SymfonyMailer.php

<?php

namespace Drupal\Core\Mail\Plugin\Mail;

use Drupal\Component\Render\MarkupInterface;
use Drupal\Core\Mail\Attribute\Mail;
use Drupal\Core\Mail\MailFormatHelper;
use Drupal\Core\Mail\MailInterface;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Utility\Error;
use Psr\Log\LoggerInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\Mailer\Mailer;
use Symfony\Component\Mailer\MailerInterface;
use Symfony\Component\Mailer\Transport;
use Symfony\Component\Mailer\Transport\Dsn;
use Symfony\Component\Mime\Email;

/**
 * Defines an experimental mail backend, based on the Symfony mailer component.
 *
 * This mail plugin acts as a drop-in replacement for the current default PHP
 * mail plugin. Mail delivery is based on the Symfony mailer component. Hence,
 * all transports registered by default in the Symfony mailer transport factory
 * are available via configurable DSN.
 *
 * By default, this plugin uses `sendmail://default` as the transport DSN. I.e.,
 * it attempts to use `/usr/sbin/sendmail -bs` in order to submit a message to
 * the MTA. Sites hosted on operating systems without a working MTA (e.g.,
 * Windows) need to configure a suitable DSN.
 *
 * The DSN can be set via the `mailer_dsn` key of the `system.mailer` config.
 *
 * The following example shows how to switch the default mail plugin to the
 * experimental Symfony mailer plugin with a custom DSN using config overrides
 * in `settings.php`:
 *
 * @code
 *   $config['system.mail']['interface'] = [ 'default' => 'symfony_mailer' ];
 *   $config['system.mail']['mailer_dsn'] = [
 *     'scheme' => 'smtp',
 *     'host' => 'smtp.example.com',
 *     'port' => 25,
 *     'user' => 'user',
 *     'password' => 'pass',
 *     'options' => [],
 *   ];
 * @endcode
 *
 * @see https://symfony.com/doc/current/mailer.html#using-built-in-transports
 *
 * @internal
 */
class SymfonyMailer implements MailInterface, ContainerFactoryPluginInterface {
    
    /**
     * A list of headers that can contain multiple email addresses.
     *
     * @see \Symfony\Component\Mime\Header\Headers::HEADER_CLASS_MAP
     */
    protected const MAILBOX_LIST_HEADERS = [
        'from',
        'to',
        'reply-to',
        'cc',
        'bcc',
    ];
    
    /**
     * List of headers to skip copying from the message array.
     *
     * Symfony mailer sets Content-Type and Content-Transfer-Encoding according to
     * the actual body content. Note that format=flowed is not supported by
     * Symfony.
     *
     * @see \Symfony\Component\Mime\Part\TextPart
     */
    protected const SKIP_HEADERS = [
        'content-type',
        'content-transfer-encoding',
    ];
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($container->get('logger.channel.mail'));
    }
    
    /**
     * Symfony mailer constructor.
     *
     * @param \Psr\Log\LoggerInterface $logger
     *   The logger service.
     * @param \Symfony\Component\Mailer\MailerInterface $mailer
     *   The mailer service. Only specify an instance in unit tests, pass NULL in
     *   production.
     */
    public function __construct(LoggerInterface $logger, ?MailerInterface $mailer = NULL) {
    }
    public function format(array $message) {
        // Convert any HTML to plain-text.
        foreach ($message['body'] as &$part) {
            if ($part instanceof MarkupInterface) {
                $part = MailFormatHelper::htmlToText($part);
            }
            else {
                $part = MailFormatHelper::wrapMail($part);
            }
        }
        // Join the body array into one string.
        $message['body'] = implode("\n\n", $message['body']);
        return $message;
    }
    public function mail(array $message) {
        try {
            $email = new Email();
            $headers = $email->getHeaders();
            foreach ($message['headers'] as $name => $value) {
                if (!in_array(strtolower($name), self::SKIP_HEADERS, TRUE)) {
                    if (in_array(strtolower($name), self::MAILBOX_LIST_HEADERS, TRUE)) {
                        // Split values by comma, but ignore commas encapsulated in double
                        // quotes.
                        $value = str_getcsv($value, ',');
                    }
                    $headers->addHeader($name, $value);
                }
            }
            $email->to($message['to'])
                ->subject($message['subject'])
                ->text($message['body']);
            $mailer = $this->getMailer();
            $mailer->send($email);
            return TRUE;
        } catch (\Exception $e) {
            Error::logException($this->logger, $e);
            return FALSE;
        }
    }
    
    /**
     * Returns a minimalistic Symfony mailer service.
     */
    protected function getMailer() : MailerInterface {
        if (!isset($this->mailer)) {
            $dsn = \Drupal::config('system.mail')->get('mailer_dsn');
            $dsnObject = new Dsn(...$dsn);
            // Symfony Mailer and Transport classes both optionally depend on the
            // event dispatcher. When provided, a MessageEvent is fired whenever an
            // email is prepared before sending.
            //
            // The MessageEvent will likely play an important role in an upcoming mail
            // API. However, emails handled by this plugin already were processed by
            // hook_mail and hook_mail_alter. Firing the MessageEvent would leak those
            // mails into the code path (i.e., event subscribers) of the new API.
            // Therefore, this plugin deliberately refrains from injecting the event
            // dispatcher.
            $factories = Transport::getDefaultFactories(logger: $this->logger);
            $transportFactory = new Transport($factories);
            $transport = $transportFactory->fromDsnObject($dsnObject);
            $this->mailer = new Mailer($transport);
        }
        return $this->mailer;
    }

}