/*
 * $Id: base64.js,v 2.6 2012/08/24 05:23:18 dankogai Exp dankogai $
 *
 *  Licensed under the MIT license.
 *  http://www.opensource.org/licenses/mit-license.php
 *
 *  References:
 *    http://en.wikipedia.org/wiki/Base64
 */

(function(global) {
'use strict';
// if node.js, we use Buffer
var buffer;
if (typeof module !== 'undefined' && module.exports) {
    buffer = require('buffer').Buffer;
}
// constants
var b64chars
    = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
var b64tab = function(bin) {
    var t = {};
    for (var i = 0, l = bin.length; i < l; i++) t[bin.charAt(i)] = i;
    return t;
}(b64chars);
var fromCharCode = String.fromCharCode;
// encoder stuff
var cb_utob = function(c) {
    var cc = c.charCodeAt(0);
    return cc < 0x80 ? c
        : cc < 0x800 ? fromCharCode(0xc0 | (cc >>> 6))
                     + fromCharCode(0x80 | (cc & 0x3f))
        : fromCharCode(0xe0 | ((cc >>> 12) & 0x0f))
        + fromCharCode(0x80 | ((cc >>>  6) & 0x3f))
        + fromCharCode(0x80 | ( cc         & 0x3f));
};
var utob = function(u) {
    return u.replace(/[^\x00-\x7F]/g, cb_utob);
};
var cb_encode = function(ccc) {
    var padlen = [0, 2, 1][ccc.length % 3],
        ord = ccc.charCodeAt(0) << 16
            | ((ccc.length > 1 ? ccc.charCodeAt(1) : 0) << 8)
            | ((ccc.length > 2 ? ccc.charCodeAt(2) : 0)),
        chars = [
            b64chars.charAt( ord >>> 18),
            b64chars.charAt((ord >>> 12) & 63),
            padlen >= 2 ? '=' : b64chars.charAt((ord >>> 6) & 63),
            padlen >= 1 ? '=' : b64chars.charAt(ord & 63)
        ];
    return chars.join('');
};
var btoa = global.btoa || function(b) {
    return b.replace(/[\s\S]{1,3}/g, cb_encode);
};
var _encode = buffer
    ? function (u) { return (new buffer(u)).toString('base64') } 
    : function (u) { return btoa(utob(u)) }
    ;
var encode = function(u, urisafe) {
    return !urisafe 
        ? _encode(u)
        : _encode(u).replace(/[+\/]/g, function(m0) {
            return m0 == '+' ? '-' : '_';
        });
};
var encodeURI = function(u) { return encode(u, true) };
// decoder stuff
var re_btou = /[\xC0-\xDF][\x80-\xBF]|[\xE0-\xEF][\x80-\xBF]{2}/g;
var cb_btou = function(ccc) {
    return fromCharCode(
        ccc.length < 3 ? ((0x1f & ccc.charCodeAt(0)) << 6)
                       |  (0x3f & ccc.charCodeAt(1))
                       : ((0x0f & ccc.charCodeAt(0)) << 12)
                       | ((0x3f & ccc.charCodeAt(1)) << 6)
                       |  (0x3f & ccc.charCodeAt(2))
    );
};
var btou = function(b) {
    return b.replace(re_btou, cb_btou);
};
var cb_decode = function(cccc) {
    var len = cccc.length,
        padlen = len % 4,
        n = (len > 0 ? b64tab[cccc.charAt(0)] << 18 : 0)
          | (len > 1 ? b64tab[cccc.charAt(1)] << 12 : 0)
          | (len > 2 ? b64tab[cccc.charAt(2)] <<  6 : 0)
          | (len > 3 ? b64tab[cccc.charAt(3)]       : 0),
        chars = [
            fromCharCode( n >>> 16),
            fromCharCode((n >>>  8) & 0xff),
            fromCharCode( n         & 0xff)
        ];
    chars.length -= [0, 0, 2, 1][padlen];
    return chars.join('');
};
var atob = global.atob || function(a){
    return a.replace(/[\s\S]{1,4}/g, cb_decode);
};
var _decode = buffer
    ? function(a) { return (new buffer(a, 'base64')).toString() }
    : function(a) { return btou(atob(a)) }
    ;
var decode = function(a){
    return _decode(
        a.replace(/[-_]/g, function(m0) { return m0 == '-' ? '+' : '/' })
         .replace(/[^A-Za-z0-9\+\/]/g, '')
    );
};
// export Base64
global.Base64 = {
    atob: atob,
    btoa: btoa,
    fromBase64: decode,
    toBase64: encode,
    utob: utob,
    encode: encode,
    encodeURI: encodeURI,
    btou: btou,
    decode: decode
};
// if ES5 is available, make Base64.extendString() available
if (typeof Object.defineProperty === 'function') {
    var noEnum = function(v){
        return {value:v,enumerable:false,writable:true,configurable:true};
    };
    global.Base64.extendString = function () {
        Object.defineProperty(
            String.prototype, 'fromBase64', noEnum(function () {
            return decode(this)
        }));
        Object.defineProperty(
            String.prototype, 'toBase64', noEnum(function (urisafe) {
                return encode(this, urisafe)
        }));
    };
}
// that's it!
})(this);