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);
} 

// Hide timeout.
var popTimer = 0;
// Array showing highlighted menu items.
var litNow = new Array();

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 we've reached the top of the hierarchy, return.
		if (menuNum == 0) return itemArray;
		itemNum = menu[menuNum][0].parentItem;
		menuNum = menu[menuNum][0].parentMenu;
	}
}

// Pass an array and a boolean to specify colour change, true = over colour.
function changeCol(changeArray, isOver) {
	for (menuCount = 0; menuCount < changeArray.length; menuCount++) {
		if (changeArray[menuCount]) {
			newCol = isOver ? menu[menuCount][0].overCol : menu[menuCount][0].backCol;
// Change the colours of the div/layer background.
			with (menu[menuCount][changeArray[menuCount]].ref) {
				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) {
// True or false - a vertical menu?
	this.isVert = isVert;
// The popout indicator used (if any) for this menu.
	this.popInd = popInd
// Position and size settings.
	this.x = x;
	this.y = y;
	this.width = width;
// Colours of menu and items.
	this.overCol = overCol;
	this.backCol = backCol;
// The stylesheet class used for item borders and the text within items.
	this.borderClass = borderClass;
	this.textClass = textClass;
// Parent menu and item numbers, indexed later.
	this.parentMenu = null;
	this.parentItem = null;
// Reference to the object's style properties (set later).
	this.ref = null;
}

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;
// Reference to the object's style properties (set later).
	this.ref = null;
}

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

	for (currMenu = 0; currMenu < menu.length; currMenu++) with (menu[currMenu][0]) {
// Variable for holding HTML for items and positions of next item.
		var str = '', itemX = 0, itemY = 0;

// Remember, items start from 1 in the array (0 is menu object itself, above).
// Also use properties of each item nested in the other with() for construction.
	for (currItem = 1; currItem < menu[currMenu].length; currItem++) with (menu[currMenu][currItem]) {
		var itemID = 'menu' + currMenu + 'item' + currItem;

// The width and height of the menu item - dependent on orientation!
	var w = (isVert ? width : length);
	var h = (isVert ? length : width);

// Create a div or layer text string with appropriate styles/properties.
// Thanks to Paul Maden (www.paulmaden.com) for helping debug this in IE4, apparently
// the width must be a miniumum of 3 for it to work in that browser.
	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 + ')">';

// Add contents of item (default: table with link inside).
// In IE/NS6+, add padding if there's a border to emulate NS4's layer padding.
// If a target frame is specified, also add that to the <a> tag.

		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) {

// Set target's parents to this menu item.
			menu[target][0].parentMenu = currMenu;
			menu[target][0].parentItem = currItem;

// Add a popout indicator.
			if (popInd) str += '<td class="' + textClass + '" align="right">' + popInd + '</td>';
		}
		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.position = 'relative';
		ref.visibility = 'hidden';
	}

// Insert a div tag to the end of the BODY with menu HTML in place for IE4.
	if (isIE4) {
		document.body.insertAdjacentHTML('beforeEnd', '<div id="menu' + currMenu + 'div" ' + 'style="position: absolute; visibility: hidden">' + str + '</div>');
		ref = getSty('menu' + currMenu + 'div');
	}

// In NS4, create a reference to a new layer and write the items to it.
	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';
  }
}

// Syntaxes: *** START EDITING HERE, READ THIS SECTION CAREFULLY! ***
//
// menu[menuNumber][0] = new Menu(Vertical menu? (true/false), 'popout indicator', left, top,
// width, 'mouseover colour', 'background colour', 'border stylesheet', 'text stylesheet');
//
// Left and Top are measured on-the-fly relative to the top-left corner of its trigger, or
// for the root menu, the top-left corner of the page.
//
// menu[menuNumber][itemNumber] = new Item('Text', 'URL', 'target frame', length of menu item,
//  additional spacing to next menu item, number of target menu to popout);
//
// If no target menu (popout) is desired, set it to 0. Likewise, if your site does not use
// frames, pass an empty string as a frame target.
//
// Something that needs explaining - the Vertical Menu setup. You can see most menus below
// are 'true', that is they are vertical, except for the first root menu. The 'length' and
// 'width' of an item depends on its orientation -- length is how long the item runs for in
// the direction of the menu, and width is the lateral dimension of the menu. Just look at
// the examples and tweak the numbers, they'll make sense eventually :).

	var menu = new Array();

// Default colours passed to most menu constructors (just passed to functions, not
// a global variable - makes things easier to change later in bulk).
//	var defOver = '#80AFFC', defBack = '#629DFD';
	var defOver = '#BEDFFC', defBack = '#FFFFFF';

// Default 'length' of menu items - item height if menu is vertical, width if horizontal.
	var defLength = 22;

// Menu 0 is the special, 'root' menu from which everything else arises.
	menu[0] = new Array();
// A non-vertical menu with a few different colours and no popout indicator, as an example.
// *** MOVE ROOT MENU AROUND HERE ***  it's positioned at (5, 0) and is 17px high now.
	menu[0][0] = new Menu(false, '', 10, 2, 17, '#80AFFC', '#629DFD', '', 'headText');
// Notice how the targets are all set to nonzero values...
// The 'length' of each of these items is 40, and there is spacing of 10 to the next item.
// Most of the links are set to '#' hashes, make sure you change them to actual files.
//	menu[0][1] = new Item('[ Home ]', '#', '', 40, 10, 0);
	menu[0][1] = new Item('[ Home ]', 'index.html', '', 55, 1, 0);
	menu[0][2] = new Item('[ Introduction ]', '#', '', 85, 1, 2);
	menu[0][3] = new Item('[ Departments ]', '#', '', 93, 1, 3);
// An example of a link with a target frame/window as well...
//	menu[0][4] = new Item('[ Strategic Planning ]', '#', '', 122, 1, 4);
	menu[0][4] = new Item('[ Site Map ]', 'sitemap.html', '', 72, 1, 0);
	menu[0][5] = new Item('[ Contact ]', 'contact.html', '', 65, 1, 0);
	menu[0][6] = new Item('<img src="../images/text_cn.jpg" border="0">', '../cn/index.html', '', 50, 1, 0);

// File menu.
	menu[1] = new Array();
// The File menu is positioned 0px across and 22 down from its trigger, and is 80 wide.
// All text in this menu has the stylesheet class 'item' -- see the <style> section above.
// We've passed a 'greater-than' sign '>' as a popout indicator. Try an image...?
	menu[1][0] = new Menu(true, '#', 0, 22, 80, defOver, defBack, 'itemBorder', 'itemText');
//	menu[1][1] = new Item('Open', '#', '', defLength, 0, 0);
//	menu[1][2] = new Item('Save', '#', '', defLength, 0, 0);
// Non-zero target means this will trigger a popout -- menu[4] which is the 'Reopen' menu.
//	menu[1][3] = new Item('Reopen', '#', '', defLength, 0, 4);
//	menu[1][4] = new Item('Exit', '#', '', defLength, 0, 0);

// Edit menu.
	menu[2] = new Array();
	menu[2][0] = new Menu(true, '>', 0, 22, 150, defOver, defBack, 'itemBorder', 'itemText');
	menu[2][1] = new Item('Message From the Dean', 'message.html', '', defLength, 0, 0);	
	menu[2][2] = new Item('Mission Of the Faculty', 'mission.html', '', defLength, 0, 0);

// Help menu
	menu[3] = new Array();
	menu[3][0] = new Menu(true, '>', 0, 22, 240, defOver, defBack, 'itemBorder', 'itemText');
	menu[3][1] = new Item('Anthropology', 'dept_ant.html', '', defLength, 0, 0);	
	menu[3][2] = new Item('Chinese Language & Literature', 'dept_ch.html', '', defLength, 0, 0);
	menu[3][3] = new Item('Cultural and Religious Studies', 'dept_crs.html', '', defLength, 0, 0);
	menu[3][4] = new Item('English', 'dept_en.html', '', defLength, 0, 0);
	menu[3][5] = new Item('Fine Arts', 'dept_fa.html', '', defLength, 0, 0);
	menu[3][6] = new Item('History', 'dept_hi.html', '', defLength, 0, 0);
	menu[3][7] = new Item('Japanese Studies', 'dept_ja.html', '', defLength, 0, 0);
	menu[3][8] = new Item('Linguistics & Modern Languages', 'dept_lin.html', '', defLength, 0, 0);
	menu[3][9] = new Item('Music', 'dept_mu.html', '', defLength, 0, 0);
	menu[3][10] = new Item('Philosophy', 'dept_ph.html', '', defLength, 0, 0);
	menu[3][11] = new Item('Translation', 'dept_tr.html', '', defLength, 0, 0);
	menu[3][12] = new Item('English Language Teaching Unit', 'dept_elt.html', '', defLength, 0, 0);
	menu[3][13] = new Item('Yale-China Chinese Language Centre', 'dept_clc.html', '', defLength, 0, 0);
// Reopen menu
	menu[4] = new Array();
// This is across but not down... a horizontal popout (with crazy stylesheets :)...
//	menu[4][0] = new Menu(true, '>', 0, 22, 240, '#80AFFC', '#629DFD', 'itemBorder', 'itemText');
	menu[4][0] = new Menu(true, '>', 0, 22, 240, defOver, defBack, 'itemBorder', 'itemText');
// These items are lengthier than normal, and have extra spacing due to the fancy borders.
/*	menu[4][1] = new Item('Anthropology', 'http://www.cuhk.edu.hk/ant/', '', defLength, 0, 0);
	menu[4][2] = new Item('Chinese Language & Literature', 'plan_ch.html', '', defLength, 0, 0);
	menu[4][3] = new Item('Cultural and Religious Studies', 'dept_re.html', '', defLength, 0, 0);
	menu[4][4] = new Item('English', 'plan_en.html', '', defLength, 0, 0);
	menu[4][5] = new Item('Fine Arts', 'plan_fa.html', '', defLength, 0, 0);
	menu[4][6] = new Item('History', 'plan_hi.html', '', defLength, 0, 0);
	menu[4][7] = new Item('Japanese Studies', 'plan_ja.html', '', defLength, 0, 0);
	menu[4][8] = new Item('Linguistics & Modern Languages', 'plan_ml.html', '', defLength, 0, 0);
	menu[4][9] = new Item('Music', 'plan_mu.html', '', defLength, 0, 0);
	menu[4][10] = new Item('Philosophy', 'plan_ph.html', '', defLength, 0, 0);
	menu[4][11] = new Item('Translation', 'plan_tr.html', '', defLength, 0, 0);
	menu[4][12] = new Item('English Language Teaching Unit', 'plan_elt.html', '', defLength, 0, 0);
	menu[4][13] = new Item('Independent Learning Centre', 'http://www.ilc.cuhk.edu.hk/', '', defLength, 0, 0);
*/
// Reopen menu
	menu[5] = new Array();
// This is across but not down... a horizontal popout (with crazy stylesheets :)...
	menu[5][0] = new Menu(true, '>', 0, 22, 120, '#80AFFC', '#629DFD', 'itemBorder', 'itemText');
// These items are lengthier than normal, and have extra spacing due to the fancy borders.
//	menu[5][1] = new Item('WebCT', 'http://course.cuhk.edu.hk/', '', defLength, 0, 0);
//	menu[5][2] = new Item('CUHK', 'http://www.cuhk.edu.hk/', '', defLength, 0, 0);

// Help About popout
//	Menu[6] = new Array();
// Leftwards popout with a negative x and y relative to its trigger.
//	menu[6][0] = new Menu(true, '>', -85, -17, 80, defOver, defBack, 'itemBorder', 'itemText');
//	menu[6][1] = new Item('Web Class', '#', '', 40, 0, 0);

//	Menu[7] = new Array();
// Leftwards popout with a negative x and y relative to its trigger.
//	menu[7][0] = new Menu(true, '>', -85, -17, 80, defOver, defBack, 'itemBorder', 'itemText');




// *** OPTIONAL CODE FROM HERE DOWN ***

// These two lines handle the window resize bug in NS4. See <body onResize="...">.
// I recommend you leave this here as otherwise when you resize NS4's width menus are hidden.

	var popOldWidth = window.innerWidth;
	nsResizeHandler = new Function('if (popOldWidth != window.innerWidth) location.reload()');


// This is a quick snippet that captures all clicks on the document and hides the menus
// every time you click. Use if you want.

	if (isNS4) document.captureEvents(Event.CLICK);
	document.onclick = clickHandle;

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


// This is just the moving command for the example.

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

function sayHello(){
	alert("Hello!");	
}