// Define required variables.
	var http = createRequestObject();  
   var ajaxaction = "";	
	var store = "";
	var selectedObjectName = "";
	var express_url = "express_ajax.php";
	var inProgress = false;   
	var previous_item_id = "";

   function handleResponse() 
   {
      if(http.readyState == 4)
      {
      	inProgress = false;
      	
      	hideLoader();
         var response = http.responseText;
         
         if(response != "")
         {
         	if(response.substr(0,1) == "#")
         	{
         		alert("Warning: " + response.substr(1,response.length - 1));
				}
				else
				{
		         if(ajaxaction == "addtocart")
		         {
		            handleAddToCart(response);
		         }	
		         else if(ajaxaction == "removefromcart")
		         {
		            handleRemoveFromCart(response);
		         }	
		         else if(ajaxaction == "loadcart")
		         {
		            handleLoadCart(response);
		         }		         		         		         			         		         								
					else
					{
						alert("Undefined action: " + ajaxaction);
					}
				}
			}
		   else if(ajaxaction == "loadjobs")
		   {
		      refreshJobList("");   
		   }
		   else
		   {
		      //alert("Invalid response from server");   
		   }		   
      }
   }
   		
	
	// Cart Functions
	function addItemToCart(evt, item_id)
	{
		if(inProgress)
			return;
			
		// Ensure the passed item_id is a valid whole number
		if((item_id == "") || (!isInteger(item_id)))
			return;
		
		// Get a handle on the relevant quantity text field
	 	var qty_item = "qty_" + item_id;
	 	var price_item = "price_" + item_id;
	 	var objQty = document.getElementById(qty_item);
	 	var objPrice = document.getElementById(price_item);
	 	
	 	if((objQty) && (objPrice))
	 	{
	 		// Get the quantity value and ensure it's a valid whole number.
	 		var qty = objQty.value; 
	 		var price = objPrice.innerHTML;
	 		
	 		if((qty == "") || (!isInteger(qty)))
	 		{
	 			alert("Please enter a valid number for item quantity");
	 			objQty.focus();
	 			return;
			}	
			
	 		if(price == "")
	 		{
	 			alert("The price for this item is invalid.");
	 			return;
			}		
			
			price = price.substring(1);
			
	 		if(!isNumeric(price))
	 		{
	 			alert("The price for this item is invalid.");
	 			return;
			}						
			
			// Show the ajax loader window so the user knows something is happening.
			showLoader(evt);
			
			// Create the ajax request and send it
			ajaxaction = "addtocart";
			store = item_id;	// Store the item_id so the handler function knows which item was processed.
			params = "action=" + ajaxaction + "&item_id=" + item_id + "&qty=" + qty + "&price=" + price;
			
			sndReq(express_url, params);
		}
	}
	
	// The handleAddToCart function is fired after an item has been successfully added to the cart.
	function handleAddToCart(response)
	{
		if(response != "OK")
		{
			alert("Sorry, the item could not be added to your cart.  Please try again later.");
			return;
		}

		// The item_id that the user just added to the cart was stored in the js variable "store".  Grab it.
		var item_id = store;
	 	var qty_item = "qty_" + item_id;
	 	var addmessage_item = "addmessage_" + item_id;
	 	var objQty = document.getElementById(qty_item);
	 	var objMessage = document.getElementById(addmessage_item);
	 	
	 	if((objQty) && (objMessage))
	 	{
	 		// Get the quantity value that we're adding to the old quantity and ensure it's a valid whole number.
	 		var qty = objQty.value; 
	 		
	 		if((qty == "") || (!isInteger(qty)))
	 		{
	 			alert("Please enter a valid number for item quantity");
	 			objQty.focus();
	 			return;
			}		
			
			// Force quantites to numeric type
			qty = qty * 1;
 	      
 	      // Reset the quantity input field to 1.
 	      objQty.value = "1";
 	      
 	      objMessage.style.visibility = 'visible';
 	      
 	      if((previous_item_id != "") && (previous_item_id != item_id))
 	      {
 	      	var obj = document.getElementById('addmessage_' + previous_item_id);
 	      	
 	      	if(obj)
 	      		obj.style.visibility = 'hidden';	
			}
			
			previous_item_id = item_id;
 	      
 	      reloadCart();
 	      
 	      //$("#accordion_view_cart").click(); 
 	      // All done.
		}		
	}
	
	// The removeFromCart method is fired when the user clicks the "Clear" link for any line item.
	// We need to invoke the relevant server method to clear the item from the cart.
	function removeFromCart(evt, item_id)
	{
		if(inProgress)
			return;
					
		// Ensure the passed item_id is a valid whole number
		if((item_id == "") || (!isInteger(item_id)))
			return;
		
		// Show the ajax loader window so the user knows something is happening.
		showLoader(evt);
		
		// Create the ajax request and send it
		ajaxaction = "removefromcart";
		store = item_id;	// Store the item_id so the handler function knows which item was processed.
		params = "action=" + ajaxaction + "&item_id=" + item_id;
		
		sndReq(express_url, params);
	}	
	
	// The handleRemoveFromCart function is fired after an item has been successfully removed from the cart.
	function handleRemoveFromCart(response)
	{
		if(response != "OK")
		{
			alert("Sorry, the item could not be removed from your cart.  Please try again later.");
			return;
		}

		// The item_id that the user just added to the cart was stored in the js variable "store".  Grab it.
		var item_id = store;
	 	var cart_qty_item = "cart_qty_" + item_id;
	 	var objCartQty = document.getElementById(cart_qty_item);
	 	
	 	if(objCartQty)
	 	{
 	      // Update the item quantity in the cart.
 	      objCartQty.innerHTML = "0";

 	      reloadCart();
 	      // All done.
		}		
	}
	
	function reloadCart()
	{
		showCartLoader();
		
		// Create the ajax request and send it
		var randomnumber = Math.floor(Math.random()*999999)
		ajaxaction = "loadcart";
		params = "action=" + ajaxaction + "&r=" + randomnumber;
		
		sndReq(express_url, params);		
	}	
	
	function handleLoadCart(response)
	{
		// Hide the cart loader
		hideCartLoader();
		
		// Get a handle on the cart div
		var objDiv = document.getElementById("sidebar_cart");
		if(objDiv)
		{
			objDiv.innerHTML = response;	
		}
	}
	
	// Utility Functions
	function isNumeric(sText)
	{
	   var ValidChars = "0123456789.";
	   var IsNumber=true;
	   var Char;

	   for (i = 0; i < sText.length && IsNumber == true; i++) 
	   { 
	      Char = sText.charAt(i); 
	      if (ValidChars.indexOf(Char) == -1) 
	      {
	         IsNumber = false;
	      }
	   }
	   
	   return IsNumber; 
	}
	
	function isInteger(sText)
	{
	   var ValidChars = "0123456789";
	   var IsNumber=true;
	   var Char;

	   for (i = 0; i < sText.length && IsNumber == true; i++) 
	   { 
	      Char = sText.charAt(i); 
	      if (ValidChars.indexOf(Char) == -1) 
	      {
	         IsNumber = false;
	      }
	   }
	   
	   return IsNumber; 
	}
	
	function mouseX(evt) 
	{
		if (evt.pageX) return evt.pageX;
		else if (evt.clientX)
		   return evt.clientX + (document.documentElement.scrollLeft ?
		   document.documentElement.scrollLeft :
		   document.body.scrollLeft);
		else return null;
	}
	
	function mouseY(evt) 
	{
		if (evt.pageY) return evt.pageY;
		else if (evt.clientY)
		   return evt.clientY + (document.documentElement.scrollTop ?
		   document.documentElement.scrollTop :
		   document.body.scrollTop);
		else return null;
	}
	
   function createRequestObject() 
   {
       var ro;
       var browser = navigator.appName;
       
       if(browser == "Microsoft Internet Explorer")
       {
           ro = new ActiveXObject("Microsoft.XMLHTTP");
       }
       else
       {
           ro = new XMLHttpRequest();
       }
       
       return ro;
   }

   function sndReq(url, params) 
   {
   	http.open('POST', url, true);
   	http.onreadystatechange = handleResponse;
		http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
		http.setRequestHeader("Content-length", params.length);
		http.setRequestHeader("Connection", "close");       
      http.send(params);

		inProgress = true;  
   }
   
   function showLoader(evt)
   {
   	var objLoader = document.getElementById("ajaxloader");
   	if(!objLoader)
   		return;
   	
   	var newTop = "300px";
   	var newLeft = "300px;"
   	
   	if(evt != null)
   	{
   		newTop = mouseY(evt) - 50 + "px";
   		newLeft = mouseX(evt) + 50 + "px";
		}
   	
   	objLoader.style.top = newTop;
   	objLoader.style.left = newLeft;
   	objLoader.style.visibility = "visible";     		
	}
	
   function hideLoader(evt)
   {
   	var objLoader = document.getElementById("ajaxloader");
   	if(!objLoader)
   		return;
   	
   	objLoader.style.visibility = "hidden";     		
	}
	
   function showCartLoader()
   {
   	var objLoader = document.getElementById("cart_loader");
   	if(!objLoader)
   		return;
   
   	objLoader.style.display = "block";     		
	}
	
   function hideCartLoader(evt)
   {
   	var objLoader = document.getElementById("cart_loader");
   	if(!objLoader)
   		return;
   	
   	objLoader.style.display = "none";     		
	}