class MessageAction

class MessageAction extends ConfigurableActionBase {

  /**
   * @var \Drupal\Core\Utility\Token
   */
  protected $token;

  /**
   * Constructs a MessageAction object.
   */
  public function __construct(array $configuration, $plugin_id, array $plugin_definition, Token $token) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->token = $token;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, array $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container
      ->get('token'));
  }

  /**
   * {@inheritdoc}
   */
  public function execute($entity = NULL) {
    if (empty($this->configuration['node'])) {
      $this->configuration['node'] = $entity;
    }
    $message = $this->token
      ->replace(Xss::filterAdmin($this->configuration['message']), $this->configuration);
    drupal_set_message($message);
  }

  /**
   * {@inheritdoc}
   */
  protected function getDefaultConfiguration() {
    return array(
      'message' => '',
    );
  }

  /**
   * {@inheritdoc}
   */
  public function form(array $form, array &$form_state) {
    $form['message'] = array(
      '#type' => 'textarea',
      '#title' => t('Message'),
      '#default_value' => $this->configuration['message'],
      '#required' => TRUE,
      '#rows' => '8',
      '#description' => t('The message to be displayed to the current user. You may include placeholders like [node:title], [user:name], and [comment:body] to represent data that will be different each time message is sent. Not all placeholders will be available in all contexts.'),
    );
    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function submit(array &$form, array &$form_state) {
    $this->configuration['message'] = $form_state['values']['message'];
    unset($this->configuration['node']);
  }

}