// ==UserScript==
// @name           Yahoo Player
// @namespace      http://hotrodscott.wordpress.com/2008/01/17/greasemonkey-yahoo-player/
// @description    Adds Yahoo player to any page it finds with links to mp3s
// @include        *
// ==/UserScript==


//check to see if there's already one on the page
var pagescripts = xpath("//script[@src='http://mediaplayer.yahoo.com/js']|//script[@src='http://mediaplayer.yahoo.com/latest']")
var mp3links = xpath("//a[contains(@href,'.mp3') or contains(@href,'.MP3')]");
if (pagescripts.snapshotLength==0 && mp3links.snapshotLength>0) { addPlayerScript(); }


//adds player to page
function addPlayerScript()
{
	var head = document.getElementsByTagName('head')[0];
	if (!head) { return; }
	var yscript = document.createElement('script');
	yscript.type = 'text/javascript';
	yscript.src = 'http://mediaplayer.yahoo.com/js';
	head.appendChild(yscript);  	
}

//Greasemonkey Xpath helper function
function xpath(query) {
    return document.evaluate(query, document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
}