/*
鐢ㄩ€旈」鐩細鑷畾涔夋粴鍔ㄦ潯瀹炵幇
*/
(function(win, doc, $){
  // 瀹氫箟鐨勬粴鍔ㄦ潯鐨勬瀯閫犲嚱鏁
  function CusScrollBar(options) {
    // 鍑芥暟鐨勮皟鐢
    this._init(options);
  }
  // 瀵硅薄鐨勫悎骞
  $.extend(CusScrollBar.prototype, {
    _init: function(options){
      // 闂寘
      var self = this;
      // 鍒濆鍖栧弬鏁
      self.options = {
        scrollDir: 'Y',       //婊氬姩鐨勬柟鍚
        contentSelector: '',  //婊氬姩鍐呭鍖洪€夋嫨鍣
        barSelector: '',      //婊氬姩鏉￠€夋嫨鍣
        sliderSelector: '',   //婊氬姩婊戝潡閫夋嫨鍣
        wheelStep: 100,        //婊氬姩姝ラ暱锛堥紶鏍囩Щ鍔ㄤ竴涓嬶紝鍐呭婊氬姩鐨勫箙搴︼級
      }
      // 瑕嗙洊鍙傛暟
      $.extend(true, self.options, options||{});
      self._initDomEvent();
      return self;
    },

    /**
     * 鍒濆鍖朌OM寮曠敤
     * @method _initDomEvent
     * @return {CusScrollBar}
     */
     _initDomEvent: function() {
      var opts = this.options;
      // 婊氬姩鍐呭鍖哄璞★紝蹇呭～椤
      this.$cont = $(opts.contentSelector);
      // 婊氬姩鏉℃粦鍧楀璞★紝蹇呴』椤
      this.$slider = $(opts.sliderSelector);
      // 婊氬姩鏉″璞
      this.$bar = opts.barSelector ? $(opts.barSelector) : self.$slider.parent();
      // 鑾峰彇鏂囨。瀵硅薄
      this.$doc = $(doc);
      // 鑾峰彇鍒濆鍖栨粦鍧楁嫋鍔ㄥ姛鑳
      this._initSliderDragEvent();
      // 鑾峰彇鍚屾婊戝潡鐨勪綅缃
      this._bindContentScroll();
      // 鑾峰彇榧犳爣婊氳疆浜嬩欢
      this._bindMousewheel();
      // 鑾峰彇鍐呭鏉ュ畾涔夋粦鍧楃殑楂樺害
      this._initSliderHeight();

     },
     // 鏍规嵁鍐呭鏉ュ畾涔夋粦鍧楃殑楂樺害
     _initSliderHeight: function() {
      var rate = this.$cont.height()/this.$cont[0].scrollHeight;
      var sliderHeight = rate*this.$bar.height();
      this.$slider.css('height',sliderHeight);
     },
     

     /**
      * 鍒濆鍖栨粦鍧楁嫋鍔ㄥ姛鑳
      * @return {[Object]} [this]
      */
    _initSliderDragEvent: function() {
      var self = this;
      // 婊戝潡鍏冪礌
      var slider = this.$slider,
          sliderEl = slider[0];
      // 濡傛灉鍏冪礌瀛樺湪
      if (sliderEl) {
        var doc = this.$doc,
            dragStartPagePostion,
            dragStartScrollPostion,
            dragContBarRate;
        function mousemoveHandler(e) {
          e.preventDefault();
          if (dragStartPagePostion == null) {
            return;
          }
          //鍐呭寮€濮嬪嵎鏇茬殑楂樺害+rate*(榧犳爣閲婃斁鐨勪綅缃?寮€濮嬬殑浣嶇疆) == 灏辨槸鍐呭婊戝姩鐨勪綅缃
          self.scrollTo(dragStartScrollPostion + (e.pageY - dragStartPagePostion)*dragContBarRate);
        }
        slider.on('mousedown', function(e){
          e.preventDefault();
          // 鑾峰彇榧犳爣鐨勭偣鍑荤殑寮€濮嬩綅缃
          dragStartPagePostion = e.pageY;
          // 鑾峰彇鍐呭鍖哄煙鐨勫悜涓婂嵎鍖虹殑楂樺害
          dragStartScrollPostion = self.$cont[0].scrollTop;
          dragContBarRate = self.getMaxScrollPosition()/self.getMaxSliderPosition();
          // 鐩戝惉鐨刣ocument瀵硅薄
          doc.on('mousemove.scroll', mousemoveHandler).on('mouseup.scroll',function(){
            doc.off('.scroll');
          });
        });
        return self;
      }
    },
    
    // 璁＄畻婊戝潡鐨勫綋鍓嶄綅缃
    getSliderPosition: function() {
      var self = this,
      // 婊戝潡鍙互绉诲姩鐨勮窛绂
          maxSliderPosition = self.getMaxSliderPosition();
          // 婊戝潡绉诲姩鐨勮窛绂
      return Math.min(maxSliderPosition, maxSliderPosition*self.$cont[0].scrollTop/self.getMaxScrollPosition());
    },

    // 鍐呭鍙粴鍔ㄧ殑楂樺害
    getMaxScrollPosition: function() {
      var self = this;
      return Math.max(self.$cont.height(), self.$cont[0].scrollHeight) - self.$cont.height();
    
    },

    //婊戝潡鍙Щ鍔ㄧ殑璺濈
    getMaxSliderPosition: function(){
      var self = this;
      return self.$bar.height() - self.$slider.height();
    },

    // 鐩戝惉鍐呭鐨勬粴鍔紝鍚屾婊戝潡鐨勪綅缃
    _bindContentScroll: function() {
      var self = this;
      self.$cont.on('scroll', function(){
        var sliderEl = self.$slider && self.$slider[0];
        if (sliderEl) {
          // 璁剧疆婊戝潡鐨勪綅缃
          sliderEl.style.top = self.getSliderPosition() + 'px';
        }
      });
      return self;
    },

    // 榧犳爣婊氳疆浜嬩欢
    _bindMousewheel: function() {
      var self = this;
      // on鐩戝惉浜嬩欢锛屽涓簨浠跺埄鐢ㄧ┖鏍煎垎寮€
      self.$cont.on('mousewheel DOMMouseScroll',function(e){
        e.preventDefault();
        // 鍒ゆ柇鍘熺敓浜嬩欢瀵硅薄鐨勫睘鎬
        var oEv = e.originalEvent,
        //鍘熺敓浜嬩欢瀵硅薄,锛堝叾浠栨祻瑙堝櫒璐熸暟鍚戜笅锛宖irefox姝ｆ暟鍚戜笅,鎵€浠ュ湪wheelDelta鍓嶉潰鏈夎礋鏁帮級
        // 鎯宠杈惧埌鐨勬晥鏋滐紝榧犳爣鍚戜笅婊氬姩锛屽唴瀹瑰悜涓嬭蛋
            wheelRange = oEv.wheelDelta ? -oEv.wheelDelta/120 : (oEv.detail || 0)/3;
            // 璋冪敤scrollTo鏂规硶銆
            self.scrollTo(self.$cont[0].scrollTop + wheelRange*self.options.wheelStep)
      });
    },

    // 鍐呭鐨勬粦鍔
    scrollTo: function(positonVal) {
      var self = this;
      self.$cont.scrollTop(positonVal);
    }
  });

  win.CusScrollBar = CusScrollBar;
})(window,document,jQuery)