/*
	Copyright (c) <2012> <xmbeat::Juan Hebert Chable Covarrubias>
 
	Permission is hereby granted, free of charge, to any
	person obtaining a copy of this software and associated
	documentation files (the "Software"), to deal in the
	Software without restriction, including without limitation
	the rights to use, copy, modify, merge, publish,
	distribute, sublicense, and/or sell copies of the
	Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:
 
	The above copyright notice and this permission notice
	shall be included in all copies or substantial portions of
	the Software.
 
	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
	KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
	WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
	PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
	OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
	OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
	SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
public class Base64 {
	private static String TABLE_64;
	private static byte INDEX_TABLE[] = new byte[256];
	private char _padChar = '=';	
	static
	{
		TABLE_64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
		for (int i = 0; i < 64; i++)
		{
			INDEX_TABLE[TABLE_64.charAt(i)] = (byte)i;
		}
	}
	public Base64(){}
	public Base64(char padChar)
	{
		_padChar = padChar;
	}
	public String encode(byte[] data)
	{
		int finalLen = data.length / 3 * 4;
		if (data.length % 3 > 0)finalLen+=4;
		StringBuffer string64 = new StringBuffer();
		string64.setLength(finalLen);
		int leftBits = 0;
		int rightBits = 0;
		int shift = 2;
		int index = 0;
		for (int i = 0; i < data.length; i++)
		{
			int curByte = data[i] & 0xFF;
			leftBits = (rightBits | (curByte >> shift));
			string64.setCharAt(index++, TABLE_64.charAt(leftBits));
			rightBits = (curByte << (6-shift)) & 0x3F;
			if (shift == 6 || i == data.length - 1)
			{
				string64.setCharAt(index++,TABLE_64.charAt(rightBits));
				rightBits = 0;
				shift = 2;
			}
			else
				shift+=2;
		}
		for (;index < finalLen; index++)
		{
			string64.setCharAt(index, _padChar);
		}
		return string64.toString();
	}
	public byte[] decode(String data)
	{
		int realLen  = data.length() - 1;
		while(data.charAt(realLen)==_padChar) realLen--;
		realLen++;
		byte []result =  new byte[realLen*3/4];
		int rightBits = 0;
		int leftBits = 0;
		int shift = 2;
		int index = 0;
		boolean procesado = false;
		for (int i = 0; i < realLen; i++)
		{
			int curByte = INDEX_TABLE[data.charAt(i)] & 0xFF;
			//Incluí todos los caractares a una tabla, para asi ganar un poco de velocidad
			//Pero a consecuencia de que si un byte no esta en la tabla lo trata como la letra
			//'A', si quieren pongan un condicional para generar una excepcion
			rightBits = curByte >> (8-shift);
			if (procesado)
			{
				result[index++]=(byte)(rightBits | leftBits);
			}
			leftBits = (curByte << shift) & 0xFF;
			if (shift == 8)
			{
				procesado = false;
				shift = 2;
			}
			else
			{
				procesado = true;
				shift += 2;
			}
		}
		return result;
	}
	public static void main(String[] args)
	{
		Base64 converter = new Base64();
		String strEncode = converter.encode("A la ***** la universidad, yo quiero ser actor porno".getBytes());
		System.out.println(strEncode);
		System.out.println(new String(converter.decode(strEncode)));		
	}
}