Track size of transferred files using GA

.env.sample

@@ -5,3 +5,4 @@ FIREBASE_URL=https://your-firebase.firebaseio.com
 FIREBASE_SECRET=qwerty
 NEW_RELIC_ENABLED=false
 NEW_RELIC_LICENSE_KEY=qwerty
+GOOGLE_ANALYTICS_ID=UA-XXXX-Y

app/index.html

@@ -21,7 +21,7 @@
     m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
     })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
 
-    ga('create', 'UA-41889586-2', 'sharedrop.io');
+    ga('create', '<!-- @echo GOOGLE_ANALYTICS_ID -->', 'auto');
     ga('send', 'pageview');
   </script>
   <!-- End Google Analytics -->
@@ -59,6 +59,7 @@
     };
   </script>
   <!-- build:js({.tmp,app}) /scripts/app.js -->
+  <script src="/scripts/app/lib/analytics.js"></script>
   <script src="/scripts/app/lib/room.js"></script>
   <script src="/scripts/app/lib/file.js"></script>
   <script src="/scripts/app/lib/webrtc.js"></script>

app/scripts/app/lib/analytics.js

@@ -0,0 +1,17 @@
+ShareDrop.Analytics = {
+    hasAnalytics: function () {
+        return window.ga && typeof window.ga === "function";
+    },
+
+    trackEvent: function (category, action, label, value) {
+        if (ShareDrop.Analytics.hasAnalytics()) {
+            window.ga('send', 'event', category, action, label, value);
+        }
+    }
+};
+
+(function () {
+    $.subscribe('file_received.p2p.peer', function (event, data) {
+        ShareDrop.Analytics.trackEvent('file', 'transferred', 'size', data.info.size);
+    });
+})();

app/scripts/app/lib/webrtc.js

@@ -98,6 +98,7 @@ ShareDrop.WebRTC.prototype._onBinaryData = function (data, connection) {
 
                 $.publish('file_received.p2p.peer', {
                     blob: file,
+                    info: info,
                     connection: connection
                 });
             } else {