package org.bodington.util;

import java.io.*;

public class Base64Decoder
{

    public Base64Decoder()
    {
        decode_buffer = new byte[4];
    }


     public void decodeBuffer(InputStream inputstream, OutputStream outputstream)
        throws IOException
    {
        int j = 0;
        decodeBufferPrefix(inputstream, outputstream);
        try
        {
            do
            {
                int k = decodeLinePrefix(inputstream, outputstream);
                int i;
                for(i = 0; i + bytesPerAtom() < k; i += bytesPerAtom())
                {
                    decodeAtom(inputstream, outputstream, bytesPerAtom());
                    j += bytesPerAtom();
                }

                if(i + bytesPerAtom() == k)
                {
                    decodeAtom(inputstream, outputstream, bytesPerAtom());
                    j += bytesPerAtom();
                }
                else
                {
                    decodeAtom(inputstream, outputstream, k - i);
                    j += k - i;
                }
                decodeLineSuffix(inputstream, outputstream);
            }
            while(true);
        }
        catch( EOFException eofex )
        {
            decodeBufferSuffix(inputstream, outputstream);
        }
    }

    public byte[] decodeBuffer(String s)
        throws IOException
    {
        byte ascii[] = s.getBytes("US-ASCII");
        ByteArrayInputStream bytearrayinputstream = new ByteArrayInputStream(ascii);
        ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
        decodeBuffer(bytearrayinputstream, bytearrayoutputstream);
        return bytearrayoutputstream.toByteArray();
    }

    public String decodeBuffer( String s, String encoding )
        throws IOException
    {
	byte[] binary = decodeBuffer( s );
	return new String( binary, encoding );
    }
    
    protected int bytesPerAtom()
    {
        return 4;
    }

    protected int bytesPerLine()
    {
        return 72;
    }

    protected void decodeBufferPrefix(InputStream inputstream, OutputStream outputstream)
        throws IOException
    {
    }

    protected void decodeBufferSuffix(InputStream inputstream, OutputStream outputstream)
        throws IOException
    {
    }

    protected int decodeLinePrefix(InputStream inputstream, OutputStream outputstream)
        throws IOException
    {
        return bytesPerLine();
    }

    protected void decodeLineSuffix(InputStream inputstream, OutputStream outputstream)
        throws IOException
    {
    }

    protected void decodeAtom( InputStream inputstream, OutputStream outputstream, int i)
        throws IOException
    {
        byte byte0 = -1;
        byte byte1 = -1;
        byte byte2 = -1;
        byte byte3 = -1;
        if(i < 2)
            throw new IOException("BASE64Decoder: Not enough bytes for an atom.");
        int j;
        do
        {
            j = inputstream.read();
            if(j == -1)
                throw new EOFException( "Unexpected end of input." );
        }
        while(j == 10 || j == 13);
        decode_buffer[0] = (byte)j;
        j = readFully(inputstream, decode_buffer, 1, i - 1);
        if(j == -1)
            throw new EOFException( "Unexpected end of input." );
        if(i > 3 && decode_buffer[3] == 61)
            i = 3;
        if(i > 2 && decode_buffer[2] == 61)
            i = 2;
        switch(i)
        {
        case 4: /* '\004' */
            byte3 = pem_convert_array[decode_buffer[3] & 0xff];
            // fall through

        case 3: /* '\003' */
            byte2 = pem_convert_array[decode_buffer[2] & 0xff];
            // fall through

        case 2: /* '\002' */
            byte1 = pem_convert_array[decode_buffer[1] & 0xff];
            byte0 = pem_convert_array[decode_buffer[0] & 0xff];
            // fall through

        default:
            switch(i)
            {
            case 2: /* '\002' */
                outputstream.write((byte)(byte0 << 2 & 0xfc | byte1 >>> 4 & 0x3));
                break;

            case 3: /* '\003' */
                outputstream.write((byte)(byte0 << 2 & 0xfc | byte1 >>> 4 & 0x3));
                outputstream.write((byte)(byte1 << 4 & 0xf0 | byte2 >>> 2 & 0xf));
                break;

            case 4: /* '\004' */
                outputstream.write((byte)(byte0 << 2 & 0xfc | byte1 >>> 4 & 0x3));
                outputstream.write((byte)(byte1 << 4 & 0xf0 | byte2 >>> 2 & 0xf));
                outputstream.write((byte)(byte2 << 6 & 0xc0 | byte3 & 0x3f));
                break;

            }
            break;

        }
    }

    protected int readFully(InputStream inputstream, byte abyte0[], int i, int j)
        throws IOException
    {
        for(int k = 0; k < j; k++)
        {
            int l = inputstream.read();
            if(l == -1)
                return k != 0 ? k : -1;
            abyte0[k + i] = (byte)l;
        }

        return j;
    }

    private static final char pem_array[] = {
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 
        'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 
        'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 
        'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 
        'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 
        'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', 
        '8', '9', '+', '/'
    };
    private static final byte pem_convert_array[];
    byte decode_buffer[];

    static 
    {
        pem_convert_array = new byte[256];
        for(int i = 0; i < 255; i++)
            pem_convert_array[i] = -1;

        for(int j = 0; j < pem_array.length; j++)
            pem_convert_array[pem_array[j]] = (byte)j;

    }
}