(function() {
    var COMMA = ',',
        OPEN_PAREN = '(',
        CLOSE_PAREN = ')',
        OPEN_PAREN_BRACKET = '([',
        CLOSE_BRACKET_PAREN = '])',
        SEMICOLON = ';',
        DOUBLE_PAREN = '()',
        // EMPTY_STRING = '',
        EQUALS = '=',
        // SET = 'set',
        CONTEXT_METHODS = [
            'arc',
            'arcTo',
            'beginPath',
            'bezierCurveTo',
            'clearRect',
            'clip',
            'closePath',
            'createLinearGradient',
            'createPattern',
            'createRadialGradient',
            'drawImage',
            'fill',
            'fillText',
            'getImageData',
            'createImageData',
            'lineTo',
            'moveTo',
            'putImageData',
            'quadraticCurveTo',
            'rect',
            'restore',
            'rotate',
            'save',
            'scale',
            'setLineDash',
            'setTransform',
            'stroke',
            'strokeText',
            'transform',
            'translate'
        ];

    /**
     * Canvas Context constructor
     * @constructor
     * @abstract
     * @memberof Konva
     */
    Konva.Context = function(canvas) {
        this.init(canvas);
    };

    Konva.Context.prototype = {
        init: function(canvas) {
            this.canvas = canvas;
            this._context = canvas._canvas.getContext('2d');

            if (Konva.enableTrace) {
                this.traceArr = [];
                this._enableTrace();
            }
        },
        /**
         * fill shape
         * @method
         * @memberof Konva.Context.prototype
         * @param {Konva.Shape} shape
         */
        fillShape: function(shape) {
            if(shape.getFillEnabled()) {
                this._fill(shape);
            }
        },
        /**
         * stroke shape
         * @method
         * @memberof Konva.Context.prototype
         * @param {Konva.Shape} shape
         */
        strokeShape: function(shape) {
            if(shape.getStrokeEnabled()) {
                this._stroke(shape);
            }
        },
        /**
         * fill then stroke
         * @method
         * @memberof Konva.Context.prototype
         * @param {Konva.Shape} shape
         */
        fillStrokeShape: function(shape) {
            var fillEnabled = shape.getFillEnabled();
            if(fillEnabled) {
                this._fill(shape);
            }
            if(shape.getStrokeEnabled()) {
                this._stroke(shape);
            }
        },
        /**
         * get context trace if trace is enabled
         * @method
         * @memberof Konva.Context.prototype
         * @param {Boolean} relaxed if false, return strict context trace, which includes method names, method parameters
         *  properties, and property values.  If true, return relaxed context trace, which only returns method names and
         *  properites.
         * @returns {String}
         */
        getTrace: function(relaxed) {
            var traceArr = this.traceArr,
                len = traceArr.length,
                str = '',
                n, trace, method, args;

            for (n=0; n<len; n++) {
                trace = traceArr[n];
                method = trace.method;

                // methods
                if (method) {
                    args = trace.args;
                    str += method;
                    if (relaxed) {
                        str += DOUBLE_PAREN;
                    }
                    else {
                        if (Konva.Util._isArray(args[0])) {
                            str += OPEN_PAREN_BRACKET + args.join(COMMA) + CLOSE_BRACKET_PAREN;
                        }
                        else {
                            str += OPEN_PAREN + args.join(COMMA) + CLOSE_PAREN;
                        }
                    }
                }
                // properties
                else {
                    str += trace.property;
                    if (!relaxed) {
                        str += EQUALS + trace.val;
                    }
                }

                str += SEMICOLON;
            }

            return str;
        },
        /**
         * clear trace if trace is enabled
         * @method
         * @memberof Konva.Context.prototype
         */
        clearTrace: function() {
            this.traceArr = [];
        },
        _trace: function(str) {
            var traceArr = this.traceArr,
                len;
 
            traceArr.push(str);
            len = traceArr.length;

            if (len >= Konva.traceArrMax) {
                traceArr.shift();
            }
        },
        /**
         * reset canvas context transform
         * @method
         * @memberof Konva.Context.prototype
         */
        reset: function() {
            var pixelRatio = this.getCanvas().getPixelRatio();
            this.setTransform(1 * pixelRatio, 0, 0, 1 * pixelRatio, 0, 0);
        },
        /**
         * get canvas
         * @method
         * @memberof Konva.Context.prototype
         * @returns {Konva.Canvas}
         */
        getCanvas: function() {
            return this.canvas;
        },
        /**
         * clear canvas
         * @method
         * @memberof Konva.Context.prototype
         * @param {Object} [bounds]
         * @param {Number} [bounds.x]
         * @param {Number} [bounds.y]
         * @param {Number} [bounds.width]
         * @param {Number} [bounds.height]
         */
        clear: function(bounds) {
            var canvas = this.getCanvas();
            
            if (bounds) {
                this.clearRect(bounds.x || 0, bounds.y || 0, bounds.width || 0, bounds.height || 0);
            }
            else {
                this.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
            }
        },
        _applyLineCap: function(shape) {
            var lineCap = shape.getLineCap();
            if(lineCap) {
                this.setAttr('lineCap', lineCap);
            }
        },
        _applyOpacity: function(shape) {
            var absOpacity = shape.getAbsoluteOpacity();
            if(absOpacity !== 1) {
                this.setAttr('globalAlpha', absOpacity);
            }
        },
        _applyLineJoin: function(shape) {
            var lineJoin = shape.getLineJoin();
            if(lineJoin) {
                this.setAttr('lineJoin', lineJoin);
            }
        },
        setAttr: function(attr, val) {
            this._context[attr] = val;
        },

        // context pass through methods
        arc: function() {
            var a = arguments;
            this._context.arc(a[0], a[1], a[2], a[3], a[4], a[5]);
        },
        beginPath: function() {
            this._context.beginPath();
        },
        bezierCurveTo: function() {
            var a = arguments;
            this._context.bezierCurveTo(a[0], a[1], a[2], a[3], a[4], a[5]);
        },
        clearRect: function() {
            var a = arguments;
            this._context.clearRect(a[0], a[1], a[2], a[3]);
        },
        clip: function() {
            this._context.clip();
        },
        closePath: function() {
            this._context.closePath();
        },
        createImageData: function() {
            var a = arguments;
            if(a.length === 2) {
                return this._context.createImageData(a[0], a[1]);
            }
            else if(a.length === 1) {
                return this._context.createImageData(a[0]);
            }
        },
        createLinearGradient: function() {
            var a = arguments;
            return this._context.createLinearGradient(a[0], a[1], a[2], a[3]);
        },
        createPattern: function() {
            var a = arguments;
            return this._context.createPattern(a[0], a[1]);
        },
        createRadialGradient: function() {
            var a = arguments;
            return this._context.createRadialGradient(a[0], a[1], a[2], a[3], a[4], a[5]);
        },
        drawImage: function() {
            var a = arguments,
                _context = this._context;

            if(a.length === 3) {
                _context.drawImage(a[0], a[1], a[2]);
            }
            else if(a.length === 5) {
                _context.drawImage(a[0], a[1], a[2], a[3], a[4]);
            }
            else if(a.length === 9) {
                _context.drawImage(a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8]);
            }
        },
        fill: function() {
            this._context.fill();
        },
        fillText: function() {
            var a = arguments;
            this._context.fillText(a[0], a[1], a[2]);
        },
        getImageData: function() {
            var a = arguments;
            return this._context.getImageData(a[0], a[1], a[2], a[3]);
        },
        lineTo: function() {
            var a = arguments;
            this._context.lineTo(a[0], a[1]);
        },
        moveTo: function() {
            var a = arguments;
            this._context.moveTo(a[0], a[1]);
        },
        rect: function() {
            var a = arguments;
            this._context.rect(a[0], a[1], a[2], a[3]);
        },
        putImageData: function() {
            var a = arguments;
            this._context.putImageData(a[0], a[1], a[2]);
        },
        quadraticCurveTo: function() {
            var a = arguments;
            this._context.quadraticCurveTo(a[0], a[1], a[2], a[3]);
        },
        restore: function() {
            this._context.restore();
        },
        rotate: function() {
            var a = arguments;
            this._context.rotate(a[0]);
        },
        save: function() {
            this._context.save();
        },
        scale: function() {
            var a = arguments;
            this._context.scale(a[0], a[1]);
        },
        setLineDash: function() {
            var a = arguments,
                _context = this._context;

            // works for Chrome and IE11
            if(this._context.setLineDash) {
                _context.setLineDash(a[0]);
            }
            // verified that this works in firefox
            else if('mozDash' in _context) {
                _context.mozDash = a[0];
            }
            // does not currently work for Safari
            else if('webkitLineDash' in _context) {
                _context.webkitLineDash = a[0];
            }

            // no support for IE9 and IE10
        },
        setTransform: function() {
            var a = arguments;
            this._context.setTransform(a[0], a[1], a[2], a[3], a[4], a[5]);
        },
        stroke: function() {
            this._context.stroke();
        },
        strokeText: function() {
            var a = arguments;
            this._context.strokeText(a[0], a[1], a[2]);
        },
        transform: function() {
            var a = arguments;
            this._context.transform(a[0], a[1], a[2], a[3], a[4], a[5]);
        },
        translate: function() {
            var a = arguments;
            this._context.translate(a[0], a[1]);
        },
        _enableTrace: function() {
            var that = this,
                len = CONTEXT_METHODS.length,
                _simplifyArray = Konva.Util._simplifyArray,
                origSetter = this.setAttr,
                n, args;

            // to prevent creating scope function at each loop
            var func = function(methodName) {
                    var origMethod = that[methodName],
                        ret;

                    that[methodName] = function() {
                        args = _simplifyArray(Array.prototype.slice.call(arguments, 0));
                        ret = origMethod.apply(that, arguments);
           
                        that._trace({
                            method: methodName,
                            args: args
                        });
                 
                        return ret;
                    };
            };
            // methods
            for (n=0; n<len; n++) {
                func(CONTEXT_METHODS[n]);
            }

            // attrs
            that.setAttr = function() {
                origSetter.apply(that, arguments);
                that._trace({
                    property: arguments[0],
                    val: arguments[1]
                });
            };
        }
    };

    Konva.SceneContext = function(canvas) {
        Konva.Context.call(this, canvas);
    };

    Konva.SceneContext.prototype = {
        _fillColor: function(shape) {
            var fill = shape.fill()
                || Konva.Util._getRGBAString({
                    red: shape.fillRed(),
                    green: shape.fillGreen(),
                    blue: shape.fillBlue(),
                    alpha: shape.fillAlpha()
                });

            this.setAttr('fillStyle', fill);
            shape._fillFunc(this);
        },
        _fillPattern: function(shape) {
            var fillPatternImage = shape.getFillPatternImage(),
                fillPatternX = shape.getFillPatternX(),
                fillPatternY = shape.getFillPatternY(),
                fillPatternScale = shape.getFillPatternScale(),
                fillPatternRotation = Konva.getAngle(shape.getFillPatternRotation()),
                fillPatternOffset = shape.getFillPatternOffset(),
                fillPatternRepeat = shape.getFillPatternRepeat();

            if(fillPatternX || fillPatternY) {
                this.translate(fillPatternX || 0, fillPatternY || 0);
            }
            if(fillPatternRotation) {
                this.rotate(fillPatternRotation);
            }
            if(fillPatternScale) {
                this.scale(fillPatternScale.x, fillPatternScale.y);
            }
            if(fillPatternOffset) {
                this.translate(-1 * fillPatternOffset.x, -1 * fillPatternOffset.y);
            }

            this.setAttr('fillStyle', this.createPattern(fillPatternImage, fillPatternRepeat || 'repeat'));
            this.fill();
        },
        _fillLinearGradient: function(shape) {
            var start = shape.getFillLinearGradientStartPoint(),
                end = shape.getFillLinearGradientEndPoint(),
                colorStops = shape.getFillLinearGradientColorStops(),
                grd = this.createLinearGradient(start.x, start.y, end.x, end.y);

            if (colorStops) {
                // build color stops
                for(var n = 0; n < colorStops.length; n += 2) {
                    grd.addColorStop(colorStops[n], colorStops[n + 1]);
                }
                this.setAttr('fillStyle', grd);
                this.fill();
            }
        },
        _fillRadialGradient: function(shape) {
            var start = shape.getFillRadialGradientStartPoint(),
                end = shape.getFillRadialGradientEndPoint(),
                startRadius = shape.getFillRadialGradientStartRadius(),
                endRadius = shape.getFillRadialGradientEndRadius(),
                colorStops = shape.getFillRadialGradientColorStops(),
                grd = this.createRadialGradient(start.x, start.y, startRadius, end.x, end.y, endRadius);
           
            // build color stops
            for(var n = 0; n < colorStops.length; n += 2) {
                grd.addColorStop(colorStops[n], colorStops[n + 1]);
            }
            this.setAttr('fillStyle', grd);
            this.fill();
        },
        _fill: function(shape) {
            var hasColor = shape.fill() || shape.fillRed() || shape.fillGreen() || shape.fillBlue(),
                hasPattern = shape.getFillPatternImage(),
                hasLinearGradient = shape.getFillLinearGradientColorStops(),
                hasRadialGradient = shape.getFillRadialGradientColorStops(),
                fillPriority = shape.getFillPriority();

            // priority fills
            if(hasColor && fillPriority === 'color') {
                this._fillColor(shape);
            }
            else if(hasPattern && fillPriority === 'pattern') {
                this._fillPattern(shape);
            }
            else if(hasLinearGradient && fillPriority === 'linear-gradient') {
                this._fillLinearGradient(shape);
            }
            else if(hasRadialGradient && fillPriority === 'radial-gradient') {
                this._fillRadialGradient(shape);
            }
            // now just try and fill with whatever is available
            else if(hasColor) {
                this._fillColor(shape);
            }
            else if(hasPattern) {
                this._fillPattern(shape);
            }
            else if(hasLinearGradient) {
                this._fillLinearGradient(shape);
            }
            else if(hasRadialGradient) {
                this._fillRadialGradient(shape);
            }
        },
        _stroke: function(shape) {
            var dash = shape.dash(),
                // ignore strokeScaleEnabled for Text
                strokeScaleEnabled = (shape.getStrokeScaleEnabled() || (shape instanceof Konva.Text));

            if(shape.hasStroke()) {
                if (!strokeScaleEnabled) {
                    this.save();
                    this.setTransform(1, 0, 0, 1, 0, 0);
                }

                this._applyLineCap(shape);
                if(dash && shape.dashEnabled()) {
                    this.setLineDash(dash);
                }

                this.setAttr('lineWidth', shape.strokeWidth());
                this.setAttr('strokeStyle', shape.stroke()
                    || Konva.Util._getRGBAString({
                        red: shape.strokeRed(),
                        green: shape.strokeGreen(),
                        blue: shape.strokeBlue(),
                        alpha: shape.strokeAlpha()
                    }));

                shape._strokeFunc(this);
                
                if (!strokeScaleEnabled) {
                    this.restore();
                }
            }
        },
        _applyShadow: function(shape) {
            var util = Konva.Util,
                absOpacity = shape.getAbsoluteOpacity(),
                color = util.get(shape.getShadowColor(), 'black'),
                blur = util.get(shape.getShadowBlur(), 5),
                shadowOpacity = util.get(shape.getShadowOpacity(), 1),
                offset = util.get(shape.getShadowOffset(), {
                    x: 0,
                    y: 0
                });

            if(shadowOpacity) {
                this.setAttr('globalAlpha', shadowOpacity * absOpacity);
            }

            this.setAttr('shadowColor', color);
            this.setAttr('shadowBlur', blur);
            this.setAttr('shadowOffsetX', offset.x);
            this.setAttr('shadowOffsetY', offset.y);
        
        }
    };
    Konva.Util.extend(Konva.SceneContext, Konva.Context);

    Konva.HitContext = function(canvas) {
        Konva.Context.call(this, canvas);
    };

    Konva.HitContext.prototype = {
        _fill: function(shape) {
            this.save();
            this.setAttr('fillStyle', shape.colorKey);
            shape._fillFuncHit(this);
            this.restore();
        },
        _stroke: function(shape) {
            if(shape.hasStroke() && shape.strokeHitEnabled()) {
                // ignore strokeScaleEnabled for Text
                var strokeScaleEnabled = (shape.getStrokeScaleEnabled() || (shape instanceof Konva.Text));
                if (!strokeScaleEnabled) {
                    this.save();
                    this.setTransform(1, 0, 0, 1, 0, 0);
                }
                this._applyLineCap(shape);
                this.setAttr('lineWidth', shape.strokeWidth());
                this.setAttr('strokeStyle', shape.colorKey);
                shape._strokeFuncHit(this);
                if (!strokeScaleEnabled) {
                    this.restore();
                }
            }
        }
    };
    Konva.Util.extend(Konva.HitContext, Konva.Context);
})();