abstract class ActionFormControllerBase

abstract class ActionFormControllerBase extends EntityFormController implements EntityControllerInterface {

  /**
   * The action plugin being configured.
   *
   * @var \Drupal\Core\Action\ActionInterface
   */
  protected $plugin;

  /**
   * The action storage controller.
   *
   * @var \Drupal\Core\Entity\EntityStorageControllerInterface
   */
  protected $storageController;

  /**
   * Constructs a new action form.
   *
   * @param \Drupal\Core\Entity\EntityStorageControllerInterface $storage_controller
   *   The action storage controller.
   */
  public function __construct(EntityStorageControllerInterface $storage_controller) {
    parent::__construct();
    $this->storageController = $storage_controller;
  }

  /**
   * {@inheritdoc}
   */
  public static function createInstance(ContainerInterface $container, $entity_type, array $entity_info) {
    return new static($container
      ->get('plugin.manager.entity')
      ->getStorageController($entity_type));
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, array &$form_state) {
    $this->plugin = $this->entity
      ->getPlugin();
    return parent::buildForm($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function form(array $form, array &$form_state) {
    $form['label'] = array(
      '#type' => 'textfield',
      '#title' => t('Label'),
      '#default_value' => $this->entity
        ->label(),
      '#maxlength' => '255',
      '#description' => t('A unique label for this advanced action. This label will be displayed in the interface of modules that integrate with actions.'),
    );
    $form['id'] = array(
      '#type' => 'machine_name',
      '#title' => t('Machine name'),
      '#default_value' => $this->entity
        ->id(),
      '#disabled' => !$this->entity
        ->isNew(),
      '#maxlength' => 64,
      '#description' => t('A unique name for this action. It must only contain lowercase letters, numbers and underscores.'),
      '#machine_name' => array(
        'exists' => array(
          $this,
          'exists',
        ),
      ),
    );
    $form['plugin'] = array(
      '#type' => 'value',
      '#value' => $this->entity
        ->get('plugin'),
    );
    $form['type'] = array(
      '#type' => 'value',
      '#value' => $this->entity
        ->getType(),
    );
    if ($this->plugin instanceof ConfigurableActionInterface) {
      $form += $this->plugin
        ->form($form, $form_state);
    }
    return parent::form($form, $form_state);
  }

  /**
   * Determines if the action already exists.
   *
   * @param string $id
   *   The action ID
   *
   * @return bool
   *   TRUE if the action exists, FALSE otherwise.
   */
  public function exists($id) {
    $actions = $this->storageController
      ->load(array(
      $id,
    ));
    return isset($actions[$id]);
  }

  /**
   * {@inheritdoc}
   */
  protected function actions(array $form, array &$form_state) {
    $actions = parent::actions($form, $form_state);
    unset($actions['delete']);
    return $actions;
  }

  /**
   * {@inheritdoc}
   */
  public function validate(array $form, array &$form_state) {
    parent::validate($form, $form_state);
    if ($this->plugin instanceof ConfigurableActionInterface) {
      $this->plugin
        ->validate($form, $form_state);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function submit(array $form, array &$form_state) {
    parent::submit($form, $form_state);
    if ($this->plugin instanceof ConfigurableActionInterface) {
      $this->plugin
        ->submit($form, $form_state);
    }
    return $this->entity;
  }

  /**
   * {@inheritdoc}
   */
  public function save(array $form, array &$form_state) {
    $this->entity
      ->save();
    drupal_set_message(t('The action has been successfully saved.'));
    $form_state['redirect'] = 'admin/config/system/actions';
  }

}