var dom = document.getElementById;
var iex = document.all;
var ns4 = document.layers;
var mouseX, mouseY, enterX, enterY;

function addEvent(event,method)
{
	this[event] = method;
	if(ns4) this.captureEvents(Event[event.substr(2,event.length).toUpperCase()]);
}

function removeEvent(event)
{
	this[event] = null;
	if(ns4) this.releaseEvents(Event[event.substr(2,event.length).toUpperCase()]);
}

function getElement(name)
{
	var el = dom ? document.getElementById(name) : iex ? document.all[name] : ns4 ? eval("document."+name) : false;
	if ( el == null ) return null;
	el.css = ns4 ? el : el.style;
	el.getTop = function(){return parseInt(el.css.top) || 0};
	el.setTop = function(y){el.css.top = ns4 ? y: y+"px"};
	el.getLeft = function(){return parseInt(el.css.left) || 0};
	el.setLeft = function(x){el.css.left = ns4 ? x: x+"px"};
	el.getHeight = function(){return ns4 ? el.document.height : el.offsetHeight};
	el.getWidth = function(){return ns4 ? el.document.width : el.offsetWidth};
	el.getClipHeight = function(){return ns4 ? el.clip.height : el.offsetHeight};
	el.hideVis = function(){el.css.visibility="hidden"};
	el.showVis = function(){el.css.visibility="visible"};
	el.addEvent = addEvent;
	el.removeEvent = removeEvent;
	return el;
}

function getYMouse(e)
{
	return iex ? event.clientY : e.pageY;
}

document.addEvent = addEvent;
document.removeEvent = removeEvent;

ScrollObj = function(speed, groupName)
{
	this.sidecar = null;
	this.speed = speed;
	this.trackObj = getElement(groupName+"ScrollTrack");
	this.upObj = getElement(groupName+"ScrollUp");
	this.downObj = getElement(groupName+"ScrollDown");
	this.dragObj = getElement(groupName+"ScrollThumb");
	this.contentMaskObj = getElement(groupName+"ContentClip");
	this.contentObj = getElement(groupName+"Content");
	this.obj = groupName+"ContentObject";
	eval(this.obj+"=this");
	
	this.contentMaskHeight = this.contentMaskObj.getClipHeight();
	this.contentHeight = this.contentObj.getHeight();
	this.contentLength = this.contentHeight-this.contentMaskHeight;
	if ( this.dragObj != null ) this.dragHeight = this.dragObj.getHeight()-2 - (iex ? 4 : 0);
	if ( this.trackObj != null ) {
		this.trackHeight = getElement(groupName+"ScrollThumbTrack").getHeight();
		this.trackTop = this.trackObj.getTop();
		this.trackLength = this.trackHeight-this.dragHeight;
		this.trackBottom = this.trackTop+this.trackLength;
		this.scrollLength = this.trackLength/this.contentLength;
	}
	this.scrollTimer = null;
	
	if ( this.trackObj != null ) {
		if (this.contentHeight <= this.contentMaskHeight) {
			this.dragObj.hideVis();
			if ( this.upObj != null ) this.upObj.hideVis();
			if ( this.downObj != null ) this.downObj.hideVis();
			this.trackObj.hideVis();
		} else {
			var self = this;
			this.trackObj.addEvent("onmousedown", function(e){self.scrollJump(e);return false});
			if ( this.upObj != null ) {
				this.upObj.addEvent("onmousedown", function(){self.scroll(self.speed);return false});
				this.upObj.addEvent("onmouseup", function(){self.stopScroll()});
				this.upObj.addEvent("onmouseout", function(){self.stopScroll()});
			}
			if ( this.downObj != null ) {
				this.downObj.addEvent("onmousedown", function(){self.scroll(-self.speed);return false});
				this.downObj.addEvent("onmouseup", function(){self.stopScroll()});
				this.downObj.addEvent("onmouseout", function(){self.stopScroll()});
			}
			this.dragObj.addEvent("onmousedown", function(e){self.startDrag(e);return false});
			if(iex) this.dragObj.addEvent("ondragstart", function(){return false});
		}
	}
}

ScrollObj.prototype.addSidecar = function( groupName )
{
	this.sidecar = new ScrollObj( this.speed, groupName);
	this.sidecar.scrollLength = this.trackLength/this.sidecar.contentLength;
}

ScrollObj.prototype.startDrag = function(e)
{
	this.dragStartMouse = getYMouse(e);
	this.dragStartOffset = this.dragObj.getTop();
	var self = this;
	document.removeEvent("onmousemove");
	document.addEvent("onmousemove", function(e){self.drag(e)});
	document.addEvent("onmouseup", function(){self.stopDrag()});
}

ScrollObj.prototype.stopDrag = function() 
{
	document.removeEvent("onmousemove");
	document.addEvent("onmousemove", getMouse);
	document.removeEvent("onmouseup");
}

ScrollObj.prototype.drag = function(e)
{
	var currentMouse = getYMouse(e);
//	var currentMouse = getMouseY();
	var mouseDifference = currentMouse-this.dragStartMouse;
	var dragDistance = this.dragStartOffset+mouseDifference;
	var dragMovement = (dragDistance<this.trackTop) ? this.trackTop : (dragDistance>this.trackBottom) ? this.trackBottom : dragDistance;
	this.dragObj.setTop(dragMovement);
	var contentMovement = -(dragMovement-this.trackTop)*(1/this.scrollLength);
	this.contentObj.setTop(contentMovement);
	if ( this.sidecar != null ) {
		contentMovement = -(dragMovement-this.trackTop)*(1/this.sidecar.scrollLength);
		this.sidecar.contentObj.setTop(contentMovement);
	}
}

ScrollObj.prototype.scroll = function(speed)
{
	var contentMovement = this.contentObj.getTop()+speed;
	var dragMovement = this.trackTop-Math.round(this.contentObj.getTop()*(this.trackLength/this.contentLength));
	if(contentMovement > 0){
		contentMovement = 0;
	}else if(contentMovement < -this.contentLength){
		contentMovement = -this.contentLength;
	}
	if ( dragMovement < this.trackTop ) {
		dragMovement = this.trackTop;
	} else if ( dragMovement > this.trackBottom ) {
		dragMovement = this.trackBottom;
	}
	this.contentObj.setTop(contentMovement);
	this.dragObj.setTop(dragMovement);
	this.scrollTimer = window.setTimeout(this.obj+".scroll("+speed+")",25);
}

ScrollObj.prototype.stopScroll = function()
{
	if(this.scrollTimer){
		window.clearTimeout(this.scrollTimer);
		this.scrollTimer = null;
	}
}

ScrollObj.prototype.scrollJump = function(e)
{
	var currentMouse = getYMouse(e);
	var dragDistance = currentMouse-(this.dragHeight/2);
	var dragMovement = (dragDistance<this.trackTop) ? this.trackTop : (dragDistance>this.trackBottom) ? this.trackBottom : dragDistance;
	this.dragObj.setTop(dragMovement);
	var contentMovement = -(dragMovement-this.trackTop)*(1/this.scrollLength);
	this.contentObj.setTop(contentMovement);
}


function getMouse(e)
{
	mouseY = iex ? event.clientY : e.pageY;
	mouseX = iex ? event.clientX : e.pageX;
}

function getMouseY()
{
	return mouseY;
}

function fixNetscape4()
{
	if ( ns4origWidth != window.innerWidth || ns4origHeight != window.innerHeight ) {
		window.location.reload();
	}	
}

if (document.layers)
{
	ns4origWidth = window.innerWidth;
	ns4origHeight = window.innerHeight;
	window.onresize = fixNetscape4;
}

document.addEvent("onmousemove", getMouse);