Add in temporary script for Google Analytics 4 ID

Author: stevebagwell

README.md

@@ -35,10 +35,16 @@ The login page looks for `/simplesamlphp/www/logo.png` which is **NOT** provided
 
 Update `/simplesamlphp/config/config.php`:
 
+Google Analytics Project ID (currently Universal Analytics, but transitioning to GA4)
 ```
 'analytics.trackingId' => 'UA-some-unique-id-for-your-site'
 ```
 
+Temporary New Google Analytics 4
+```
+'analytics.trackingIdGA4' => 'G-some-unique-id-for-your-site'
+```
+
 _[ssp-base](https://github.com/silinternational/ssp-base) provides a convenience by loading this config with whatever is in the environment variable `ANALYTICS_ID`._
 
 ### Announcements

themes/material/common-head-elements.php

@@ -7,7 +7,10 @@
 
 <?php
 $trackingId = htmlentities($this->configuration->getValue('analytics.trackingId'));
+$hasGATracking = false;
+
 if (! empty($trackingId)) {
+    $hasGATracking = true;
 ?>
     <script>
         window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date;
@@ -16,7 +19,30 @@
     </script>
     <script async src='https://www.google-analytics.com/analytics.js'></script>
 <?php
-} else {
+}
+?>
+
+
+<?php
+// This block of code is intended to be temporary until the transition from
+// Google's Universal Analytics to GA4 type projects has been completed
+$trackingIdGA4 = htmlentities($this->configuration->getValue('analytics.trackingIdGA4'));
+if (! empty($trackingIdGA4)) {
+    $hasGATracking = true;
+?>
+    <!-- Google tag (gtag.js) -->
+    <script async src="https://www.googletagmanager.com/gtag/js?id=<?= $trackingIdGA4 ?>"></script>
+    <script>
+        window.dataLayer = window.dataLayer || [];
+        function gtag(){dataLayer.push(arguments);}
+        gtag('js', new Date());
+
+        gtag('config', '<?= $trackingIdGA4 ?>');
+    </script>
+<?php
+}
+
+if (! $hasGATracking) {
 ?>
     <script>
         window.ga = function () {