/*

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

Code licensed under the BSD License:

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

version: 3.0.0b1

build: 1163

*/

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 _toString = Object.prototype.toString,

    Lang      = Y.Lang,

    isFunction= Lang.isFunction,

    isArray   = Lang.isArray,

    type      = Lang.type,

    STRING    = 'string',

    NUMBER    = 'number',

    BOOLEAN   = 'boolean',

    OBJECT    = 'object',

    ARRAY     = 'array',

    REGEXP    = 'regexp',

    ERROR     = 'error',

    NULL      = 'null',

    DATE      = 'date',

    EMPTY     = '',

    OPEN_O    = '{',

    CLOSE_O   = '}',

    OPEN_A    = '[',

    CLOSE_A   = ']',

    COMMA     = ',',

    COMMA_CR  = ",\n",

    CR        = "\n",

    COLON     = ':',

    COLON_SP  = ': ',

    QUOTE     = '"';

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

    /**

     * Regex used to capture characters that need escaping before enclosing

     * their containing string in quotes.

     *

     * @property _SPECIAL_CHARS

     * @type {RegExp}

     * @protected

     */

    _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.

     *

     * @property _CHARS

     * @type {Object}

     * @static

     * @protected

     */

    _CHARS : {

        '\b': '\\b',

        '\t': '\\t',

        '\n': '\\n',

        '\f': '\\f',

        '\r': '\\r',

        '"' : '\\"',

        '\\': '\\\\'

    },

    /**

     * 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 QUOTE + d.getUTCFullYear()   + '-' +

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

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

              _zeroPad(d.getUTCHours())     + COLON +

              _zeroPad(d.getUTCMinutes())   + COLON +

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

    },

    /**

     * <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) {

        var m      = Y.JSON._CHARS,

            str_re = Y.JSON._SPECIAL_CHARS,

            rep    = isFunction(w) ? w : null,

            pstack = [], // Processing stack used for cyclical ref protection

            _date  = Y.JSON.dateToString, // Use configured date serialization

            format = _toString.call(ind).match(/String|Number/);

        if (rep || typeof w !== 'object') {

            w = undefined;

        }

        if (format) {

            // String instances and primatives are left alone.  String objects

            // coerce for the indenting operations.

            if (format[0] === 'Number') {

                // force numeric indent values between {0,100} per the spec

                // This also converts Number instances to primative

                ind = new Array(Math.min(Math.max(0,ind),100)+1).join(" ");

            }

            // turn off formatting for 0 or empty string

            format = ind;

        }

        // escape encode special characters

        function _char(c) {

            if (!m[c]) {

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

            }

            return m[c];

        }

        // Enclose the escaped string in double quotes

        function _string(s) {

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

        }

        // Check for cyclical references

        function _cyclicalTest(o) {

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

                if (pstack[i] === o) {

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

                }

            }

            return false;

        }

        function _indent(s) {

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

        }

        function _object(o,arr) {

            // Add the object to the processing stack

            pstack.push(o);

            var a = [],

                colon = format ? COLON_SP : COLON,

                i, j, len, k, v;

            if (arr) { // Array

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

                    a[i] = _stringify(o,i) || NULL;

                }

            } else {   // Object

                // If whitelist provided, take only those keys

                k = isArray(w) ? w : Y.Object.keys(o);

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

                    if (typeof k[i] === STRING) {

                        v = _stringify(o,k[i]);

                        if (v) {

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

                        }

                    }

                }

            }

            // remove the array from the stack

            pstack.pop();

            if (format && a.length) {

                return arr ?

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

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

            } else {

                return arr ?

                    OPEN_A + a.join(COMMA) + CLOSE_A :

                    OPEN_O + a.join(COMMA) + CLOSE_O;

            }

        }

        // Worker function.  Fork behavior on data type and recurse objects.

        function _stringify(h,key) {

            var o = isFunction(rep) ? rep.call(h,key,h[key]) : h[key],

                t = type(o);

            if (t === OBJECT) {

                if (/String|Number|Boolean/.test(_toString.call(o))) {

                    o = o.valueOf();

                    t = type(o);

                }

            }

            switch (t) {

                case STRING  : return _string(o);

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

                case BOOLEAN : return o+EMPTY;

                case DATE    : return _date(o);

                case NULL    : return NULL;

                case ARRAY   : _cyclicalTest(o); return _object(o,true);

                case REGEXP  : // intentional fall through

                case ERROR   : // intentional fall through

                case OBJECT  : _cyclicalTest(o); return _object(o);

                default      : return undefined;

            }

        }

        // process the input

        return _stringify({'':o},EMPTY);

    }

});

}, '3.0.0b1' );