/**
 * Display the child navigation we need for the given window.contentId
 * we are currently working
**/
function displaySubNavigation() {
	var hierarchy = new Array();
	hierarchy.push(window.contentId);
	
	currentPage = window.contentId;

	var parent = pageArray[currentPage];
	var grandparent = null;	
	
	if(parent != 'null')
	{
		grandparent = pageArray[parent];
	}

	if(grandparent != 'null' && grandparent != null)
	{
		if (document.getElementById("nav_item_"+currentPage)) {
			var child = document.getElementById("link_item_"+currentPage);
			child.className = "item_nav_link_on";
			var image = document.getElementById("nav_arrow_"+currentPage);
			image.src = "http://www.dallasnews.com/images/arrow_yellow_down.gif";
		}
		
		var grandparentDiv = document.getElementById("parent_"+grandparent);		
		var parents = grandparentDiv.getElementsByTagName("div");
		for (var x=0; x < parents.length; x++)
		{
			if(parents[x].className == "child_item")
			{
				parents[x].style.display = "block";				
			}
		}
		//alert(parent);
		displayChildElements(parent);
		parent = grandparent;
		
	}	
	else if (parent != 'null') {
		// we are on a "child page" so that means we need to figure out
		// which one we are on, and do two things:
		// 1. unfold its parent
		// 2. highlight which child we are on
		
		if (document.getElementById("nav_item_"+currentPage)) {
			var child = document.getElementById("link_item_"+currentPage);
			child.className = "item_nav_link_on";
			var image = document.getElementById("nav_arrow_"+currentPage);
			image.src = "/images/arrow_yellow_down.gif";
		}
		if (document.getElementById("child_items_"+currentPage))
		{
			displayChildElements(currentPage);
		}
		else if(document.getElementById("subnav_box_"+currentPage))
		{
			displayChildElements(parent);
			toggleEmptySection(currentPage);
		}
		else {
			displayChildElements(parent);
		}
	}
	else 
	{
		// this is a root section or page
		parent = currentPage;
	}	
	
	var leftNav = document.getElementById("subnav_container");	
	var navDiv = document.getElementById("parent_" + parent);
	var navDivHeader = document.getElementById("group_header_" + parent);	
	
	if(navDiv == null || navDivHeader == null || leftNav == null) return;
	leftNav.appendChild(navDivHeader);
	leftNav.appendChild(navDiv);
}

function displayChildElements (parent) {
	var element = document.getElementById("child_items_"+parent);
	if(element == null) return;
	element.style.display = "block";
	
	if (document.getElementById("subnav_link_text_"+parent)) {
		var parentLinkText = document.getElementById("subnav_link_text_"+parent);
		parentLinkText.className = "sub_nav_link_on";
	}
	
}

function toggleNav (id) {
	var element = document.getElementById("child_items_"+id);
	if (element.style.display == "none") {
		element.style.display = "block";
	} else {
		element.style.display = "none";
	}
}

function toggleEmptySection(id)
{
	var parentLinkText = document.getElementById("subnav_link_text_"+id);
	parentLinkText.className = "sub_nav_link_on";
}