(function ($, window, document, undefined) {
    var Drag = function (ele, opt) {
        this.$ele = ele, this.x = 0, this.y = 0, this.defaults = {
            parent: 'parent',
            randomPosition: true,
            direction: 'all',
            handler: false,
            grid:null,
            dragStart: function (x, y) {},
            dragEnd: function (x, y) {},
            dragMove: function (x, y) {}
        }, this.options = $.extend({}, this.defaults, opt)
    }
    Drag.prototype = {
        run: function () {
            var $this = this;
            var element = this.$ele;
            var randomPosition = this.options.randomPosition;
            var direction = this.options.direction;
            var handler = this.options.handler;
            var parent = this.options.parent;
            var isDown = false;
            var grid = this.options.grid
            var fun = this.options;
            var X = 0,
                Y = 0,
                moveX, moveY;
            element.find('*').not('img').mousedown(function (e) {
                e.stopPropagation();
            });
            if (parent == 'parent') {
                parent = element.parent();
            } else {
                parent = element.parents(parent);
            }
            if (!handler) {
                handler = element;
            } else {
                handler = element.find(handler);
            }
            parent.css({
                position: 'relative'
            });
            element.css({
                position: 'absolute'
            });
            var boxWidth = 0,
                boxHeight = 0,
                sonWidth = 0,
                sonHeight = 0;
            initSize();
            if (randomPosition) {
                randomPlace();
            }
            $(window).resize(function () {
                initSize();
                if (randomPosition) {
                    randomPlace();
                }
            });

            function initSize() {
                boxWidth = parent.outerWidth();
                boxHeight = parent.outerHeight();
                sonWidth = element.outerWidth();
                sonHeight = element.outerHeight();
            }

            function randomPlace() {
                if (randomPosition) {
                    var randX = parseInt(Math.random() * (boxWidth - sonWidth));
                    var randY = parseInt(Math.random() * (boxHeight - sonHeight));
                    if (direction.toLowerCase() == 'x') {
                        element.css({
                            left: randX
                        });
                    } else if (direction.toLowerCase() == 'y') {
                        element.css({
                            top: randY
                        });
                    } else {
                        element.css({
                            left: randX,
                            top: randY
                        });
                    }
                }
            }
            handler.css({
                cursor: 'move'
            }).mousedown(function (e) {
                isDown = true;
                X = e.pageX;
                Y = e.pageY;
                $this.x = element.position().left;
                $this.y = element.position().top;
                element.addClass('on');
                fun.dragStart(parseInt(element.css('left')), parseInt(element.css('top')));
                return false;
            });
            $(document).mouseup(function (e) {
                fun.dragEnd(parseInt(element.css('left')), parseInt(element.css('top')));
                element.removeClass('on');
                isDown = false;
            });
            $(document).mousemove(function (e) {
                moveX = $this.x + e.pageX - X;
                moveY = $this.y + e.pageY - Y;
		        if(grid!==null){
		        	var gx = grid[0];
		            var gy = grid[1];
		        	moveX=  Math.floor((moveX + gx/ 2) / gx) * gx;
					moveY=  Math.floor((moveY+ gy / 2) / gy) * gy;
		        }
				
                function thisXMove() {
                    if (isDown == true) {
                        element.css({
                            left: moveX
                        });
                    } else {
                        return;
                    }
                    if (moveX < 0) {
                        element.css({
                            left: 0
                        });
                    }
                    if (moveX > (boxWidth - sonWidth)) {
                        element.css({
                            left: boxWidth - sonWidth
                        });
                    }
                    return moveX;
                }

                function thisYMove() {
                    if (isDown == true) {
                        element.css({
                            top: moveY
                        });
                    } else {
                        return;
                    }
                    if (moveY < 0) {
                        element.css({
                            top: 0
                        });
                    }
                    if (moveY > (boxHeight - sonHeight)) {
                        element.css({
                            top: boxHeight - sonHeight
                        });
                    }
                    return moveY;
                }

                function thisAllMove() {
                    if (isDown == true) {
                        element.css({
                            left: moveX,
                            top: moveY
                        });
                    } else {
                        return;
                    }
                    if (moveX < 0) {
                        element.css({
                            left: 0
                        });
                    }
                    if (moveX > (boxWidth - sonWidth)) {
                        element.css({
                            left: boxWidth - sonWidth
                        });
                    }
                    if (moveY < 0) {
                        element.css({
                            top: 0
                        });
                    }
                    if (moveY > (boxHeight - sonHeight)) {
                        element.css({
                            top: boxHeight - sonHeight
                        });
                    }
                }
                if (isDown) {
                    fun.dragMove(parseInt(element.css('left')), parseInt(element.css('top')));
                } else {
                    return false;
                }
                if (direction.toLowerCase() == "x") {
                    thisXMove();
                } else if (direction.toLowerCase() == "y") {
                    thisYMove();
                } else {
                    thisAllMove();
                }
            });
        }
    }
    $.fn.myDrag = function (options) {
        var drag = new Drag(this, options);
        drag.run();
        return this;
    }
})(jQuery, window, document);