// todo: check http://ejohn.org/blog/ecmascript-5-strict-mode-json-and-more/

Ox = {
    //jQuery: jQuery || {}, // fixme: make this private
    version: "0.1.2"
};

/*
================================================================================
Core functions
================================================================================
*/

Ox.getset = function(obj, args, callback, context) {
    /*
    generic getter and setter function
    Ox.getset(obj)                                      returns obj
    Ox.getset(obj, str)                                 returns obj.str
    Ox.getset(obj, {key: val, ...}, callback, context)  sets obj.key to val,
                                                        calls callback(key, val),
                                                        returns context
    */
    var obj_ = obj,
        args = args || {},
        callback = callback || function() {},
        context = context || {},
        length = args.length,
        ret;
    if (length == 0) {
        // getset()
        ret = obj;
    } else if (length == 1 && typeof arguments[0] == "string") {
        // getset(str)
        ret = obj[args[0]]
    } else {
        // getset(str, val) or getset({str: val, ...})
        // translate (str, val) to ({str: val})
        args = Ox.makeObject(args);
        obj = $.extend(obj, args);
        $.each(args, function(key, value) {
            if (!obj_ || !obj_[key] || obj_[key] !== value) {
                callback(key, value);
            }
        });
        ret = context;                            
    }
    return ret;
}

Ox.print = function() {
    /*
    */
    if (typeof console != "undefined") {
        var args = $.makeArray(arguments),
            date = new Date;
        args.unshift(Ox.formatDate(date, "%H:%M:%S") + "." +
            (Ox.pad(+date % 1000, 3)));
        console.log.apply(console, args);
    }
}

Ox.uid = function() {
    /*
    >>> Ox.uid() == Ox.uid()
    false
    */
    var uid = 0;
    return function() {
        return uid++;
    };
}();

Ox.user = function() {
    $.get("http://www.maxmind.com/app/locate_my_ip", function(data) {
        var arr = data.split("tblProduct1"),
            re = />(.+?)<\/td>\n<td class=output align="center">\n(.*?)\n/,
            results = {};
        arr.shift();
        $.each(arr, function(i, v) {
            var result = re(v);
            results[result[1].replace(/Your |\*/, "")] = result[2];
        });
        Ox.print(results)
    });
    return {
        document: {
            referrer: document.referrer
        },
        history: {
            length: history.length
        },
        navigator: navigator,
        innerHeight: innerHeight,
        innerWidth: innerWidth,
        screen: screen,
        outerHeight: outerHeight,
        outerWidth: outerWidth
    }
}

/*
================================================================================
Array and Object functions
================================================================================
*/

Ox.avg = function(obj) {
    /*
    >>> Ox.avg([-1, 0, 1])
    0
    >>> Ox.avg({"a": 1, "b": 2, "c": 3})
    2
    */
    return Ox.sum(obj) / Ox.length(obj);
};

Ox.each = function(obj, fn) {
    /*
    Ox.each() works for arrays, objects and strings,
    like $.each(), unlike [].forEach()
    >>> Ox.each([0, 1, 2], function(i, v) {})
    [0, 1, 2]
    >>> Ox.each({a: 1, b: 2, c: 3}, function(k, v) {}).a
    1
    >>> Ox.each("foo", function(i, v) {})
    "foo"
    */
    var i;
    for (i in obj) {
        if (fn(i, obj[i]) === false) {
            break;
        }
    }
    return obj;
};

Ox.equals = function() { // unused
    /*
    ... core? type?
    */
    var ret = false;
    if (obj0.length == obj1.length) {
        Ox.each(obj0, function(k, v) {
            if (Ox.isObject(v)) {
                
            } else {
                
            }
            return ret;
        });
    }
    return ret;
}

Ox.every = function(obj, fn) {
    /*
    Ox.every() forks for arrays, objects and strings, unlike [].every()
    >>> Ox.every([0, 1, 2], function(v, i) { return i == v; })
    true
    >>> Ox.every({a: 1, b: 2, c: 3}, function(v) { return v == 1; })
    false
    >>> Ox.every("foo", function(v) { return v == "f"; })
    false
    */
    return Ox.filter(Ox.values(obj), fn).length == Ox.length(obj);
};

Ox.filter = function(arr, fn) {
    /*
    Ox.filter works for arrays and strings, like $.grep(), unlike [].filter()
    >>> Ox.filter([2, 1, 0], function(v, i) { return v == i; })
    [1]
    >>> Ox.filter("210", function(v, i) { return v == i; })
    [1]
    */
    var i, len = arr.length, ret = [];
    for (i = 0; i < len; i++) {
        if (fn(arr[i], i)) {
            ret.push(arr[i]);
        }
    }
    return ret;
};

Ox.keys = function(obj) {
    /*
    >>> Ox.keys({"a": 1, "b": 2, "c": 3})
    ["a", "b", "c"]
    */
    var keys = [];
    Ox.each(obj, function(k) {
        keys.push(k);
    });
    return keys;
};

Ox.length = function(obj) {
    /*
    >>> Ox.length({"a": 1, "b": 2, "c": 3})
    3
    */
    var length = 0;
    Ox.each(obj, function() {
        length++;
    });
    return length;
};

Ox.makeArray = function(arr) {
    /*
    like $.makeArray()
    >>> Ox.makeArray("foo")
    ["foo"]
    >>> Ox.makeArray(["foo"])
    ["foo"]
    >>> (function() { return Ox.makeArray(arguments); })("foo")
    ["foo"]
    >>> (function() { return Ox.makeArray(arguments); })(["foo"])
    ["foo"]
    */
    var ret = [], i = 0, len = arr.length;
    if (Ox.isString(arr)) {
        ret = [arr];
    } else {
        for (i = 0; i < len; i++) {
            ret.push(arr[i]);
        }
    }
    return ret;
};

Ox.makeObject = function(arr) {
    /*
    >>> Ox.makeObject("foo", "bar").foo
    "bar"
    >>> Ox.makeObject({foo: "bar"}).foo
    "bar"
    >/>> (function() { return Ox.makeObject(arguments); })("foo", "bar").foo // fixme
    "bar"
    >/>> (function() { return Ox.makeObject(arguments); })({foo: "bar"}).foo
    "bar"
    */
    var obj = {};
    if (arguments.length == 1) {
        obj = arguments[0];
    } else {
        obj[arguments[0]] = arguments[1];
    }
    return obj;
};

Ox.map = function(arr, fn) {
    /*
    Ox.map() works for arrays and strings, like $.map(), unlike [].map()
    >>> Ox.map([1, 1, 1], function(v, i) { return v == i; })
    [false, true, false]
    >>> Ox.map("111", function(v, i) { return v == i; })
    [false, true, false]
    >>> Ox.map(new Array(3), function(v, i) { return i; })
    [0, 1, 2]
    */
    var i, len = arr.length, val, ret = [];
    for (i = 0; i < len; i++) {
        if ((val = fn(arr[i], i)) !== null) {
            ret.push(val);
        }
    }
    return ret;
};

Ox.max = function(obj) {
    /*
    >>> Ox.max([-1, 0, 1])
    1
    >>> Ox.max({"a": 1, "b": 2, "c": 3})
    3
    */
    return Math.max.apply(Math, Ox.values(obj));
};

Ox.min = function(obj) {
    /*
    >>> Ox.min([-1, 0, 1])
    -1
    >>> Ox.min({"a": 1, "b": 2, "c": 3})
    1
    */
    return Math.min.apply(Math, Ox.values(obj));
};

Ox.range = function(start, stop, step) {
    /*
    >>> Ox.range(3)
    [0, 1, 2]
    >>> Ox.range(3, 0)
    [3, 2, 1]
    >>> Ox.range(1, 2, 0.5)
    [1, 1.5]
    */
    stop = arguments.length > 1 ? stop : arguments[0];
    start = arguments.length > 1 ? start : 0;
    step = step || (start <= stop ? 1 : -1);
    var range = [],
        i;
    for (i = start; step > 0 ? i < stop : i > stop; i += step) {
        range.push(i);
    }
    return range;
};

Ox.shuffle = function(arr) {
    /*
    >>> Ox.shuffle([1, 2, 3]).length
    3
    */
    var shuffle = arr;
    return shuffle.sort(function() {
        return Math.random() - 0.5;
    });
};

Ox.some = function(obj, fn) {
    /*
    Ox.some() forks for arrays, objects and strings, unlike [].some()
    >>> Ox.some([2, 1, 0], function(i, v) { return i == v; })
    true
    >>> Ox.some({a: 1, b: 2, c: 3}, function(v) { return v == 1; })
    true
    >>> Ox.some("foo", function(v) { return v == "f"; })
    true
    */
    return Ox.filter(Ox.values(obj), fn).length > 0;
};

Ox.sum = function(obj) {
    /*
    >>> Ox.sum([-1, 0, 1])
    0
    >>> Ox.sum({"a": 1, "b": 2, "c": 3})
    6
    */
    var sum = 0;
    Ox.each(obj, function(k, v) {
        sum += v;
    });
    return sum;
};

Ox.values = function(obj) {
    /*
    >>> Ox.values({"a": 1, "b": 2, "c": 3}).join(",")
    [1, 2, 3]
    >>> Ox.values([1, 2, 3]).join(",")
    [1, 2, 3]
    */
    var values = [];
    Ox.each(obj, function(k, v) {
        values.push(v);
    });
    return values;
};

Ox.zip = function() {
    /*
    // fixme: Ox.each doesn't work here
    >>> Ox.zip([[0, 1], [2, 3], [4, 5]])
    [[0, 2, 4], [1, 3, 5]]
    >>> Ox.zip([0, 1, 2], [3, 4, 5])
    [[0, 3], [1, 4], [2, 5]]
    */
    var args = arguments.length == 1 ? arguments[0] : Ox.makeArray(arguments),
        arr = [];
    args[0].forEach(function(v, i) {
        arr[i] = [];
        args.forEach(function(v_, i_) {
            arr[i].push(v_[i]);
        });
    });
    return arr;
};

/*
================================================================================
Color functions
================================================================================
*/

Ox.hsl = function(rgb) {
    /*
    >>> Ox.hsl([0, 0, 0])
    [0, 0, 0]
    >>> Ox.hsl([255, 255, 255])
    [0, 0, 1]
    >>> Ox.hsl([0, 255, 0])
    [120, 1, 0.5]
    */
    rgb = rgb.map(function(v) {
        return v / 255;
    });
    var max = Ox.max(rgb),
        min = Ox.min(rgb),
        hsl = [0, 0, 0];
    hsl[2] = 0.5 * (max + min);
    if (max == min) {
        hsl[0] = 0;
        hsl[1] = 0;
    } else {
        if (max == rgb[0]) {
            hsl[0] = (60 * (rgb[1] - rgb[2]) / (max - min) + 360) % 360;
        } else if (max == rgb[1]) {
            hsl[0] = 60 * (rgb[2] - rgb[0]) / (max - min) + 120;
        } else if (max == rgb[2]) {
            hsl[0] = 60 * (rgb[0] - rgb[1]) / (max - min) + 240;
        }
        if (hsl[2] <= 0.5) {
            hsl[1] = (max - min) / (2 * hsl[2]);
        } else {
            hsl[1] = (max - min) / (2 - 2 * hsl[2]);
        }
    }
    return hsl;
};

Ox.rgb = function(hsl) {
    /*
    >>> Ox.rgb([0, 0, 0])
    [0, 0, 0]
    >>> Ox.rgb([0, 0, 1])
    [255, 255, 255]
    >>> Ox.rgb([120, 1, 0.5])
    [0, 255, 0]
    */
    hsl[0] /= 360;
    var rgb = [0, 0, 0],
        v1, v2, v3;
    if (hsl[1] == 0) {
        rgb = [hsl[2], hsl[2], hsl[2]];
    } else {
        if (hsl[2] < 0.5) {
            v2 = hsl[2] * (1 + hsl[1]); 
        } else {
            v2 = hsl[1] + hsl[2] - (hsl[1] * hsl[2]);
        }
        v1 = 2 * hsl[2] - v2;
        rgb.forEach(function(v, i) {
            v3 = hsl[0] + (1 - i) * 1/3;
            if (v3 < 0) {
                v3++;
            } else if (v3 > 1) {
                v3--;
            }
            if (v3 < 1/6) {
                rgb[i] = v1 + ((v2 - v1) * 6 * v3);
            } else if (v3 < 0.5) {
                rgb[i] = v2;
            } else if (v3 < 2/3) {
                rgb[i] = v1 + ((v2 - v1) * 6 * (2/3 - v3));
            } else {
                rgb[i] = v1;
            }
        });
    }
    return rgb.map(function(v) {
        return v * 255;
    });
};

/*
================================================================================
Date functions
================================================================================
*/

Ox.getFirstDayOfTheYear = function(date) {
    /*
    Decimal weekday of January 1 (0-6, Sunday as first day)
    >>> Ox.getFirstDayOfTheYear(new Date("01/01/00"))
    6
    */
    var date_ = date ? new Date(date.valueOf()) : new Date();
    date_.setMonth(0);
    date_.setDate(1);
    return date_.getDay();
};

Ox.getDayOfTheYear = function() {
    /*
    >>> Ox.getDayOfTheYear(new Date("12/31/2004"))
    366
    */
    var days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
    return function(date) {
        date = date || new Date();
        var day = date.getDate(),
            month = date.getMonth(),
            i;
        for (i = 0; i < month; i++) {
            day += days[i];
        }
        if (month >= 2 && Ox.isLeapYear(date.getFullYear())) {
            day++;
        }
        return day;
    };
}();

Ox.getISODate = function(date) {
    /*
    >>> Ox.getISODate(new Date("01/01/2000"))
    "2000-01-01T00:00:00Z"
    */
    return Ox.formatDate(date || new Date(), '%FT%TZ');
};

Ox.getISODay = function(date) {
    /*
    Decimal weekday (1-7, Monday as first day)
    >>> Ox.getISODay(new Date("01/01/2000"))
    6
    >>> Ox.getISODay(new Date("01/02/2000"))
    7
    >>> Ox.getISODay(new Date("01/03/2000"))
    1
    */
    return (date || new Date()).getDay() || 7;
};

Ox.getISOWeek = function(date) {
    /*
    see http://en.wikipedia.org/wiki/ISO_8601
    >>> Ox.getISOWeek(new Date("01/01/2000"))
    52
    >>> Ox.getISOWeek(new Date("01/02/2000"))
    52
    >>> Ox.getISOWeek(new Date("01/03/2000"))
    1
    */
    date = date || new Date();
    var date_ = new Date(date.valueOf());
    // set date to Thursday of the same week
    date_.setDate(date.getDate() - Ox.getISODay(date) + 4);
    return Math.floor((Ox.getDayOfTheYear(date_) - 1) / 7) + 1;
};

Ox.getISOYear = function(date) {
    /*
    see http://en.wikipedia.org/wiki/ISO_8601
    >>> Ox.getISOYear(new Date("01/01/2000"))
    1999
    >>> Ox.getISOYear(new Date("01/02/2000"))
    1999
    >>> Ox.getISOYear(new Date("01/03/2000"))
    2000
    */
    date = date || new Date();
    var date_ = new Date(date.valueOf());
    // set date to Thursday of the same week
    date_.setDate(date.getDate() - Ox.getISODay(date) + 4);
    return date_.getFullYear();
};

Ox.getTime = function() {
    return +new Date();
}

Ox.getTimezoneOffsetString = function(date) {
    /*
    Time zone offset string (-1200 - +1200)
    >>> Ox.getTimezoneOffsetString(new Date("01/01/2000"))
    "+0100"
    */
    var offset = (date || new Date()).getTimezoneOffset();
    return (offset < 0 ? '+' : '-') +
        Ox.pad(Math.floor(Math.abs(offset) / 60), 2) +
        Ox.pad(Math.abs(offset) % 60, 2);
};

Ox.getWeek = function(date) {
    /*
    Week of the year (0-53, Sunday as first day)
    >>> Ox.getWeek(new Date("01/01/2000"))
    0
    >>> Ox.getWeek(new Date("01/02/2000"))
    1
    >>> Ox.getWeek(new Date("01/03/2000"))
    1
    */
    date = date || new Date();
    return Math.floor((Ox.getDayOfTheYear(date) +
        Ox.getFirstDayOfTheYear(date) - 1) / 7);
};

Ox.isLeapYear = function(year) {
    /*
    >>> Ox.isLeapYear(2000)
    false
    */
    return year % 4 == 0 && year % 400 != 0;
};

/*
================================================================================
DOM functions
================================================================================
*/

Ox.canvas = function() {
    // Ox.canvas(img) or Ox.canvas(width, height)
    var c = {}, isImage = arguments.length == 1,
        image = isImage ? arguments[0] : {
            width: arguments[0], height: arguments[1]
        };
    c.context = (c.canvas = Ox.element("canvas").attr({
        width: image.width, height: image.height
    })[0]).getContext("2d");
    if (isImage) {
        c.context.drawImage(image, 0, 0);
    }
    c.data = (c.imageData = c.context.getImageData(0, 0,
            image.width, image.height)).data;
    return c;
};

Ox.element = function(str) {
    /*
    >>> Ox.element("div").attr({id: "foo"}).attr("id")
    "foo"
    >>> Ox.element("div").html("foo").html()
    "foo"
    */
    return {
        0: str[0] == "#" ? document.getElementById(str.substr(1)) :
                document.createElement(str),
        attr: function() {
            var args, ret, that = this;
            if (arguments.length == 1 && Ox.isString(arguments[0])) {
                ret = this[0].getAttribute(arguments[0]);
            } else {
                Ox.each(Ox.makeObject.apply(this, arguments), function(k, v) {
                    that[0].setAttribute(k, v);
                });
                ret = this;
            }
            return ret;
        },
        html: function(str) {
            var ret;
            if (Ox.isUndefined(str)) {
                ret = this[0].innerHTML;
            } else {
                this[0].innerHTML = str;
                ret = this;
            }
            return ret;
        }
    }
};

/*
================================================================================
Encoding functions
================================================================================
*/

(function() {

    var aliases = {"I": "1", "L": "1", "O": "0", "U": "V"},
        digits = "0123456789ABCDEFGHJKMNPQRSTVWXYZ";

    function max(width, height) {
        // returns maximum encoding capacity of an image
        return parseInt(width * height * 3/8) - 4;
    }

    function seek(data, px) {
        // returns this, or the next, opaque pixel
        while (data[px * 4 + 3] < 255) {
            if (++px * 4 == data.length) {
                throwPNGError("de");
            }
        }
        return px;
    }

    function xor(byte) {
        // returns "1"-bits-in-byte % 2
        var xor = 0;
        $.each(new Array(8), function(i) { // fixme: Ox.each doesn't work
            xor ^= byte >> i & 1;
        });
        return xor;
    }

    function throwPNGError(str) {
        throw new RangeError("PNG codec can't " +
            (str == "en" ? "encode data" : "decode image"));
    }

    function throwUTF8Error(byte, pos) {
        throw new RangeError("UTF-8 codec can't decode byte 0x" +
            byte.toString(16).toUpperCase() + " at position " + pos);
    }

    Ox.encodeBase32 = function(num) {
        // see http://www.crockford.com/wrmg/base32.html
        /*
        >>> Ox.encodeBase32(15360)
        "F00"
        >>> Ox.encodeBase32(33819)
        "110V"
        */
        return Ox.map(num.toString(32), function(char) {
            return digits[parseInt(char, 32)];
        }).join("");
    }

    Ox.decodeBase32 = function(str) {
        /*
        >>> Ox.decodeBase32("foo")
        15360
        >>> Ox.decodeBase32("ilou")
        33819
        >>> Ox.decodeBase32("?").toString() // fixme: toString shouldn't be necessary here
        "NaN"
        */
        return parseInt($.map(str.toUpperCase(), function(char) {
            var index = digits.indexOf(aliases[char] || char);
            return (index == -1 ? " " : index).toString(32);
        }).join(""), 32);
    }

    Ox.encodeBase64 = function(num) {
        /*
        >>> Ox.encodeBase64(32394)
        "foo"
        */
        return btoa(Ox.encodeBase256(num)).replace(/=/g, "");
    }

    Ox.decodeBase64 = function(str) {
        /*
        >>> Ox.decodeBase64("foo")
        32394
        */
        return Ox.decodeBase256(atob(str));
    }

    Ox.encodeBase128 = function(num) {
        /*
        >>> Ox.encodeBase128(1685487)
        "foo"
        */
        var str = "";
        while (num) {
            str = Ox.char(num & 127) + str;
            num >>= 7;
        }
        return str;
    }

    Ox.decodeBase128 = function(str) {
        /*
        >>> Ox.decodeBase128("foo")
        1685487
        */
        var num = 0, len = str.length;
        Ox.each(str, function(i, char) {
            num += char.charCodeAt(0) << (len - i - 1) * 7;
        });
        return num;
    }

    Ox.encodeBase256 = function(num) {
        /*
        >>> Ox.encodeBase256(6713199)
        "foo"
        */
        var str = "";
        while (num) {
            str = Ox.char(num & 255) + str;
            num >>= 8;
        }
        return str;
    }

    Ox.decodeBase256 = function(str) {
        /*
        >>> Ox.decodeBase256("foo")
        6713199
        */
        var num = 0, len = str.length;
        Ox.each(str, function(i, char) {
            num += char.charCodeAt(0) << (len - i - 1) * 8;
        });
        return num;
    }

    Ox.encodeDeflate = function(str) {
        // encodes string, using deflate
        /*
        in fact, the string is written to the rgb channels of a canvas element,
        then the dataURL is decoded from base64, and some head and tail cut off
        */
        str = Ox.encodeUTF8(str);
        var len = str.length, c = Ox.canvas(Math.ceil((4 + len) / 3), 1), data;
        str = Ox.pad(Ox.encodeBase256(len), 4, Ox.char(0)) + str +
                Ox.repeat("\u00FF", (4 - len % 4) % 4); // simpler? Ox.pad()?
        /* fixme: why does map not work here?
        c.data = $.map(c.data, function(v, i) {
            return i % 4 < 3 ? str.charCodeAt(i - parseInt(i / 4)) : 255;
        });
        */
        for (i = 0; i < c.data.length; i += 1) {
            c.data[i] = i % 4 < 3 ? str.charCodeAt(i - parseInt(i / 4)) : 255;
        }
        c.context.putImageData(c.imageData, 0, 0);
        data = atob(c.canvas.toDataURL().split(",")[1]);
        //Ox.print("deflate", len, "->", data.length - 20);
        return data.substr(8, data.length - 20);
    }

    Ox.decodeDeflate = function(str) {
        var image = new Image();
        image.src = "data:image/png;base64," + btoa("\u0089PNG\r\n\u001A\n" +
                str + Ox.repeat("\u0000", 4) + "IEND\u00AEB`\u0082");
        while (!image.width) {} // wait for image data
        str = Ox.map(Ox.canvas(image).data, function(v, i) {
            return i % 4 < 3 ? Ox.char(v) : "";
        }).join("");
        //Ox.print(str.length, "len", Ox.decodeBase256(str.substr(0, 4)), str)
        return Ox.decodeUTF8(str.substr(4, Ox.decodeBase256(str.substr(0, 4))));
    }

    Ox.encodeHTML = function() {
        /*
        >>> Ox.encodeHTML("'<\"&\">'")
        "&apos;&lt;&quot;&amp;&quot;&gt;&apos;"
        >>> Ox.encodeHTML("äbçdê")
        "&#x00E4;b&#x00E7;d&#x00EA;"
        */
        var entities = {
            '"': "&quot;", "&": "&amp;", "'": "&apos;", "<": "&lt;", ">": "&gt;"
        };
        return function(str) {
            return $.map(Array.prototype.slice.call(str), function(v) {
                var code = v.charCodeAt(0);
                return code < 128 ? (v in entities ? entities[v] : v) :
                    "&#x" + Ox.pad(code.toString(16).toUpperCase(), 4) + ";";
            }).join("");
        };
    }();

    Ox.decodeHTML = function(str) {
        /*
        >>> Ox.decodeHTML("&apos;&lt;&quot;&amp;&quot;&gt;&apos;")
        "'<\"&\">'"
        >>> Ox.decodeHTML("&#x0027;&#x003C;&#x0022;&#x0026;&#x0022;&#x003E;&#x0027;")
        "'<\"&\">'"
        >>> Ox.decodeHTML("&auml;b&ccedil;d&ecirc;")
        "äbçdê"
        >>> Ox.decodeHTML("&#x00E4;b&#x00E7;d&#x00EA;")
        "äbçdê"
        */
        // relies on dom, but shorter than using this:
        // http://www.w3.org/TR/html5/named-character-references.html
        return $("<div/>").html(str)[0].childNodes[0].nodeValue;
    };

    Ox.encodePNG = function(img, str) {
        // encodes string into image, returns new image url
        /*
        the message is compressed with deflate (by proxy of canvas),
        then the string (four bytes length) + (length bytes message)
        is encoded bitwise into the r/g/b bytes of all opaque pixels
        by flipping, if necessary, the least significant bit, so that
        (number of "1"-bits of the byte) % 2 is the bit of the string
        wishlist:
        - only use deflate if it actually shortens the message
        - in deflate, strip and later re-insert the chunk types
        - encode a decoy message into the least significant bit
          (and flip the second least significant bit, if at all)
        - write an extra png chunk containing some key
        */
        str = Ox.encodeDeflate(str);
        var c = Ox.canvas(img), len = str.length, px = 0;
        if (len == 0 || len > max(img.width, img.height)) {
            throwPNGError("en")
        }
        len = Ox.pad(Ox.encodeBase256(len), 4, Ox.char(0));
        Ox.each(Ox.map(len + str, function(byte) {
            return Ox.map(new Array(8), function(v, i) {
                return byte.charCodeAt(0) >> 7 - i & 1;
            }).join("");
        }).join(""), function(i, bit) {
            var index = parseInt((px = seek(c.data, px)) * 4 + i % 3),
                byte = c.data[index];
            c.data[index] = bit == xor(byte) ? byte :
                    byte & 254 | !(byte & 1);
            px += i % 3 == 2;
        });
        c.context.putImageData(c.imageData, 0, 0);
        return c.canvas.toDataURL();
    }

    Ox.decodePNG = function(img) {
        // decodes image, returns string
        var data = Ox.canvas(img).data, bits = "", str = "",
        px = 0, i = 0; len = 4, flag = false;
        do {
            bits += xor(data[parseInt((px = seek(data, px)) * 4 + i % 3)]);
            px += i % 3 == 2;
            if (++i % 8 == 0) {
                str += Ox.char(parseInt(bits, 2));
                bits = "";
                len--;
                if (len == 0 && !flag) {
                    len = Ox.decodeBase256(str);
                    if (len <= 0 || len > max(img.width, img.height)) {
                        Ox.print(len);
                        throwPNGError("de");
                    }
                    str = "";
                    flag = true;
                }
            }
        } while (len);
        try {
            return Ox.decodeDeflate(str);
        } catch(e) {
            Ox.print(e.toString());
            throwPNGError("de");
        }
    }

    Ox.encodeUTF8 = function(str) {
        /*
        see http://en.wikipedia.org/wiki/UTF-8
        >>> Ox.encodeUTF8("foo")
        "foo"
        >>> Ox.encodeUTF8("¥€$")
        "\u00C2\u00A5\u00E2\u0082\u00AC\u0024"
        */
        return $.map(Array.prototype.slice.call(str), function(char) { // fixme: why not str?
            var code = char.charCodeAt(0),
                str = "";
            if (code < 128) {
                str = char;
            } else if (code < 2048) {
                str = String.fromCharCode(code >> 6 | 192) +
                    String.fromCharCode(code & 63 | 128);
            } else {
                str = String.fromCharCode(code >> 12 | 224) +
                    String.fromCharCode(code >> 6 & 63 | 128) +
                    String.fromCharCode(code & 63 | 128);
            }
            return str;
        }).join("");
    }

    Ox.decodeUTF8 = function(str) {
        /*
        >>> Ox.decodeUTF8("foo")
        "foo"
        >>> Ox.decodeUTF8("\u00C2\u00A5\u00E2\u0082\u00AC\u0024")
        "¥€$"
        */
        var bytes = $.map(str, function(v) {
                return v.charCodeAt(0);
            }),
            i = 0,
            len = str.length,
            str = "";
        while (i < len) {
            if (bytes[i] <= 128) {
                str += String.fromCharCode(bytes[i]);
                i++;
            } else if (bytes[i] >= 192 && bytes[i] < 240 &&
                    i < len - (bytes[i] < 224 ? 1 : 2)) {
                if (bytes[i + 1] >= 128 && bytes[i + 1] < 192) {
                    if (bytes[i] < 224) {
                        str += String.fromCharCode((bytes[i] & 31) << 6 |
                            bytes[i + 1] & 63);
                        i += 2;
                    } else if (bytes[i + 2] >= 128 && bytes[i + 2] < 192) {
                        str += String.fromCharCode((bytes[i] & 15) << 12 |
                            (bytes[i + 1] & 63) << 6 | bytes[i + 2] & 63);
                        i += 3;
                    } else {
                        throwUTF8Error(bytes[i + 2], i + 2);
                    }
                } else {
                    throwUTF8Error(bytes[i + 1], i + 1);
                }
            } else {
                throwUTF8Error(bytes[i], i);
            }
        }
        return str;
    };

})();

/*
================================================================================
Format functions
================================================================================
*/

Ox.formatDate = function() {
    /*
    See http://developer.apple.com/documentation/Darwin/Reference/ManPages/man3/strftime.3.html
    and http://en.wikipedia.org/wiki/ISO_8601
    >>> _date = new Date("01/02/05 00:03:04")
    "Sun Jan 02 2005 00:03:04 GMT+0100 (CET)"
    >>> Ox.formatDate(_date, "%A") // Full weekday
    "Sunday"
    >>> Ox.formatDate(_date, "%a") // Abbreviated weekday
    "Sun"
    >>> Ox.formatDate(_date, "%B") // Full month
    "January"
    >>> Ox.formatDate(_date, "%b") // Abbreviated month
    "Jan"
    >>> Ox.formatDate(_date, "%C") // Century
    "20"
    >>> Ox.formatDate(_date, "%c") // US time and date
    "01/02/05 12:03:04 AM"
    >>> Ox.formatDate(_date, "%D") // US date
    "01/02/05"
    >>> Ox.formatDate(_date, "%d") // Zero-padded day of the month
    "02"
    >>> Ox.formatDate(_date, "%e") // Space-padded day of the month
    " 2"
    >>> Ox.formatDate(_date, "%F") // Date
    "2005-01-02"
    >>> Ox.formatDate(_date, "%G") // Full ISO-8601 year
    "2004"
    >>> Ox.formatDate(_date, "%g") // Abbreviated ISO-8601 year
    "04"
    >>> Ox.formatDate(_date, "%H") // Zero-padded hour (24-hour clock)
    "00"
    >>> Ox.formatDate(_date, "%h") // Abbreviated month
    "Jan"
    >>> Ox.formatDate(_date, "%I") // Zero-padded hour (12-hour clock)
    "12"
    >>> Ox.formatDate(_date, "%j") // Zero-padded day of the year
    "002"
    >>> Ox.formatDate(_date, "%k") // Space-padded hour (24-hour clock)
    " 0"
    >>> Ox.formatDate(_date, "%l") // Space-padded hour (12-hour clock)
    "12"
    >>> Ox.formatDate(_date, "%M") // Zero-padded minute
    "03"
    >>> Ox.formatDate(_date, "%m") // Zero-padded month
    "01"
    >>> Ox.formatDate(_date, "%n") // Newline
    "\n"
    >>> Ox.formatDate(_date, "%p") // AM or PM
    "AM"
    >>> Ox.formatDate(_date, "%Q") // Quarter of the year
    "1"
    >>> Ox.formatDate(_date, "%R") // Zero-padded hour and minute
    "00:03"
    >>> Ox.formatDate(_date, "%r") // US time
    "12:03:04 AM"
    >>> Ox.formatDate(_date, "%S") // Zero-padded second
    "04"
    >>> Ox.formatDate(_date, "%s") // Number of seconds since the Epoch
    "1104620584"
    >>> Ox.formatDate(_date, "%T") // Time
    "00:03:04"
    >>> Ox.formatDate(_date, "%t") // Tab
    "\t"
    >>> Ox.formatDate(_date, "%U") // Zero-padded week of the year (00-53, Sunday as first day)
    "01"
    >>> Ox.formatDate(_date, "%u") // Decimal weekday (1-7, Monday as first day)
    "7"
    >>> Ox.formatDate(_date, "%V") // Zero-padded ISO-8601 week of the year
    "53"
    >>> Ox.formatDate(_date, "%v") // Formatted date
    " 2-Jan-2005"
    >>> Ox.formatDate(_date, "%W") // Zero-padded week of the year (00-53, Monday as first day)
    "00"
    >>> Ox.formatDate(_date, "%w") // Decimal weekday (0-6, Sunday as first day)
    "0"
    >>> Ox.formatDate(_date, "%X") // US time
    "12:03:04 AM"
    >>> Ox.formatDate(_date, "%x") // US date
    "01/02/05"
    >>> Ox.formatDate(_date, "%Y") // Full year
    "2005"
    >>> Ox.formatDate(_date, "%y") // Abbreviated year
    "05"
    >>> Ox.formatDate(_date, "%Z") // Time zone name
    "CET"
    >>> Ox.formatDate(_date, "%z") // Time zone offset
    "+0100"
    >>> Ox.formatDate(_date, "%+") // Formatted date and time
    "Sun Jan  2 00:03:04 CET 2005"
    >>> Ox.formatDate(_date, "%%")
    "%"
    >>> delete _date
    true
    >>> Ox.formatDate(new Date("01/01/2000"), "%W")
    "00"
    >>> Ox.formatDate(new Date("01/02/2000"), "%W")
    "00"
    >>> Ox.formatDate(new Date("01/03/2000"), "%W")
    "01"
    */
    var ampm = ["AM", "PM"],
        days = ["Monday", "Tuesday", "Wednesday", "Thursday",
            "Friday", "Saturday", "Sunday"],
        months = ["January", "February", "March", "April", "May", "June",
            "July", "August", "September", "October", "November", "December"],
        format = [
            ["%", function() {return "%{%}";}],
            ["c", function() {return "%x %X";}],
            ["X", function() {return "%r";}],
            ["x", function() {return "%D";}],
            ["D", function() {return "%m/%d/%y";}],
            ["F", function() {return "%Y-%m-%d";}],
            ["h", function() {return "%b";}],
            ["R", function() {return "%H:%M";}],
            ["r", function() {return "%I:%M:%S %p";}],
            ["T", function() {return "%H:%M:%S";}],
            ["v", function() {return "%e-%b-%Y";}],
            ["\\+", function() {return "%a %b %e %H:%M:%S %Z %Y";}],
            ["A", function(d) {return days[(d.getDay() + 6) % 7];}],
            ["a", function(d) {return days[(d.getDay() + 6) % 7].toString().substr(0, 3);}],
            ["B", function(d) {return months[d.getMonth()];}],
            ["b", function(d) {return months[d.getMonth()].toString().substr(0, 3);}],
            ["C", function(d) {return d.getFullYear().toString().substr(0, 2);}],
            ["d", function(d) {return Ox.pad(d.getDate(), 2);}],
            ["e", function(d) {return Ox.pad(d.getDate(), 2, " ");}],
            ["G", function(d) {return Ox.getISOYear(d);}],
            ["g", function(d) {return Ox.getISOYear(d).toString().substr(-2);}],
            ["H", function(d) {return Ox.pad(d.getHours(), 2);}],
            ["I", function(d) {return Ox.pad((d.getHours() + 11) % 12 + 1, 2);}],
            ["j", function(d) {return Ox.pad(Ox.getDayOfTheYear(d), 3);}],
            ["k", function(d) {return Ox.pad(d.getHours(), 2, " ");}],
            ["l", function(d) {return Ox.pad(((d.getHours() + 11) % 12 + 1), 2, " ");}],
            ["M", function(d) {return Ox.pad(d.getMinutes(), 2);}],
            ["m", function(d) {return Ox.pad((d.getMonth() + 1), 2);}],
            ["p", function(d) {return ampm[Math.floor(d.getHours() / 12)];}],
            ["Q", function(d) {return Math.floor(d.getMonth() / 4) + 1;}],
            ["S", function(d) {return Ox.pad(d.getSeconds(), 2);}],
            ["s", function(d) {return Math.floor(d.getTime() / 1000);}],
            ["U", function(d) {return Ox.pad(Ox.getWeek(d), 2);}],
            ["u", function(d) {return Ox.getISODay(d);}],
            ["V", function(d) {return Ox.pad(Ox.getISOWeek(d), 2);}],
            ["W", function(d) {return Ox.pad(Math.floor((Ox.getDayOfTheYear(d) +
                (Ox.getFirstDayOfTheYear(d) || 7) - 2) / 7), 2);}],
            ["w", function(d) {return d.getDay();}],
            ["Y", function(d) {return d.getFullYear();}],
            ["y", function(d) {return d.getFullYear().toString().substr(-2);}],
            ["Z", function(d) {return d.toString().split("(")[1].replace(")", "");}],
            ["z", function(d) {return Ox.getTimezoneOffsetString(d);}],
            ["n", function() {return "\n";}],
            ["t", function() {return "\t";}],
            ["\\{%\\}", function() {return "%";}]
        ];
    $.each(format, function(i, v) {
        format[i][0] = new RegExp("%" + v[0] + "", "g");
    });
    return function(date, str) {
        str = str || date;
        date = arguments.length == 2 ? date : new Date();
        $.each(format, function(i, v) {
            str = str.replace(v[0], v[1](date));
        });
        return str;
    };
}();

Ox.formatDuration = function(sec, dec, format) {
    /*
    >>> Ox.formatDuration(123456.789, 3)
    1:10:17:36.789
    >>> Ox.formatDuration(12345.6789)
    03:25:46
    >>> Ox.formatDuration(12345.6789, true)
    0:03:25:46
    >>> Ox.formatDuration(3599.999, 3)
    00:59:59.999
    >>> Ox.formatDuration(3599.999)
    01:00:00
    */
    var format = arguments.length == 3 ? format : (Ox.isString(dec) ? dec : "short"),
        dec = (arguments.length == 3 || Ox.isNumber(dec)) ? dec : 0,
        sec = dec ? sec : Math.round(sec),
        val = [
            Math.floor(sec / 31536000),
            Math.floor(sec % 31536000 / 86400),
            Math.floor(sec % 86400 / 3600),
            Math.floor(sec % 3600 / 60),
            format == "short" ? Ox.formatNumber(sec % 60, dec) : sec % 60
        ],
        str = {
            medium: ["y", "d", "h", "m", "s"],
            long: ["year", "day", "hour", "minute", "second"]
        },
        pad = [0, 3, 2, 2, dec ? dec + 3 : 2];
    while (!val[0] && val.length > (format == "short" ? 3 : 1)) {
        val.shift();
        str.medium.shift();
        str.long.shift();
        pad.shift();
    }
    while (format != "short" && !val[val.length - 1] && val.length > 1) {
        val.pop();
        str.medium.pop();
        str.long.pop();
    }
    return $.map(val, function(v, i) {
        return format == "short" ? Ox.pad(v, pad[i]) :
                v + (format == "long" ? " " : "") + str[format][i] +
                (format == "long" && v != 1 ? "s" : "");
    }).join(format == "short" ? ":" : " ");
};

Ox.formatNumber = function(num, dec) {
    /*
    >>> Ox.formatNumber(123456789, 3)
    "123,456,789.000"
    >>> Ox.formatNumber(-2000000 / 3, 3)
    "-666,666.667"
    >>> Ox.formatNumber(666666.666)
    "666,667"
    */
    var str = Math.abs(num).toFixed(dec || 0),
        spl = str.split("."),
        arr = [];
    while (spl[0]) {
        arr.unshift(spl[0].substr(-3));
        spl[0] = spl[0].substr(0, spl[0].length - 3);
    }
    spl[0] = arr.join(",");
    return (num < 0 ? "-" : "") + spl.join(".");
};

Ox.formatValue = function(num, str) {
    /*
    >>> Ox.formatValue(0, "B")
    ???
    >>> Ox.formatValue(123456789, "B")
    ???
    */
    var val = "";
    $.each(["K", "M", "G", "T", "P"], function(i, v) {
        if (num < Math.pow(1024, i + 2) || i == len - 1) {
            val = Ox.formatNumber(num / Math.pow(1024, i + 1), i) + " " + v + str;
            return false;
        }
    });
    return val;
};

/*
================================================================================
Math functions
================================================================================
*/

Ox.asinh = function(x) {
    /*
    fixme: no test
    */
    return Math.log(x + Math.sqrt(x * x + 1));
};

Ox.deg = function(rad) {
    /*
    >>> Ox.deg(2 * Math.PI)
    360
    */
    return rad * 180 / Math.PI;
};

Ox.limit = function(num, min, max) {
    /*
    >>> Ox.limit(1, 2, 3)
    2
    >>> Ox.limit(2, 1)
    1
    */
    var len = arguments.length;
    max = arguments[len - 1];
    min = len == 3 ? min : 0;
    return Math.min(Math.max(num, min), max);
};

Ox.log = function(x, base) {
    /*
    >>> Ox.log(100, 10)
    2
    >>> Ox.log(Math.E)
    1
    */
    return Math.log(x) / Math.log(base || Math.E);
};

Ox.rad = function(deg) {
    /*
    >>> Ox.rad(360)
    2 * Math.PI
    */
    return deg * Math.PI / 180;
};

Ox.random = function() {
    /*
    >>> Ox.random(3) in {0: 0, 1: 0, 2: 0, 3: 0}
    true
    >>> Ox.random(1, 2) in {1: 0, 2: 0}
    true
    */
    var len = arguments.length,
        min = len == 1 ? 0 : arguments[0],
        max = arguments[len - 1];
    return min + parseInt(Math.random() * (max - min + 1));
};

Ox.round = function(num, dec) {
    /*
    >>> Ox.round(2 / 3, 6)
    0.666667
    >>> Ox.round(1 / 2, 3)
    0.5
    */
    var pow = Math.pow(10, dec || 0);
    return Math.round(num * pow) / pow;
};

Ox.sinh = function(x) {
    /*
    fixme: no test
    */
    return (Math.exp(x) - Math.exp(-x)) / 2;
};

/*
================================================================================
String functions
================================================================================
*/

Ox.basename = function(str) {
    /*
    fixme: this should go into Path functions
    >>> Ox.basename("foo/bar/foo.bar")
    "foo.bar"
    >>> Ox.basename("foo.bar")
    "foo.bar"
    */
    return str.replace(/^.*[\/\\]/g, "");
};

Ox.char = String.fromCharCode;

Ox.clean = function(str) {
    /*
    >>> Ox.clean("foo  bar")
    "foo bar"
    >>> Ox.clean(" foo  bar ")
    "foo bar"
    */
    return Ox.trim(str.replace(/\s+/g, " "));
};

Ox.endsWith = function(str, sub) {
    /*
    >>> Ox.endsWith("foobar", "bar")
    true
    */
    return str.substr(-sub.length) === sub;
};

Ox.pad = function(str, len, pad, pos) {
    /*
    >>> Ox.pad(1, 2)
    "01"
    >>> Ox.pad("abc", 6, ".", "right")
    "abc..."
    >>> Ox.pad("foobar", 3, ".", "right")
    "foo"
    >>> Ox.pad("abc", 6, "123456", "right")
    "abc123"
    >>> Ox.pad("abc", 6, "123456", "left")
    "456abc"
    */
    str = str.toString().substr(0, len);
    pad = Ox.repeat(pad || "0", len - str.length);
    pos = pos || "left";
    str = pos == "left" ? pad + str : str + pad;
    str = pos == "left" ? str.substr(str.length - len, str.length) :
        str.substr(0, len);
    return str;
};

Ox.repeat = function(str, num) {
    /*
    >>> Ox.repeat(1, 3)
    "111"
    >>> Ox.repeat("foo", 3)
    "foofoofoo"
    */
    return num >= 1 ? new Array(num + 1).join(str.toString()) : "";
};

Ox.reverse = function(str) {
    /*
    Ox.reverse("foo")
    oof
    */
    return str.split("").reverse().join("");
};

Ox.startsWith = function(str, sub) {
    /*
    >>> Ox.startsWith("foobar", "foo")
    true
    */
    return str.substr(0, sub.length) === sub;
};

Ox.stripTags = function(str) {
    /*
    >>> Ox.stripTags("f<span>o</span>o")
    foo
    */
    return str.replace(/(<.*?>)/gi, "");
};

Ox.toCamelCase = function(str) {
    /*
    >>> Ox.toCamelCase("foo-bar-baz")
    "fooBarBaz"
    >>> Ox.toCamelCase("foo/bar/baz")
    "fooBarBaz"
    >>> Ox.toCamelCase("foo_bar_baz")
    "fooBarBaz"
    */
    return str.replace(/[\-_\/][a-z]/g, function(str) {
        return str[1].toUpperCase();
    });
};

Ox.toDashes = function(str) {
    /*
    >>> Ox.toDashes("fooBarBaz")
    "foo-bar-baz"
    */
    return str.replace(/[A-Z]/g, function(str) {
        return '-' + str.toLowerCase();
    });
};

Ox.toSlashes = function(str) {
    /*
    >>> Ox.toSlashes("fooBarBaz")
    "foo/bar/baz"
    */
    return str.replace(/[A-Z]/g, function(str) {
        return '/' + str.toLowerCase();
    });
};

Ox.toTitleCase = function(str) {
    /*
    >>> Ox.toTitleCase("foo")
    "Foo"
    >>> Ox.toTitleCase("Apple releases iPhone, IBM stock plummets")
    "Apple Releases iPhone, IBM Stock Plummets"
    */
    return $.map(str.split(" "), function(v) {
        var sub = v.substr(1),
            low = sub.toLowerCase();
        if (sub == low) {
            v = v.substr(0, 1).toUpperCase() + low;
        }
        return v;
    }).join(" ");
};

Ox.toUnderscores = function(str) {
    /*
    >>> Ox.toUnderscores("fooBarBaz")
    "foo_bar_baz"
    */
    return str.replace(/[A-Z]/g, function(str) {
        return '_' + str.toLowerCase();
    });
};

Ox.trim = function(str) { // is in jQuery
    /*
    Ox.trim(" foo ")
    "foo"
    */
    return str.replace(/^\s+|\s+$/g, "");
}

/*
================================================================================
Type functions
================================================================================
*/

Ox.isArray = function(val) { // is in jQuery
    /*
    >>> Ox.isArray([])
    true
    */
    return val instanceof Array;
}

Ox.isBoolean = function(val) {
    /*
    >>> Ox.isBoolean(false)
    true
    */
    return typeof val == "boolean";
};

Ox.isDate = function(val) {
    /*
    >>> Ox.isDate(new Date())
    true
    */
    return val instanceof Date;
};

Ox.isFunction = function(val) { // is in jQuery
    /*
    >>> Ox.isFunction(function() {})
    true
    >>> Ox.isFunction(/ /)
    false
    */
    return typeof val == "function" && !Ox.isRegExp(val);
};

Ox.isNull = function(val) {
    /*
    >>> Ox.isNull(null)
    true
    */
    return val === null;
};

Ox.isNumber = function(val) {
    /*
    >>> Ox.isNumber(0)
    true
    >>> Ox.isNumber(Infinity)
    false
    >>> Ox.isNumber(NaN)
    false
    */
    return typeof val == "number" && isFinite(val);
};

Ox.isObject = function(val) {
    /*
    >>> Ox.isObject({})
    true
    >>> Ox.isObject([])
    false
    >>> Ox.isObject(new Date())
    false
    >>> Ox.isObject(null)
    false
    */
    return typeof val == "object" && !$.isArray(val) &&
            !Ox.isDate(val) && !Ox.isNull(val);
};

Ox.isRegExp = function(val) {
    /*
    >>> Ox.isRegExp(/ /)
    true
    */
    return val instanceof RegExp;
};

Ox.isString = function(val) {
    /*
    >>> Ox.isString("")
    true
    */
    return typeof val == "string";
};

Ox.isUndefined = function(val) {
    /*
    >>> Ox.isUndefined()
    true
    */
    return typeof val == "undefined";
};