/* 
 * 移动端模拟导航可点击自动滑动 0.1.4 
 * Date: 2017-11-21 
 * by: hb
 * 导航可左右滑动，可点击边缘的一个，自动滚动下一个到可视范围【依赖于iscroll.js】 
 */
(function ($) {
    $.fn.navbarscroll = function (options) {
        //各种属性、参数 
        var _defaults = {
            //className:'cur', //当前选中点击元素的class类名 
            clickScrollTime:300, //点击后滑动时间 
            duibiScreenWidth:0.4, //单位以rem为准，默认为0.4rem 
            scrollerWidth:3, //单位以px为准，默认为3,[仅用于特殊情况：外层宽度因为小数点造成的不精准情况] 
            defaultSelect:0, //初始选中第n个，默认第0个 
            fingerClick:0, //目标第0或1个选项触发,必须每一项长度一致，方可用此项 
            endClickScroll:function(thisObj){}//回调函数 
        }
        var _opt = $.extend(_defaults, options);
        this.each(function () {
            //插件实现代码
            var _wrapper = $(this);
            var _win = $(window);
            var _win_width = _win.width(),_wrapper_width = _wrapper.width(),_wrapper_off_left = _wrapper.offset().left;
            var _wrapper_off_right=_win_width-_wrapper_off_left-_wrapper_width;
            var _obj_scroller = _wrapper.children('.scroller');
            var _obj_ul = _obj_scroller.children('ul');
            var _obj_li = _obj_ul.children('li');
            var _scroller_w = 0;
            _obj_li.css({"margin-left":"0","margin-right":"0"});
            for (var i = 0; i < _obj_li.length; i++) {
                _scroller_w += _obj_li[i].offsetWidth;
            }
            _obj_scroller.width(_scroller_w+_opt.scrollerWidth);
            var myScroll = new IScroll('#'+_wrapper.attr('id'), {
                eventPassthrough: true,
                scrollX: true,
                scrollY: false,
                preventDefault: false
            });
            _init(_obj_li.eq(_opt.defaultSelect));
            _obj_li.click(function(){
                _init($(this));
            });
			//解决PC端谷歌浏览器模拟的手机屏幕出现莫名的卡顿现象，滑动时禁止默认事件（2017-01-11）
			_wrapper[0].addEventListener('touchmove',function (e){e.preventDefault();},false);
            function _init(thiObj){
                var $this_obj=thiObj;
                var duibi=_opt.duibiScreenWidth*_win_width/10,this_index=$this_obj.index(),this_off_left=$this_obj.offset().left,this_pos_left=$this_obj.position().left,this_width=$this_obj.width(),this_prev_width=$this_obj.prev('li').width(),this_next_width=$this_obj.next('li').width();
                var this_off_right=_win_width-this_off_left-this_width;
                if(_scroller_w+2>_wrapper_width){
                    if(_opt.fingerClick==1){
                        if(this_index==1){
                            myScroll.scrollTo(-this_pos_left+this_prev_width,0, _opt.clickScrollTime);
                        }else if(this_index==0){
                            myScroll.scrollTo(-this_pos_left,0, _opt.clickScrollTime);
                        }else if(this_index==_obj_li.length-2){
                            myScroll.scrollBy(this_off_right-_wrapper_off_right-this_width,0, _opt.clickScrollTime);
                        }else if(this_index==_obj_li.length-1){
                            myScroll.scrollBy(this_off_right-_wrapper_off_right,0, _opt.clickScrollTime);
                        }else{
                            if(this_off_left-_wrapper_off_left-(this_width*_opt.fingerClick)<duibi){
                                myScroll.scrollTo(-this_pos_left+this_prev_width+(this_width*_opt.fingerClick),0, _opt.clickScrollTime);
                            }else if(this_off_right-_wrapper_off_right-(this_width*_opt.fingerClick)<duibi){
                                myScroll.scrollBy(this_off_right-this_next_width-_wrapper_off_right-(this_width*_opt.fingerClick),0, _opt.clickScrollTime);
                            }
                        }
                    }else{
                        if(this_index==1){
                            myScroll.scrollTo(-this_pos_left+this_prev_width,0, _opt.clickScrollTime);
                        }else if(this_index==_obj_li.length-1){
                            if(this_off_right-_wrapper_off_right>1||this_off_right-_wrapper_off_right<-1){
                                myScroll.scrollBy(this_off_right-_wrapper_off_right,0, _opt.clickScrollTime);
                            }
                        }else{
                            if(this_off_left-_wrapper_off_left<duibi){
                                myScroll.scrollTo(-this_pos_left+this_prev_width,0, _opt.clickScrollTime);
                            }else if(this_off_right-_wrapper_off_right<duibi){
                                myScroll.scrollBy(this_off_right-this_next_width-_wrapper_off_right,0, _opt.clickScrollTime);
                            }
                        }
                    }
                }
                $this_obj.addClass(_opt.className).siblings('li').removeClass(_opt.className);
                _opt.endClickScroll.call(this,$this_obj);
            }
        });
    };
})(jQuery);