Effect.Scroll = Class.create();
Object.extend(Object.extend(Effect.Scroll.prototype, Effect.Base.prototype), {
  initialize: function(element) {
    this.element = $(element);
    if(!this.element) throw(Effect._elementDoesNotExistError);
    this.start(Object.extend({x: 0, y: 0}, arguments[1] || {}));
  },
  setup: function() {
    var scrollOffsets = (this.element == window) 
                ? document.viewport.getScrollOffsets() 
                : Element._returnOffset(this.element.scrollLeft, this.element.scrollTop) ;
    this.originalScrollLeft = scrollOffsets.left;
    this.originalScrollTop  = scrollOffsets.top;
  },
  update: function(pos) {
    this.element.scrollTo(Math.round(this.options.x * pos + this.originalScrollLeft), Math.round(this.options.y * pos + this.originalScrollTop));
  }
});

document.observe('dom:loaded', function(event){
	$$('a[href*="#"]').each(function(anchor){
		anchor.observe('click', function(event) {
			var pageAnchor   = $$('a[name~="#{href}"]'.interpolate({href: this.href.split('#')[1]})).first();
			var delta        = pageAnchor.offsetTop - document.viewport.getScrollOffsets().top;
			var updateUrl    = function(){ location.href = this.href }.bind(this);

			new Effect.Scroll(window, { y: delta, afterFinish: updateUrl, duration: 1 });
			Event.stop(event);
		});
	});
});