var isDOM = (document.getElementById ? true : false); 
var isIE4 = ((document.all && !isDOM) ? true : false);
var isNS4 = (document.layers ? true : false);

function getRef(id) 
{
	if (isDOM) return document.getElementById(id);
	if (isIE4) return document.all[id];
	if (isNS4) return document.layers[id];
}

function getSty(id) 
{
	return (isNS4 ? getRef(id) : getRef(id).style);
} 

var popTimer = 0; // Hide timeout.
var litNow = new Array(); // Array showing highlighted menu items.
function popOver(menuNum, itemNum) 
{
	clearTimeout(popTimer);
	hideAllBut(menuNum);
	litNow = getTree(menuNum, itemNum);
	changeCol(litNow, true);
	targetNum = menu[menuNum][itemNum].target;
	if (targetNum > 0) 
		{
		thisX = parseInt(menu[menuNum][0].ref.left) + parseInt(menu[menuNum][itemNum].ref.left);
		thisY = parseInt(menu[menuNum][0].ref.top) + parseInt(menu[menuNum][itemNum].ref.top);
		with (menu[targetNum][0].ref) 
			{
			left = parseInt(thisX + menu[targetNum][0].x);
			top = parseInt(thisY + menu[targetNum][0].y);
			visibility = 'visible';
			}
		}
}

function popOut(menuNum, itemNum) 
{
	if ((menuNum == 0) && !menu[menuNum][itemNum].target)
	hideAllBut(0)
	else
	popTimer = setTimeout('hideAllBut(0)', 500);
}

function getTree(menuNum, itemNum) 
{
// Array index is the menu number. The contents are null (if that menu is not a parent)
// or the item number in that menu that is an ancestor (to light it up).
	itemArray = new Array(menu.length);
	while(1) 
	{
	itemArray[menuNum] = itemNum;
	if (menuNum == 0) return itemArray; // If we've reached the top of the hierarchy, return.
	itemNum = menu[menuNum][0].parentItem;
	menuNum = menu[menuNum][0].parentMenu;
	}
}

function changeCol(changeArray, isOver) // Pass an array and a boolean to specify colour change, true = over colour.
{
	for (menuCount = 0; menuCount < changeArray.length; menuCount++) 
	{
		if (changeArray[menuCount]) 
		{
			newCol = isOver ? menu[menuCount][0].overCol : menu[menuCount][0].backCol;
			with (menu[menuCount][changeArray[menuCount]].ref) // Change the colours of the div/layer background.
			{
				if (isNS4) bgColor = newCol;
				else backgroundColor = newCol;
			}
		}
	}
}

function hideAllBut(menuNum) 
{
	var keepMenus = getTree(menuNum, 1);
	for (count = 0; count < menu.length; count++)
	if (!keepMenus[count])
	menu[count][0].ref.visibility = 'hidden';
	changeCol(litNow, false);
}

// *** MENU CONSTRUCTION FUNCTIONS ***

function Menu(isVert, popInd, x, y, width, overCol, backCol, borderClass, textClass) 
{
	this.isVert = isVert;  // True or false - a vertical menu?
	this.popInd = popInd // The popout indicator used (if any) for this menu.
	this.x = x; // Position and size settings.
	this.y = y;
	this.width = width;
	this.overCol = overCol; // Colours of menu and items.
	this.backCol = backCol;
	this.borderClass = borderClass; // The stylesheet class used for item borders and the text within items.
	this.textClass = textClass;
	this.parentMenu = null; // Parent menu and item numbers, indexed later.
	this.parentItem = null;
	this.ref = null; // Reference to the object's style properties (set later).
}

function Item(text, href, frame, length, spacing, target) 
{
	this.text = text;
	this.href = href;
	this.frame = frame;
	this.length = length;
	this.spacing = spacing;
	this.target = target;
	this.ref = null; // Reference to the object's style properties (set later).
}

function writeMenus() 
{
	if (!isDOM && !isIE4 && !isNS4) return;

	for (currMenu = 0; currMenu < menu.length; currMenu++) with (menu[currMenu][0]) 
	{
		var str = '', itemX = 0, itemY = 0; // Variable for holding HTML for items and positions of next item.
		for (currItem = 1; currItem < menu[currMenu].length; currItem++) with (menu[currMenu][currItem]) 
		{
			var itemID = 'menu' + currMenu + 'item' + currItem;
			var w = (isVert ? width : length); // The width and height of the menu item - dependent on orientation!
			var h = (isVert ? length : width);
			if (isDOM || isIE4) 
			{
				str += '<div id="' + itemID + '" style="position: absolute; left: ' + itemX + '; top: ' + itemY + '; width: ' + w + '; height: ' + h + '; visibility: inherit; ';
				if (backCol) str += 'background: ' + backCol + '; ';
				str += '" ';
			}
			if (isNS4) 
			{
				str += '<layer id="' + itemID + '" left="' + itemX + '" top="' + itemY + '" width="' +  w + '" height="' + h + '" visibility="inherit" ';
				if (backCol) str += 'bgcolor="' + backCol + '" ';
			}
			if (borderClass) str += 'class="' + borderClass + '" '; // Add mouseover handlers and finish div/layer.
			str += 'onMouseOver="popOver(' + currMenu + ',' + currItem + ')" onMouseOut="popOut(' + currMenu + ',' + currItem + ')">';
			str += '<table width="' + (w - 8) + '" border="0" cellspacing="0" cellpadding="' + (!isNS4 && borderClass ? 3 : 0) + '"><tr><td align="left" height="' + (h - 7) + '">' + '<a class="' + textClass + '" href="' + href + '"' + (frame ? ' target="' + frame + '">' : '>') + text + '</a></td>';
			if (target > 0) 
			{
				menu[target][0].parentMenu = currMenu; // Set target's parents to this menu item.
				menu[target][0].parentItem = currItem;
				if (popInd) str += '<td class="' + textClass + '" align="right">' + popInd + '</td>'; // Add a popout indicator.
			}
			str += '</tr></table>' + (isNS4 ? '</layer>' : '</div>');
			if (isVert) itemY += length + spacing;
			else itemX += length + spacing;
		}
		if (isDOM) 
		{
			var newDiv = document.createElement('div');
			document.getElementsByTagName('body').item(0).appendChild(newDiv);
			newDiv.innerHTML = str;
			ref = newDiv.style;
			ref.position = 'absolute';
			ref.visibility = 'hidden';
		}
		if (isIE4) 
		{
			document.body.insertAdjacentHTML('beforeEnd', '<div id="menu' + currMenu + 'div" ' + 'style="position: absolute; visibility: hidden">' + str + '</div>');
			ref = getSty('menu' + currMenu + 'div');
		}
		if (isNS4) 
		{
			ref = new Layer(0);
			ref.document.write(str);
			ref.document.close();
		}
		for (currItem = 1; currItem < menu[currMenu].length; currItem++) 
		{
			itemName = 'menu' + currMenu + 'item' + currItem;
			if (isDOM || isIE4) menu[currMenu][currItem].ref = getSty(itemName);
			if (isNS4) menu[currMenu][currItem].ref = ref.document[itemName];
		}
	}
	with(menu[0][0]) 
	{
		ref.left = x;
		ref.top = y;
		ref.visibility = 'visible';
	}
}

var menu = new Array();
var defOver = '#0033FF', defBack = '#0033FF'; // Default colours passed to most menu constructors 
var defLength = 35; // Default 'length' of menu items - item height if menu is vertical, width if horizontal.

menu[0] = new Array(); // 'root' menu from which everything else arises, positioned at (65,95) and is 15px high 
menu[0][0] = new Menu(false, '', 65, 105, 15, '#0033FF', '#0033FF', '', 'itemText');
menu[0][1] = new Item('Meeting Information', 'meeting.html', '', 120, 40, 1); // triggers menu 1
menu[0][2] = new Item('Presentations', 'presentations.html', '', 100, 40, 2); //triggers menu 2
menu[0][3] = new Item('Partners', 'partners.html', '', 100, 40, 0); 
menu[0][4] = new Item('Home', 'index.html', '', 100, 40, 0);

menu[1] = new Array(); // Meeting Information menu, positioned 0px across and 22 down from its trigger, and is 80 wide.
menu[1][0] = new Menu(true, '>', 0, 22, 125, defOver, defBack, 'itemBorder', 'itemText');
menu[1][1] = new Item('Schedule', 'schedule.html', '', defLength, 0, 0); 
menu[1][2] = new Item('Logistics', 'logistics.html', '', defLength, 0, 0); 
menu[1][3] = new Item('Participants', 'participants.html', '', defLength, 0, 0);  

menu[2] = new Array(); // Presentations sub-menu
menu[2][0] = new Menu(true, '>', 0, 22, 125, defOver, defBack, 'itemBorder', 'itemText');
menu[2][1] = new Item('Gateway Development', 'lucidea.html', '', defLength, 0, 0);
menu[2][2] = new Item('CI Technology Overview', 'core_integration.html', '', defLength, 0, 0);
menu[2][3] = new Item('Gateway Evaluation', 'survey.html', '', defLength, 0, 0);
menu[2][4] = new Item('Core Taxonomy', 'taxonomy.html', '', defLength, 0, 0); 
menu[2][5] = new Item('NSDL CAT', 'http://commserv.comm.nsdl.org', '', defLength, 0, 0);
menu[2][6] = new Item('Best Practices', 'BestPractices/BestPractices.xhtml', '', defLength, 0, 0); 
menu[2][7] = new Item('Math on the Web', 'MathML/MathML.xhtml', '', defLength, 0, 0);
menu[2][8] = new Item('Croquet-on-Mars', 'croquet-on-mars.html', '', defLength, 0, 0);



if (isNS4) document.captureEvents(Event.CLICK); // captures all clicks on the document and hides the menus every time you click
document.onclick = clickHandle;

function clickHandle(evt)
{
 if (isNS4) document.routeEvent(evt);
 hideAllBut(0);
}

function moveRoot() 
{
 with(menu[0][0].ref) left = ((parseInt(left) < 100) ? 100 : 5);
}