//ernav.js
//detects URL and assigns home button from that
function setCurrentPageButton() {
	if(! location || ! document.getElementById)
		return;
	//determine current page
	var loc = location.href;
	var locparts = loc.split("/");
	//loc is filename (last substring after a / and minus the extension)
	loc = locparts[locparts.length - 1].split(".")[0];
	
	if(loc == "")
		loc = "index";
	
	var currentbutton = document.getElementById(loc);
	if(currentbutton) {
		currentImg(currentbutton);

		//set current class, must come after swap
		currentbutton.className += "current";		
	}
}

function swapImg(currentbutton) {
	//only rollover non-current page images
	if(currentbutton.className.indexOf("current") != -1)
		return;
	var currentsrc = currentbutton.src;
	var srcparts = currentsrc.split("/");
	//currentsrc is current src path after last / and minus extension
	currentsrc = srcparts[srcparts.length - 1].split(".")[0];
	//set img src to over version
	if(currentsrc.indexOf("_hover") == -1)
		currentbutton.src = currentbutton.src.replace(currentsrc, currentsrc + "_hover");	
	else
		currentbutton.src = currentbutton.src.replace("_hover", "");			
}

function currentImg(currentbutton) {
	var currentsrc = currentbutton.src;
	var srcparts = currentsrc.split("/");
	//currentsrc is current src path after last / and minus extension
	currentsrc = srcparts[srcparts.length - 1].split(".")[0];
	//set img src to "current" version
	currentbutton.src = currentbutton.src.replace(currentsrc, currentsrc + "_current");	
}

function flipImage() {
	var button = this.getElementsByTagName("img")[0];
	swapImg(button);
};

//go through header table and add rollovers
function setupRollovers() {
	if(! document.getElementById)
		return;
	//get first (and only) table
	var tbl = document.getElementsByTagName("table")[0];
	//get all links
	var links = tbl.getElementsByTagName("a");
	for(var i = 0; i < links.length; i++) {
		link = links[i];
		link.onmouseover = flipImage;
		link.onmouseout = flipImage;
	}
}

function addLoader(loader) {
	var currentload = window.onload;
	if(typeof(currentload) == "function")
		window.onload = function() {
			currentload();
			loader();
		};
	else
		window.onload = function() {
			loader();
		};
}

addLoader(setCurrentPageButton);
addLoader(setupRollovers);

//preloads images after page load, nav buttons first, then other rollovers
function preloadImgs(){
	var imgs = ["contact_hover", "home_hover", "what_is_erate_hover", "what_we_do_hover"];
	for(var i = 0; i < imgs.length; i++) {
		imgs["image" + i] = new Image();
		imgs["image" + i].src = "images/" + imgs[i] + ".gif";
	}
}

addLoader(preloadImgs);