# Inject piwik HTML code if required
	private fun add_piwik
	do
		var tracker_url = catalog.piwik_tracker
		if tracker_url == null then return

		var site_id = catalog.piwik_site_id

		tracker_url = tracker_url.trim
		if tracker_url.chars.last != '/' then tracker_url += "/"
		add """
<!-- Piwik -->
<script type="text/javascript">
var _paq = _paq || [];
_paq.push(['trackPageView']);
_paq.push(['enableLinkTracking']);
(function() {
var u=(("https:" == document.location.protocol) ? "https" : "http") + "://{{{tracker_url.escape_to_c}}}";
_paq.push(['setTrackerUrl', u+'piwik.php']);
_paq.push(['setSiteId', {{{site_id}}}]);
var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript';
g.defer=true; g.async=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
})();

</script>
<noscript><p><img src="http://{{{tracker_url.html_escape}}}piwik.php?idsite={{{site_id}}}" style="border:0;" alt="" /></p></noscript>
<!-- End Piwik Code -->
"""

	end