class UserBlock

class UserBlock extends RulesActionBase implements ContainerFactoryPluginInterface {
  
  /**
   * Session manager.
   *
   * @var \Drupal\Core\Session\SessionManagerInterface
   */
  protected $sessionManager;
  
  /**
   * Constructs a UserBlock 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\Session\SessionManagerInterface $session_manager
   *   The session manager service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, SessionManagerInterface $session_manager) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->sessionManager = $session_manager;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container->get('session_manager'));
  }
  
  /**
   * Flag that indicates if the entity should be auto-saved later.
   *
   * @var bool
   */
  protected $saveLater = FALSE;
  
  /**
   * Block a user.
   *
   * @param \Drupal\user\UserInterface $user
   *   The user object.
   */
  protected function doExecute(UserInterface $user) {
    // Do nothing if user is anonymous or already blocked.
    if ($user->isAuthenticated() && $user->isActive()) {
      $user->block();
      $this->sessionManager
        ->delete($user->id());
      // Set flag that indicates if the entity should be auto-saved later.
      $this->saveLater = TRUE;
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function autoSaveContext() {
    if ($this->saveLater) {
      return [
        'user',
      ];
    }
    return [];
  }

}