o2.widget = o2.widget || {};
o2.widget.DragScroll = new Class({

	// We'd like to use the Options Class Mixin
	Implements : [ Options, Events ],

	// Default options
	options : {
		friction : 5,
		axis : {
			x : true,
			y : true
		}
	},

	initialize : function(element, options) {
		element = this.element = document.id(element);
		this.content = element.getFirst();
		this.setOptions(options);

		// Drag speed
		var prevTime, prevScroll, scroll;
		//var timer;
		var speed=[];
		var timerFn = function() {
			var now = Date.now();
		//	var s = element.getScroll();
		//	scroll = [ s.x, s.y ];
			scroll = [ element.scrollLeft, element.scrollTop ];
			if (prevTime) {
				var dt = now - prevTime + 1;
				speed = [ 1000 * (scroll[0] - prevScroll[0]) / dt,
						1000 * (scroll[1] - prevScroll[1]) / dt ];
			}
			prevScroll = scroll;
			prevTime = now;
		};
//		var timerFn1 = function() {
//			var now = Date.now();
//		//	var s = element.getScroll();
//		//	scroll = [ s.x, s.y ];
//			scroll = [ element.scrollLeft, element.scrollTop ];
//			if (prevTime) {
//
//				var dt = now - prevTime + 1;
//				speed = [ 1000 * (scroll[0] - prevScroll[0]) / dt,
//						1000 * (scroll[1] - prevScroll[1]) / dt ];
//			}
//			prevScroll = scroll;
//			prevTime = now;
//		};

		// Use Fx.Scroll for scrolling to the right position after the dragging
		var fx = this.fx = new Fx.Scroll(element, {
			transition : Fx.Transitions.Expo.easeOut
		});

		// Set initial scroll
		fx.set.apply(fx, this.limit(element.scrollLeft, element.scrollTop));

		var self = this;
		friction = this.options.friction, axis = this.options.axis;

		// Make the element draggable
		self.drag = this.drag = new Drag(element, {
			style : false,
			invert : true,
			modifiers : {
				x : axis.x && 'scrollLeft',
				y : axis.y && 'scrollTop'
			},
			onStart : function() {
				// Start the speed measuring

				self.fireEvent("dragStart");
				timerFn();
		//		timer = setInterval(timerFn, 1000 / 60);
				// cancel any fx if they are still running
				fx.cancel();
			},
			onDrag: function(){
				self.fireEvent("drag");
			},
			onComplete : function() {
				// Stop the speed measuring
		//		clearInterval(timer);

				timerFn();

				prevTime = false;
				// Scroll to the new location
				var tmpx = 0;
				var tmpy = 0;
				if (speed[0]) tmpx = speed[0];
				if (speed[1]) tmpy = speed[1];
				

				var l = self.limit(scroll[0] + tmpx/friction, scroll[1] + tmpy/friction);
				
				fx.start.apply(fx, l);
				
				self.fireEvent("dragComplete", l);
			}
		});

	},

	// Calculate the limits
	getLimit : function() {
		var limit = [ [ 0, 0 ], [ 0, 0 ] ], element = this.element;
		var styles = Object.values(
				this.content.getStyles('padding-left', 'border-left-width',
						'margin-left', 'padding-top', 'border-top-width',
						'margin-top', 'width', 'height')).invoke('toInt');
		var size = this.content.getComputedSize();
		if (!styles[7]) styles[7] = size.totalHeight;
		if (!styles[6])	styles[6] = size.totalWidth;
		limit[0][0] = this.sum(styles.slice(0, 3));
		limit[0][1] = styles[6] + limit[0][0] - element.clientWidth;
		limit[1][0] = this.sum(styles.slice(3, 6));
		limit[1][1] = styles[7] + limit[1][0] - element.clientHeight;
		return limit;
	},

	// Apply the limits to the x and y values
	limit : function(x, y) {
		var limit = this.getLimit();
		return [ x.limit(limit[0][0], limit[0][1]),
				y.limit(limit[1][0], limit[1][1]) ];
	},
	sum: function(array){
	  var result = 0;
	  for (var l = array.length; l--;) result += array[l];
	  return result;
	}

});