(function() {
    // CONSTANTS
    var STAGE = 'Stage',
        STRING = 'string',
        PX = 'px',

        MOUSEOUT = 'mouseout',
        MOUSELEAVE = 'mouseleave',
        MOUSEOVER = 'mouseover',
        MOUSEENTER = 'mouseenter',
        MOUSEMOVE = 'mousemove',
        MOUSEDOWN = 'mousedown',
        MOUSEUP = 'mouseup',
        CLICK = 'click',
        DBL_CLICK = 'dblclick',
        TOUCHSTART = 'touchstart',
        TOUCHEND = 'touchend',
        TAP = 'tap',
        DBL_TAP = 'dbltap',
        TOUCHMOVE = 'touchmove',

        CONTENT_MOUSEOUT = 'contentMouseout',
        CONTENT_MOUSELEAVE = 'contentMouseleave',
        CONTENT_MOUSEOVER = 'contentMouseover',
        CONTENT_MOUSEENTER = 'contentMouseenter',
        CONTENT_MOUSEMOVE = 'contentMousemove',
        CONTENT_MOUSEDOWN = 'contentMousedown',
        CONTENT_MOUSEUP = 'contentMouseup',
        CONTENT_CLICK = 'contentClick',
        CONTENT_DBL_CLICK = 'contentDblclick',
        CONTENT_TOUCHSTART = 'contentTouchstart',
        CONTENT_TOUCHEND = 'contentTouchend',
        CONTENT_TAP = 'contentTap',
        CONTENT_DBL_TAP = 'contentDbltap',
        CONTENT_TOUCHMOVE = 'contentTouchmove',

        DIV = 'div',
        RELATIVE = 'relative',
        INLINE_BLOCK = 'inline-block',
        KINETICJS_CONTENT = 'kineticjs-content',
        SPACE = ' ',
        UNDERSCORE = '_',
        CONTAINER = 'container',
        EMPTY_STRING = '',
        EVENTS = [MOUSEDOWN, MOUSEMOVE, MOUSEUP, MOUSEOUT, TOUCHSTART, TOUCHMOVE, TOUCHEND, MOUSEOVER],

        // cached variables
        eventsLength = EVENTS.length;

    function addEvent(ctx, eventName) {
      ctx.content.addEventListener(eventName, function(evt) {
        ctx[UNDERSCORE + eventName](evt);
      }, false);
    }

    Kinetic.Util.addMethods(Kinetic.Stage, {
        ___init: function(config) {
            this.nodeType = STAGE;
            // call super constructor
            Kinetic.Container.call(this, config);
            this._id = Kinetic.idCounter++;
            this._buildDOM();
            this._bindContentEvents();
            this._enableNestedTransforms = false;
            Kinetic.stages.push(this);
        },
        _validateAdd: function(child) {
            if (child.getType() !== 'Layer') {
                Kinetic.Util.error('You may only add layers to the stage.');
            }
        },
        /**
         * set container dom element which contains the stage wrapper div element
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {DomElement} container can pass in a dom element or id string
         */
        setContainer: function(container) {
            if( typeof container === STRING) {
                container = document.getElementById(container);
            }
            this._setAttr(CONTAINER, container);
            return this;
        },
        shouldDrawHit: function() {
            return true;
        },
        draw: function() {
            Kinetic.Node.prototype.draw.call(this);
            return this;
        },
        /**
         * draw layer scene graphs
         * @name draw
         * @method
         * @memberof Kinetic.Stage.prototype
         */

        /**
         * draw layer hit graphs
         * @name drawHit
         * @method
         * @memberof Kinetic.Stage.prototype
         */

        /**
         * set height
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {Number} height
         */
        setHeight: function(height) {
            Kinetic.Node.prototype.setHeight.call(this, height);
            this._resizeDOM();
            return this;
        },
        /**
         * set width
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {Number} width
         */
        setWidth: function(width) {
            Kinetic.Node.prototype.setWidth.call(this, width);
            this._resizeDOM();
            return this;
        },
        /**
         * clear all layers
         * @method
         * @memberof Kinetic.Stage.prototype
         */
        clear: function() {
            var layers = this.children,
                len = layers.length,
                n;

            for(n = 0; n < len; n++) {
                layers[n].clear();
            }
            return this;
        },
        /**
         * remove stage
         * @method
         * @memberof Kinetic.Stage.prototype
         */
        destroy: function() {
            var content = this.content;
            Kinetic.Container.prototype.destroy.call(this);

            if(content && Kinetic.Util._isInDocument(content)) {
                this.getContainer().removeChild(content);
            }
        },
        /**
         * get pointer position which can be a touch position or mouse position
         * @method
         * @memberof Kinetic.Stage.prototype
         */
        getPointerPosition: function() {
            return this.pointerPos;
        },
        getStage: function() {
            return this;
        },
        /**
         * get stage content div element which has the
         *  the class name "kineticjs-content"
         * @method
         * @memberof Kinetic.Stage.prototype
         */
        getContent: function() {
            return this.content;
        },
        /**
         * Creates a composite data URL and requires a callback because the composite is generated asynchronously.
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {Object} config
         * @param {Function} config.callback function executed when the composite has completed
         * @param {String} [config.mimeType] can be "image/png" or "image/jpeg".
         *  "image/png" is the default
         * @param {Number} [config.x] x position of canvas section
         * @param {Number} [config.y] y position of canvas section
         * @param {Number} [config.width] width of canvas section
         * @param {Number} [config.height] height of canvas section
         * @param {Number} [config.quality] jpeg quality.  If using an "image/jpeg" mimeType,
         *  you can specify the quality from 0 to 1, where 0 is very poor quality and 1
         *  is very high quality
         */
        toDataURL: function(config) {
            config = config || {};

            var mimeType = config.mimeType || null,
                quality = config.quality || null,
                x = config.x || 0,
                y = config.y || 0,
                canvas = new Kinetic.SceneCanvas({
                    width: config.width || this.getWidth(),
                    height: config.height || this.getHeight(),
                    pixelRatio: 1
                }),
                _context = canvas.getContext()._context,
                layers = this.children;

            if(x || y) {
                _context.translate(-1 * x, -1 * y);
            }

            function drawLayer(n) {
                var layer = layers[n],
                    layerUrl = layer.toDataURL(),
                    imageObj = new Image();

                imageObj.onload = function() {
                    _context.drawImage(imageObj, 0, 0);

                    if(n < layers.length - 1) {
                        drawLayer(n + 1);
                    }
                    else {
                        config.callback(canvas.toDataURL(mimeType, quality));
                    }
                };
                imageObj.src = layerUrl;
            }
            drawLayer(0);
        },
        /**
         * converts stage into an image.
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {Object} config
         * @param {Function} config.callback function executed when the composite has completed
         * @param {String} [config.mimeType] can be "image/png" or "image/jpeg".
         *  "image/png" is the default
         * @param {Number} [config.x] x position of canvas section
         * @param {Number} [config.y] y position of canvas section
         * @param {Number} [config.width] width of canvas section
         * @param {Number} [config.height] height of canvas section
         * @param {Number} [config.quality] jpeg quality.  If using an "image/jpeg" mimeType,
         *  you can specify the quality from 0 to 1, where 0 is very poor quality and 1
         *  is very high quality
         */
        toImage: function(config) {
            var cb = config.callback;

            config.callback = function(dataUrl) {
                Kinetic.Util._getImage(dataUrl, function(img) {
                    cb(img);
                });
            };
            this.toDataURL(config);
        },
        /**
         * get visible intersection shape. This is the preferred
         *  method for determining if a point intersects a shape or not
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {Object} pos
         * @param {Number} pos.x
         * @param {Number} pos.y
         * @returns {Kinetic.Shape}
         */
        getIntersection: function(pos) {
            var layers = this.getChildren(),
                len = layers.length,
                end = len - 1,
                n, shape;

            for(n = end; n >= 0; n--) {
                shape = layers[n].getIntersection(pos);
                if (shape) {
                    return shape;
                } 
            }

            return null;
        },
        _resizeDOM: function() {
            if(this.content) {
                var width = this.getWidth(),
                    height = this.getHeight(),
                    layers = this.getChildren(),
                    len = layers.length,
                    n, layer;

                // set content dimensions
                this.content.style.width = width + PX;
                this.content.style.height = height + PX;

                this.bufferCanvas.setSize(width, height);
                this.bufferHitCanvas.setSize(width, height);

                // set layer dimensions
                for(n = 0; n < len; n++) {
                    layer = layers[n];
                    layer.getCanvas().setSize(width, height);
                    layer.hitCanvas.setSize(width, height);
                    layer.draw();
                }
            }
        },
        /**
         * add layer to stage
         * @method
         * @memberof Kinetic.Stage.prototype
         * @param {Kinetic.Layer} layer
         */
        add: function(layer) {
            Kinetic.Container.prototype.add.call(this, layer);
            layer.canvas.setSize(this.attrs.width, this.attrs.height);
            layer.hitCanvas.setSize(this.attrs.width, this.attrs.height);

            // draw layer and append canvas to container
            layer.draw();
            this.content.appendChild(layer.canvas._canvas);

            // chainable
            return this;
        },
        getParent: function() {
            return null;
        },
        getLayer: function() {
            return null;
        },
        /**
         * returns a {@link Kinetic.Collection} of layers
         * @method
         * @memberof Kinetic.Stage.prototype
         */
        getLayers: function() {
            return this.getChildren();
        },
        _bindContentEvents: function() {
            var that = this,
                n;

            for (n = 0; n < eventsLength; n++) {
              addEvent(this, EVENTS[n]);
            }
        },
        _mouseover: function(evt) {
            this._fire(CONTENT_MOUSEOVER, evt);
        },
        _mouseout: function(evt) {
            this._setPointerPosition(evt);
            var targetShape = this.targetShape;

            if(targetShape && !Kinetic.isDragging()) {
                targetShape._fireAndBubble(MOUSEOUT, evt);
                targetShape._fireAndBubble(MOUSELEAVE, evt);
                this.targetShape = null;
            }
            this.pointerPos = undefined;

            this._fire(CONTENT_MOUSEOUT, evt);
        },
        _mousemove: function(evt) {
            this._setPointerPosition(evt);
            var dd = Kinetic.DD,
                shape = this.getIntersection(this.getPointerPosition());

            if(shape && shape.isListening()) {
                if(!Kinetic.isDragging() && (!this.targetShape || this.targetShape._id !== shape._id)) {
                    if(this.targetShape) {
                        this.targetShape._fireAndBubble(MOUSEOUT, evt, shape);
                        this.targetShape._fireAndBubble(MOUSELEAVE, evt, shape);
                    }
                    shape._fireAndBubble(MOUSEOVER, evt, this.targetShape);
                    shape._fireAndBubble(MOUSEENTER, evt, this.targetShape);
                    this.targetShape = shape;
                }
                else {
                    shape._fireAndBubble(MOUSEMOVE, evt);
                }
            }
            /*
             * if no shape was detected, clear target shape and try
             * to run mouseout from previous target shape
             */
            else {
              if(this.targetShape && !Kinetic.isDragging()) {
                this.targetShape._fireAndBubble(MOUSEOUT, evt);
                this.targetShape._fireAndBubble(MOUSELEAVE, evt);
                this.targetShape = null;
              }

            }

            // content event
            this._fire(CONTENT_MOUSEMOVE, evt);

            if(dd) {
                dd._drag(evt);
            }

            // always call preventDefault for desktop events because some browsers
            // try to drag and drop the canvas element
            if (evt.preventDefault) {
                evt.preventDefault();
            }
        },
        _mousedown: function(evt) {
            this._setPointerPosition(evt);
            var shape = this.getIntersection(this.getPointerPosition());

            Kinetic.listenClickTap = true;

            if (shape && shape.isListening()) {
                this.clickStartShape = shape;
                shape._fireAndBubble(MOUSEDOWN, evt);
            }

            // content event
            this._fire(CONTENT_MOUSEDOWN, evt);

            // always call preventDefault for desktop events because some browsers
            // try to drag and drop the canvas element
            if (evt.preventDefault) {
                evt.preventDefault();
            }
        },
        _mouseup: function(evt) {
            this._setPointerPosition(evt);
            var that = this,
                shape = this.getIntersection(this.getPointerPosition()),
                clickStartShape = this.clickStartShape,
                fireDblClick = false;

            if(Kinetic.inDblClickWindow) {
                fireDblClick = true;
                Kinetic.inDblClickWindow = false;
            }
            else {
                Kinetic.inDblClickWindow = true;
            }

            setTimeout(function() {
                Kinetic.inDblClickWindow = false;
            }, Kinetic.dblClickWindow);

            if (shape && shape.isListening()) {
                shape._fireAndBubble(MOUSEUP, evt);

                // detect if click or double click occurred
                if(Kinetic.listenClickTap && clickStartShape && clickStartShape._id === shape._id) {
                    shape._fireAndBubble(CLICK, evt);

                    if(fireDblClick) {
                        shape._fireAndBubble(DBL_CLICK, evt);
                    }
                }
            }
            // content events
            this._fire(CONTENT_MOUSEUP, evt);
            if (Kinetic.listenClickTap) {
                this._fire(CONTENT_CLICK, evt);
                if(fireDblClick) {
                    this._fire(CONTENT_DBL_CLICK, evt);
                }
            }

            Kinetic.listenClickTap = false;

            // always call preventDefault for desktop events because some browsers
            // try to drag and drop the canvas element
            if (evt.preventDefault) {
                evt.preventDefault();
            }
        },
        _touchstart: function(evt) {
            this._setPointerPosition(evt);
            var shape = this.getIntersection(this.getPointerPosition());

            Kinetic.listenClickTap = true;

            if (shape && shape.isListening()) {
                this.tapStartShape = shape;
                shape._fireAndBubble(TOUCHSTART, evt);

                // only call preventDefault if the shape is listening for events
                if (shape.isListening() && evt.preventDefault) {
                    evt.preventDefault();
                }
            }
            // content event
            this._fire(CONTENT_TOUCHSTART, evt);
        },
        _touchend: function(evt) {
            this._setPointerPosition(evt);
            var that = this,
                shape = this.getIntersection(this.getPointerPosition());
                fireDblClick = false;

                if(Kinetic.inDblClickWindow) {
                    fireDblClick = true;
                    Kinetic.inDblClickWindow = false;
                }
                else {
                    Kinetic.inDblClickWindow = true;
                }

                setTimeout(function() {
                    Kinetic.inDblClickWindow = false;
                }, Kinetic.dblClickWindow);

            if (shape && shape.isListening()) {
                shape._fireAndBubble(TOUCHEND, evt);

                // detect if tap or double tap occurred
                if(Kinetic.listenClickTap && shape._id === this.tapStartShape._id) {
                    shape._fireAndBubble(TAP, evt);

                    if(fireDblClick) {
                        shape._fireAndBubble(DBL_TAP, evt);
                    }
                }
                // only call preventDefault if the shape is listening for events
                if (shape.isListening() && evt.preventDefault) {
                    evt.preventDefault();
                }
            }
            // content events
            if (Kinetic.listenClickTap) {
                this._fire(CONTENT_TOUCHEND, evt);
                if(fireDblClick) {
                    this._fire(CONTENT_DBL_TAP, evt);
                }
            }

            Kinetic.listenClickTap = false;
        },
        _touchmove: function(evt) {
            this._setPointerPosition(evt);
            var dd = Kinetic.DD,
                shape = this.getIntersection(this.getPointerPosition());

            if (shape && shape.isListening()) {
                shape._fireAndBubble(TOUCHMOVE, evt);

                // only call preventDefault if the shape is listening for events
                if (shape.isListening() && evt.preventDefault) {
                    evt.preventDefault();
                }
            }
            this._fire(CONTENT_TOUCHMOVE, evt);

            // start drag and drop
            if(dd) {
                dd._drag(evt);
            }
        },
        _setPointerPosition: function(evt) {
            var evt = evt ? evt : window.event,
                contentPosition = this._getContentPosition(),
                offsetX = evt.offsetX,
                clientX = evt.clientX,
                x = null,
                y = null,
                touch;

            // touch events
            if(evt.touches !== undefined) {
                // currently, only handle one finger
                if (evt.touches.length === 1) {

                    touch = evt.touches[0];

                    // get the information for finger #1
                    x = touch.clientX - contentPosition.left;
                    y = touch.clientY - contentPosition.top; 
                }
            }
            // mouse events
            else {
                // if offsetX is defined, assume that offsetY is defined as well
                if (offsetX !== undefined) {
                    x = offsetX;
                    y = evt.offsetY;
                }
                // we unforunately have to use UA detection here because accessing
                // the layerX or layerY properties in newer veresions of Chrome
                // throws a JS warning.  layerX and layerY are required for FF
                // when the container is transformed via CSS.
                else if (Kinetic.UA.browser === 'mozilla') {
                    x = evt.layerX;
                    y = evt.layerY;
                }
                // if clientX is defined, assume that clientY is defined as well
                else if (clientX !== undefined && contentPosition) {
                    x = clientX - contentPosition.left;
                    y = evt.clientY - contentPosition.top;
                }
            }

            if (x !== null && y !== null) {
                this.pointerPos = {
                    x: x,
                    y: y
                };
            }
        },
        _getContentPosition: function() {
            var rect = this.content.getBoundingClientRect ? this.content.getBoundingClientRect() : { top: 0, left: 0 };
            return {
                top: rect.top,
                left: rect.left
            };
        },
        _buildDOM: function() {
            var container = this.getContainer();

            // clear content inside container
            container.innerHTML = EMPTY_STRING;

            // content
            this.content = document.createElement(DIV);
            this.content.style.position = RELATIVE;
            this.content.style.display = INLINE_BLOCK;
            this.content.className = KINETICJS_CONTENT;
            this.content.setAttribute('role', 'presentation');
            container.appendChild(this.content);

            // the buffer canvas pixel ratio must be 1 because it is used as an 
            // intermediate canvas before copying the result onto a scene canvas.
            // not setting it to 1 will result in an over compensation
            this.bufferCanvas = new Kinetic.SceneCanvas({
                pixelRatio: 1
            });
            this.bufferHitCanvas = new Kinetic.HitCanvas();

            this._resizeDOM();
        },
        _onContent: function(typesStr, handler) {
            var types = typesStr.split(SPACE),
                len = types.length,
                n, baseEvent;

            for(n = 0; n < len; n++) {
                baseEvent = types[n];
                this.content.addEventListener(baseEvent, handler, false);
            }
        }
    });
    Kinetic.Util.extend(Kinetic.Stage, Kinetic.Container);

    // add getters and setters
    Kinetic.Factory.addGetter(Kinetic.Stage, 'container');

    /**
     * get container DOM element
     * @name getContainer
     * @method
     * @memberof Kinetic.Stage.prototype
     */

})();