function LotteryDraw(obj, callback) {
	this.timer = null; //计时器
	this.startIndex = obj.startIndex-1 || 0; //从第几个位置开始抽奖 [默认为零]
	this.count = 0; //计数，跑的圈数
	this.winingIndex = obj.winingIndex || 0;//获奖的位置
	this.totalCount = obj.totalCount || 6;//抽奖跑的圈数
	this.speed = obj.speed || 100;
	this.domData=obj.domData;
	this.rollFn();
	this.callback = callback;
}

LotteryDraw.prototype = {
	rollFn: function() {
		var that = this;
		// 活动index值增加，即移动到下一个格子
		this.startIndex++;
		
		//startIndex是最后一个时一圈走完，重新开始
		if (this.startIndex >= this.domData.length - 1) {
			this.startIndex = 0;
			this.count++;
		}
		
		// 当跑的圈数等于设置的圈数，且活动的index值是奖品的位置时停止
		if (this.count >= this.totalCount && this.startIndex === this.winingIndex) {
			if (typeof this.callback === 'function') {
				setTimeout(function() {
					that.callback(that.startIndex,that.count); //执行回调函数，抽奖完成的相关操作
				}, 400);
			}
			clearInterval(this.timer);
		}else { //重新开始一圈
			if (this.count >= this.totalCount - 1) {
				this.speed += 30;
			}
			this.timer = setTimeout(function() {
				that.callback(that.startIndex,that.count);
				that.rollFn();
			}, this.speed);
		}
	}
}

module.exports = LotteryDraw;