Add subscriber to WP user subject transformer

[MAILPOET-5168]

mailpoet/lib/Automation/Integrations/MailPoet/SubjectTransformers/SubscriberSubjectToWordPressUserSubjectTransformer.php

@@ -0,0 +1,40 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Automation\Integrations\MailPoet\SubjectTransformers;
+
+use MailPoet\Automation\Engine\Data\Subject;
+use MailPoet\Automation\Engine\Integration\SubjectTransformer;
+use MailPoet\Automation\Integrations\MailPoet\Subjects\SubscriberSubject;
+use MailPoet\Automation\Integrations\WordPress\Subjects\UserSubject;
+use MailPoet\Subscribers\SubscribersRepository;
+
+class SubscriberSubjectToWordPressUserSubjectTransformer implements SubjectTransformer {
+  /** @var SubscribersRepository */
+  private $subscribersRepository;
+
+  public function __construct(
+    SubscribersRepository $subscribersRepository
+  ) {
+    $this->subscribersRepository = $subscribersRepository;
+  }
+
+  public function accepts(): string {
+    return SubscriberSubject::KEY;
+  }
+
+  public function returns(): string {
+    return UserSubject::KEY;
+  }
+
+  public function transform(Subject $data): Subject {
+    if ($this->accepts() !== $data->getKey()) {
+      throw new \InvalidArgumentException('Invalid subject type');
+    }
+
+    $subscriber = $this->subscribersRepository->findOneById((int)$data->getArgs()['subscriber_id']);
+    if (!$subscriber) {
+      throw new \InvalidArgumentException('Subscriber not found');
+    }
+    return new Subject(UserSubject::KEY, ['user_id' => $subscriber->getWpUserId()]);
+  }
+}