Use findBy() instead of getReference() to get segment entities

Initially, I had opted to use getReference() to avoid querying the
database to get the segment entities as all we need is the segment ID.
But I hadn't realized that this could cause problems if a segment that
is saved in the settings in the option woocommerce.segments is deleted.
Using findBy() here protects against this problem as, if the segment
doesn't exist anymore, it won't be returned.

[MAILPOET-4365]

mailpoet/lib/WooCommerce/Subscription.php

@@ -2,7 +2,6 @@
 
 namespace MailPoet\WooCommerce;
 
-use MailPoet\Entities\SegmentEntity;
 use MailPoet\Entities\StatisticsUnsubscribeEntity;
 use MailPoet\Entities\SubscriberEntity;
 use MailPoet\Entities\SubscriberSegmentEntity;
@@ -16,7 +15,6 @@ use MailPoet\Subscribers\SubscribersRepository;
 use MailPoet\Util\Helpers;
 use MailPoet\WP\Functions as WPFunctions;
 use MailPoetVendor\Carbon\Carbon;
-use MailPoetVendor\Doctrine\ORM\EntityManager;
 
 class Subscription {
   const CHECKOUT_OPTIN_INPUT_NAME = 'mailpoet_woocommerce_checkout_optin';
@@ -73,9 +71,6 @@ class Subscription {
   /** @var SubscriberSegmentRepository */
   private $subscriberSegmentRepository;
 
-  /** @var EntityManager */
-  private $entityManager;
-
   public function __construct(
     SettingsController $settings,
     ConfirmationEmailMailer $confirmationEmailMailer,
@@ -84,8 +79,7 @@ class Subscription {
     SubscribersRepository $subscribersRepository,
     Unsubscribes $unsubscribesTracker,
     SegmentsRepository $segmentsRepository,
-    SubscriberSegmentRepository $subscriberSegmentRepository,
+    SubscriberSegmentRepository $subscriberSegmentRepository
-    EntityManager $entityManager
   ) {
     $this->settings = $settings;
     $this->wp = $wp;
@@ -95,7 +89,6 @@ class Subscription {
     $this->unsubscribesTracker = $unsubscribesTracker;
     $this->segmentsRepository = $segmentsRepository;
     $this->subscriberSegmentRepository = $subscriberSegmentRepository;
-    $this->entityManager = $entityManager;
   }
 
   public function extendWooCommerceCheckoutForm() {
@@ -219,7 +212,12 @@ class Subscription {
    */
   public function handleSubscriberOptin(SubscriberEntity $subscriber, bool $checkoutOptinEnabled, bool $checkoutOptin): bool {
     $wcSegment = $this->segmentsRepository->getWooCommerceSegment();
-    $moreSegmentsToSubscribe = $this->getOptinSegments();
+
+    $segmentIds = (array)$this->settings->get(self::OPTIN_SEGMENTS_SETTING_NAME, []);
+    $moreSegmentsToSubscribe = [];
+    if (!empty($segmentIds)) {
+      $moreSegmentsToSubscribe = $this->segmentsRepository->findBy(['id' => $segmentIds]);
+    }
     $signupConfirmation = $this->settings->get('signup_confirmation');
 
     if (!$checkoutOptin) {
@@ -287,15 +285,4 @@ class Subscription {
       $this->unsubscribesTracker->track((int)$subscriber->getId(), StatisticsUnsubscribeEntity::SOURCE_ORDER_CHECKOUT);
     }
   }
-
-  private function getOptinSegments(): array {
-    $segments = [];
-    $segmentsIds = (array)$this->settings->get(self::OPTIN_SEGMENTS_SETTING_NAME, []);
-
-    foreach ($segmentsIds as $segmentId) {
-      $segments[] = $this->entityManager->getReference(SegmentEntity::class, $segmentId);
-    }
-
-    return $segments;
-  }
 }