/*xb_scroll*/


;(function($, window, document,undefined) {

$.fn.xb_scroll = function(options)
{
	var scroll_config={
		"speed":25,
		"isMaxHeight":false,
		"barOffTop":2,
		"barOffBottom":2,
		"barOffRight":2,
		"boxWidth":2,
		"barWidth":2,
		"childPanel":"._panel-box",
		"boxClass":"_scroll_box",
		"barClass":"_scroll_bar"
	}
	
	var opts = $.extend({},scroll_config,options)
	var w = {};
	w.FlagName = "_Prefix";	
	var elem = $(this) , id = $(this).attr("id") , elChild;

	elem.css({"position":"relative","overflow":"hidden"});
	elChild = elem.find(opts.childPanel);
	elChild.css({"position":"absolute","width":"100%","top":"0"});

	if(opts.isMaxHeight)
	{
		var sham = $("<div style='position:relative;background:transparent;z-index:-1;height:"+elChild.outerHeight()+"px'></div>");
		sham.appendTo(elem);
	}

	var jqScrollBox = $("<div style='position:absolute;width:"+opts.boxWidth+"px;top:"+opts.barOffTop+"px;right:"+opts.barOffRight+"px;bottom:"+opts.barOffBottom+"px;border-radius: 5px;background:#345bc2;'></div>");
	jqScrollBox.addClass(opts.boxClass);
	var jqScrollBar= $("<div style='position:absolute;width:"+opts.barWidth+"px;top:"+opts.barOffTop+"px;right:"+opts.barOffRight+"px;border-radius: 5px;background: #6f95fc;'></div>");
	jqScrollBar.addClass(opts.barClass);
	jqScrollBox.appendTo(elem);
	jqScrollBar.appendTo(elem);
	
	var iRate = elem.innerHeight()/elChild.outerHeight();	
	var iScrollBoxHeight = jqScrollBox.innerHeight() ;
	var iScrollBarHeight = Math.round(iRate*iScrollBoxHeight);
	if(iRate >= 1){
		jqScrollBox.hide();
		jqScrollBar.css("height",0);
	}
	else
	{
		jqScrollBar.css("height",iScrollBarHeight);
	}	
	var iMinTop = elem.innerHeight() - elChild.outerHeight();
	var sMaxTop = iScrollBoxHeight - iScrollBarHeight + opts.barOffTop;

	var sMouseWheel = "mousewheel";
	if(!("onmousewheel" in document)){						/*浏览器鼠标滚动事件的简单兼容*/
		sMouseWheel = "DOMMouseScroll";
	}   	
	elem.on(sMouseWheel,function(ev){
		ev.preventDefault();
		ev = ev.originalEvent;
		if(iRate >= 1)
			return;
		if(ev.wheelDelta){
				iWheelDelta = ev.wheelDelta/120;
		}else{
				iWheelDelta = -ev.detail/3;
		}		
		if(iMinTop>0){
			elChild.css("top",0);
			return;
		}
		var iTop = parseInt(elChild.css("top"));
		var iTop = iTop + opts.speed*iWheelDelta;
		iTop = iTop > 0 ? 0 : iTop;
		iTop = iTop < iMinTop ? iMinTop : iTop;
		elChild.css("top",iTop);
		fnScrollContent(elem,elChild,jqScrollBox,jqScrollBar,opts.barOffTop);
	});

	var isS_B = false ,  doc_py , barTop , conTop;			/*滚动条拖拽*/
	jqScrollBar.on("mousedown",function(ev){
		isS_B = true;
		elem.css({"-moz-user-select": "none","-khtml-user-select": "none","user-select": "none"});
		jqScrollBar.css({"background":"#6f95fc"});
		barTop = parseInt(jqScrollBar.css("top"));
		conTop = parseInt(elChild.css("top"));		
	});
	$(document).on("mousedown",function(ev){
		if(isS_B)
			doc_py = ev.pageY;
	});
	$(document).on("mousemove",function(ev){
		if(isS_B)
		{			
			var rate = ev.pageY - doc_py;			

			var sTop = barTop + rate;
			sTop = sTop < opts.barOffTop ? opts.barOffTop : sTop;
			sTop = sTop > sMaxTop ? sMaxTop : sTop;
			jqScrollBar.css("top",sTop);

			var jqCon_rate = elChild.outerHeight() * (rate/iScrollBoxHeight) * -1;
			var iTop = conTop + jqCon_rate;
			iTop = iTop > 0 ? 0 : iTop;
			iTop = iTop < iMinTop ? iMinTop : iTop;
			elChild.css("top",iTop);		
		}
	});
	$(document).on("mouseup",function(ev){	
		elem.css({"-moz-user-select": "","-khtml-user-select": "","user-select": ""});
		jqScrollBar.css({"background":"#6f95fc"});
		isS_B = false;	
	});	


	elChild.bind('DOMNodeInserted', function(e) {			/*容器内元素添加*/
		fnContentResize();
	});
	elChild.bind('DOMNodeRemoved', function(e) {		    /*容器内元素移除*/
		setTimeout(function(){fnContentResize();},100);		
	});
	function fnContentResize()								/*容器内元素变动更新滚动*/
	{
		if(opts.isMaxHeight)
		{
			sham.css({"height":elChild.outerHeight()+"px"});
		}
		iRate = elem.innerHeight()/elChild.outerHeight();
		if(iRate >= 1){
			jqScrollBox.hide();
			jqScrollBar.css("height",0);
			elChild.css("top",0);	
			return;
		}	
		jqScrollBox.show();
		iScrollBoxHeight = jqScrollBox.outerHeight();
		iScrollBarHeight = Math.round(iRate*iScrollBoxHeight);
		jqScrollBar.css("height",iScrollBarHeight);
		iMinTop = elem.innerHeight() - elChild.outerHeight();
		sMaxTop = iScrollBoxHeight - iScrollBarHeight ;
		var nowConTop = parseInt(elChild.css("top"));		
		fnScrollContent(elem,elChild,jqScrollBox,jqScrollBar,0,0);	
		if(nowConTop<iMinTop)
		{
			elChild.css("top",iMinTop);	
			jqScrollBar.css("top",sMaxTop);
		}		
	}
	
	function fnScrollContent(jqWrapper,jqContent,jqFollowWrapper,jqFlollowContent,iOffset){
		var rate = parseInt(jqContent.css("top"))/(jqContent.outerHeight()-jqWrapper.innerHeight())//卷起的比率
		var iTop = (jqFlollowContent.outerHeight()-jqFollowWrapper.innerHeight())*rate + iOffset;
		jqFlollowContent.css("top",iTop);

	}

	elem.data(w.FlagName,true);
}

})(jQuery, window, document);