// 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);
};


/**
 * 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 + '.' : '';
};