class EmailAction

class EmailAction extends ConfigurableActionBase implements ContainerFactoryPluginInterface {
    
    /**
     * The token service.
     *
     * @var \Drupal\Core\Utility\Token
     */
    protected $token;
    
    /**
     * The user storage.
     *
     * @var \Drupal\Core\Entity\EntityStorageInterface
     */
    protected $storage;
    
    /**
     * A logger instance.
     *
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;
    
    /**
     * The mail manager
     *
     * @var \Drupal\Core\Mail\MailManagerInterface
     */
    protected $mailManager;
    
    /**
     * The language manager.
     *
     * @var \Drupal\Core\Language\LanguageManagerInterface
     */
    protected $languageManager;
    
    /**
     * The email validator.
     *
     * @var \Drupal\Component\Utility\EmailValidatorInterface
     */
    protected $emailValidator;
    
    /**
     * Constructs a EmailAction 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\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity manager.
     * @param \Psr\Log\LoggerInterface $logger
     *   A logger instance.
     * @param \Drupal\Core\Mail\MailManagerInterface $mail_manager
     *   The mail manager.
     * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
     *   The language manager.
     * @param \Drupal\Component\Utility\EmailValidatorInterface $email_validator
     *   The email validator.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, Token $token, EntityTypeManagerInterface $entity_type_manager, LoggerInterface $logger, MailManagerInterface $mail_manager, LanguageManagerInterface $language_manager, EmailValidatorInterface $email_validator) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->token = $token;
        $this->storage = $entity_type_manager->getStorage('user');
        $this->logger = $logger;
        $this->mailManager = $mail_manager;
        $this->languageManager = $language_manager;
        $this->emailValidator = $email_validator;
    }
    
    /**
     * {@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('entity_type.manager'), $container->get('logger.factory')
            ->get('action'), $container->get('plugin.manager.mail'), $container->get('language_manager'), $container->get('email.validator'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function execute($entity = NULL) {
        if (empty($this->configuration['node'])) {
            $this->configuration['node'] = $entity;
        }
        $recipient = PlainTextOutput::renderFromHtml($this->token
            ->replace($this->configuration['recipient'], $this->configuration));
        // If the recipient is a registered user with a language preference, use
        // the recipient's preferred language. Otherwise, use the system default
        // language.
        $recipient_accounts = $this->storage
            ->loadByProperties([
            'mail' => $recipient,
        ]);
        $recipient_account = reset($recipient_accounts);
        if ($recipient_account) {
            $langcode = $recipient_account->getPreferredLangcode();
        }
        else {
            $langcode = $this->languageManager
                ->getDefaultLanguage()
                ->getId();
        }
        $params = [
            'context' => $this->configuration,
        ];
        $message = $this->mailManager
            ->mail('system', 'action_send_email', $recipient, $langcode, $params);
        // Error logging is handled by \Drupal\Core\Mail\MailManager::mail().
        if ($message['result']) {
            $this->logger
                ->notice('Sent email to %recipient', [
                '%recipient' => $recipient,
            ]);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        return [
            'recipient' => '',
            'subject' => '',
            'message' => '',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
        $form['recipient'] = [
            '#type' => 'textfield',
            '#title' => t('Recipient email address'),
            '#default_value' => $this->configuration['recipient'],
            '#maxlength' => '254',
            '#description' => t('You may also use tokens: [node:author:mail], [comment:author:mail], etc. Separate recipients with a comma.'),
        ];
        $form['subject'] = [
            '#type' => 'textfield',
            '#title' => t('Subject'),
            '#default_value' => $this->configuration['subject'],
            '#maxlength' => '254',
            '#description' => t('The subject of the message.'),
        ];
        $form['message'] = [
            '#type' => 'textarea',
            '#title' => t('Message'),
            '#default_value' => $this->configuration['message'],
            '#cols' => '80',
            '#rows' => '20',
            '#description' => t('The message that should be sent. 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 validateConfigurationForm(array &$form, FormStateInterface $form_state) {
        if (!$this->emailValidator
            ->isValid($form_state->getValue('recipient')) && strpos($form_state->getValue('recipient'), ':mail') === FALSE) {
            // We want the literal %author placeholder to be emphasized in the error message.
            $form_state->setErrorByName('recipient', t('Enter a valid email address or use a token email address such as %author.', [
                '%author' => '[node:author:mail]',
            ]));
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
        $this->configuration['recipient'] = $form_state->getValue('recipient');
        $this->configuration['subject'] = $form_state->getValue('subject');
        $this->configuration['message'] = $form_state->getValue('message');
    }
    
    /**
     * {@inheritdoc}
     */
    public function access($object, AccountInterface $account = NULL, $return_as_object = FALSE) {
        $result = AccessResult::allowed();
        return $return_as_object ? $result : $result->isAllowed();
    }

}