/**********************************************************
Author:
Adam Barry
Klestrup | partners
www.klestrup-partners.dk

Date: February 20 2008

© 2008 Adam Barry, all rights reserved
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Name:
Google Analytics track links script

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Inspiration
http://www.terenzani.it/54/urchintrack-utility-tracciare-link-esterni-e-download-con-google-analytics
GA urchin.trackLinks 0.2

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Description:
Function that enables Google Analytics tracking of
downloaded files - when placed in an <a> structure.

NB. This version is not compatible with the old Google
Analytics/Urchin tracking code.

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Usage:
Simply place a link to the this script in the head-section
of the XHTML page. The script will then automatically
execute on page load.

<script type="text/javascript" src="GA.trackLinks.js"></script>

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Example:
<script type="text/javascript" src="GA.trackLinks.js"></script>

<a href="filename.pdf">Download tracked PDF file</a>

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Dependencies:
This script depends on the windowOnLoad-script to execute

**********************************************************/

function urchin() {
 // It contains the download extension separated by a "|"
	this.trackDownload = '';

 	this.trackLinks = function() {
  		var a = document.getElementsByTagName('a');

	 // Extract the domain from the location (the domain is in domain[2])
		var domain = /^(http|https):\/\/([a-z-.0-9]+)[\/]{0,1}/i.exec(window.location);
	 	if (!domain) return;

	 // Expression that checks for internal links
		var internalLink = new RegExp("^(http|https):\/\/"+domain[2], "i");

	 // Expression that checks for downloads
		var isDownload = new RegExp("("+this.trackDownload+")$", "i");

	  // For each anchor
		for(var i = 0; i < a.length; i++) {
		// If href points to an internal resource
			if(internalLink.test(a[i].href)) {
		// ... and if the file extension is in this.trackDownload ...
				if(this.trackDownload && isDownload.test(a[i].href))
				a[i].onclick = function() {
		  // Clean and track the URL
				pageTracker._trackPageview('/download/'+this.href.replace(/^(http|https):\/\/([a-z-.0-9]+)\//i, '').split('/').join('--'));
				}
			}

			else
				// is external
				a[i].onclick = function() {
				// Clean and track the URL
				pageTracker._trackPageview('/outgoing/'+this.href.replace(/^http:\/\/|https:\/\//i, '').split('/').join('--'));
			}
		}
 	}
}

function initDownloadTracker () {
  	urchin = new urchin();
  	urchin.trackDownload = "zip|rar|pdf|exe|gz|dmg|avi|jpg|gif|png|doc|dot|ashx";
  	urchin.trackLinks();
}addLoadEvent(function(){initDownloadTracker();});