/*
 * base64.js - Base64 encoding and decoding functions
 *
 * See: http://developer.mozilla.org/en/docs/DOM:window.btoa
 *      http://developer.mozilla.org/en/docs/DOM:window.atob
 *
 * Copyright (c) 2007, David Lindquist <david.lindquist@gmail.com>
 * Released under the MIT license
 */
var Base64 = {
	    // public method for encoding
	    encode : function (str) {
	        var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
	        var encoded = [];
	        var c = 0;
	        while (c < str.length) {
	            var b0 = str.charCodeAt(c++);
	            var b1 = str.charCodeAt(c++);
	            var b2 = str.charCodeAt(c++);
	            var buf = (b0 << 16) + ((b1 || 0) << 8) + (b2 || 0);
	            var i0 = (buf & (63 << 18)) >> 18;
	            var i1 = (buf & (63 << 12)) >> 12;
	            var i2 = isNaN(b1) ? 64 : (buf & (63 << 6)) >> 6;
	            var i3 = isNaN(b2) ? 64 : (buf & 63);
	            encoded[encoded.length] = chars.charAt(i0);
	            encoded[encoded.length] = chars.charAt(i1);
	            encoded[encoded.length] = chars.charAt(i2);
	            encoded[encoded.length] = chars.charAt(i3);
	        }
	        return encoded.join('');
	    },

		// public method for decoding
	    decode : function (str) {
	        var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
	        var invalid = {
	            strlen: (str.length % 4 != 0),
	            chars:  new RegExp('[^' + chars + ']').test(str),
	            equals: (/=/.test(str) && (/=[^=]/.test(str) || /={3}/.test(str)))
	        };
	        if (invalid.strlen || invalid.chars || invalid.equals)
	        {
	        	return str;
	            // throw new Error('Invalid base64 data');
	        }
	        var decoded = [];
	        var c = 0;
	        while (c < str.length) {
	            var i0 = chars.indexOf(str.charAt(c++));
	            var i1 = chars.indexOf(str.charAt(c++));
	            var i2 = chars.indexOf(str.charAt(c++));
	            var i3 = chars.indexOf(str.charAt(c++));
	            var buf = (i0 << 18) + (i1 << 12) + ((i2 & 63) << 6) + (i3 & 63);
	            var b0 = (buf & (255 << 16)) >> 16;
	            var b1 = (i2 == 64) ? -1 : (buf & (255 << 8)) >> 8;
	            var b2 = (i3 == 64) ? -1 : (buf & 255);
	            decoded[decoded.length] = String.fromCharCode(b0);
	            if (b1 >= 0) decoded[decoded.length] = String.fromCharCode(b1);
	            if (b2 >= 0) decoded[decoded.length] = String.fromCharCode(b2);
	        }
	        return decoded.join('');
	    }
}