Fx.Scroll = new Class({

	Extends: Fx,

	options: {
		offset: {'x': 0, 'y': 0},
		wheelStops: true
	},

	initialize: function(element, options){
		this.element = this.subject = $(element);
		this.parent(options);
		var cancel = this.cancel.bind(this, false);

		if ($type(this.element) != 'element') this.element = $(this.element.getDocument().body);

		var stopper = this.element;

		if (this.options.wheelStops){
			this.addEvent('start', function(){
				stopper.addEvent('mousewheel', cancel);
			}, true);
			this.addEvent('complete', function(){
				stopper.removeEvent('mousewheel', cancel);
			}, true);
		}
	},

	set: function(){
		var now = Array.flatten(arguments);
		this.element.scrollTo(now[0], now[1]);
	},

	compute: function(from, to, delta){
		var now = [];
		var x = 2;
		x.times(function(i){
			now.push(Fx.compute(from[i], to[i], delta));
		});
		return now;
	},

	start: function(x, y){
		if (!this.check(arguments.callee, x, y)) return this;
		var offsetSize = this.element.getSize(), scrollSize = this.element.getScrollSize();
		var scroll = this.element.getScroll(), values = {x: x, y: y};
		for (var z in values){
			var max = scrollSize[z] - offsetSize[z];
			if ($chk(values[z])) values[z] = ($type(values[z]) == 'number') ? values[z].limit(0, max) : max;
			else values[z] = scroll[z];
			values[z] += this.options.offset[z];
		}
		return this.parent([scroll.x, scroll.y], [values.x, values.y]);
	},

	toTop: function(){
		return this.start(false, 0);
	},

	toLeft: function(){
		return this.start(0, false);
	},

	toRight: function(){
		return this.start('right', false);
	},

	toBottom: function(){
		return this.start(false, 'bottom');
	},

	toElement: function(el){
		var position = $(el).getPosition(this.element);
		return this.start(position.x, position.y);
	}

});

var SmoothScroll = new Class({

	Extends: Fx.Scroll,

	initialize: function(options, context){
		context = context || document;
		var doc = context.getDocument(), win = context.getWindow();
		this.parent(doc, options);
		this.links = (this.options.links) ? $$(this.options.links) : $$(doc.links);
		var location = win.location.href.match(/^[^#]*/)[0] + '#';
		this.links.each(function(link){
			if (link.href.indexOf(location) != 0) return;
			var anchor = link.href.substr(location.length);
			if (anchor && $(anchor)) this.useLink(link, anchor);
		}, this);
		if (!Browser.Engine.webkit419) this.addEvent('complete', function(){
			win.location.hash = this.anchor;
		}, true);
	},

	useLink: function(link, anchor){
		link.addEvent('click', function(event){
			this.anchor = anchor;
			this.toElement(anchor);
			event.stop();
		}.bind(this));
	}

});

window.addEvent( 'domready', function() {
	
	new SmoothScroll();
	
});