var SellerScroll = function(options){
	this.SetOptions(options);
	this.lButton = this.options.lButton;
	this.rButton = this.options.rButton;
	this.oList = this.options.oList;
	this.showSum = this.options.showSum;
	
	this.iList = $("#" + this.options.oList + " > li");
	this.iListSum = this.iList.length;
	this.iListWidth = this.iList.outerWidth(true);
	this.moveWidth = this.iListWidth * this.showSum;
	
	this.dividers = Math.ceil(this.iListSum / this.showSum);	//共分为多少块
	this.moveMaxOffset = (this.dividers - 1) * this.moveWidth;
	this.LeftScroll();
	this.RightScroll();
};
SellerScroll.prototype = {
	SetOptions: function(options){
		this.options = {
			lButton: "left_scroll",
			rButton: "right_scroll",
			oList: "carousel_ul",
			showSum: 4	//一次滚动多少个items
		};
		$.extend(this.options, options || {});
	},
	ReturnLeft: function(){
		return isNaN(parseInt($("#" + this.oList).css("left"))) ? 0 : parseInt($("#" + this.oList).css("left"));
	},
	LeftScroll: function(){
		if(this.dividers == 1) return;
		var _this = this, currentOffset;
		$("#" + this.lButton).click(function(){
			currentOffset = _this.ReturnLeft();
			if(currentOffset == 0){
				for(var i = 1; i <= _this.showSum; i++){
					$(_this.iList[_this.iListSum - i]).prependTo($("#" + _this.oList));
				}
				$("#" + _this.oList).css({ left: -_this.moveWidth });
				$("#" + _this.oList + ":not(:animated)").animate( { left: "+=" + _this.moveWidth }, { duration: "slow", complete: function(){
					for(var j = _this.showSum + 1; j <= _this.iListSum; j++){
						$(_this.iList[_this.iListSum - j]).prependTo($("#" + _this.oList));
					}
					$("#" + _this.oList).css({ left: -_this.moveWidth * (_this.dividers - 1) });
				} } );
			}else{
				$("#" + _this.oList + ":not(:animated)").animate( { left: "+=" + _this.moveWidth }, "slow" );
			}
		});
	},
	RightScroll: function(){
		if(this.dividers == 1) return;
		var _this = this, currentOffset;
		$("#" + this.rButton).click(function(){
			currentOffset = _this.ReturnLeft();
			if(Math.abs(currentOffset) >= _this.moveMaxOffset){
				for(var i = 0; i < _this.showSum; i++){
					$(_this.iList[i]).appendTo($("#" + _this.oList));
				}
				$("#" + _this.oList).css({ left: -_this.moveWidth * (_this.dividers - 2) });
				
				$("#" + _this.oList + ":not(:animated)").animate( { left: "-=" + _this.moveWidth }, { duration: "slow", complete: function(){
					for(var j = _this.showSum; j < _this.iListSum; j++){
						$(_this.iList[j]).appendTo($("#" + _this.oList));
					}
					$("#" + _this.oList).css({ left: 0 });
				} } );
			}else{
				$("#" + _this.oList + ":not(:animated)").animate( { left: "-=" + _this.moveWidth }, "slow" );
			}
		});
	}
};