package net.flashpunk 
{
    import flash.display.BitmapData;
    import flash.display.Sprite;
    import flash.display.Stage;
    import flash.geom.Matrix;
    import flash.geom.Point;
    import flash.geom.Rectangle;
    import flash.media.SoundMixer;
    import flash.media.SoundTransform;
    import flash.system.System;
    import flash.utils.ByteArray;
    import flash.utils.getTimer;
    import net.flashpunk.*;
    import net.flashpunk.debug.Console;
    import net.flashpunk.tweens.misc.MultiVarTween;
    
    /**
     * Static catch-all class used to access global properties and functions.
     */
    public class FP 
    {
        /**
         * The FlashPunk major version.
         */
        public static const VERSION:String = "1.4";
        
        /**
         * Width of the game.
         */
        public static var width:uint;
        
        /**
         * Height of the game.
         */
        public static var height:uint;
        
        /**
         * If the game is running at a fixed framerate.
         */
        public static var fixed:Boolean;
        
        /**
         * The framerate assigned to the stage.
         */
        public static var frameRate:Number;
        
        /**
         * The framerate assigned to the stage.
         */
        public static var assignedFrameRate:Number;
        
        /**
         * Time elapsed since the last frame (non-fixed framerate only).
         */
        public static var elapsed:Number;
        
        /**
         * Timescale applied to FP.elapsed (non-fixed framerate only).
         */
        public static var rate:Number = 1;
        
        /**
         * The Screen object, use to transform or offset the Screen.
         */
        public static var screen:Screen;
        
        /**
         * The current screen buffer, drawn to in the render loop.
         */
        public static var buffer:BitmapData;
        
        /**
         * A rectangle representing the size of the screen.
         */
        public static var bounds:Rectangle;
        
        /**
         * Point used to determine drawing offset in the render loop.
         */
        public static var camera:Point = new Point;
        
        /**
         * Half the screen width.
         */
        public static function get halfWidth():Number { return width / 2; }
        
        /**
         * Half the screen height.
         */
        public static function get halfHeight():Number { return height / 2; }
        
        /**
         * The currently active World object. When you set this, the World is flagged
         * to switch, but won't actually do so until the end of the current frame.
         */
        public static function get world():World { return _world; }
        public static function set world(value:World):void
        {
            if (_world == value) return;
            _goto = value;
        }
        
        /**
         * Sets the camera position.
         * @param    x    X position.
         * @param    y    Y position.
         */
        public static function setCamera(x:Number = 0, y:Number = 0):void
        {
            camera.x = x;
            camera.y = y;
        }
        
        /**
         * Resets the camera position.
         */
        public static function resetCamera():void
        {
            camera.x = camera.y = 0;
        }
        
        /**
         * Global volume factor for all sounds, a value from 0 to 1.
         */
        public static function get volume():Number { return _volume; }
        public static function set volume(value:Number):void
        {
            if (value < 0) value = 0;
            if (_volume == value) return;
            _soundTransform.volume = _volume = value;
            SoundMixer.soundTransform = _soundTransform;
        }
        
        /**
         * Global panning factor for all sounds, a value from -1 to 1.
         */
        public static function get pan():Number { return _pan; }
        public static function set pan(value:Number):void
        {
            if (value < -1) value = -1;
            if (value > 1) value = 1;
            if (_pan == value) return;
            _soundTransform.pan = _pan = value;
            SoundMixer.soundTransform = _soundTransform;
        }
        
        /**
         * Randomly chooses and returns one of the provided values.
         * @param    ...objs        The Objects you want to randomly choose from. Can be ints, Numbers, Points, etc.
         * @return    A randomly chosen one of the provided parameters.
         */
        public static function choose(...objs):*
        {
            var c:* = (objs.length == 1 && (objs[0] is Array || objs[0] is Vector.<*>)) ? objs[0] : objs;
            return c[rand(c.length)];
        }
        
        /**
         * Finds the sign of the provided value.
         * @param    value        The Number to evaluate.
         * @return    1 if value > 0, -1 if value < 0, and 0 when value == 0.
         */
        public static function sign(value:Number):int
        {
            return value < 0 ? -1 : (value > 0 ? 1 : 0);
        }
        
        /**
         * Approaches the value towards the target, by the specified amount, without overshooting the target.
         * @param    value    The starting value.
         * @param    target    The target that you want value to approach.
         * @param    amount    How much you want the value to approach target by.
         * @return    The new value.
         */
        public static function approach(value:Number, target:Number, amount:Number):Number
        {
            return value < target ? (target < value + amount ? target : value + amount) : (target > value - amount ? target : value - amount);
        }
        
        /**
         * Linear interpolation between two values.
         * @param    a        First value.
         * @param    b        Second value.
         * @param    t        Interpolation factor.
         * @return    When t=0, returns a. When t=1, returns b. When t=0.5, will return halfway between a and b. Etc.
         */
        public static function lerp(a:Number, b:Number, t:Number = 1):Number
        {
            return a + (b - a) * t;
        }
        
        /**
         * Linear interpolation between two colors.
         * @param    fromColor        First color.
         * @param    toColor            Second color.
         * @param    t                Interpolation value. Clamped to the range [0, 1].
         * return    RGB component-interpolated color value.
         */
        public static function colorLerp(fromColor:uint, toColor:uint, t:Number = 1):uint
        {
            if (t <= 0) { return fromColor; }
            if (t >= 1) { return toColor; }
            var a:uint = fromColor >> 24 & 0xFF,
                r:uint = fromColor >> 16 & 0xFF,
                g:uint = fromColor >> 8 & 0xFF,
                b:uint = fromColor & 0xFF,
                dA: int = (toColor >> 24 & 0xFF) - a,
                dR: int = (toColor >> 16 & 0xFF) - r,
                dG: int = (toColor >> 8 & 0xFF) - g,
                dB: int = (toColor & 0xFF) - b;
            a += dA * t;
            r += dR * t;
            g += dG * t;
            b += dB * t;
            return a << 24 | r << 16 | g << 8 | b;
        }
        
        /**
         * Steps the object towards a point.
         * @param    object        Object to move (must have an x and y property).
         * @param    x            X position to step towards.
         * @param    y            Y position to step towards.
         * @param    distance    The distance to step (will not overshoot target).
         */
        public static function stepTowards(object:Object, x:Number, y:Number, distance:Number = 1):void
        {
            point.x = x - object.x;
            point.y = y - object.y;
            if (point.length <= distance)
            {
                object.x = x;
                object.y = y;
                return;
            }
            point.normalize(distance);
            object.x += point.x;
            object.y += point.y;
        }
        
        /**
         * Anchors the object to a position.
         * @param    object        The object to anchor.
         * @param    anchor        The anchor object.
         * @param    distance    The max distance object can be anchored to the anchor.
         */
        public static function anchorTo(object:Object, anchor:Object, distance:Number = 0):void
        {
            point.x = object.x - anchor.x;
            point.y = object.y - anchor.y;
            if (point.length > distance) point.normalize(distance);
            object.x = anchor.x + point.x;
            object.y = anchor.y + point.y;
        }
        
        /**
         * Finds the angle (in degrees) from point 1 to point 2.
         * @param    x1        The first x-position.
         * @param    y1        The first y-position.
         * @param    x2        The second x-position.
         * @param    y2        The second y-position.
         * @return    The angle from (x1, y1) to (x2, y2).
         */
        public static function angle(x1:Number, y1:Number, x2:Number, y2:Number):Number
        {
            var a:Number = Math.atan2(y2 - y1, x2 - x1) * DEG;
            return a < 0 ? a + 360 : a;
        }
        
        /**
         * Sets the x/y values of the provided object to a vector of the specified angle and length.
         * @param    object        The object whose x/y properties should be set.
         * @param    angle        The angle of the vector, in degrees.
         * @param    length        The distance to the vector from (0, 0).
         * @param    x            X offset.
         * @param    y            Y offset.
         */
        public static function angleXY(object:Object, angle:Number, length:Number = 1, x:Number = 0, y:Number = 0):void
        {
            angle *= RAD;
            object.x = Math.cos(angle) * length + x;
            object.y = Math.sin(angle) * length + y;
        }
        
        /**
         * Rotates the object around the anchor by the specified amount.
         * @param    object        Object to rotate around the anchor.
         * @param    anchor        Anchor to rotate around.
         * @param    angle        The amount of degrees to rotate by.
         */
        public static function rotateAround(object:Object, anchor:Object, angle:Number = 0, relative:Boolean = true):void
        {
            if (relative) angle += FP.angle(anchor.x, anchor.y, object.x, object.y);
            FP.angleXY(object, angle, FP.distance(anchor.x, anchor.y, object.x, object.y), anchor.x, anchor.y);
        }
        
        /**
         * Find the distance between two points.
         * @param    x1        The first x-position.
         * @param    y1        The first y-position.
         * @param    x2        The second x-position.
         * @param    y2        The second y-position.
         * @return    The distance.
         */
        public static function distance(x1:Number, y1:Number, x2:Number = 0, y2:Number = 0):Number
        {
            return Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
        }
        
        /**
         * Find the distance between two rectangles. Will return 0 if the rectangles overlap.
         * @param    x1        The x-position of the first rect.
         * @param    y1        The y-position of the first rect.
         * @param    w1        The width of the first rect.
         * @param    h1        The height of the first rect.
         * @param    x2        The x-position of the second rect.
         * @param    y2        The y-position of the second rect.
         * @param    w2        The width of the second rect.
         * @param    h2        The height of the second rect.
         * @return    The distance.
         */
        public static function distanceRects(x1:Number, y1:Number, w1:Number, h1:Number, x2:Number, y2:Number, w2:Number, h2:Number):Number
        {
            if (x1 < x2 + w2 && x2 < x1 + w1)
            {
                if (y1 < y2 + h2 && y2 < y1 + h1) return 0;
                if (y1 > y2) return y1 - (y2 + h2);
                return y2 - (y1 + h1);
            }
            if (y1 < y2 + h2 && y2 < y1 + h1)
            {
                if (x1 > x2) return x1 - (x2 + w2);
                return x2 - (x1 + w1)
            }
            if (x1 > x2)
            {
                if (y1 > y2) return distance(x1, y1, (x2 + w2), (y2 + h2));
                return distance(x1, y1 + h1, x2 + w2, y2);
            }
            if (y1 > y2) return distance(x1 + w1, y1, x2, y2 + h2)
            return distance(x1 + w1, y1 + h1, x2, y2);
        }
        
        /**
         * Find the distance between a point and a rectangle. Returns 0 if the point is within the rectangle.
         * @param    px        The x-position of the point.
         * @param    py        The y-position of the point.
         * @param    rx        The x-position of the rect.
         * @param    ry        The y-position of the rect.
         * @param    rw        The width of the rect.
         * @param    rh        The height of the rect.
         * @return    The distance.
         */
        public static function distanceRectPoint(px:Number, py:Number, rx:Number, ry:Number, rw:Number, rh:Number):Number
        {
            if (px >= rx && px <= rx + rw)
            {
                if (py >= ry && py <= ry + rh) return 0;
                if (py > ry) return py - (ry + rh);
                return ry - py;
            }
            if (py >= ry && py <= ry + rh)
            {
                if (px > rx) return px - (rx + rw);
                return rx - px;
            }
            if (px > rx)
            {
                if (py > ry) return distance(px, py, rx + rw, ry + rh);
                return distance(px, py, rx + rw, ry);
            }
            if (py > ry) return distance(px, py, rx, ry + rh)
            return distance(px, py, rx, ry);
        }
        
        /**
         * Clamps the value within the minimum and maximum values.
         * @param    value        The Number to evaluate.
         * @param    min            The minimum range.
         * @param    max            The maximum range.
         * @return    The clamped value.
         */
        public static function clamp(value:Number, min:Number, max:Number):Number
        {
            if (max > min)
            {
                value = value < max ? value : max;
                return value > min ? value : min;
            }
            value = value < min ? value : min;
            return value > max ? value : max;
        }
        
        /**
         * Clamps the object inside the rectangle.
         * @param    object        The object to clamp (must have an x and y property).
         * @param    x            Rectangle's x.
         * @param    y            Rectangle's y.
         * @param    width        Rectangle's width.
         * @param    height        Rectangle's height.
         */
        public static function clampInRect(object:Object, x:Number, y:Number, width:Number, height:Number, padding:Number = 0):void
        {
            object.x = clamp(object.x, x + padding, x + width - padding);
            object.y = clamp(object.y, y + padding, y + height - padding);
        }
        
        /**
         * Transfers a value from one scale to another scale. For example, scale(.5, 0, 1, 10, 20) == 15, and scale(3, 0, 5, 100, 0) == 40.
         * @param    value        The value on the first scale.
         * @param    min            The minimum range of the first scale.
         * @param    max            The maximum range of the first scale.
         * @param    min2        The minimum range of the second scale.
         * @param    max2        The maximum range of the second scale.
         * @return    The scaled value.
         */
        public static function scale(value:Number, min:Number, max:Number, min2:Number, max2:Number):Number
        {
            return min2 + ((value - min) / (max - min)) * (max2 - min2);
        }
        
        /**
         * Transfers a value from one scale to another scale, but clamps the return value within the second scale.
         * @param    value        The value on the first scale.
         * @param    min            The minimum range of the first scale.
         * @param    max            The maximum range of the first scale.
         * @param    min2        The minimum range of the second scale.
         * @param    max2        The maximum range of the second scale.
         * @return    The scaled and clamped value.
         */
        public static function scaleClamp(value:Number, min:Number, max:Number, min2:Number, max2:Number):Number
        {
            value = min2 + ((value - min) / (max - min)) * (max2 - min2);
            if (max2 > min2)
            {
                value = value < max2 ? value : max2;
                return value > min2 ? value : min2;
            }
            value = value < min2 ? value : min2;
            return value > max2 ? value : max2;
        }
        
        /**
         * The random seed used by FP's random functions.
         */
        public static function get randomSeed():uint { return _getSeed; }
        public static function set randomSeed(value:uint):void
        {
            _seed = clamp(value, 1, 2147483646);
            _getSeed = _seed;
        }
        
        /**
         * Randomizes the random seed using Flash's Math.random() function.
         */
        public static function randomizeSeed():void
        {
            randomSeed = 2147483647 * Math.random();
        }
        
        /**
         * A pseudo-random Number produced using FP's random seed, where 0 <= Number < 1.
         */
        public static function get random():Number
        {
            _seed = (_seed * 16807) % 2147483647;
            return _seed / 2147483647;
        }
        
        /**
         * Returns a pseudo-random uint.
         * @param    amount        The returned uint will always be 0 <= uint < amount.
         * @return    The uint.
         */
        public static function rand(amount:uint):uint
        {
            _seed = (_seed * 16807) % 2147483647;
            return (_seed / 2147483647) * amount;
        }
        
        /**
         * Returns the next item after current in the list of options.
         * @param    current        The currently selected item (must be one of the options).
         * @param    options        An array of all the items to cycle through.
         * @param    loop        If true, will jump to the first item after the last item is reached.
         * @return    The next item in the list.
         */
        public static function next(current:*, options:Array, loop:Boolean = true):*
        {
            if (loop) return options[(options.indexOf(current) + 1) % options.length];
            return options[Math.max(options.indexOf(current) + 1, options.length - 1)];
        }
        
        /**
         * Returns the item previous to the current in the list of options.
         * @param    current        The currently selected item (must be one of the options).
         * @param    options        An array of all the items to cycle through.
         * @param    loop        If true, will jump to the last item after the first is reached.
         * @return    The previous item in the list.
         */
        public static function prev(current:*, options:Array, loop:Boolean = true):*
        {
            if (loop) return options[((options.indexOf(current) - 1) + options.length) % options.length];
            return options[Math.max(options.indexOf(current) - 1, 0)];
        }
        
        /**
         * Swaps the current item between a and b. Useful for quick state/string/value swapping.
         * @param    current        The currently selected item.
         * @param    a            Item a.
         * @param    b            Item b.
         * @return    Returns a if current is b, and b if current is a.
         */
        public static function swap(current:*, a:*, b:*):*
        {
            return current == a ? b : a;
        }
        
        /**
         * Creates a color value by combining the chosen RGB values.
         * @param    R        The red value of the color, from 0 to 255.
         * @param    G        The green value of the color, from 0 to 255.
         * @param    B        The blue value of the color, from 0 to 255.
         * @return    The color uint.
         */
        public static function getColorRGB(R:uint = 0, G:uint = 0, B:uint = 0):uint
        {
            return R << 16 | G << 8 | B;
        }
        
        /**
         * Creates a color value with the chosen HSV values.
         * @param    h        The hue of the color (from 0 to 1).
         * @param    s        The saturation of the color (from 0 to 1).
         * @param    v        The value of the color (from 0 to 1).
         * @return    The color uint.
         */
        public static function getColorHSV(h:Number, s:Number, v:Number):uint
        {
            h = int(h * 360);
            var hi:int = Math.floor(h / 60) % 6,
                f:Number = h / 60 - Math.floor(h / 60),
                p:Number = (v * (1 - s)),
                q:Number = (v * (1 - f * s)),
                t:Number = (v * (1 - (1 - f) * s));
            switch (hi)
            {
                case 0: return int(v * 255) << 16 | int(t * 255) << 8 | int(p * 255);
                case 1: return int(q * 255) << 16 | int(v * 255) << 8 | int(p * 255);
                case 2: return int(p * 255) << 16 | int(v * 255) << 8 | int(t * 255);
                case 3: return int(p * 255) << 16 | int(q * 255) << 8 | int(v * 255);
                case 4: return int(t * 255) << 16 | int(p * 255) << 8 | int(v * 255);
                case 5: return int(v * 255) << 16 | int(p * 255) << 8 | int(q * 255);
                default: return 0;
            }
            return 0;
        }
        
        /**
         * Finds the red factor of a color.
         * @param    color        The color to evaluate.
         * @return    A uint from 0 to 255.
         */
        public static function getRed(color:uint):uint
        {
            return color >> 16 & 0xFF;
        }
        
        /**
         * Finds the green factor of a color.
         * @param    color        The color to evaluate.
         * @return    A uint from 0 to 255.
         */
        public static function getGreen(color:uint):uint
        {
            return color >> 8 & 0xFF;
        }
        
        /**
         * Finds the blue factor of a color.
         * @param    color        The color to evaluate.
         * @return    A uint from 0 to 255.
         */
        public static function getBlue(color:uint):uint
        {
            return color & 0xFF;
        }
        
        /**
         * Fetches a stored BitmapData object represented by the source.
         * @param    source        Embedded Bitmap class.
         * @return    The stored BitmapData object.
         */
        public static function getBitmap(source:Class):BitmapData
        {
            if (_bitmap[String(source)]) return _bitmap[String(source)];
            return (_bitmap[String(source)] = (new source).bitmapData);
        }
        
        /**
         * Sets a time flag.
         * @return    Time elapsed (in milliseconds) since the last time flag was set.
         */
        public static function timeFlag():uint
        {
            var t:uint = getTimer(),
                e:uint = t - _time;
            _time = t;
            return e;
        }
        
        /**
         * The global Console object.
         */
        public static function get console():Console
        {
            if (!_console) _console = new Console;
            return _console;
        }
        
        /**
         * Logs data to the console.
         * @param    ...data        The data parameters to log, can be variables, objects, etc. Parameters will be separated by a space (" ").
         */
        public static function log(...data):void
        {
            if (_console)
            {
                if (data.length > 1)
                {
                    var i:int = 0, s:String = "";
                    while (i < data.length)
                    {
                        if (i > 0) s += " ";
                        s += data[i ++].toString();
                    }
                    _console.log(s);
                }
                else _console.log(data[0]);
            }
        }
        
        /**
         * Adds properties to watch in the console's debug panel.
         * @param    ...properties        The properties (strings) to watch.
         */
        public static function watch(...properties):void
        {
            if (_console)
            {
                if (properties.length > 1) _console.watch(properties);
                else _console.watch(properties[0]);
            }
        }
        
        /**
         * Loads the file as an XML object.
         * @param    file        The embedded file to load.
         * @return    An XML object representing the file.
         */
        public static function getXML(file:Class):XML
        {
            var bytes:ByteArray = new file;
            return XML(bytes.readUTFBytes(bytes.length));
        }
        
        /**
         * Tweens numeric public properties of an Object. Shorthand for creating a MultiVarTween tween, starting it and adding it to a Tweener.
         * @param    object        The object containing the properties to tween.
         * @param    values        An object containing key/value pairs of properties and target values.
         * @param    duration    Duration of the tween.
         * @param    options        An object containing key/value pairs of the following optional parameters:
         *                         type        Tween type.
         *                         complete    Optional completion callback function.
         *                         ease        Optional easer function.
         *                         tweener        The Tweener to add this Tween to.
         * @return    The added MultiVarTween object.
         * 
         * Example: FP.tween(object, { x: 500, y: 350 }, 2.0, { ease: easeFunction, complete: onComplete } );
         */
        public static function tween(object:Object, values:Object, duration:Number, options:Object = null):MultiVarTween
        {
            var type:uint = Tween.ONESHOT,
                complete:Function = null,
                ease:Function = null,
                tweener:Tweener = FP.world;
            if (object is Tweener) tweener = object as Tweener;
            if (options)
            {
                if (options.hasOwnProperty("type")) type = options.type;
                if (options.hasOwnProperty("complete")) complete = options.complete;
                if (options.hasOwnProperty("ease")) ease = options.ease;
                if (options.hasOwnProperty("tweener")) tweener = options.tweener;
            }
            var tween:MultiVarTween = new MultiVarTween(complete, type);
            tween.tween(object, values, duration, ease);
            tweener.addTween(tween);
            return tween;
        }
        
        /**
         * Gets an array of frame indices.
         * @param    from    Starting frame.
         * @param    to        Ending frame.
         * @param    skip    Skip amount every frame (eg. use 1 for every 2nd frame).
         */
        public static function frames(from:int, to:int, skip:int = 0):Array
        {
            var a:Array = [];
            skip ++;
            if (from < to)
            {
                while (from <= to)
                {
                    a.push(from);
                    from += skip;
                }
            }
            else
            {
                while (from >= to)
                {
                    a.push(from);
                    from -= skip;
                }
            }
            return a;
        }
        
        /**
         * Shuffles the elements in the array.
         * @param    a        The Object to shuffle (an Array or Vector).
         */
        public static function shuffle(a:Object):void
        {
            if (a is Array || a is Vector.<*>)
            {
                var i:int = a.length, j:int, t:*;
                while (-- i)
                {
                    t = a[i];
                    a[i] = a[j = FP.rand(i + 1)];
                    a[j] = t;
                }
            }
        }
        
        /**
         * Sorts the elements in the array.
         * @param    object        The Object to sort (an Array or Vector).
         * @param    ascending    If it should be sorted ascending (true) or descending (false).
         */
        public static function sort(object:Object, ascending:Boolean = true):void
        {
            if (object is Array || object is Vector.<*>) quicksort(object, 0, object.length - 1, ascending);
        }
        
        /**
         * Sorts the elements in the array by a property of the element.
         * @param    object        The Object to sort (an Array or Vector).
         * @param    property    The numeric property of object's elements to sort by.
         * @param    ascending    If it should be sorted ascending (true) or descending (false).
         */
        public static function sortBy(object:Object, property:String, ascending:Boolean = true):void
        {
            if (object is Array || object is Vector.<*>) quicksortBy(object, 0, object.length - 1, ascending, property);
        }
        
        /** @private Quicksorts the array. */ 
        private static function quicksort(a:Object, left:int, right:int, ascending:Boolean):void
        {
            var i:int = left, j:int = right, t:Number,
                p:* = a[Math.round((left + right) * .5)];
            if (ascending)
            {
                while (i <= j)
                {
                    while (a[i] < p) i ++;
                    while (a[j] > p) j --;
                    if (i <= j)
                    {
                        t = a[i];
                        a[i ++] = a[j];
                        a[j --] = t;
                    }
                }
            }
            else
            {
                while (i <= j)
                {
                    while (a[i] > p) i ++;
                    while (a[j] < p) j --;
                    if (i <= j)
                    {
                        t = a[i];
                        a[i ++] = a[j];
                        a[j --] = t;
                    }
                }
            }
            if (left < j) quicksort(a, left, j, ascending);
            if (i < right) quicksort(a, i, right, ascending);
        }
        
        /** @private Quicksorts the array by the property. */ 
        private static function quicksortBy(a:Object, left:int, right:int, ascending:Boolean, property:String):void
        {
            var i:int = left, j:int = right, t:Object,
                p:* = a[Math.round((left + right) * .5)][property];
            if (ascending)
            {
                while (i <= j)
                {
                    while (a[i][property] < p) i ++;
                    while (a[j][property] > p) j --;
                    if (i <= j)
                    {
                        t = a[i];
                        a[i ++] = a[j];
                        a[j --] = t;
                    }
                }
            }
            else
            {
                while (i <= j)
                {
                    while (a[i][property] > p) i ++;
                    while (a[j][property] < p) j --;
                    if (i <= j)
                    {
                        t = a[i];
                        a[i ++] = a[j];
                        a[j --] = t;
                    }
                }
            }
            if (left < j) quicksortBy(a, left, j, ascending, property);
            if (i < right) quicksortBy(a, i, right, ascending, property);
        }
        
        // World information.
        /** @private */ internal static var _world:World;
        /** @private */ internal static var _goto:World;
        
        // Console information.
        /** @private */ internal static var _console:Console;
        
        // Time information.
        /** @private */ internal static var _time:uint;
        /** @private */ public static var _updateTime:uint;
        /** @private */ public static var _renderTime:uint;
        /** @private */ public static var _gameTime:uint;
        /** @private */ public static var _flashTime:uint;
        
        // Bitmap storage.
        /** @private */ private static var _bitmap:Object = { };
        
        // Pseudo-random number generation (the seed is set in Engine's contructor).
        /** @private */ private static var _seed:uint = 0;
        /** @private */ private static var _getSeed:uint;
        
        // Volume control.
        /** @private */ private static var _volume:Number = 1;
        /** @private */ private static var _pan:Number = 0;
        /** @private */ private static var _soundTransform:SoundTransform = new SoundTransform;
        
        // Used for rad-to-deg and deg-to-rad conversion.
        /** @private */ public static const DEG:Number = -180 / Math.PI;
        /** @private */ public static const RAD:Number = Math.PI / -180;
        
        // Global Flash objects.
        /** @private */ public static var stage:Stage;
        /** @private */ public static var engine:Engine;
        
        // Global objects used for rendering, collision, etc.
        /** @private */ public static var point:Point = new Point;
        /** @private */ public static var point2:Point = new Point;
        /** @private */ public static var zero:Point = new Point;
        /** @private */ public static var rect:Rectangle = new Rectangle;
        /** @private */ public static var matrix:Matrix = new Matrix;
        /** @private */ public static var sprite:Sprite = new Sprite;
        /** @private */ public static var entity:Entity;
    }
}