var upH = 50; // Height of up-arrow
var upW = 50; // Width of up-arrow
var downH = 50; // Height of down-arrow
var downW = 50; // Width of down-arrow
var dragH = 16; // Height of scrollbar
var dragW = 51; // Width of scrollbar
var scrollH = 246; // Height of scrollbar
var speed = 4; // Scroll speed

// Browser detection
var dom = document.getElementById ? true:false;
var nn4 = document.layers ? true:false;
var ie4 = document.all ? true:false;

var mouseY; // Mouse Y position onclick
var mouseX; // Mouse X position onclick

var clickUp = false; // If click on up-arrow
var clickDown = false; // If click on down-arrow
var clickDrag = false; // If click on scrollbar
var clickAbove = false; // If click above scrollbar
var clickBelow = false; // If click below scrollbar

var timer = setTimeout("",500); // Repeat variable
var upL; // Up-arrow X
var upT; // Up-arrow Y
var downL; // Down-arrow X
var downT; // Down-arrow Y
var dragL; // Scrollbar X
var dragT; // Scrollbar Y
var rulerL; // Ruler X
var rulerT; // Ruler Y
var contentT; // Content layer Y;
var contentH; // Content height
var contentClipH; // Content clip height
var scrollLength; // Number of pixels scrollbar should move
var startY; // Keeps track of offset between mouse and span

// Mousedown
function down(e,button){
	if((document.layers && e.which!=1) || (document.all && event.button!=1)) return true; // Enables the right mousebutton
	getMouse(e);
	startY = (mouseY - dragT);
	
	// If click on up-arrow
	if(mouseX >= upL && (mouseX <= (upL + upW)) && mouseY >= upT && (mouseY <= (upT + upH)))
	{
		clickUp = true;
		return scrollUp();
	}	
	// Else if click on down-arrow
	else if(mouseX >= downL && (mouseX <= (downL + downW)) && mouseY >= downT && (mouseY <= (downT + downH))){
		clickDown = true;
		return scrollDown();
	}
	// Else if click on scrollbar
	else if(mouseX >= dragL && (mouseX <= (dragL + dragW)) && mouseY >= dragT && (mouseY <= (dragT + dragH))){
		clickDrag = true;
		return false;
	}
	else if(mouseX >= dragL && (mouseX <= (dragL + dragW)) && mouseY >= rulerT && (mouseY <= (rulerT + scrollH))){
		// If click above drag
		if(mouseY < dragT){
			clickAbove = true;
			clickUp = true;
			return scrollUp();
		}
		// Else click below drag
		else{
			clickBelow = true;
			clickDown = true;
			return scrollDown();
		}
	}
	// If no scrolling is to take place
	else{
		return true;
	}
}

// Drag function
function move(e){
	if(clickDrag && contentH > contentClipH){
		getMouse(e);
		dragT = (mouseY - startY);
		
		if(dragT < (rulerT))
			dragT = rulerT;		
		if(dragT > (rulerT + scrollH - dragH))
			dragT = (rulerT + scrollH - dragH);
		
		contentT = ((dragT - rulerT)*(1/scrollLength));
		contentT = eval('-' + contentT);

		moveTo();
		
		// So ie-pc doesn't select gifs
		if(ie4)
			return false;
	}
}

function up(){
	clearTimeout(timer);
	// Resetting variables
	clickUp = false;
	clickDown = false;
	clickDrag = false;
	clickAbove = false;
	clickBelow = false;
	return true;
}

// Reads content layer top
function getT(){
	if(ie4)
		contentT = document.all.content.style.pixelTop;
	else if(nn4)
		contentT = document.contentClip.document.content.top;
	else if(dom)
		contentT = parseInt(document.getElementById("content").style.top);
}

// Reads mouse X and Y coordinates
function getMouse(e){
	if(ie4){
		mouseY = event.clientY + document.body.scrollTop;
		mouseX = event.clientX + document.body.scrollLeft;
	}
	else if(nn4 || dom){
		mouseY = e.pageY;
		mouseX = e.pageX;
	}
  
  var offset = getScreenOffset(document.getElementById('ScrollArea'));

	mouseX = mouseX - offset[0]; 
	mouseY = mouseY - offset[1]; 
}

function getScreenOffset(obj)
{
  var ret;
  if(obj.offsetParent && obj.offsetParent.tagName != 'BODY')
    ret = getScreenOffset(obj.offsetParent);
  else
    ret = new Array(0,0);
  
  ret[0] += obj.offsetLeft;
  ret[1] += obj.offsetTop;

  return ret;
}

// Moves the layer
function moveTo(){
	if(ie4){
		document.all.content.style.top = contentT;
		document.all.ruler.style.top = dragT;
		document.all.drag.style.top = dragT;
	}
	else if(nn4){
		document.contentClip.document.content.top = contentT;
		document.ruler.top = dragT;
		document.drag.top = dragT;
	}
	else if(dom){
		document.getElementById("content").style.top = contentT + "px";
		document.getElementById("drag").style.top = dragT + "px";
		document.getElementById("ruler").style.top = dragT + "px";
	}
}

// Scrolls up
function scrollUp(){
	getT();
	
	if(clickAbove){
		if(dragT <= (mouseY-(dragH/2)))
			return up();
	}
	
	if(clickUp){
		if(contentT < 0){		
			dragT = dragT - (speed*scrollLength);
			
			if(dragT < (rulerT))
				dragT = rulerT;
				
			contentT = contentT + speed;
			if(contentT > 0)
				contentT = 0;
			
			moveTo();
			timer = setTimeout("scrollUp()",25);
		}
	}
	return false;
}

// Scrolls down
function scrollDown(){
	getT();
	
	if(clickBelow){
		if(dragT >= (mouseY-(dragH/2)))
			return up();
	}

	if(clickDown){
		if(contentT > -(contentH - contentClipH)){			
			dragT = dragT + (speed*scrollLength);
			if(dragT > (rulerT + scrollH - dragH))
				dragT = (rulerT + scrollH - dragH);
			
			contentT = contentT - speed;
			if(contentT < -(contentH - contentClipH))
				contentT = -(contentH - contentClipH);
			
			moveTo();
			timer = setTimeout("scrollDown()",25);
		}
	}
	return false;
}

// reloads page to position the layers again
function reloadPage(){
	location.reload();
}

// Preload
function eventLoader()
{
  var upEl = document.getElementById("up");
  var downEl = document.getElementById("down");
  var dragEl = document.getElementById("drag");
  
  if(!upEl || !downEl || !dragEl)
    return;
  
	// Up-arrow X and Y variables
	upL = parseInt(upEl.offsetLeft, 10);
	upT = parseInt(upEl.offsetTop, 10);
	// Down-arrow X and Y variables
	downL = parseInt(downEl.offsetLeft, 10);
	downT = parseInt(downEl.offsetTop, 10);
	// Scrollbar X and Y variables
	dragL = parseInt(dragEl.offsetLeft, 10);
	dragT = parseInt(dragEl.offsetTop, 10);
	// Ruler Y variable
	rulerT = parseInt(document.getElementById("ruler").offsetTop, 10);
	// Height of content layer and clip layer
	contentH = parseInt(document.getElementById("content").offsetHeight, 10);
	contentClipH = parseInt(document.getElementById("contentClip").offsetHeight, 10);
	document.getElementById("content").style.top = 0 + "px";
	
	var filter = contentH < contentClipH ? "gray" : "none";
	
	upEl.style.filter = filter;
	downEl.style.filter = filter;
	dragEl.style.filter = filter;
	
	// Number of pixels scrollbar should move
	scrollLength = ((scrollH-dragH)/(contentH-contentClipH));
	// Initializes event capturing
	if(nn4){
		document.captureEvents(Event.MOUSEDOWN | Event.MOUSEMOVE | Event.MOUSEUP);
		window.onresize = reloadPage;
	}
	document.onmousedown = down;
	document.onmousemove = move;
	document.onmouseup = up;

}