<?php
// $Id$

/**
 * @file
 * Displays the Drupal administration interface in an overlay.
 */

/**
 * Implements hook_menu().
 */
function overlay_menu() {
  $items['overlay-ajax/%'] = array(
    'title' => '',
    'page callback' => 'overlay_ajax_render_region',
    'page arguments' => array(1),
    'access arguments' => array('access overlay'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_permission().
 */
function overlay_permission() {
  return array(
    'access overlay' => array(
      'title' => t('Access the administrative overlay'),
      'description' => t('View administrative pages in the overlay.'),
    ),
  );
}

/**
 * Implements hook_init().
 *
 * Determine whether the current page request is destined to appear in the
 * parent window or in the overlay window, and format the page accordingly.
 *
 * @see overlay_set_mode()
 */
function overlay_init() {
  // @todo: custom_theme does not exist anymore.
  global $custom_theme;
  // Only act if the user has access to administration pages. Other modules can
  // also enable the overlay directly for other uses of the JavaScript.
  if (user_access('access overlay')) {
    if (isset($_GET['render']) && $_GET['render'] == 'overlay') {
      // If this page shouldn't be rendered here, redirect to the parent.
      if (!path_is_admin($_GET['q'])) {
        overlay_close_dialog();
      }
      // If system module did not switch the theme yet (i.e. this is not an
      // admin page, per se), we should switch the theme here.
      $admin_theme = variable_get('admin_theme', 0);
      if ($custom_theme != $admin_theme) {
        $custom_theme = $admin_theme;
        drupal_add_css(drupal_get_path('module', 'system') . '/admin.css');
      }
      // Indicate that we are viewing an overlay child page.
      overlay_set_mode('child');
    }
    else {
      // Otherwise add overlay parent code and our behavior.
      overlay_set_mode('parent');
    }
  }
}

/**
 * Implements hook_exit().
 *
 * When viewing an overlay child page, check if we need to trigger a refresh of
 * the supplemental regions of the overlay on the next page request.
 */
function overlay_exit() {
  // Check that we are in an overlay child page. Note that this should never
  // return TRUE on a cached page view, since the child mode is not set until
  // overlay_init() is called.
  if (overlay_get_mode() == 'child') {
    // Load any markup that was stored earlier in the page request, via calls
    // to overlay_store_rendered_content(). If none was stored, this is not a
    // page request where we expect any changes to the overlay supplemental
    // regions to have occurred, so we do not need to proceed any further.
    $original_markup = overlay_get_rendered_content();
    if (!empty($original_markup)) {
      // Compare the original markup to the current markup that we get from
      // rendering each overlay supplemental region now. If they don't match,
      // something must have changed, so we request a refresh of that region
      // within the parent window on the next page request.
      foreach (overlay_supplemental_regions() as $region) {
        if (!isset($original_markup[$region]) || $original_markup[$region] != overlay_render_region($region)) {
          overlay_request_refresh($region);
        }
      }
    }
  }
}

/**
 * Implements hook_element_info_alter().
 */
function overlay_element_info_alter(&$types) {
  foreach (array('submit', 'button', 'image_button', 'form') as $type) {
    $types[$type]['#after_build'][] = 'overlay_form_after_build';
  }
}

/**
 * Implements hook_library().
 */
function overlay_library() {
  $module_path = drupal_get_path('module', 'overlay');

  // Overlay parent.
  $libraries['parent'] = array(
    'title' => 'Overlay: Parent',
    'website' => 'http://drupal.org/node/517688',
    'version' => '1.0',
    'js' => array(
      $module_path . '/overlay-parent.js' => array(),
    ),
    'css' => array(
      $module_path . '/overlay-parent.css' => array(),
    ),
    'dependencies' => array(
      array('system', 'ui.dialog'),
      array('system', 'jquery-bbq'),
    ),
  );
  // Overlay child.
  $libraries['child'] = array(
    'title' => 'Overlay: Child',
    'website' => 'http://drupal.org/node/517688',
    'version' => '1.0',
    'js' => array(
      $module_path . '/overlay-child.js' => array(),
    ),
    'dependencies' => array(
      array('system', 'ui'),
    ),
  );

  return $libraries;
}

/**
 * Implements hook_form_alter().
 *
 * For forms displayed in the overlay, add a hidden form field that lets us pass
 * the parent window's URL into the form.
 */
function overlay_form_alter(&$form, &$form_state, $form_id) {
  if (overlay_get_mode() == 'child') {
    $form['overlay_parent_url'] = array(
      '#type' => 'hidden',
    );
  }
}

/**
 * Implements hook_drupal_goto_alter().
 *
 * If the current page request is inside the overlay, add ?render=overlay to
 * the new path, so that it appears correctly inside the overlay.
 *
 * @see overlay_get_mode()
 */
function overlay_drupal_goto_alter(&$path, &$options, &$http_response_code) {
  if (overlay_get_mode() == 'child') {
    if (isset($options['query'])) {
      $options['query'] += array('render' => 'overlay');
    }
    else {
      $options['query'] = array('render' => 'overlay');
    }
  }
}

/**
 * Implements hook_batch_alter().
 *
 * If the current page request is inside the overlay, add ?render=overlay to
 * the success callback URL, so that it appears correctly within the overlay.
 *
 * @see overlay_get_mode()
 */
function overlay_batch_alter(&$batch) {
  if (overlay_get_mode() == 'child') {
    if (isset($batch['url_options']['query'])) {
      $batch['url_options']['query']['render'] = 'overlay';
    }
    else {
      $batch['url_options']['query'] = array('render' => 'overlay');
    }
  }
}

/**
 * Implements hook_page_alter().
 */
function overlay_page_alter(&$page) {
  // If we are limiting rendering to a subset of page regions, deny access to
  // all other regions so that they will not be processed.
  if ($regions_to_render = overlay_get_regions_to_render()) {
    $skipped_regions = array_diff(element_children($page), $regions_to_render);
    foreach ($skipped_regions as $skipped_region) {
      $page[$skipped_region]['#access'] = FALSE;
    }
  }
}

/**
 * Implements hook_block_info_alter().
 */
function overlay_block_info_alter(&$blocks) {
  // If we are limiting rendering to a subset of page regions, hide all blocks
  // which appear in regions not on that list. Note that overlay_page_alter()
  // does a more comprehensive job of preventing unwanted regions from being
  // displayed (regardless of whether they contain blocks or not), but the
  // reason for duplicating effort here is performance; we do not even want
  // these blocks to be built if they are not going to be displayed.
  if ($regions_to_render = overlay_get_regions_to_render()) {
    foreach ($blocks as $bid => $block) {
      if (!in_array($block->region, $regions_to_render)) {
        unset($blocks[$bid]);
      }
    }
  }
}

/**
 * Implements hook_system_info_alter().
 *
 * Add default regions for the overlay.
 */
function overlay_system_info_alter(&$info, $file, $type) {
  if ($type == 'theme') {
    $info['overlay_regions'][] = 'content';
    $info['overlay_regions'][] = 'help';
  }
}

/**
 * Preprocess template variables for html.tpl.php.
 *
 * If the current page request is inside the overlay, add appropriate classes
 * to the <body> element, and simplify the page title.
 *
 * @see overlay_get_mode()
 */
function overlay_preprocess_html(&$variables) {
  if (overlay_get_mode() == 'child') {
    // Add overlay class, so themes can react to being displayed in the overlay.
    $variables['classes_array'][] = 'overlay';
    // Do not include site name or slogan in the overlay title.
    $variables['head_title'] = drupal_get_title();
  }
}

/**
 * Preprocess template variables for page.tpl.php.
 *
 * Display breadcrumbs correctly inside the overlay.
 *
 * @see overlay_get_mode()
 */
function overlay_preprocess_page(&$variables) {
  if (overlay_get_mode() == 'child') {
    // Remove 'Home' from the breadcrumbs.
    $overlay_breadcrumb = drupal_get_breadcrumb();
    array_shift($overlay_breadcrumb);
    $variables['breadcrumb'] = theme('breadcrumb', array('breadcrumb' => $overlay_breadcrumb));
  }
}

/**
 * Preprocess template variables for toolbar.tpl.php.
 *
 * Adding the 'overlay-displace-top' class to the toolbar pushes the overlay
 * down, so it appears below the toolbar.
 */
function overlay_preprocess_toolbar(&$variables) {
  $variables['classes_array'][] = "overlay-displace-top";
}

/**
 * Form after_build callback.
 *
 * After all hook_form_alter() implementations have been processed, we look at
 * the list of submit handlers and add our own at the end. The added handler
 * determines whether or not the user is redirected done at the end of form
 * processing, so that it's possible to close the overlay after submitting
 * a form.
 *
 * @see _form_builder_handle_input_element()
 * @see _form_builder_ie_cleanup()
 * @see form_execute_handlers()
 * @see form_builder()
 * @see overlay_form_submit()
 *
 * @ingroup forms
 */
function overlay_form_after_build($form, &$form_state) {
  if (isset($_GET['render']) && $_GET['render'] == 'overlay') {
    // Form API may have already captured submit handlers from the submitted
    // button before after_build callback is invoked. This may have been done
    // by _form_builder_handle_input_element(). If so, the list of submit
    // handlers is stored in the $form_state array, which is something we can
    // also alter from here, luckily. Rememeber: our goal here is to set
    // $form_state['redirect'] to FALSE if the API function
    // overlay_request_dialog_close() has been invoked. That's because we want
    // to tell the parent window to close the overlay.
    if (!empty($form_state['submit_handlers']) && !in_array('overlay_form_submit', $form_state['submit_handlers'])) {
      $form_state['submit_handlers'][] = 'overlay_form_submit';
    }
    // If this element has submit handlers, then append our own.
    if (isset($form['#submit'])) {
      $form['#submit'][] = 'overlay_form_submit';
    }
  }
  return $form;
}

/**
 * Generic form submit handler.
 *
 * When we are requested to close an overlay, we don't want Form API to
 * perform any redirection once the submitted form has been processed.
 *
 * When $form_state['redirect'] is set to FALSE, then Form API will simply
 * re-render the form with the values still in its fields. And this is all
 * we need to output the JavaScript that will tell the parent window to close
 * the child dialog.
 *
 * @see overlay_get_mode()
 * @ingroup forms
 */
function overlay_form_submit($form, &$form_state) {
  $settings = &drupal_static(__FUNCTION__);

  // Check if we have a request to close the overlay.
  $args = overlay_request_dialog_close();

  // Close the overlay if the overlay module has been disabled
  if (!module_exists('overlay')) {
    $args = overlay_request_dialog_close(TRUE);
  }

  // If there is a form redirect to a non-admin page, close the overlay.
  if (isset($form_state['redirect'])) {
    // A destination set in the URL trumps $form_state['redirect'].
    if (isset($_GET['destination'])) {
      $url = $_GET['destination'];
      $url_settings = array();
    }
    elseif (is_array($form_state['redirect'])) {
      $url = $form_state['redirect'][0];
      $url_settings = $form_state['redirect'][1];
    }
    else {
      $url = $form_state['redirect'];
      $url_settings = array();
    }
    if (!path_is_admin($url)) {
      $args = overlay_request_dialog_close(TRUE);
    }
  }

  // If the overlay is to be closed, pass that information through JavaScript.
  if ($args !== FALSE) {
    if (!isset($settings)) {
      $settings = array(
        'overlayChild' => array(
          'closeOverlay' => TRUE,
          'statusMessages' => theme('status_messages'),
          'args' => $args,
        ),
      );
      // Tell the child window to perform the redirection when requested to.
      if (!empty($form_state['redirect'])) {
        $settings['overlayChild']['redirect'] = url($url, $settings);
      }
      // If the redirect destination is the same as the parent window, just
      // close the overlay without redirecting the parent.
      if (url($form['overlay_parent_url']['#value']) == $settings['overlayChild']['redirect']) {
        unset($settings['overlayChild']['redirect']);
      }
      drupal_add_js($settings, array('type' => 'setting'));
    }
    // Tell FAPI to redraw the form without redirection after all submit
    // callbacks have been processed.
    $form_state['redirect'] = FALSE;
  }
}

/**
 * Get the current overlay mode.
 *
 * @see overlay_set_mode()
 */
function overlay_get_mode() {
  return overlay_set_mode(NULL);
}

/**
 * Set overlay mode and add proper JavaScript and styles to the page.
 *
 * @param $mode
 *   To set the mode, pass in either 'parent' or 'child'. 'parent' is used in
 *   the context of a parent window (a regular browser window), and JavaScript
 *   is added so that administrative links in the parent window will open in
 *   an overlay. 'child' is used in the context of the child overlay window (the
 *   page actually appearing within the overlay iframe) and JavaScript and CSS
 *   are added so that Drupal behaves nicely from within the overlay.
 *
 *   This parameter is optional, and if omitted, the current mode will be
 *   returned with no action taken.
 *
 * @return
 *   The current mode, if any has been set, or NULL if no mode has been set.
 *
 * @ingroup overlay_api
 */
function overlay_set_mode($mode = NULL) {
  global $base_path;
  $overlay_mode = &drupal_static(__FUNCTION__);

  // Make sure external resources are not included more than once. Also return
  // the current mode, if no mode was specified.
  if (isset($overlay_mode) || !isset($mode)) {
    return $overlay_mode;
  }
  $overlay_mode = $mode;

  switch ($overlay_mode) {
    case 'parent':
      drupal_add_library('overlay', 'parent');
      drupal_add_library('overlay', 'jquery-bbq');

      // Allow modules to act upon overlay events.
      module_invoke_all('overlay_parent_initialize');
      break;

    case 'child':
      drupal_add_library('overlay', 'child');

      // Allow modules to act upon overlay events.
      module_invoke_all('overlay_child_initialize');
      break;
  }
  return $overlay_mode;
}

/**
 * Implements hook_overlay_parent_initialize().
 */
function overlay_overlay_parent_initialize() {
  // Let the client side know which paths are administrative.
  $paths = path_get_admin_paths();
  foreach ($paths as &$type) {
    $type = str_replace('<front>', variable_get('site_frontpage', 'node'), $type);
  }
  drupal_add_js(array('overlay' => array('paths' => $paths)), 'setting');
  // Pass along the AJAX callback for rerendering sections of the parent window.
  drupal_add_js(array('overlay' => array('ajaxCallback' => 'overlay-ajax')), 'setting');
}

/**
 * Implements hook_overlay_child_initialize().
 */
function overlay_overlay_child_initialize() {
  // Check if the parent window needs to refresh any page regions on this page
  // request.
  overlay_trigger_regions_to_refresh();
  // If this is a POST request, or a GET request with a token parameter, we
  // have an indication that something in the supplemental regions of the
  // overlay might change during the current page request. We therefore store
  // the initial rendered content of those regions here, so that we can compare
  // it to the same content rendered in overlay_exit(), at the end of the page
  // request. This allows us to check if anything actually did change, and, if
  // so, trigger an AJAX refresh of the parent window.
  if (!empty($_POST) || isset($_GET['token'])) {
    foreach (overlay_supplemental_regions() as $region) {
      overlay_store_rendered_content($region, overlay_render_region($region));
    }
  }
  // Indicate that when the main page rendering occurs later in the page
  // request, only the regions that appear within the overlay should be
  // rendered.
  overlay_set_regions_to_render(overlay_regions());
}

/**
 * Callback to request that the overlay close on the next page load.
 *
 * @param $value
 *   By default, the dialog will not close. Set to TRUE or a value evaluating to
 *   TRUE to request the dialog to close. Use FALSE to disable closing the
 *   dialog (if it was previously enabled). The value passed will be forwarded
 *   to the onOverlayClose callback of the overlay.
 *
 * @return
 *   The current overlay close dialog mode, a value evaluating to TRUE if the
 *   overlay should close or FALSE if it should not (default).
 */
function overlay_request_dialog_close($value = NULL) {
  $close = &drupal_static(__FUNCTION__, FALSE);
  if (isset($value)) {
    $close = $value;
  }
  return $close;
}

/**
 * Close the overlay and redirect the parent window to a new path.
 *
 * @param $redirect
 *   The path that should open in the parent window after the overlay closes.
 */
function overlay_close_dialog($redirect = NULL) {
  if (empty($redirect)) {
    $path = $_GET['q'];
  }
  $settings = array(
    'overlayChild' => array(
      'closeOverlay' => TRUE,
      'statusMessages' => theme('status_messages'),
      'args' => $args,
      'redirect' => url($redirect),
    ),
  );
  drupal_add_js($settings, array('type' => 'setting'));
  return $settings;
}

/**
 * Returns a list of page regions that appear in the overlay.
 *
 * Overlay regions correspond to the entire contents of the overlay child
 * window and are refreshed each time a new page request is made within the
 * overlay.
 *
 * @return
 *   An array of region names that correspond to those which appear in the
 *   overlay, within the theme that is being used to display the current page.
 *
 * @see overlay_supplemental_regions()
 */
function overlay_regions() {
  return _overlay_region_list('overlay_regions');
}

/**
 * Returns a list of supplemental page regions for the overlay.
 *
 * Supplemental overlay regions are those which are technically part of the
 * parent window, but appear to the user as being related to the overlay
 * (usually because they are displayed next to, rather than underneath, the
 * main overlay regions) and therefore need to be dynamically refreshed if any
 * administrative actions taken within the overlay change their contents.
 *
 * An example of a typical overlay supplemental region would be the 'page_top'
 * region, in the case where a toolbar is being displayed there.
 *
 * @return
 *   An array of region names that correspond to supplemental overlay regions,
 *   within the theme that is being used to display the current page.
 *
 * @see overlay_regions()
 */
function overlay_supplemental_regions() {
  return _overlay_region_list('overlay_supplemental_regions');
}

/**
 * Helper function for returning a list of page regions related to the overlay.
 *
 * @param $type
 *   The type of regions to return. This can either be 'overlay_regions' or
 *   'overlay_supplemental_regions'.
 *
 * @return
 *   An array of region names of the given type, within the theme that is being
 *   used to display the current page.
 *
 * @see overlay_regions()
 * @see overlay_supplemental_regions()
 */
function _overlay_region_list($type) {
  // Obtain the current theme. We need to first make sure the theme system is
  // initialized, since this function can be called early in the page request.
  drupal_theme_initialize();
  $themes = list_themes();
  $theme = $themes[$GLOBALS['theme']];
  // Return the list of regions stored within the theme's info array, or an
  // empty array if no regions of the appropriate type are defined.
  return !empty($theme->info[$type]) ? $theme->info[$type] : array();
}

/**
 * Returns a list of page regions that rendering should be limited to.
 *
 * @return
 *   An array containing the names of the regions that will be rendered when
 *   drupal_render_page() is called. If empty, then no limits will be imposed,
 *   and all regions of the page will be rendered.
 *
 * @see overlay_page_alter()
 * @see overlay_block_info_alter()
 * @see overlay_set_regions_to_render()
 */
function overlay_get_regions_to_render() {
  return overlay_set_regions_to_render();
}

/**
 * Sets the regions of the page that rendering will be limited to.
 *
 * @param $regions
 *   (Optional) An array containing the names of the regions that should be
 *   rendered when drupal_render_page() is called. Pass in an empty array to
 *   remove all limits and cause drupal_render_page() to render all page
 *   regions (the default behavior). If this parameter is omitted, no change
 *   will be made to the current list of regions to render.
 *
 * @return
 *   The current list of regions to render, or an empty array if the regions
 *   are not being limited.
 *
 * @see overlay_page_alter()
 * @see overlay_block_info_alter()
 * @see overlay_get_regions_to_render()
 */
function overlay_set_regions_to_render($regions = NULL) {
  $regions_to_render = &drupal_static(__FUNCTION__, array());
  if (isset($regions)) {
    $regions_to_render = $regions;
  }
  return $regions_to_render;
}

/**
 * Renders an individual page region.
 *
 * This function is primarily intended to be used for checking the content of
 * supplemental overlay regions (e.g., a region containing a toolbar). Passing
 * in a region that is intended to display the main page content is not
 * supported; the region will be rendered by this function, but the main page
 * content will not appear in it.
 *
 * @param $region
 *   The name of the page region that should be rendered.
 *
 * @return
 *   The rendered HTML of the provided region.
 */
function overlay_render_region($region) {
  // Indicate the region that we will be rendering, so that other regions will
  // be hidden by overlay_page_alter() and overlay_block_info_alter().
  overlay_set_regions_to_render(array($region));
  // Do what is necessary to force drupal_render_page() to only display HTML
  // from the requested region. Specifically, declare that the main page
  // content does not need to automatically be added to the page, and pass in
  // a page array that has all theme functions removed (so that overall HTML
  // for the page will not be added either).
  $system_main_content_added = &drupal_static('system_main_content_added');
  $system_main_content_added = TRUE;
  $page = array(
    '#type' => 'page',
    '#theme' => NULL,
    '#theme_wrappers' => array(),
  );
  $markup = drupal_render_page($page);
  // Indicate that the main page content has not, in fact, been displayed, so
  // that future calls to drupal_render_page() will be able to render it
  // correctly.
  $system_main_content_added = FALSE;
  // Restore the original behavior of rendering all regions for the next time
  // drupal_render_page() is called.
  overlay_set_regions_to_render(array());
  return $markup;
}

/**
 * Returns any rendered content that was stored earlier in the page request.
 *
 * @return
 *   An array of all rendered HTML that was stored earlier in the page request,
 *   keyed by the identifier with which it was stored. If no content was
 *   stored, an empty array is returned.
 *
 * @see overlay_store_rendered_content()
 */
function overlay_get_rendered_content() {
  return overlay_store_rendered_content();
}

/**
 * Stores strings representing rendered HTML content.
 *
 * This function is used to keep a static cache of rendered content that can be
 * referred to later in the page request.
 *
 * @param $id
 *   (Optional) An identifier for the content which is being stored, which will
 *   be used as an array key in the returned array. If omitted, no change will
 *   be made to the current stored data.
 * @param $content
 *   (Optional) A string representing the rendered data to store. This only has
 *   an effect if $id is also provided.
 *
 * @return
 *   An array representing all data that is currently being stored, or an empty
 *   array if there is none.
 *
 * @see overlay_get_rendered_content()
 */
function overlay_store_rendered_content($id = NULL, $content = NULL) {
  $rendered_content = &drupal_static(__FUNCTION__, array());
  if (isset($id)) {
    $rendered_content[$id] = $content;
  }
  return $rendered_content;
}

/**
 * Request that the parent window refresh a particular page region.
 *
 * @param $region
 *   The name of the page region to refresh. The parent window will trigger a
 *   refresh of this region on the next page load.
 *
 * @see overlay_trigger_regions_to_refresh()
 * @see Drupal.overlay.refreshRegions()
 */
function overlay_request_refresh($region) {
  $class = drupal_region_class($region);
  $_SESSION['overlay_regions_to_refresh'][] = array($class => $region);
}

/**
 * Check if the parent window needs to refresh any regions on this page load.
 *
 * If the previous page load requested that any page regions be refreshed, pass
 * that request via JavaScript to the child window, so it can in turn pass the
 * request to the parent window.
 *
 * @see overlay_request_refresh()
 * @see Drupal.overlay.refreshRegions()
 */
function overlay_trigger_regions_to_refresh() {
  if (!empty($_SESSION['overlay_regions_to_refresh'])) {
    $settings = array(
      'overlayChild' => array(
        'refreshRegions' => $_SESSION['overlay_regions_to_refresh'],
      ),
    );
    drupal_add_js($settings, array('type' => 'setting'));
    unset($_SESSION['overlay_regions_to_refresh']);
  }
}

/**
 * Prints the markup obtained by rendering a single region of the page.
 *
 * This function is intended to be called via AJAX.
 *
 * @param $region
 *   The name of the page region to render.
 *
 * @see Drupal.overlay.refreshRegions()
 */
function overlay_ajax_render_region($region) {
  print overlay_render_region($region);
}