class EditController

class EditController extends ContainerAware {

  /**
   * Returns the metadata for a set of fields.
   *
   * Given a list of field edit IDs as POST parameters, run access checks on the
   * entity and field level to determine whether the current user may edit them.
   * Also retrieves other metadata.
   *
   * @return \Symfony\Component\HttpFoundation\JsonResponse
   *   The JSON response.
   */
  public function metadata(Request $request) {
    $fields = $request->request
      ->get('fields');
    if (!isset($fields)) {
      throw new NotFoundHttpException();
    }
    $metadataGenerator = $this->container
      ->get('edit.metadata.generator');
    $metadata = array();
    foreach ($fields as $field) {
      list($entity_type, $entity_id, $field_name, $langcode, $view_mode) = explode('/', $field);

      // Load the entity.
      if (!$entity_type || !entity_get_info($entity_type)) {
        throw new NotFoundHttpException();
      }
      $entity = entity_load($entity_type, $entity_id);
      if (!$entity) {
        throw new NotFoundHttpException();
      }

      // Validate the field name and language.
      if (!$field_name || !($instance = field_info_instance($entity
        ->entityType(), $field_name, $entity
        ->bundle()))) {
        throw new NotFoundHttpException();
      }
      if (!$langcode || field_valid_language($langcode) !== $langcode) {
        throw new NotFoundHttpException();
      }
      $metadata[$field] = $metadataGenerator
        ->generate($entity, $instance, $langcode, $view_mode);
    }
    return new JsonResponse($metadata);
  }

  /**
   * Returns AJAX commands to load in-place editors' attachments.
   *
   * Given a list of in-place editor IDs as POST parameters, render AJAX
   * commands to load those in-place editors.
   *
   * @return \Drupal\Core\Ajax\AjaxResponse
   *   The Ajax response.
   */
  public function attachments(Request $request) {
    $response = new AjaxResponse();
    $editors = $request->request
      ->get('editors');
    if (!isset($editors)) {
      throw new NotFoundHttpException();
    }
    $editorSelector = $this->container
      ->get('edit.editor.selector');
    $elements['#attached'] = $editorSelector
      ->getEditorAttachments($editors);
    drupal_process_attached($elements);
    return $response;
  }

  /**
   * Returns a single field edit form as an Ajax response.
   *
   * @param \Drupal\Core\Entity\EntityInterface $entity
   *   The entity being edited.
   * @param string $field_name
   *   The name of the field that is being edited.
   * @param string $langcode
   *   The name of the language for which the field is being edited.
   * @param string $view_mode_id
   *   The view mode the field should be rerendered in.
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The current request object containing the search string.
   *
   * @return \Drupal\Core\Ajax\AjaxResponse
   *   The Ajax response.
   */
  public function fieldForm(EntityInterface $entity, $field_name, $langcode, $view_mode_id, Request $request) {
    $response = new AjaxResponse();
    $form_state = array(
      'langcode' => $langcode,
      'no_redirect' => TRUE,
      'build_info' => array(
        'args' => array(
          $entity,
          $field_name,
        ),
      ),
    );
    $form = drupal_build_form('edit_field_form', $form_state);
    if (!empty($form_state['executed'])) {

      // The form submission took care of saving the updated entity. Return the
      // updated view of the field.
      $entity = entity_load($form_state['entity']
        ->entityType(), $form_state['entity']
        ->id(), TRUE);

      // @todo Remove when http://drupal.org/node/1346214 is complete.
      $entity = $entity
        ->getBCEntity();
      $output = field_view_field($entity, $field_name, $view_mode_id, $langcode);
      $response
        ->addCommand(new FieldFormSavedCommand(drupal_render($output)));
    }
    else {
      $response
        ->addCommand(new FieldFormCommand(drupal_render($form)));
      $errors = form_get_errors();
      if (count($errors)) {
        $status_messages = array(
          '#theme' => 'status_messages',
        );
        $response
          ->addCommand(new FieldFormValidationErrorsCommand(drupal_render($status_messages)));
      }
    }

    // When working with a hidden form, we don't want any CSS or JS to be loaded.
    if ($request->request
      ->get('nocssjs') === 'true') {
      drupal_static_reset('drupal_add_css');
      drupal_static_reset('drupal_add_js');
    }
    return $response;
  }

}