shimmie2/ext/google_analytics/main.php

<?php declare(strict_types=1);

class GoogleAnalytics extends Extension
{
    # Add analytics to config
    public function onSetupBuilding(SetupBuildingEvent $event)
    {
        $sb = new SetupBlock("Google Analytics");
        $sb->add_text_option("google_analytics_id", "Analytics ID: ");
        $sb->add_label("<br>(eg. UA-xxxxxxxx-x)");
        $event->panel->add_block($sb);
    }

    # Load Analytics tracking code on page request
    public function onPageRequest(PageRequestEvent $event)
    {
        global $config, $page;

        $google_analytics_id = $config->get_string('google_analytics_id', '');
        if (stristr($google_analytics_id, "UA-")) {
            $page->add_html_header("<script type='text/javascript'>
                    var _gaq = _gaq || [];
                    _gaq.push(['_setAccount', '$google_analytics_id']);
                    _gaq.push(['_trackPageview']);
                    (function() {
                      var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
                      ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
                      var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
                    })();</script>");
        }
    }
}