/*

Copyright (c) 2009, Yahoo! Inc. All rights reserved.

Code licensed under the BSD License:

http://developer.yahoo.net/yui/license.txt

version: 3.0.0

build: 1549

*/

YUI.add('json-stringify', function(Y) {

/**

 * Provides Y.JSON.stringify method for converting objects to JSON strings.

 *

 * @module json

 * @submodule json-stringify

 * @for JSON

 * @static

 */

var _JSON     = Y.config.win.JSON,

    Lang      = Y.Lang,

    isFunction= Lang.isFunction,

    isObject  = Lang.isObject,

    isArray   = Lang.isArray,

    _toStr    = Object.prototype.toString,

    Native    = (_toStr.call(_JSON) === '[object JSON]' && _JSON),

    UNDEFINED = 'undefined',

    OBJECT    = 'object',

    NULL      = 'null',

    STRING    = 'string',

    NUMBER    = 'number',

    BOOLEAN   = 'boolean',

    DATE      = 'date',

    _allowable= {

        'undefined'        : UNDEFINED,

        'string'           : STRING,

        '[object String]'  : STRING,

        'number'           : NUMBER,

        '[object Number]'  : NUMBER,

        'boolean'          : BOOLEAN,

        '[object Boolean]' : BOOLEAN,

        '[object Date]'    : DATE,

        '[object RegExp]'  : OBJECT

    },

    EMPTY     = '',

    OPEN_O    = '{',

    CLOSE_O   = '}',

    OPEN_A    = '[',

    CLOSE_A   = ']',

    COMMA     = ',',

    COMMA_CR  = ",\n",

    CR        = "\n",

    COLON     = ':',

    COLON_SP  = ': ',

    QUOTE     = '"',

    // Regex used to capture characters that need escaping before enclosing

    // their containing string in quotes.

    _SPECIAL_CHARS = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,

    // Character substitution map for common escapes and special characters.

    _CHARS = {

        '\b': '\\b',

        '\t': '\\t',

        '\n': '\\n',

        '\f': '\\f',

        '\r': '\\r',

        '"' : '\\"',

        '\\': '\\\\'

    };

// Utility function used to determine how to serialize a variable.

function _type(o) {

    var t = typeof o;

    return  _allowable[t] ||              // number, string, boolean, undefined

            _allowable[_toStr.call(o)] || // Number, String, Boolean, Date

            (t === OBJECT ?

                (o ? OBJECT : NULL) :     // object, array, null, misc natives

                UNDEFINED);               // function, unknown

}

// Escapes a special character to a safe Unicode representation

function _char(c) {

    if (!_CHARS[c]) {

        _CHARS[c] =  '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);

    }

    return _CHARS[c];

}

// Enclose escaped strings in quotes

function _string(s) {

    return QUOTE + s.replace(_SPECIAL_CHARS, _char) + QUOTE;

}

// Adds the provided space to the beginning of every line in the input string

function _indent(s,space) {

    return s.replace(/^/gm, space);

}

// JavaScript implementation of stringify (see API declaration of stringify)

function _stringify(o,w,space) {

    if (o === undefined) {

        return undefined;

    }

    var replacer = isFunction(w) ? w : null,

        format   = _toStr.call(space).match(/String|Number/) || [],

        _date    = Y.JSON.dateToString,

        stack    = [],

        tmp,i,len;

    if (replacer || !isArray(w)) {

        w = undefined;

    }

    // Ensure whitelist keys are unique (bug 2110391)

    if (w) {

        tmp = {};

        for (i = 0, len = w.length; i < len; ++i) {

            tmp[w[i]] = true;

        }

        w = tmp;

    }

    // Per the spec, strings are truncated to 10 characters and numbers

    // are converted to that number of spaces (max 10)

    space = format[0] === 'Number' ?

                new Array(Math.min(Math.max(0,space),10)+1).join(" ") :

                (space || EMPTY).slice(0,10);

    function _serialize(h,key) {

        var value = h[key],

            t     = _type(value),

            a     = [],

            colon = space ? COLON_SP : COLON,

            arr, i, keys, k, v;

        // Per the ECMA 5 spec, toJSON is applied before the replacer is

        // called.  Also per the spec, Date.prototype.toJSON has been added, so

        // Date instances should be serialized prior to exposure to the

        // replacer.  I disagree with this decision, but the spec is the spec.

        if (isObject(value) && isFunction(value.toJSON)) {

            value = value.toJSON(key);

        } else if (t === DATE) {

            value = _date(value);

        }

        if (isFunction(replacer)) {

            value = replacer.call(h,key,value);

        }

        if (value !== h[key]) {

            t = _type(value);

        }

        switch (t) {

            case DATE    : // intentional fallthrough.  Pre-replacer Dates are

                           // serialized in the toJSON stage.  Dates here would

                           // have been produced by the replacer.

            case OBJECT  : break;

            case STRING  : return _string(value);

            case NUMBER  : return isFinite(value) ? value+EMPTY : NULL;

            case BOOLEAN : return value+EMPTY;

            case NULL    : return NULL;

            default      : return undefined;

        }

        // Check for cyclical references in nested objects

        for (i = stack.length - 1; i >= 0; --i) {

            if (stack[i] === value) {

                throw new Error("JSON.stringify. Cyclical reference");

            }

        }

        arr = isArray(value);

        // Add the object to the processing stack

        stack.push(value);

        if (arr) { // Array

            for (i = value.length - 1; i >= 0; --i) {

                a[i] = _serialize(value, i) || NULL;

            }

        } else {   // Object

            // If whitelist provided, take only those keys

            keys = w || value;

            i = 0;

            for (k in keys) {

                if (keys.hasOwnProperty(k)) {

                    v = _serialize(value, k);

                    if (v) {

                        a[i++] = _string(k) + colon + v;

                    }

                }

            }

        }

        // remove the array from the stack

        stack.pop();

        if (space && a.length) {

            return arr ?

                OPEN_A + CR + _indent(a.join(COMMA_CR), space) + CR + CLOSE_A :

                OPEN_O + CR + _indent(a.join(COMMA_CR), space) + CR + CLOSE_O;

        } else {

            return arr ?

                OPEN_A + a.join(COMMA) + CLOSE_A :

                OPEN_O + a.join(COMMA) + CLOSE_O;

        }

    }

    // process the input

    return _serialize({'':o},'');

}

Y.mix(Y.namespace('JSON'),{

    /**

     * Leverage native JSON stringify if the browser has a native

     * implementation.  In general, this is a good idea.  See the Known Issues

     * section in the JSON user guide for caveats.  The default value is true

     * for browsers with native JSON support.

     *

     * @property JSON.useNativeStringify

     * @type Boolean

     * @default true

     * @static

     */

    useNativeStringify : !!Native,

    /**

     * Serializes a Date instance as a UTC date string.  Used internally by

     * stringify.  Override this method if you need Dates serialized in a

     * different format.

     *

     * @method dateToString

     * @param d {Date} The Date to serialize

     * @return {String} stringified Date in UTC format YYYY-MM-DDTHH:mm:SSZ

     * @static

     */

    dateToString : function (d) {

        function _zeroPad(v) {

            return v < 10 ? '0' + v : v;

        }

        return d.getUTCFullYear()           + '-' +

              _zeroPad(d.getUTCMonth() + 1) + '-' +

              _zeroPad(d.getUTCDate())      + 'T' +

              _zeroPad(d.getUTCHours())     + COLON +

              _zeroPad(d.getUTCMinutes())   + COLON +

              _zeroPad(d.getUTCSeconds())   + 'Z';

    },

    /**

     * <p>Converts an arbitrary value to a JSON string representation.</p>

     *

     * <p>Objects with cyclical references will trigger an exception.</p>

     *

     * <p>If a whitelist is provided, only matching object keys will be

     * included.  Alternately, a replacer function may be passed as the

     * second parameter.  This function is executed on every value in the

     * input, and its return value will be used in place of the original value.

     * This is useful to serialize specialized objects or class instances.</p>

     *

     * <p>If a positive integer or non-empty string is passed as the third

     * parameter, the output will be formatted with carriage returns and

     * indentation for readability.  If a String is passed (such as "\t") it

     * will be used once for each indentation level.  If a number is passed,

     * that number of spaces will be used.</p>

     *

     * @method stringify

     * @param o {MIXED} any arbitrary value to convert to JSON string

     * @param w {Array|Function} (optional) whitelist of acceptable object

     *                  keys to include, or a replacer function to modify the

     *                  raw value before serialization

     * @param ind {Number|String} (optional) indentation character or depth of

     *                  spaces to format the output.

     * @return {string} JSON string representation of the input

     * @static

     */

    stringify : function (o,w,ind) {

        return Native && Y.JSON.useNativeStringify ?

            Native.stringify(o,w,ind) : _stringify(o,w,ind);

    }

});

}, '3.0.0' );