   An array containing the following information.
 *
 * - 'name': The name of the page as used in the page manager admin UI.
 * - 'task': The plugin for the task in use. If this is a system page it
 *   will contain information about that page, such as what functions
 *   it uses.
 * - 'subtask': The plugin for the subtask. If this is a custom page, this
 *   will contain information about that custom page. See 'subtask' in this
 *   array to get the actual page object.
 * - 'handler': The actual handler object used. If using panels, see
 *   $page['handler']->conf['display'] for the actual panels display
 *   used to render.
 * - 'contexts': The context objects used to render this page.
 * - 'arguments': The raw arguments from the URL used on this page.
 */
function page_manager_get_current_page($page = NULL) {
  static $current = array();
  if (isset($page)) {
    $current = $page;
  }

  return $current;
}

/**
 * Implementation of hook_panels_dashboard_blocks().
 *
 * Adds page information to the Panels dashboard.
 */
function page_manager_panels_dashboard_blocks(&$vars) {
  $vars['links']['page_manager'] = array(
    'weight' => -100,
    'title' => l(t('Panel page'), 'admin/structure/pages/add'),
    'description' => t('Panel pages can be used as landing pages. They have a URL path, accept arguments and can have menu entries.'),
  );

  module_load_include('inc', 'page_manager', 'page_manager.admin');
  $tasks = page_manager_get_tasks_by_type('page');
  $pages = array('operations' => array());

  page_manager_get_pages($tasks, $pages);
  $count = 0;
  $rows = array();
  foreach ($pages['rows'] as $id => $info) {
    $rows[] = array(
      'data' => array(
        $info['data']['title'],
        $info['data']['operations'],
      ),
      'class' => $info['class'],
    );

    // Only show 10.
    if (++$count >= 10) {
      break;
    }
  }

  $vars['blocks']['page_manager'] = array(
    'weight' => -100,
    'title' => t('Manage pages'),
    'link' => l(t('Go to list'), 'admin/structure/pages'),
    'content' => theme('table', array('header' => array(), 'rows' => $rows, 'attributes' => array('class' => 'panels-manage'))),
    'class' => 'dashboard-pages',
    'section' => 'right',
  );
}

/**
 * Implement pseudo-hook to fetch addressable content.
 *
 * For Page Manager, the address will be an array. The first
 * element will be the $task and the second element will be the
 * $task_handler. The third elements will be the arguments
 * provided.
 */
function page_manager_addressable_content($address, $type) {
  if (count($address) < 3) {
    return;
  }

  $task_name = array_shift($address);
  $subtask_name = array_shift($address);
  $handler_name = array_shift($address);
  if ($address) {
    $arguments = array_shift($address);
  }

  // Since $arguments is an array of arbitrary size, we need to implode it:
  if (!empty($arguments)) {
    // The only choices we have for separators since :: is already
    // used involve ., - or _. Since - and _ are more common than .
    // in URLs, let's try .. as an argument separator.
    $arguments = explode('..', $arguments);
  }
  else {
    // implode does not return an empty array on an empty
    // string so do it specifically.
    $arguments = array();
  }

  $task = page_manager_get_task($task_name);
  if (!$task) {
    return;
  }

  $handler = page_manager_load_task_handler($task, $subtask_name, $handler_name);
  if (!$handler) {
    return;
  }

  $handler_plugin = page_manager_get_task_handler($handler->handler);
  if (!$handler_plugin) {
    return;
  }

  // Load the contexts for the task.
  ctools_include('context');
  ctools_include('context-task-handler');
  $contexts = ctools_context_handler_get_task_contexts($task, $subtask_name, $arguments);

  // With contexts loaded, ensure the task is accessible. Tasks without a callback
  // are automatically accessible.
  $function = ctools_plugin_get_function($task, 'access callback');
  if ($function && !$function($task, $subtask_name, $contexts)) {
    return;
  }

  $function = ctools_plugin_get_function($handler_plugin, 'addressable callback');
  if ($function) {
    return $function($task, $subtask_name, $handler, $address, $contexts, $arguments, $type);
  }
}
