if (window.Node && Node.prototype && !Node.prototype.contains) {
	Node.prototype.contains = function (arg) {
		return !!(this.compareDocumentPosition(arg) & 16);
	};
}

(function($) {

	//Make nodes selectable by expression
	$.extend($.expr[':'], { sortable: "(' '+a.className+' ').indexOf(' ui-sortable ')" });

	$.fn.extend({
		sortable: function(options) {
			if ( options == "serialize" )
				return $.data(this, "ui-sortable").serialize();
			
			return this.each(function() {
				if (typeof options == "string") {
					var sort = $.data(this, "ui-sortable");
					sort[options].apply(sort, args);

				} else if(!$.data(this, "ui-sortable"))
					new $.ui.sortable(this, options);
			});
		}
	});
	
	$.ui.sortable = function(element, options) {
		//Initialize needed constants
		var self = this;
		
		this.element = $(element);
		
		$.data(element, "ui-sortable", this);
		this.element.addClass("ui-sortable");

		//Prepare the passed options
		this.options = $.extend({}, options);
		var o = this.options;
		$.extend(o, {
			items: this.options.items || '> *',
			zIndex: this.options.zIndex || 1000,
			startCondition: function() {
				return !self.disabled;	
			}		
		});
		
		$(element).bind("setData.sortable", function(event, key, value){
			self.options[key] = value;
		}).bind("getData.sortable", function(event, key){
			return self.options[key];
		});
		
		//Get the items
		this.refresh();

		//Let's determine if the items are floating
		this.floating = /left|right/.test(this.items[0].item.css('float'));
		
		//Let's determine the parent's offset
		if(!/(relative|absolute|fixed)/.test(this.element.css('position'))) this.element.css('position', 'relative');
		this.offset = this.element.offset({ border: false });

		//Initialize mouse events for interaction
		this.element.mouseInteraction({
			executor: this,
			delay: o.delay,
			distance: o.distance || 0,
			dragPrevention: o.prevention ? o.prevention.toLowerCase().split(',') : ['input','textarea','button','select','option'],
			start: this.start,
			stop: this.stop,
			drag: this.drag,
			condition: function(e) {

				if(this.disabled) return false;

				//Find out if the clicked node (or one of its parents) is a actual item in this.items
				var currentItem = null, nodes = $(e.target).parents().andSelf().each(function() {
					if($.data(this, 'ui-sortable-item')) currentItem = $(this);
				});
				if(currentItem) {
					this.currentItem = currentItem;
					return true;
				} else return false; 

			}
		});

	};
	
	$.extend($.ui.sortable.prototype, {
		plugins: {},
		ui: function() {
			return {
				helper: this.helper,
				placeholder: this.placeholder || $([]),
				position: this.position,
				absolutePosition: this.positionAbs,
				instance: this,
				options: this.options
			};		
		},
		propagate: function(n,e) {
			$.ui.plugin.call(this, n, [e, this.ui()]);
			this.element.triggerHandler(n == "sort" ? n : "sort"+n, [e, this.ui()], this.options[n]);
		},
		serialize: function(o) {
			
			var items = $(this.options.items, this.element); //Only the items of the sortable itself
			var str = '';
			o = o || {};
			
			$(this.options.items, this.element).each(function() {
				var res = (this.getAttribute(o.attribute || 'id') || '').match(o.expression || /(.+)[-=_](.+)/);
				if(res) str += res[1]+'[]='+res[2];				
			});
			
			return str;
			
		},
		intersectsWith: function(item) {
			
			var x1 = this.positionAbs.left, x2 = x1 + this.helperProportions.width,
			    y1 = this.positionAbs.top, y2 = y1 + this.helperProportions.height;
			var l = item.left, r = l + item.width, 
			    t = item.top,  b = t + item.height;
			
			return (   l < x1 + (this.helperProportions.width  / 2)        // Right Half
				&&     x2 - (this.helperProportions.width  / 2) < r    // Left Half
				&& t < y1 + (this.helperProportions.height / 2)        // Bottom Half
				&&     y2 - (this.helperProportions.height / 2) < b ); // Top Half
			
		},
		refresh: function() {
			
			this.items = [];
			var items = this.items;
			var queries = [$(this.options.items, this.element)];
			
			if(this.options.connectWith) {
				for (var i = this.options.connectWith.length - 1; i >= 0; i--){
					var inst = $.data($(this.options.connectWith[i])[0], 'ui-sortable');
					if(inst && !inst.disabled) queries.push($(inst.options.items, inst.element));
				};
			}
			
			for (var i = queries.length - 1; i >= 0; i--){
				queries[i].each(function() {
					$.data(this, 'ui-sortable-item', true); // Data for target checking (mouse manager)
					items.push({
						item: $(this),
						width: 0, height: 0,
						left: 0, top: 0
					});
				});
			};

		},
		refreshPositions: function(fast) {
			for (var i = this.items.length - 1; i >= 0; i--){
				if(!fast) this.items[i].width = this.items[i].item.outerWidth();
				if(!fast) this.items[i].height = this.items[i].item.outerHeight();
				var p = this.items[i].item.offset();
				this.items[i].left = p.left;
				this.items[i].top = p.top;
			};
		},
		destroy: function() {
			this.element
				.removeClass("ui-sortable ui-sortable-disabled")
				.removeData("ui-sortable")
				.unbind(".sortable")
				.removeMouseInteraction();
			
			for ( var i = this.items.length - 1; i >= 0; i-- )
				this.items[i].item.removeData("ui-sortable-item");
		},
		enable: function() {
			this.element.removeClass("ui-sortable-disabled");
			this.disabled = false;
		},
		disable: function() {
			this.element.addClass("ui-sortable-disabled");
			this.disabled = true;
		},
		createPlaceholder: function() {
			this.placeholderElement = this.options.placeholderElement ? $(this.options.placeholderElement, this.currentItem) : this.currentItem;
			this.placeholder = $('<div></div>')
				.addClass(this.options.placeholder)
				.appendTo('body')
				.css({ position: 'absolute' })
				.css(this.placeholderElement.offset())
				.css({ width: this.placeholderElement.outerWidth(), height: this.placeholderElement.outerHeight() })
				;
		},
		recallOffset: function(e) {

			var elementPosition = { left: this.elementOffset.left - this.offsetParentOffset.left, top: this.elementOffset.top - this.offsetParentOffset.top };
			var r = this.helper.css('position') == 'relative';

			//Generate the original position
			this.originalPosition = {
				left: (r ? parseInt(this.helper.css('left')) || 0 : elementPosition.left + (this.offsetParent[0] == document.body ? 0 : this.offsetParent[0].scrollLeft)),
				top: (r ? parseInt(this.helper.css('top')) || 0 : elementPosition.top + (this.offsetParent[0] == document.body ? 0 : this.offsetParent[0].scrollTop))
			};
			
			//Generate a flexible offset that will later be subtracted from e.pageX/Y
			this.offset = {
				left: this._pageX - this.originalPosition.left + (parseInt(this.currentItem.css('marginLeft')) || 0),
				top: this._pageY - this.originalPosition.top + (parseInt(this.currentItem.css('marginTop')) || 0)
			};
			
		},
		start: function(e) {
			
			var o = this.options;

			//Refresh the droppable items
			this.refresh(); this.refreshPositions();

			//Create and append the visible helper
			this.helper = typeof o.helper == 'function' ? $(o.helper.apply(this.element[0], [e, this.currentItem])) : this.currentItem.clone();
			this.helper.appendTo(this.currentItem[0].parentNode).css('position', 'absolute').css('float', 'none').css('clear', 'both');

			//Find out the next positioned parent
			this.offsetParent = (function(cp) {
				while(cp) {
					if(cp.style && (/(absolute|relative|fixed)/).test($.css(cp,'position'))) return $(cp);
					cp = cp.parentNode ? cp.parentNode : null;
				}; return $("body");		
			})(this.helper[0].parentNode);
			
			//Prepare variables for position generation
			this.elementOffset = this.currentItem.offset();
			this.offsetParentOffset = this.offsetParent.offset();
			var elementPosition = { left: this.elementOffset.left - this.offsetParentOffset.left, top: this.elementOffset.top - this.offsetParentOffset.top };
			this._pageX = e.pageX; this._pageY = e.pageY;
			this.clickOffset = { left: e.pageX - this.elementOffset.left, top: e.pageY - this.elementOffset.top };
			var r = this.helper.css('position') == 'relative';
			
			//Generate the original position
			this.originalPosition = {
				left: (r ? parseInt(this.helper.css('left')) || 0 : elementPosition.left + (this.offsetParent[0] == document.body ? 0 : this.offsetParent[0].scrollLeft)),
				top: (r ? parseInt(this.helper.css('top')) || 0 : elementPosition.top + (this.offsetParent[0] == document.body ? 0 : this.offsetParent[0].scrollTop))
			};
			
			//Generate a flexible offset that will later be subtracted from e.pageX/Y
			//I hate margins - they need to be removed before positioning the element absolutely..
			this.offset = {
				left: e.pageX - this.originalPosition.left + (parseInt(this.currentItem.css('marginLeft')) || 0),
				top: e.pageY - this.originalPosition.top + (parseInt(this.currentItem.css('marginTop')) || 0)
			};

			//Save the first time position
			this.position = { top: e.pageY - this.offset.top, left: e.pageX - this.offset.left };
			this.positionAbs = { left: e.pageX - this.clickOffset.left, top: e.pageY - this.clickOffset.top };
			this.positionDOM = this.currentItem.prev()[0];

			//If o.placeholder is used, create a new element at the given position with the class
			if(o.placeholder) this.createPlaceholder();

			//Call plugins and callbacks
			this.propagate("start", e);

			//Save and store the helper proportions
			this.helperProportions = { width: this.helper.outerWidth(), height: this.helper.outerHeight() };
			
			//Set the original element visibility to hidden to still fill out the white space	
			$(this.currentItem).css('visibility', 'hidden');

			return false;
						
		},
		stop: function(e) {

			this.propagate("stop", e); //Call plugins and trigger callbacks
			if(this.positionDOM != this.currentItem.prev()[0]) this.propagate("update", e);
			
			if(this.cancelHelperRemoval) return false;			
			$(this.currentItem).css('visibility', 'visible');
			if(this.placeholder) this.placeholder.remove();
			this.helper.remove();

			return false;
			
		},
		drag: function(e) {

			//Compute the helpers position
			this.direction = (this.floating && this.positionAbs.left > e.pageX - this.clickOffset.left) || (this.positionAbs.top > e.pageY - this.clickOffset.top) ? 'down' : 'up';
			this.position = { top: e.pageY - this.offset.top, left: e.pageX - this.offset.left };
			this.positionAbs = { left: e.pageX - this.clickOffset.left, top: e.pageY - this.clickOffset.top };

			//Rearrange
			for (var i = this.items.length - 1; i >= 0; i--) {
				if(this.intersectsWith(this.items[i]) && this.items[i].item[0] != this.currentItem[0] && (this.options.tree ? !this.currentItem[0].contains(this.items[i].item[0]) : true)) {
					//Rearrange the DOM
					this.items[i].item[this.direction == 'down' ? 'before' : 'after'](this.currentItem);
					this.refreshPositions(true); //Precompute after each DOM insertion, NOT on mousemove
					if(this.placeholderElement) this.placeholder.css(this.placeholderElement.offset());
					this.propagate("change", e); //Call plugins and callbacks
					break;
				}
			}

			this.propagate("sort", e); //Call plugins and callbacks
			this.helper.css({ left: this.position.left+'px', top: this.position.top+'px' }); // Stick the helper to the cursor
			return false;
			
		}
	});

})(jQuery);