//written by nathan faubion: http://n-son.com
//use this or edit how you want, just give me
//some credit!
function jsscrollbar (o, s, a, ev) {
	var self = this;
	
	this.reset = function () {
		//arguments that were passed
		this._parent = o;
		this._src    = s;
		this.auto    = a ? a : false;
		this.eventhandler = ev ? ev : function () {};
		//component objects
		this._up   = this._findcomponent("scrollbar-up", this._parent);
		this._down = this._findcomponent("scrollbar-down", this._parent);
		this._ytrack  = this._findcomponent("scrollbar-track", this._parent);
		this._yhandle = this._findcomponent("scrollbar-handle", this._ytrack);
		//height and position properties
		this._tracktop = findoffsettop(this._ytrack);
		this._trackheight  = this._ytrack.offsetheight;
		this._handleheight = this._yhandle.offsetheight;
		this._x = 0;
		this._y = 0;
		//misc. variables
		this._scrolldist  = 5;
		this._scrolltimer = null;
		this._selectfunc  = null;
		this._grabpoint   = null;
		this._temptarget  = null;
		this._tempdistx   = 0;
		this._tempdisty   = 0;
		this._disabled    = false;
		this._ratio = (this._src.totalheight - this._src.viewableheight)/(this._trackheight - this._handleheight);
		
		this._yhandle.ondragstart  = function () {return false;};
		this._yhandle.onmousedown = function () {return false;};
		this._addevent(this._src.content, "mousewheel", this._scrollbarwheel);
		this._removeevent(this._parent, "mousedown", this._scrollbarclick);
		this._addevent(this._parent, "mousedown", this._scrollbarclick);
		
		this._src.reset();
		with (this._yhandle.style) {
			top  = "0px";
			left = "0px";
		}
		this._movecontent();
		
		if (this._src.totalheight < this._src.viewableheight) {
			this._disabled = true;
			this._yhandle.style.visibility = "hidden";
			if (this.auto) this._parent.style.visibility = "hidden";
		} else {
			this._disabled = false;
			this._yhandle.style.visibility = "visible";
			this._parent.style.visibility  = "visible";
		}
	};
	this._addevent = function (o, t, f) {
		if (o.addeventlistener) {
		    o.addeventlistener(t, f, false);
		    if(t=="mousewheel"){
		       o.addeventlistener("dommousescroll", f, false); 
		    }
		}
		else if (o.attachevent) {o.attachevent('on'+ t, f);}
		else {o['on'+ t] = f;}
	};
	this._removeevent = function (o, t, f) {
		if (o.removeeventlistener) o.removeeventlistener(t, f, false);
		else if (o.detachevent) o.detachevent('on'+ t, f);
		else o['on'+ t] = null;
	};
	this._findcomponent = function (c, o) {
		var kids = o.childnodes;
		for (var i = 0; i < kids.length; i++) {
			if (kids[i].classname && kids[i].classname == c) {
				return kids[i];
			}
		}
	};
	//thank you, quirksmode
	function findoffsettop (o) {
		var t = 0;
		if (o.offsetparent) {
			while (o.offsetparent) {
				t += o.offsettop;
				o  = o.offsetparent;
			}
		}
		return t;
	};
	this._scrollbarclick = function (e) {
		if (self._disabled) return false;
		
		e = e ? e : event;
		if (!e.target) e.target = e.srcelement;
		
		if (e.target.classname.indexof("scrollbar-up") > -1) self._scrollup(e);
		else if (e.target.classname.indexof("scrollbar-down") > -1) self._scrolldown(e);
		else if (e.target.classname.indexof("scrollbar-track") > -1) self._scrolltrack(e);
		else if (e.target.classname.indexof("scrollbar-handle") > -1) self._scrollhandle(e);
		
		self._temptarget = e.target;
		self._selectfunc = document.onselectstart;
		document.onselectstart = function () {return false;};
		
		self.eventhandler(e.target, "mousedown");
		self._addevent(document, "mouseup", self._stopscroll, false);
		
		return false;
	};
	this._scrollbardrag = function (e) {
		e = e ? e : event;
		var t = parseint(self._yhandle.style.top);
		var v = e.clienty + document.body.scrolltop - self._tracktop;
		with (self._yhandle.style) {
			if (v >= self._trackheight - self._handleheight + self._grabpoint)
				top = self._trackheight - self._handleheight +"px";
			else if (v <= self._grabpoint) top = "0px";
			else top = v - self._grabpoint +"px";
			self._y = parseint(top);
		}
		
		self._movecontent();
	};
	this._scrollbarwheel = function (e) {
		if (!e) e = window.event; 
		var dir = 0;
		if (e.wheeldelta >= 120) dir = -1;
		if (e.wheeldelta <= -120) dir = 1;
		if (e.detail  >= 3) dir = 1; //for firefox
		if (e.detail  <= -3) dir = -1; //for firefox
		//alert(dir);
		self.scrollby(0, dir * 20);
		if(window.event) e.returnvalue = false;
		else e.preventdefault();//for firefox
	};
	this._startscroll = function (x, y) {
		this._tempdistx = x;
		this._tempdisty = y;
		this._scrolltimer = window.setinterval(function () {
			self.scrollby(self._tempdistx, self._tempdisty); 
		}, 40);
	};
	this._stopscroll = function () {
		self._removeevent(document, "mousemove", self._scrollbardrag, false);
		self._removeevent(document, "mouseup", self._stopscroll, false);
		
		if (self._selectfunc) document.onselectstart = self._selectfunc;
		else document.onselectstart = function () { return true; };
		
		if (self._scrolltimer) window.clearinterval(self._scrolltimer);
		self.eventhandler (self._temptarget, "mouseup");
	};
	this._scrollup = function (e) {this._startscroll(0, -this._scrolldist);};
	this._scrolldown = function (e) {this._startscroll(0, this._scrolldist);};
	this._scrolltrack = function (e) {
		var cury = e.clienty + document.body.scrolltop;
		this._scroll(0, cury - this._tracktop - this._handleheight/2);
	};
	this._scrollhandle = function (e) {
		var cury = e.clienty + document.body.scrolltop;
		this._grabpoint = cury - findoffsettop(this._yhandle);
		this._addevent(document, "mousemove", this._scrollbardrag, false);
	};
	this._scroll = function (x, y) {
		if (y > this._trackheight - this._handleheight) 
			y = this._trackheight - this._handleheight;
		if (y < 0) y = 0;
		
		this._yhandle.style.top = y +"px";
		this._y = y;
		
		this._movecontent();
	};
	this._movecontent = function () {
		this._src.scrollto(0, math.round(this._y * this._ratio));
	};
	
	this.scrollby = function (x, y) {
		this._scroll(0, (-this._src._y + y)/this._ratio);
	};
	this.scrollto = function (x, y) {
		this._scroll(0, y/this._ratio);
	};
	this.swapcontent = function (o, w, h) {
		this._removeevent(this._src.content, "mousewheel", this._scrollbarwheel, false);
		this._src.swapcontent(o, w, h);
		this.reset();
	};
	
	this.reset();
};