/**
 * draggable - jQuery EasyUI
 * 
 * Copyright (c) 2009-2013 www.jeasyui.com. All rights reserved.
 *
 * Licensed under the GPL or commercial licenses
 * To use it on other terms please contact us: jeasyui@gmail.com
 * http://www.gnu.org/licenses/gpl.txt
 * http://www.jeasyui.com/license_commercial.php
 */
(function($){
	var isDragging = false;
	function drag(e){
		var state = $.data(e.data.target, 'draggable');
		var opts = state.options;
		var proxy = state.proxy;
		
		var dragData = e.data;
		var left = dragData.startLeft + e.pageX - dragData.startX;
		var top = dragData.startTop + e.pageY - dragData.startY;
		
		if (proxy){
			if (proxy.parent()[0] == document.body){
				if (opts.deltaX != null && opts.deltaX != undefined){
					left = e.pageX + opts.deltaX;
				} else {
					left = e.pageX - e.data.offsetWidth;
				}
				if (opts.deltaY != null && opts.deltaY != undefined){
					top = e.pageY + opts.deltaY;
				} else {
					top = e.pageY - e.data.offsetHeight;
				}
			} else {
				if (opts.deltaX != null && opts.deltaX != undefined){
					left += e.data.offsetWidth + opts.deltaX;
				}
				if (opts.deltaY != null && opts.deltaY != undefined){
					top += e.data.offsetHeight + opts.deltaY;
				}
			}
		}
		
//		if (opts.deltaX != null && opts.deltaX != undefined){
//			left = e.pageX + opts.deltaX;
//		}
//		if (opts.deltaY != null && opts.deltaY != undefined){
//			top = e.pageY + opts.deltaY;
//		}
		
		if (e.data.parent != document.body) {
			left += $(e.data.parent).scrollLeft();
			top += $(e.data.parent).scrollTop();
		}
		
		if (opts.axis == 'h') {
			dragData.left = left;
		} else if (opts.axis == 'v') {
			dragData.top = top;
		} else {
			dragData.left = left;
			dragData.top = top;
		}
	}
	
	function applyDrag(e){
		var state = $.data(e.data.target, 'draggable');
		var opts = state.options;
		var proxy = state.proxy;
		if (!proxy){
			proxy = $(e.data.target);
		}
//		if (proxy){
//			proxy.css('cursor', opts.cursor);
//		} else {
//			proxy = $(e.data.target);
//			$.data(e.data.target, 'draggable').handle.css('cursor', opts.cursor);
//		}
		proxy.css({
			left:e.data.left,
			top:e.data.top
		});
		$('body').css('cursor', opts.cursor);
	}
	
	function doDown(e){
		isDragging = true;
		var state = $.data(e.data.target, 'draggable');
		var opts = state.options;
		
		var droppables = $('.droppable').filter(function(){
			return e.data.target != this;
		}).filter(function(){
			var accept = $.data(this, 'droppable').options.accept;
			if (accept){
				return $(accept).filter(function(){
					return this == e.data.target;
				}).length > 0;
			} else {
				return true;
			}
		});
		state.droppables = droppables;
		
		var proxy = state.proxy;
		if (!proxy){
			if (opts.proxy){
				if (opts.proxy == 'clone'){
					proxy = $(e.data.target).clone().insertAfter(e.data.target);
				} else {
					proxy = opts.proxy.call(e.data.target, e.data.target);
				}
				state.proxy = proxy;
			} else {
				proxy = $(e.data.target);
			}
		}
		
		proxy.css('position', 'absolute');
		drag(e);
		applyDrag(e);
		
		opts.onStartDrag.call(e.data.target, e);
		return false;
	}
	
	function doMove(e){
		var state = $.data(e.data.target, 'draggable');
		drag(e);
		if (state.options.onDrag.call(e.data.target, e) != false){
			applyDrag(e);
		}
		
		var source = e.data.target;
		state.droppables.each(function(){
			var dropObj = $(this);
			if (dropObj.droppable('options').disabled){return;}
			
			var p2 = dropObj.offset();
			if (e.pageX > p2.left && e.pageX < p2.left + dropObj.outerWidth()
					&& e.pageY > p2.top && e.pageY < p2.top + dropObj.outerHeight()){
				if (!this.entered){
					$(this).trigger('_dragenter', [source]);
					this.entered = true;
				}
				$(this).trigger('_dragover', [source]);
			} else {
				if (this.entered){
					$(this).trigger('_dragleave', [source]);
					this.entered = false;
				}
			}
		});
		
		return false;
	}
	
	function doUp(e){
		isDragging = false;
//		drag(e);
		doMove(e);
		
		var state = $.data(e.data.target, 'draggable');
		var proxy = state.proxy;
		var opts = state.options;
		if (opts.revert){
			if (checkDrop() == true){
				$(e.data.target).css({
					position:e.data.startPosition,
					left:e.data.startLeft,
					top:e.data.startTop
				});
			} else {
				if (proxy){
					var left, top;
					if (proxy.parent()[0] == document.body){
						left = e.data.startX - e.data.offsetWidth;
						top = e.data.startY - e.data.offsetHeight;
					} else {
						left = e.data.startLeft;
						top = e.data.startTop;
					}
					proxy.animate({
						left: left,
						top: top
					}, function(){
						removeProxy();
					});
				} else {
					$(e.data.target).animate({
						left:e.data.startLeft,
						top:e.data.startTop
					}, function(){
						$(e.data.target).css('position', e.data.startPosition);
					});
				}
			}
		} else {
			$(e.data.target).css({
				position:'absolute',
				left:e.data.left,
				top:e.data.top
			});
			checkDrop();
		}
		
		opts.onStopDrag.call(e.data.target, e);
		
		$(document).unbind('.draggable');
		setTimeout(function(){
			$('body').css('cursor','');
		},100);
		
		function removeProxy(){
			if (proxy){
				proxy.remove();
			}
			state.proxy = null;
		}
		
		function checkDrop(){
			var dropped = false;
			state.droppables.each(function(){
				var dropObj = $(this);
				if (dropObj.droppable('options').disabled){return;}
				
				var p2 = dropObj.offset();
				if (e.pageX > p2.left && e.pageX < p2.left + dropObj.outerWidth()
						&& e.pageY > p2.top && e.pageY < p2.top + dropObj.outerHeight()){
					if (opts.revert){
						$(e.data.target).css({
							position:e.data.startPosition,
							left:e.data.startLeft,
							top:e.data.startTop
						});
					}
					removeProxy();
					$(this).trigger('_drop', [e.data.target]);
					dropped = true;
					this.entered = false;
					return false;
				}
			});
			if (!dropped && !opts.revert){
				removeProxy();
			}
			return dropped;
		}
		
		return false;
	}
	
	$.fn.draggable = function(options, param){
		if (typeof options == 'string'){
			return $.fn.draggable.methods[options](this, param);
		}
		
		return this.each(function(){
			var opts;
			var state = $.data(this, 'draggable');
			if (state) {
				state.handle.unbind('.draggable');
				opts = $.extend(state.options, options);
			} else {
				opts = $.extend({}, $.fn.draggable.defaults, $.fn.draggable.parseOptions(this), options || {});
			}
			
			if (opts.disabled == true) {
				$(this).css('cursor', '');
//				$(this).css('cursor', 'default');
				return;
			}
			
			var handle = null;
            if (typeof opts.handle == 'undefined' || opts.handle == null){
                handle = $(this);
            } else {
                handle = (typeof opts.handle == 'string' ? $(opts.handle, this) : opts.handle);
            }
			$.data(this, 'draggable', {
				options: opts,
				handle: handle
			});
			
			handle.unbind('.draggable').bind('mousemove.draggable', {target:this}, function(e){
				if (isDragging) return;
				var opts = $.data(e.data.target, 'draggable').options;
				if (checkArea(e)){
					$(this).css('cursor', opts.cursor);
				} else {
					$(this).css('cursor', '');
				}
			}).bind('mouseleave.draggable', {target:this}, function(e){
				$(this).css('cursor', '');
			}).bind('mousedown.draggable', {target:this}, function(e){
				if (checkArea(e) == false) return;
				$(this).css('cursor', '');

				var position = $(e.data.target).position();
				var offset = $(e.data.target).offset();
				var data = {
					startPosition: $(e.data.target).css('position'),
					startLeft: position.left,
					startTop: position.top,
					left: position.left,
					top: position.top,
					startX: e.pageX,
					startY: e.pageY,
					offsetWidth: (e.pageX - offset.left),
					offsetHeight: (e.pageY - offset.top),
					target: e.data.target,
					parent: $(e.data.target).parent()[0]
				};
				
				$.extend(e.data, data);
				var opts = $.data(e.data.target, 'draggable').options;
				if (opts.onBeforeDrag.call(e.data.target, e) == false) return;
				
				$(document).bind('mousedown.draggable', e.data, doDown);
				$(document).bind('mousemove.draggable', e.data, doMove);
				$(document).bind('mouseup.draggable', e.data, doUp);
//				$('body').css('cursor', opts.cursor);
			});
			
			// check if the handle can be dragged
			function checkArea(e) {
				var state = $.data(e.data.target, 'draggable');
				var handle = state.handle;
				var offset = $(handle).offset();
				var width = $(handle).outerWidth();
				var height = $(handle).outerHeight();
				var t = e.pageY - offset.top;
				var r = offset.left + width - e.pageX;
				var b = offset.top + height - e.pageY;
				var l = e.pageX - offset.left;
				
				return Math.min(t,r,b,l) > state.options.edge;
			}
			
		});
	};
	
	$.fn.draggable.methods = {
		options: function(jq){
			return $.data(jq[0], 'draggable').options;
		},
		proxy: function(jq){
			return $.data(jq[0], 'draggable').proxy;
		},
		enable: function(jq){
			return jq.each(function(){
				$(this).draggable({disabled:false});
			});
		},
		disable: function(jq){
			return jq.each(function(){
				$(this).draggable({disabled:true});
			});
		}
	};
	
	$.fn.draggable.parseOptions = function(target){
		var t = $(target);
		return $.extend({}, 
				$.parser.parseOptions(target, ['cursor','handle','axis',
				       {'revert':'boolean','deltaX':'number','deltaY':'number','edge':'number'}]), {
			disabled: (t.attr('disabled') ? true : undefined)
		});
	};
	
	$.fn.draggable.defaults = {
		proxy:null,	// 'clone' or a function that will create the proxy object, 
					// the function has the source parameter that indicate the source object dragged.
		revert:false,
		cursor:'move',
		deltaX:null,
		deltaY:null,
		handle: null,
		disabled: false,
		edge:0,
		axis:null,	// v or h
		
		onBeforeDrag: function(e){},
		onStartDrag: function(e){},
		onDrag: function(e){},
		onStopDrag: function(e){}
	};
})(jQuery);
