/**

 * @author zhousg

 * @Date 2016-02-04

 * @Method 滑动方法  针对一个大容器内部的容器做滑动封装

 * @param

 * args args.swipeDom 大容器对象

 * args.swipeType 滑动类型

 * args.swipeDistance 缓冲距离

 * 注意：子容器的高宽度是取的内容的高宽 所以padding的大小有影响

 */

if(!window.lcf){

    window.lcf = {};

}

lcf.iScroll = function(args){

    /*调用的时候没有初始化的话就是初始化一次*/

    if(!(this instanceof arguments.callee)) return new arguments.callee(args);

    this.init(args);

};

lcf.iScroll.prototype = {

    constructor:lcf.iScroll,

    init:function(args){

        /*局部变量来接受当前的this*/

        var that  = this;

        /*如果传入的对象是一个Dom对象就把他看作是我们的大容器盒子*/

        if(args.swipeDom && typeof  args.swipeDom == 'object'){

            that.parentDom = args.swipeDom;

        }

        /*如果不存在父容器就停止初始化*/

        if(!that.parentDom) return false;

        /*找到子容器*/

        that.childDom = that.parentDom.children&&that.parentDom.children[0]?that.parentDom.children[0]:'';

        /*如果不存在子容器就停止初始化*/

        if(!that.childDom) return false;

        /*初始化传入的参数*/

        that.settings = {};

        /*默认类型  默认的Y轴滑动 如果不是y的话就是以x轴开始滑动*/

        that.settings.swipeType = args.swipeType?args.swipeType:'y';

        /*默认的缓冲滑动距离*/

        that.settings.swipeDistance = args.swipeDistance>=0?args.swipeDistance:150;

        /*初始化滑动*/

        that._scroll();

    },

    /*对外开放的设置定位的方法*/

    setTranslate:function(translate){

        this.currPostion = translate;

        this._addTransition();

        this._changeTranslate(this.currPostion);

    },

    _addTransition:function(){

        this.childDom.style.transition = "all .2s ease";

        this.childDom.style.webkitTransition = "all .2s ease";/*兼容 老版本webkit内核浏览器*/

    },

    _removeTransition:function(){

        this.childDom.style.transition = "none";

        this.childDom.style.webkitTransition = "none";/*兼容 老版本webkit内核浏览器*/

    },

    _changeTranslate:function(translate){

        if(this.settings.swipeType == 'y'){

            this.childDom.style.transform = "translateY("+translate+"px)";

            this.childDom.style.webkitTransform = "translateY("+translate+"px)";

        }else{

            this.childDom.style.transform = "translateX("+translate+"px)";

            this.childDom.style.webkitTransform = "translateX("+translate+"px)";

        }

    },

    _scroll:function(){

        /*局部变量来接受当前的this*/

        var that = this;

        /*滑动的类型*/

        var type = that.settings.swipeType == 'y'?true:false;

        /*父容器的高度或宽度*/

        var parentHeight = type?that.parentDom.offsetHeight:that.parentDom.offsetWidth;

        /*子容器的高度或宽度*/

        var childHeight = type?that.childDom.offsetHeight:that.childDom.offsetWidth;

        /*子容器没有父容器大的时候*/

        if(childHeight < parentHeight){

            if(type){

                that.childDom.style.height = parentHeight + 'px';

                childHeight = parentHeight;

            }else{

                that.childDom.style.width = parentHeight + 'px';

                childHeight = parentHeight;

            }

        }

        /*缓冲距离*/

        var distance = that.settings.swipeDistance;

        /*区间*/

        /*左侧盒子定位的区间*/

        that.maxPostion = 0;

        that.minPostion = -(childHeight-parentHeight);

        /*设置滑动的当前位置*/

        that.currPostion = 0;

        that.startPostion = 0;

        that.endPostion = 0;

        that.movePostion = 0;

        /*1.滑动*/

        that.childDom.addEventListener('touchstart',function(e){

            /*初始的Y的坐标*/

            that.startPostion = type?e.touches[0].clientY: e.touches[0].clientX;

        },false);

        that.childDom.addEventListener('touchmove',function(e){

            e.preventDefault();

            /*不停的做滑动的时候记录的endY的值*/

            that.endPostion = type?e.touches[0].clientY: e.touches[0].clientX;

            that.movePostion = that.startPostion - that.endPostion;/*计算了移动的距离*/

            /*2.滑动区间*/

            /*就是滑动区间*/

            if((that.currPostion-that.movePostion)<(that.maxPostion+distance)

                &&

                (that.currPostion-that.movePostion)>(that.minPostion -distance)){

                that._removeTransition();

                that._changeTranslate(that.currPostion-that.movePostion);

            }

        },false);

        window.addEventListener('touchend',function(e){

            /*在限制滑动区间之后 重新计算当前定位*/

            /*判断是否在我们的合理定位区间内*/

            /*先向下滑动 */

            if((that.currPostion-that.movePostion) > that.maxPostion){

                that.currPostion = that.maxPostion;

                that._addTransition();

                that._changeTranslate(that.currPostion);

            }

            /*想上滑动的时候*/

            else if((that.currPostion-that.movePostion) < that.minPostion){

                that.currPostion = that.minPostion;

                that._addTransition();

                that._changeTranslate(that.currPostion);

            }

            /*正常的情况*/

            else{

                that.currPostion = that.currPostion-that.movePostion;

            }

            that._reset();

        },false);

    },

    _reset:function(){

        var that = this;

        that.startPostion = 0;

        that.endPostion = 0;

        that.movePostion = 0;

    }

};