window.onload = function(){
	init_menu();
}

function init_menu(){
	var menu = document.getElementById('main_menu');
	var li = menu.getElementsByTagName('li');
	var current_sub = null;
	var add = 10;
	var menu_wrapper = document.getElementById('menu');
	var subs = menu_wrapper.getElementsByTagName('div');
	
	//var subs = document.getElementsByClassName('sub_menu');
	for(var i = 0; i < li.length; i++){
		var a = li[i].getElementsByTagName('a');
		if (a && a[0]) {
			a[0].onmouseover = function(event){
				var evt = event || window.event;
				var target = evt.target || evt.srcElement;
				var li = target.parentNode;
				if(li){
					var id = li['id'].split('_')[1];
					var sub_menu = document.getElementById('sub_' + id);
					if(sub_menu){
						sub_menu.style.top = (li.offsetTop + li.offsetHeight + add) + 'px';
						sub_menu.style.display = 'block';
						current_sub = sub_menu;
					}
				}
			}
		}
	}
	
	
	document.onmousemove = function(event){
		var evt = event || window.event;
		if(current_sub){
			var id = current_sub['id'].split('_')[1];
			var par = document.getElementById('item_' + id);
			////console.log(par.clientHeight);
			//alert(par.offsetHeight);
			//alert(document.documentElement.scrollTop);
			var p = find_pos(current_sub);
			var x1s = p[0];
			var y1s = p[1] - par.offsetHeight - add;
			var x2s = x1s + current_sub.clientWidth;
			var y2s = p[1] + current_sub.clientHeight;
			var x = evt.clientX;
			var y = evt.clientY + document.documentElement.scrollTop;
			if((x < x1s || x > x2s) || (y < y1s || y > y2s)){
				current_sub.style.display = 'none';
				current_sub = null;
				for(var i = 0; i < subs.length; i++){
					if(subs[i].style.display != 'none'){
						subs[i].style.display = 'none';
						current_sub = null;
					}
				}
			}
		}
	}
}

function find_pos(obj){
	var curleft = curtop = 0;
	if (obj.offsetParent) {
		curleft = obj.offsetLeft
		curtop = obj.offsetTop
		while (obj = obj.offsetParent) {
			curleft += obj.offsetLeft
			curtop += obj.offsetTop
		}
	}
	return [curleft, curtop];
}

function show_menu(){
	
}