var ScrollBar = new Class({

		Implements: [Events, Options],

		options: {
			maxThumbSize: 15,
			wheel: 8,
			arrows: true
		},

		initialize: function(main, content, options){
			this.setOptions(options);
			
			this.main = $(main);
			this.content = $(content);
			
			if (this.options.arrows == true){
				this.arrowOffset = 30;
			} else {
				this.arrowOffset = 0;
			}

			this.vScrollbar = new Element('div', {
    				'class': 'vScrollbar'
				}).injectAfter(this.content);				

			if (this.options.arrows == true){				
				this.arrowUp = new Element('div', {
    					'class': 'arrowUp'
					}).injectInside(this.vScrollbar);
			}	

			this.vTrack = new Element('div', {
    				'class': 'vTrack'
				}).injectInside(this.vScrollbar);
				
			this.vThumb = new Element('div', {
    				'class': 'vThumb'
				}).injectInside(this.vTrack);

			if (this.options.arrows == true){				
				this.arrowDown = new Element('div', {
    					'class': 'arrowDown'
					}).injectInside(this.vScrollbar);
			}		
			
			this.bound = {
				'vStart': this.vStart.bind(this),			
				'end': this.end.bind(this),
				'vDrag': this.vDrag.bind(this),			
				'wheel': this.wheel.bind(this),
				'vPage': this.vPage.bind(this)			
			};

			this.vPosition = {};			
			this.vMouse = {};		
			this.update();
			this.attach();
		},

		update: function(){
			
			this.main.setStyle('height', this.content.offsetHeight);
			this.vTrack.setStyle('height', this.content.offsetHeight - this.arrowOffset);
						
			this.main.setStyle('width', this.content.offsetWidth);
			
			// Remove and replace vertical scrollbar			
			if (this.content.scrollHeight <= this.main.offsetHeight) {
				this.vScrollbar.setStyle('display', 'none');
				this.content.setStyle('width', this.content.offsetWidth);	
			} else {
				this.vScrollbar.setStyle('display', 'block');			
			}
	

			// Vertical
			
			this.vContentSize = this.content.offsetHeight;
			this.vContentScrollSize = this.content.scrollHeight;
			this.vTrackSize = this.vTrack.offsetHeight;

			this.vContentRatio = this.vContentSize / this.vContentScrollSize;

			this.vThumbSize = (this.vTrackSize * this.vContentRatio).limit(this.options.maxThumbSize, this.vTrackSize);
			
			this.vScrollRatio = this.vContentScrollSize / this.vTrackSize;

			this.vThumb.setStyle('height', this.vThumbSize);

			this.vUpdateThumbFromContentScroll();
			this.vUpdateContentFromThumbPosition();
			
		},

		vUpdateContentFromThumbPosition: function(){
			this.content.scrollTop = this.vPosition.now * this.vScrollRatio;
		},

		vUpdateThumbFromContentScroll: function(){
			this.vPosition.now = (this.content.scrollTop / this.vScrollRatio).limit(0, (this.vTrackSize - this.vThumbSize));
			this.vThumb.setStyle('top', this.vPosition.now);
		},

		attach: function(){
			this.vThumb.addEvent('mousedown', this.bound.vStart);
			if (this.options.wheel) this.content.addEvent('mousewheel', this.bound.wheel);
			this.vTrack.addEvent('mouseup', this.bound.vPage);
			
			if (this.options.arrows == true){
				this.arrowUp.addEvent('mousedown', function(event){
						this.interval = (function(event){
						this.content.scrollTop -= this.options.wheel;
						this.vUpdateThumbFromContentScroll();
					}.bind(this).periodical(40))
				}.bind(this));
			
				this.arrowUp.addEvent('mouseup', function(event){
					$clear(this.interval);
				}.bind(this));
			
				this.arrowUp.addEvent('mouseout', function(event){
					$clear(this.interval);
				}.bind(this));
						
				this.arrowDown.addEvent('mousedown', function(event){
						this.interval = (function(event){
						this.content.scrollTop += this.options.wheel;
						this.vUpdateThumbFromContentScroll();
					}.bind(this).periodical(40))
				}.bind(this));
			
				this.arrowDown.addEvent('mouseup', function(event){
					$clear(this.interval);
				}.bind(this));
			
				this.arrowDown.addEvent('mouseout', function(event){
					$clear(this.interval);
				}.bind(this));
			}			
						
		},
		
		wheel: function(event){
			this.content.scrollTop -= event.wheel * this.options.wheel;
			this.vUpdateThumbFromContentScroll();
			event.stop();
		},

		vPage: function(event){
			if (event.page.y > this.vThumb.getPosition().y) this.content.scrollTop += this.content.offsetHeight;
			else this.content.scrollTop -= this.content.offsetHeight;
			this.vUpdateThumbFromContentScroll();
			event.stop();
		},

		vStart: function(event){
			this.vMouse.start = event.page.y;
			this.vPosition.start = this.vThumb.getStyle('top').toInt();
			document.addEvent('mousemove', this.bound.vDrag);
			document.addEvent('mouseup', this.bound.end);
			this.vThumb.addEvent('mouseup', this.bound.end);
			event.stop();
		},

		end: function(event){
			document.removeEvent('mousemove', this.bound.vDrag);			
			document.removeEvent('mouseup', this.bound.end);
			this.vThumb.removeEvent('mouseup', this.bound.end);		
			event.stop();
		},

		vDrag: function(event){
			this.vMouse.now = event.page.y;
			this.vPosition.now = (this.vPosition.start + (this.vMouse.now - this.vMouse.start)).limit(0, (this.vTrackSize - this.vThumbSize));
			this.vUpdateContentFromThumbPosition();
			this.vUpdateThumbFromContentScroll();
			event.stop();
		}

	});