/**
  * Prepares the AJAX commands to attach assets.
  *
  * @param \Drupal\Core\Ajax\AjaxResponse $response
  *   The AJAX response to update.
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object that the AJAX is responding to.
  *
  * @return array
  *   An array of commands ready to be returned as JSON.
  */
 protected function buildAttachmentsCommands(AjaxResponse $response, Request $request)
 {
     $ajax_page_state = $request->request->get('ajax_page_state');
     // Aggregate CSS/JS if necessary, but only during normal site operation.
     $optimize_css = !defined('MAINTENANCE_MODE') && $this->config->get('css.preprocess');
     $optimize_js = !defined('MAINTENANCE_MODE') && $this->config->get('js.preprocess');
     $attachments = $response->getAttachments();
     // Resolve the attached libraries into asset collections.
     $assets = new AttachedAssets();
     $assets->setLibraries(isset($attachments['library']) ? $attachments['library'] : [])->setAlreadyLoadedLibraries(isset($ajax_page_state['libraries']) ? explode(',', $ajax_page_state['libraries']) : [])->setSettings(isset($attachments['drupalSettings']) ? $attachments['drupalSettings'] : []);
     $css_assets = $this->assetResolver->getCssAssets($assets, $optimize_css);
     list($js_assets_header, $js_assets_footer) = $this->assetResolver->getJsAssets($assets, $optimize_js);
     // Render the HTML to load these files, and add AJAX commands to insert this
     // HTML in the page. Settings are handled separately, afterwards.
     $settings = [];
     if (isset($js_assets_header['drupalSettings'])) {
         $settings = $js_assets_header['drupalSettings']['data'];
         unset($js_assets_header['drupalSettings']);
     }
     if (isset($js_assets_footer['drupalSettings'])) {
         $settings = $js_assets_footer['drupalSettings']['data'];
         unset($js_assets_footer['drupalSettings']);
     }
     // Prepend commands to add the assets, preserving their relative order.
     $resource_commands = array();
     if ($css_assets) {
         $css_render_array = $this->cssCollectionRenderer->render($css_assets);
         $resource_commands[] = new AddCssCommand((string) $this->renderer->renderPlain($css_render_array));
     }
     if ($js_assets_header) {
         $js_header_render_array = $this->jsCollectionRenderer->render($js_assets_header);
         $resource_commands[] = new PrependCommand('head', (string) $this->renderer->renderPlain($js_header_render_array));
     }
     if ($js_assets_footer) {
         $js_footer_render_array = $this->jsCollectionRenderer->render($js_assets_footer);
         $resource_commands[] = new AppendCommand('body', (string) $this->renderer->renderPlain($js_footer_render_array));
     }
     foreach (array_reverse($resource_commands) as $resource_command) {
         $response->addCommand($resource_command, TRUE);
     }
     // Prepend a command to merge changes and additions to drupalSettings.
     if (!empty($settings)) {
         // During Ajax requests basic path-specific settings are excluded from
         // new drupalSettings values. The original page where this request comes
         // from already has the right values. An Ajax request would update them
         // with values for the Ajax request and incorrectly override the page's
         // values.
         // @see system_js_settings_alter()
         unset($settings['path']);
         $response->addCommand(new SettingsCommand($settings, TRUE), TRUE);
     }
     $commands = $response->getCommands();
     $this->moduleHandler->alter('ajax_render', $commands);
     return $commands;
 }