var productWheelObj;

var productUnitWidth=178;
var productAvailWidth=productUnitWidth*3;
var productCount=0;

var productTimerID;
var productLock=false;
var productObjs;
var productMovingLength;
/*
para1:捲動物件ID
para2:大圖DIV ID
para3:title ID
para4:content ID
para5:link ID
*/
function initProduct(wheelobj)
{
	productWheelObj=document.getElementById(wheelobj);	
	productObjs=productWheelObj.getElementsByTagName("DIV");
	productCount=productObjs.length;	
	productWheelObj.style.width=productCount*productUnitWidth+'px';	
}

function productMoveLeft()
{
	if(!productLock && productCount>3)
	{
		productStopMove();
		productLock=true;	
		productMovingLength=productAvailWidth;
		productTimerID=setInterval("productStartMove('left')",5);
	}
}
function productMoveRight()
{	
	if(!productLock && productCount>3)
	{
		productStopMove();		
		productLock=true;
		productMovingLength=productAvailWidth;
		productTimerID=setInterval("productStartMove('right')",5);
	}
}

function productStopMove()
{
	clearInterval(productTimerID);	
}

function productStartMove(move)
{	
	var nowPosition=parseInt(productWheelObj.style.left.slice(0,-2));
	var rate=0;
	
	if(productMovingLength > 267)
	{
		rate=18;
	}
	else if(productMovingLength > 89)
	{
		rate=9;
	}
	else if(productMovingLength > 9)
	{
		rate=3;
	}
	else if(productMovingLength > 0)
	{
		rate=1;
	}
//	document.getElementById('footer_links').innerHTML+=nowPosition+"("+productMovingLength+"),";
	if(productMovingLength>0)
	{		
		productMovingLength-=rate;
		if(move=='right')
		{
			if(nowPosition>=0)
			{
				var newNode=productObjs[productCount-1].cloneNode(true);
				productWheelObj.insertBefore(newNode,productObjs[0]);
				productWheelObj.removeChild(productObjs[productCount]);
					
				nowPosition=-178;
				productWheelObj.style.left=nowPosition+'px';
			}
			
			productWheelObj.style.left=(nowPosition+rate)+'px';
		}
		else if(move=='left')
		{
			if(nowPosition<=(-178))
			{
				nowPosition=0;
				productWheelObj.style.left=0+'px';
				var newNode=productObjs[0].cloneNode(true);
				productWheelObj.appendChild(newNode);
				productWheelObj.removeChild(productObjs[0]);
			}
			productWheelObj.style.left=(nowPosition-rate)+'px';
		}
	}
	else
	{
		if(move=='left')
		{
			var newNode=productObjs[0].cloneNode(true);
			productWheelObj.appendChild(newNode);
			productWheelObj.removeChild(productObjs[0]);			
		}
		productWheelObj.style.left=0+'px';
		
		productStopMove();
		productLock=false;		
	}
}

function changeProductImg(img_path,img_alt)
{
	document.getElementById('product_img_show').src=img_path;
	document.getElementById('product_img_show').alt=img_alt;
}