[Mailer] Add support for multiple mailers

Author: fabpot

CHANGELOG.md

@@ -4,6 +4,7 @@ CHANGELOG
 4.4.0
 -----
 
+ * added support for multiple transports on a `Mailer` instance
  * [BC BREAK] removed the `auth_mode` DSN option (it is now always determined automatically)
  * STARTTLS cannot be enabled anymore (it is used automatically if TLS is disabled and the server supports STARTTLS)
  * [BC BREAK] Removed the `encryption` DSN option (use `smtps` instead)

Mailer.php

@@ -22,7 +22,7 @@
 /**
  * @author Fabien Potencier <fabien@symfony.com>
  */
-class Mailer implements MailerInterface
+final class Mailer implements MailerInterface
 {
     private $transport;
     private $bus;

Transport.php

@@ -27,6 +27,7 @@
 use Symfony\Component\Mailer\Transport\Smtp\EsmtpTransportFactory;
 use Symfony\Component\Mailer\Transport\TransportFactoryInterface;
 use Symfony\Component\Mailer\Transport\TransportInterface;
+use Symfony\Component\Mailer\Transport\Transports;
 use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 use Symfony\Contracts\HttpClient\HttpClientInterface;
 
@@ -54,6 +55,13 @@ public static function fromDsn(string $dsn, EventDispatcherInterface $dispatcher
         return $factory->fromString($dsn);
     }
 
+    public static function fromDsns(array $dsns, EventDispatcherInterface $dispatcher = null, HttpClientInterface $client = null, LoggerInterface $logger = null): TransportInterface
+    {
+        $factory = new self(iterator_to_array(self::getDefaultFactories($dispatcher, $client, $logger)));
+
+        return $factory->fromStrings($dsns);
+    }
+
     /**
      * @param TransportFactoryInterface[] $factories
      */
@@ -62,6 +70,16 @@ public function __construct(iterable $factories)
         $this->factories = $factories;
     }
 
+    public function fromStrings(array $dsns): Transports
+    {
+        $transports = [];
+        foreach ($dsns as $name => $dsn) {
+            $transports[$name] = $this->fromString($dsn);
+        }
+
+        return new Transports($transports);
+    }
+
     public function fromString(string $dsn): TransportInterface
     {
         $dsns = preg_split('/\s++\|\|\s++/', $dsn);

Transport/Transports.php

@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Mailer\Transport;
+
+use Symfony\Component\Mailer\Exception\InvalidArgumentException;
+use Symfony\Component\Mailer\Exception\LogicException;
+use Symfony\Component\Mailer\SentMessage;
+use Symfony\Component\Mailer\SmtpEnvelope;
+use Symfony\Component\Mime\Message;
+use Symfony\Component\Mime\RawMessage;
+
+/**
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class Transports implements TransportInterface
+{
+    private $transports;
+    private $default;
+
+    /**
+     * @param TransportInterface[] $transports
+     */
+    public function __construct(iterable $transports)
+    {
+        $this->transports = [];
+        foreach ($transports as $name => $transport) {
+            if (null === $this->default) {
+                $this->default = $transport;
+            }
+            $this->transports[$name] = $transport;
+        }
+
+        if (!$this->transports) {
+            throw new LogicException(sprintf('"%s" must have at least one transport configured.', __CLASS__));
+        }
+    }
+
+    public function send(RawMessage $message, SmtpEnvelope $envelope = null): ?SentMessage
+    {
+        /** @var Message $message */
+        if (RawMessage::class === \get_class($message) || !$message->getHeaders()->has('X-Transport')) {
+            return $this->default->send($message, $envelope);
+        }
+
+        $headers = $message->getHeaders();
+        $transport = $headers->get('X-Transport');
+        $headers->remove('X-Transport');
+
+        if (!isset($this->transports[$transport])) {
+            throw new InvalidArgumentException(sprintf('The "%s" transport does not exist.', $transport));
+        }
+
+        return $this->transports[$transport]->send($message, $envelope);
+    }
+
+    public function __toString(): string
+    {
+        return 'all';
+    }
+}