// JavaScript Document

var W3CDOM = (document.createElement && document.getElementsByTagName);

var mouseOvers = new Array();
var mouseOuts = new Array();

function init()
{
	if (!W3CDOM) return;
	var nav = document.getElementById('nav');
	var imgs = nav.getElementsByTagName('img');
	for (var i=0;i<imgs.length;i++)
	{
		if(imgs[i].src.lastIndexOf('_on')==-1) {
			imgs[i].onmouseover = mouseGoesOver;
			imgs[i].onmouseout = mouseGoesOut;
			var suffix = imgs[i].src.substring(imgs[i].src.lastIndexOf('.'));
			mouseOuts[i] = new Image();
			mouseOuts[i].src = imgs[i].src;
			mouseOvers[i] = new Image();
			
			// We extract "_OFF"
			newName = replaceCharacters(imgs[i].src,"_off","")
			mouseOvers[i].src = imgs[i].src.substring(0,newName.lastIndexOf('.')) + "_on" + suffix;
			//mouseOvers[i].src = imgs[i].src.substring(0,imgs[i].src.lastIndexOf('.')) + "_on" + suffix;
			imgs[i].number = i;
		}
	}
}

function mouseGoesOver()
{
	this.src = mouseOvers[this.number].src;
	
}

function mouseGoesOut()
{
	this.src = mouseOuts[this.number].src;
	checkNavTopic();
}

function checkNavTopic(){
			var found = false;

			if (!W3CDOM) return;
			var nav = document.getElementById('nav');
			var anchors = nav.getElementsByTagName('a');
			var imgs = nav.getElementsByTagName('img');
			for (var i=0;i<anchors.length;i++)
			{
				currentLink = anchors[i].getAttribute("href");
				currentImg = imgs[i].getAttribute("src");
				if (window.location.href.indexOf(currentLink) > 0) {
					newImg = replaceCharacters(currentImg,"_off","_on");
					imgs[i].setAttribute("src",newImg);
					found = true;
				}

			}
		return found;
}

window.onload=function(){
    if(!document.getElementById && !document.createTextNode){return;}
    externallinks();
    init();
	checkNavTopic();
}

function replaceCharacters(conversionString,inChar,outChar)
{
  var convertedString = conversionString.split(inChar);
  convertedString = convertedString.join(outChar);
  return convertedString;
}

function externallinks() { 
	if (!document.getElementsByTagName) return; 
	var anchors = document.getElementsByTagName("a"); 
	for (var i=0; i<anchors.length; i++) { 
		var anchor = anchors[i]; 
		if (anchor.getAttribute("href") && 
			anchor.getAttribute("rel") == "external") 
			anchor.target = "_blank"; 
	} 
}