Implement NewsletterTempates::save() API using Doctrine

[MAILPOET-2647]

lib/NewsletterTemplates/NewsletterTemplatesRepository.php

@@ -3,6 +3,7 @@
 namespace MailPoet\NewsletterTemplates;
 
 use MailPoet\Doctrine\Repository;
+use MailPoet\Entities\NewsletterEntity;
 use MailPoet\Entities\NewsletterTemplateEntity;
 
 /**
@@ -29,4 +30,38 @@ class NewsletterTemplatesRepository extends Repository {
       ->getQuery()
       ->getResult();
   }
+
+  public function createOrUpdate(array $data): NewsletterTemplateEntity {
+    $template = !empty($data['newsletter_id'])
+      ? $this->findOneBy(['newsletter' => (int)$data['newsletter_id']])
+      : null;
+
+    if (!$template) {
+      $template = new NewsletterTemplateEntity();
+      $this->entityManager->persist($template);
+    }
+
+    if (isset($data['newsletter_id'])) {
+      $template->setNewsletter($this->entityManager->getReference(NewsletterEntity::class, (int)$data['newsletter_id']));
+    }
+
+    if (isset($data['name'])) {
+      $template->setName($data['name']);
+    }
+
+    if (isset($data['thumbnail'])) {
+      $template->setThumbnail($data['thumbnail']);
+    }
+
+    if (isset($data['body'])) {
+      $template->setBody(json_decode($data['body'], true));
+    }
+
+    if (isset($data['categories'])) {
+      $template->setCategories($data['categories']);
+    }
+
+    $this->entityManager->flush();
+    return $template;
+  }
 }