var prev_item = -1; // No shopping item displayed yet. Random index will be set.

function loadXMLShop(url){
	var xhr;
	var dom_str,element1,element2,cat,item;
	if(window.XMLHttpRequest){// code for IE7+, Firefox, Chrome, Opera, Safari
		xhr=new XMLHttpRequest();
	}else{// code for IE6, IE5
		xhr=new ActiveXObject("Microsoft.XMLHTTP");
	}
	xhr.onreadystatechange=function(){
		if(xhr.readyState==4 && xhr.status==200){
			var rand_i;
			element1=xhr.responseXML.documentElement.getElementsByTagName("shop");
			if(prev_item == -1){ // This is the first time to show since the webpage has been loaded
				rand_i = Math.floor(Math.random() * (element1.length)); // set random between 0 ~ length of xml data.
			}else{
				if(prev_item<element1.length-1){ // Don't exceed	 the length of array
					rand_i = prev_item+1;
				}else{
					rand_i = 0; // Instead of "overflowing array index", set zero
				}
			}
			prev_item = rand_i; // remember which index was displayed.
			dom_str='';
			cat=element1[rand_i].getElementsByTagName("category_id");
			item=element1[rand_i].getElementsByTagName("item_id");
			element2=element1[rand_i].getElementsByTagName("image");			
			if(element2[0]){
				try{
					dom_str=dom_str + '<a href="store/store_item.php?category='+cat[0].firstChild.nodeValue+'&item='+item[0].firstChild.nodeValue+'"><img class="shopImage" src="' + element2[0].firstChild.nodeValue + '" alt="" /></a>';
				}catch(er){
					dom_str=dom_str + '';
				}
			}
		
			element2=element1[rand_i].getElementsByTagName("shop_name");
			if(element2[0]){
				try{
					dom_str=dom_str + '<div class="shopName"><a href="store/store_item.php?category='+cat[0].firstChild.nodeValue+'&item='+item[0].firstChild.nodeValue+'" class="cellLink">' + element2[0].firstChild.nodeValue + '</a></div>';
				}catch(er){
					dom_str=dom_str + '';
				}
			}
			element2=element1[rand_i].getElementsByTagName("desc");
			if(element2[0]){
				try{
					dom_str=dom_str + '<div class="shopDesc">' + element2[0].firstChild.nodeValue + '</div>';
				}catch(er){
					dom_str=dom_str + '';
				}
			}
			element2=element1[rand_i].getElementsByTagName("price");
			if(element2[0]){
				try{
					dom_str=dom_str + '<div class="shopPrice">' + element2[0].firstChild.nodeValue + '</div>';
				}catch(er){
					dom_str=dom_str + '';
				}
			}
			function nextShop(){
				$("#shop #shop_content").html(dom_str);
			}
			$("#shop #shop_content").effect('slide', { direction: "left", mode: "hide"},250,nextShop);
			
			$("#shop #shop_content").effect('slide', { direction: "right", mode: "show"},500);
		}
	}
	xhr.open("GET",url,true);
	xhr.send();
	t=setTimeout("loadXMLShop('shop_data.php')", 4000);
}

$(document).ready(function(){
	loadXMLShop('shop_data.php');
});