class MessageAction

class MessageAction extends ConfigurableActionBase implements ContainerFactoryPluginInterface {
    
    /**
     * The token service.
     *
     * @var \Drupal\Core\Utility\Token
     */
    protected $token;
    
    /**
     * The renderer.
     *
     * @var \Drupal\Core\Render\RendererInterface
     */
    protected $renderer;
    
    /**
     * The messenger.
     *
     * @var \Drupal\Core\Messenger\MessengerInterface
     */
    protected $messenger;
    
    /**
     * Constructs a MessageAction object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin ID for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Utility\Token $token
     *   The token service.
     * @param \Drupal\Core\Render\RendererInterface $renderer
     *   The renderer.
     * @param \Drupal\Core\Messenger\MessengerInterface $messenger
     *   The messenger.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, Token $token, RendererInterface $renderer, MessengerInterface $messenger) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->token = $token;
        $this->renderer = $renderer;
        $this->messenger = $messenger;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('token'), $container->get('renderer'), $container->get('messenger'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function execute($entity = NULL) {
        if (empty($this->configuration['node'])) {
            $this->configuration['node'] = $entity;
        }
        $message = $this->token
            ->replace($this->configuration['message'], $this->configuration);
        $build = [
            '#markup' => $message,
        ];
        // @todo Fix in https://www.drupal.org/node/2577827
        $this->messenger
            ->addStatus($this->renderer
            ->renderInIsolation($build));
    }
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        return [
            'message' => '',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
        $form['message'] = [
            '#type' => 'textarea',
            '#title' => $this->t('Message'),
            '#default_value' => $this->configuration['message'],
            '#required' => TRUE,
            '#rows' => '8',
            '#description' => $this->t('The message to be displayed to the current user. You may include placeholders like [node:title], [user:account-name], [user:display-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 submitConfigurationForm(array &$form, FormStateInterface $form_state) {
        $this->configuration['message'] = $form_state->getValue('message');
        unset($this->configuration['node']);
    }
    
    /**
     * {@inheritdoc}
     */
    public function access($object, ?AccountInterface $account = NULL, $return_as_object = FALSE) {
        $result = AccessResult::allowed();
        return $return_as_object ? $result : $result->isAllowed();
    }

}