feat: send mailings over MailJet smtp in dedicated worker process

src/Service/Teamer/TeamerMailingService.php

@@ -4,6 +4,7 @@ namespace App\Service\Teamer;
 
 use App\Email\Mailer;
 use App\Entity\User;
+use App\Message\SendTeamerMailing;
 use App\Model\TeamerFilterDto;
 use App\Model\TeamerMailingDto;
 use App\Model\TeamerMailingRecipient;
@@ -26,10 +27,20 @@ class TeamerMailingService
     private const TEMPLATE = 'email/teamer_mailing.html.twig';
     private const PREVIEW_SUBJECT_PREFIX = '[Vorschau] ';
 
+    /**
+     * The mailer transport a mailing goes out over: Mailjet, rather than the webhoster's
+     * relay that carries every other mail, which would risk the hosting account over a few
+     * hundred recipients. Configured in mailer.yaml.
+     */
+    private const TRANSPORT = 'mailing';
+
     public function __construct(
         private readonly TeamerRepository $teamerRepository,
         private readonly Mailer $mailer,
         private readonly LoggerInterface $logger,
+        // messenger transport, "mailing" in production and "sync" in dev and test,
+        // see the parameter of the same name in services.yaml
+        private readonly string $mailingBusTransport,
     ) {
     }
 
@@ -68,32 +79,35 @@ class TeamerMailingService
     }
 
     /**
-     * Send the mailing to everyone eligible and return how many mails went out.
+     * Hand every recipient of a confirmed mailing to the mailer.
+     *
+     * This runs in the worker, not in the request that confirmed the mailing, so it
+     * reports nothing back: each mail becomes a queued message of its own and whether it
+     * reaches anyone is decided long after this method returns. A caller that wants to
+     * know how many mails were actually delivered has to ask the mail provider.
      */
-    public function send(TeamerMailingDto $mailingDto, TeamerMailingRecipientsDto $recipients): int
+    public function sendMailing(SendTeamerMailing $mailing): void
     {
-        foreach ($recipients->getEligible() as $recipient) {
-            // resolveRecipients() already guaranteed the address, this only narrows the type
-            if (null === $email = $recipient->getEmail()) {
-                continue;
-            }
-
-            $values = $this->placeholderValuesFor($recipient);
+        foreach ($mailing->getRecipients() as $recipient) {
+            $values = $this->buildValues(
+                $recipient['firstName'],
+                $recipient['lastName'],
+                $recipient['fullName']
+            );
 
             $this->sendTo(
-                $email,
-                $this->render($mailingDto->getSubject(), $values),
-                $this->render($mailingDto->getMessage(), $values)
+                $recipient['email'],
+                $this->render($mailing->getSubject(), $values),
+                $this->render($mailing->getMessage(), $values),
+                self::TRANSPORT,
+                $this->mailingBusTransport
             );
         }
 
         $this->logger->info('Send teamer mailing', [
-            'subject' => $mailingDto->getSubject(),
-            'recipients' => $recipients->getEligibleCount(),
-            'skipped' => $recipients->getSkippedCount(),
+            'subject' => $mailing->getSubject(),
+            'recipients' => $mailing->getRecipientCount(),
         ]);
-
-        return $recipients->getEligibleCount();
     }
 
     /**
@@ -173,14 +187,26 @@ class TeamerMailingService
         ];
     }
 
-    private function sendTo(string $email, string $subject, string $message): void
-    {
+    /**
+     * The preview leaves the transports unset on purpose: it goes out over the same relay
+     * and the same queue as the rest of the application, so it arrives while the admin is
+     * still looking at the compose page.
+     */
+    private function sendTo(
+        string $email,
+        string $subject,
+        string $message,
+        ?string $transport = null,
+        ?string $busTransport = null,
+    ): void {
         $this->mailer->createAndSendEmail([
             'message' => $message,
         ], [
             'to' => $email,
             'subject' => $subject,
             'template' => self::TEMPLATE,
+            'transport' => $transport,
+            'bus_transport' => $busTransport,
         ]);
     }
 }