add piwik installation

www/analytics/plugins/Overlay/javascripts/Overlay_Helper.js

@@ -0,0 +1,31 @@
+/*!
+ * Piwik - Web Analytics
+ *
+ * @link http://piwik.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ */
+
+var Overlay_Helper = {
+
+    /** Encode the iframe url to put it behind the hash in sidebar mode */
+    encodeFrameUrl: function (url) {
+        // url encode + replace % with $ to make sure that browsers don't break the encoding
+        return encodeURIComponent(url).replace(/%/g, '$')
+    },
+
+    /** Decode the url after reading it from the hash */
+    decodeFrameUrl: function (url) {
+        // reverse encodeFrameUrl()
+        return decodeURIComponent(url.replace(/\$/g, '%'));
+    },
+
+    /** Get the url to launch overlay */
+    getOverlayLink: function (idSite, period, date, link) {
+        var url = 'index.php?module=Overlay&period=' + period + '&date=' + date + '&idSite=' + idSite;
+        if (link) {
+            url += '#l=' + Overlay_Helper.encodeFrameUrl(link);
+        }
+        return url;
+    }
+
+};