Add referral id to global JS variables

[MAILPOET-2182]

lib/AdminPages/PageRenderer.php

@@ -4,6 +4,8 @@ namespace MailPoet\AdminPages;
 
 use MailPoet\Config\Renderer;
 use MailPoet\Features\FeaturesController;
+use MailPoet\Referrals\ReferralDetector;
+use MailPoet\Settings\SettingsController;
 use MailPoet\WP\Notice as WPNotice;
 
 if (!defined('ABSPATH')) exit;
@@ -15,9 +17,17 @@ class PageRenderer {
   /** @var FeaturesController */
   private $features_controller;
 
-  function __construct(Renderer $renderer, FeaturesController $features_controller) {
+  /** @var SettingsController */
+  private $settings;
+
+  function __construct(
+    Renderer $renderer,
+    FeaturesController $features_controller,
+    SettingsController $settings
+  ) {
     $this->renderer = $renderer;
     $this->features_controller = $features_controller;
+    $this->settings = $settings;
   }
 
   /**
@@ -28,6 +38,7 @@ class PageRenderer {
   function displayPage($template, array $data = []) {
     $defaults = [
       'feature_flags' => $this->features_controller->getAllFlags(),
+      'referral_id' => $this->settings->get(ReferralDetector::REFERRAL_SETTING_NAME),
     ];
     try {
       echo $this->renderer->render($template, $data + $defaults);