/* Base64 library for ActionScript 3.0.

 * Based on: Ma Bingyao code.

 * Optimized by: Jean-Philippe Auclair  / jpauclair.wordpress.com

 * Copyright (C) 2007 Ma Bingyao <andot@ujn.edu.cn>

 * LastModified: Oct 26, 2009

 * This library is free.  You can redistribute it and/or modify it.

 */

package com.hurlant.util{

    import flash.utils.ByteArray;

    public class Base64

    {

        private static const _encodeChars : Vector.<int> = InitEncoreChar();

        private static const _decodeChars : Vector.<int> = InitDecodeChar();

        public static function encodeByteArray(data : ByteArray) : String

        {

            var out : ByteArray = new ByteArray();

            //Presetting the length keep the memory smaller and optimize speed since there is no "grow" needed

            out.length = (2 + data.length - ((data.length + 2) % 3)) * 4 / 3; //Preset length //1.6 to 1.5 ms

            var i : int = 0;

            var r : int = data.length % 3;

            var len : int = data.length - r;

            var c : int;   //read (3) character AND write (4) characters

            while (i < len)

            {

                //Read 3 Characters (8bit * 3 = 24 bits)

                c = data[i++] << 16 | data[i++] << 8 | data[i++];

                //Cannot optimize this to read int because of the positioning overhead. (as3 bytearray seek is slow)

                //Convert to 4 Characters (6 bit * 4 = 24 bits)

                c = (_encodeChars[c >>> 18] << 24) | (_encodeChars[c >>> 12 & 0x3f] << 16) | (_encodeChars[c >>> 6 & 0x3f] << 8) | _encodeChars[c & 0x3f];

                //Optimization: On older and slower computer, do one write Int instead of 4 write byte: 1.5 to 0.71 ms

                out.writeInt(c);

                /*

                 out.writeByte(_encodeChars[c >> 18] );

                 out.writeByte(_encodeChars[c >> 12 & 0x3f]);

                 out.writeByte(_encodeChars[c >> 6 & 0x3f]);

                 out.writeByte(_encodeChars[c & 0x3f]);

                 */

            }

            if (r == 1) //Need two "=" padding

            {

                //Read one char, write two chars, write padding

                c = data[i];

                c = (_encodeChars[c >>> 2] << 24) | (_encodeChars[(c & 0x03) << 4] << 16) | 61 << 8 | 61;

                out.writeInt(c);

            }

            else if (r == 2) //Need one "=" padding

            {

                c = data[i++] << 8 | data[i];

                c = (_encodeChars[c >>> 10] << 24) | (_encodeChars[c >>> 4 & 0x3f] << 16) | (_encodeChars[(c & 0x0f) << 2] << 8) | 61;

                out.writeInt(c);

            }

            out.position = 0;

            return out.readUTFBytes(out.length);

        }

        public static function decodeToByteArray(str : String) : ByteArray

        {

            var c1 : int;

            var c2 : int;

            var c3 : int;

            var c4 : int;

            var i : int;

            var len : int;

            var out : ByteArray;

            len = str.length;

            i = 0;

            out = new ByteArray();

            var byteString : ByteArray = new ByteArray();

            byteString.writeUTFBytes(str);

            while (i < len)

            {

                //c1

                do

                {

                    c1 = _decodeChars[byteString[i++]];

                } while (i < len && c1 == -1);

                if (c1 == -1) break;

                //c2

                do

                {

                    c2 = _decodeChars[byteString[i++]];

                } while (i < len && c2 == -1);

                if (c2 == -1) break;

                out.writeByte((c1 << 2) | ((c2 & 0x30) >> 4));

                //c3

                do

                {

                    c3 = byteString[i++];

                    if (c3 == 61) return out;

                    c3 = _decodeChars[c3];

                } while (i < len && c3 == -1);

                if (c3 == -1) break;

                out.writeByte(((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2));

                //c4

                do {

                    c4 = byteString[i++];

                    if (c4 == 61) return out;

                    c4 = _decodeChars[c4];

                } while (i < len && c4 == -1);

                if (c4 == -1) break;

                out.writeByte(((c3 & 0x03) << 6) | c4);

            }

            out.position = 0;

            return out;

        }

        public static function encode(data : String) : String {

            // Convert string to ByteArray

            var bytes : ByteArray = new ByteArray();

            bytes.writeUTFBytes(data);

            // Return encoded ByteArray

            return encodeByteArray(bytes);

        }

        public static function decode(data : String) : String {

            // Decode data to ByteArray

            var bytes : ByteArray = decodeToByteArray(data);

            // Convert to string and return

            return bytes.readUTFBytes(bytes.length);

        }

        public static function InitEncoreChar() : Vector.<int>

        {

            var encodeChars : Vector.<int> = new Vector.<int>();

            // We could push the number directly, but i think it's nice to see the characters (with no overhead on encode/decode)

            var chars : String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

            for (var i : int = 0; i < 64; i++)

            {

                encodeChars.push(chars.charCodeAt(i));

            }

            /*

             encodeChars.push(

             65, 66, 67, 68, 69, 70, 71, 72,

             73, 74, 75, 76, 77, 78, 79, 80,

             81, 82, 83, 84, 85, 86, 87, 88,

             89, 90, 97, 98, 99, 100, 101, 102,

             103, 104, 105, 106, 107, 108, 109, 110,

             111, 112, 113, 114, 115, 116, 117, 118,

             119, 120, 121, 122, 48, 49, 50, 51,

             52, 53, 54, 55, 56, 57, 43, 47);

             */

            return encodeChars;

        }

        public static function InitDecodeChar() : Vector.<int>

        {

            var decodeChars : Vector.<int> = new Vector.<int>();

            decodeChars.push(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,

                    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,

                    -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

                    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,

                    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

                    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1

                    - 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1);

            return decodeChars;

        }

    }

}