class SystemEmailToUsersOfRole

class SystemEmailToUsersOfRole extends RulesActionBase implements ContainerFactoryPluginInterface {
  
  /**
   * @var \Drupal\Core\Logger\LoggerChannelInterface
   */
  protected $logger;
  
  /**
   * @var \Drupal\Core\Mail\MailManagerInterface
   */
  protected $mailManager;
  
  /**
   * @var \Drupal\user\UserStorageInterface
   */
  protected $userStorage;
  
  /**
   * Constructs a SystemEmailToUsersOfRole 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\Logger\LoggerChannelInterface $logger
   *   The rules logger service.
   * @param \Drupal\Core\Mail\MailManagerInterface $mail_manager
   *   The mail manager service.
   * @param \Drupal\user\UserStorageInterface $userStorage
   *   The user storage service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, LoggerChannelInterface $logger, MailManagerInterface $mail_manager, UserStorageInterface $userStorage) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->logger = $logger;
    $this->mailManager = $mail_manager;
    $this->userStorage = $userStorage;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container->get('logger.factory')
      ->get('rules'), $container->get('plugin.manager.mail'), $container->get('entity_type.manager')
      ->getStorage('user'));
  }
  
  /**
   * Sends an email to all users of the specified role(s).
   *
   * @param \Drupal\user\RoleInterface[] $roles
   *   Array of user roles.
   * @param string $subject
   *   Subject of the email.
   * @param string $message
   *   Email message text.
   * @param string $reply
   *   (optional) Reply to email address.
   * @param \Drupal\Core\Language\LanguageInterface $language
   *   (optional) Language object. If not specified, email will be sent to each
   *   recipient in the recipient's preferred language.
   */
  protected function doExecute(array $roles, $subject, $message, $reply = NULL, LanguageInterface $language = NULL) {
    if (empty($roles)) {
      return;
    }
    $rids = array_map(function ($role) {
      return $role->id();
    }, $roles);
    // Set a unique key for this email.
    $key = 'rules_action_mail_' . $this->getPluginId();
    // Select only active users, based on the roles given. We do not want to
    // send email to blocked users.
    $accounts = $this->userStorage
      ->loadByProperties([
      'roles' => $rids,
      'status' => 1,
    ]);
    $params = [
      'subject' => $subject,
      'message' => $message,
    ];
    // Loop over users and send email to each individually using that user's
    // preferred language (or a fixed language, if passed in the context).
    $number = 0;
    foreach ($accounts as $account) {
      // Language to use. Value passed in the context takes precedence.
      // ORIG.
      $langcode = isset($language) ? $language->getId() : $account->getPreferredLangcode();
      // @todo Is this better?
      $langcode = isset($language) && $language->getId() != LanguageInterface::LANGCODE_NOT_SPECIFIED ? $language->getId() : $account->getPreferredLangcode();
      $message = $this->mailManager
        ->mail('rules', $key, $account->getEmail(), $langcode, $params, NULL);
      $number += $message['result'] ? 1 : 0;
    }
    $this->logger
      ->notice('Successfully sent email to %number out of %count users having the role(s) %roles', [
      '%number' => $number,
      '%count' => count($accounts),
      '%roles' => implode(', ', $rids),
    ]);
  }

}