ÿþ// Copyright 2011 Google Inc. All Rights Reserved.



/**

 * @fileoverview A simple script to automatically track Facebook and Twitter

 * buttons using Google Analytics social tracking feature.

 * @author api.nickm@google.com (Nick Mihailovski)

 */





/**

 * Namespace.

 * @type {Object}.

 */

var _ga = _ga || {};





/**

 * Ensure global _gaq Google Analytics queue has been initialized.

 * @type {Array}

 */

var _gaq = _gaq || [];





/**

 * Helper method to track social features. This assumes all the social

 * scripts / apis are loaded synchronously. If they are loaded async,

 * you might need to add the nextwork specific tracking call to the

 * a callback once the network's script has loaded.

 * @param {string} opt_pageUrl An optional URL to associate the social

 *     tracking with a particular page.

 * @param {string} opt_trackerName An optional name for the tracker object.

 */

_ga.trackSocial = function(opt_pageUrl, opt_trackerName) {

  _ga.trackFacebook(opt_pageUrl, opt_trackerName);

  _ga.trackTwitter(opt_pageUrl, opt_trackerName);

};





/**

 * Tracks Facebook likes, unlikes and sends by suscribing to the Facebook

 * JSAPI event model. Note: This will not track facebook buttons using the

 * iFrame method.

 * @param {string} opt_pageUrl An optional URL to associate the social

 *     tracking with a particular page.

 * @param {string} opt_trackerName An optional name for the tracker object.

 */

_ga.trackFacebook = function(opt_pageUrl, opt_trackerName) {

  var trackerName = _ga.buildTrackerName_(opt_trackerName);

  try {

    if (FB && FB.Event && FB.Event.subscribe) {

      FB.Event.subscribe('edge.create', function(targetUrl) {

        _gaq.push([trackerName + '_trackSocial', 'facebook', 'like',

            targetUrl, opt_pageUrl]);

      });

      FB.Event.subscribe('edge.remove', function(targetUrl) {

        _gaq.push([trackerName + '_trackSocial', 'facebook', 'unlike',

            targetUrl, opt_pageUrl]);

      });

      FB.Event.subscribe('message.send', function(targetUrl) {

        _gaq.push([trackerName + '_trackSocial', 'facebook', 'send',

            targetUrl, opt_pageUrl]);

      });

    }

  } catch (e) {}

};





/**

 * Returns the normalized tracker name configuration parameter.

 * @param {string} opt_trackerName An optional name for the tracker object.

 * @return {string} If opt_trackerName is set, then the value appended with

 *     a . Otherwise an empty string.

 * @private

 */

_ga.buildTrackerName_ = function(opt_trackerName) {

  return opt_trackerName ? opt_trackerName + '.' : '';

};





/**

 * Tracks everytime a user clicks on a tweet button from Twitter.

 * This subscribes to the Twitter JS API event mechanism to listen for

 * clicks coming from this page. Details here:

 * http://dev.twitter.com/pages/intents-events#click

 * This method should be called once the twitter API has loaded.

 * @param {string} opt_pageUrl An optional URL to associate the social

 *     tracking with a particular page.

 * @param {string} opt_trackerName An optional name for the tracker object.

 */

_ga.trackTwitter = function(opt_pageUrl, opt_trackerName) {

  var trackerName = _ga.buildTrackerName_(opt_trackerName);

  try {

    if (twttr && twttr.events && twttr.events.bind) {

      twttr.events.bind('tweet', function(event) {

        if (event) {

          var targetUrl; // Default value is undefined.

          if (event.target && event.target.nodeName == 'IFRAME') {

            targetUrl = _ga.extractParamFromUri_(event.target.src, 'url');

          }

          _gaq.push([trackerName + '_trackSocial', 'twitter', 'tweet',

            targetUrl, opt_pageUrl]);

        }

      });

    }

  } catch (e) {}

};





/**

 * Extracts a query parameter value from a URI.

 * @param {string} uri The URI from which to extract the parameter.

 * @param {string} paramName The name of the query paramater to extract.

 * @return {string} The un-encoded value of the query paramater. underfined

 *     if there is no URI parameter.

 * @private

 */

_ga.extractParamFromUri_ = function(uri, paramName) {

  if (!uri) {

    return;

  }

  var uri = uri.split('#')[0];  // Remove anchor.

  var parts = uri.split('?');  // Check for query params.

  if (parts.length == 1) {

    return;

  }

  var query = decodeURI(parts[1]);



  // Find url param.

  paramName += '=';

  var params = query.split('&');

  for (var i = 0, param; param = params[i]; ++i) {

    if (param.indexOf(paramName) === 0) {

      return unescape(param.split('=')[1]);

    }

  }

  return;

};