Move dynamic segments from Premium plugin

[MAILPOET-2382]

lib/DynamicSegments/Persistence/Loading/SubscribersIds.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace MailPoet\Premium\DynamicSegments\Persistence\Loading;
+
+use MailPoet\Models\Subscriber;
+use MailPoet\Premium\Models\DynamicSegment;
+
+class SubscribersIds {
+
+  /**
+   * Finds subscribers in a dynamic segment and returns their ids.
+   *
+   * @param DynamicSegment $dynamic_segment
+   * @param array $limit_to_subscribers_ids If passed the result will be limited only to ids within this array
+   *
+   * @return Subscriber[]
+   */
+  function load(DynamicSegment $dynamic_segment, $limit_to_subscribers_ids = null) {
+    $orm = Subscriber::selectExpr(Subscriber::$_table . '.id');
+    foreach ($dynamic_segment->getFilters() as $filter) {
+      $orm = $filter->toSql($orm);
+    }
+    if ($limit_to_subscribers_ids) {
+      $orm->whereIn(Subscriber::$_table . '.id', $limit_to_subscribers_ids);
+    }
+    return $orm->findMany();
+  }
+
+}