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/*
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 * $Revision$
 * $Date$
  *
  * ====================================================================
  *
  * The Apache Software License, Version 1.1
  *
  * Copyright (c) 2003 The Apache Software Foundation.  All rights
  * reserved.
  *
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  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
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  *    the documentation and/or other materials provided with the
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  *    any, must include the following acknowlegement:
  *       "This product includes software developed by the
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowlegement may appear in the software itself,
  *    if and wherever such third-party acknowlegements normally appear.
  *
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  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation.  For more
  * information on the Apache Software Foundation, please see
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  *
  * [Additional notices, if required by prior licensing conditions]
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  */
package ilex.util;

/**
* This class provides encode/decode for RFC 2045 Base64 as
* defined by RFC 2045, N. Freed and N. Borenstein.  RFC 2045:
* Multipurpose Internet Mail Extensions (MIME) Part One: Format of
* Internet Message Bodies. Reference 1996
* 
* @author Jeffrey Rodriguez
* @author Daniel Rall
* @author Martin Redington
* @since 1.0-dev
* 
*/
public class Base64 {

    // Create constants pertaining to the chunk requirement
    static final int CHUNK_SIZE = 76;
    static final byte[] CHUNK_SEPARATOR = "\n".getBytes();

    // Create numerical and byte constants 
    static final int BASELENGTH = 255;
    static final int LOOKUPLENGTH = 64;
    static final int TWENTYFOURBITGROUP = 24;
    static final int EIGHTBIT = 8;
    static final int SIXTEENBIT = 16;
    static final int SIXBIT = 6;
    static final int FOURBYTE = 4;
    static final int SIGN = -128;
    static final byte PAD = (byte)'=';

    // Create arrays to hold the base64 characters and a 
    // lookup for base64 chars
    private static byte[] base64Alphabet = new byte[BASELENGTH];
    private static byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];

    // Populating the lookup and character arrays
    static {
        for (int i = 0; i < BASELENGTH; i++) {
            base64Alphabet[i] = (byte) -1;
        }
        for (int i = 'Z'; i >= 'A'; i--) {
            base64Alphabet[i] = (byte) (i - 'A');
        }
        for (int i = 'z'; i >= 'a'; i--) {
            base64Alphabet[i] = (byte) (i - 'a' + 26);
        }
        for (int i = '9'; i >= '0'; i--) {
            base64Alphabet[i] = (byte) (i - '0' + 52);
        }

        base64Alphabet['+'] = 62;
        base64Alphabet['/'] = 63;

        for (int i = 0; i <= 25; i++) {
            lookUpBase64Alphabet[i] = (byte) ('A' + i);
        }

        for (int i = 26, j = 0; i <= 51; i++, j++) {
            lookUpBase64Alphabet[i] = (byte) ('a' + j);
        }

        for (int i = 52, j = 0; i <= 61; i++, j++) {
            lookUpBase64Alphabet[i] = (byte) ('0' + j);
        }

        lookUpBase64Alphabet[62] = (byte) '+';
        lookUpBase64Alphabet[63] = (byte) '/';
    }

    /**
	* @param octect
	* @return true if this octet is valid in base 64.
	*/
	private static boolean isBase64( byte octect ) {
        if (octect == PAD) {
            return true;
        } 
        else if (base64Alphabet[octect] == -1) {
            return false;
        } 
        else {
            return true;
        }
    }

    /**
	* @param arrayOctect
	* @return boolean
	*/
	public static boolean isArrayByteBase64( byte[] arrayOctect ) {

        arrayOctect = discardWhitespace(arrayOctect);

        int length = arrayOctect.length;
        if (length == 0) {
            // shouldn't a 0 length array be valid base64 data?
            // return false;
            return true;
        }
        for (int i = 0; i < length; i++) {
            if (!isBase64(arrayOctect[i])) {
                return false;
            }
        }
        return true;
    }


    /**
	* @param binaryData
	* @return
	*/
	public static byte[] encodeBase64( byte[] binaryData ) {
        return (encodeBase64(binaryData, false));
    }

    /**
	* @param binaryData
	* @return byte array
	*/
	public static byte[] encodeBase64Chunked( byte[] binaryData ) {
        return (encodeBase64(binaryData, true));
    }

    //public Object decode(Object pObject) throws DecoderException {
    /**
	* @param pObject
	* @return @throws Exception
	*/
	public Object decode( Object pObject ) throws Exception {

        Object result;

        if (!(pObject instanceof byte[])) {
            throw new Exception(
                "Parameter supplied to "
                    + "Base64 "
                    + "decode is not a byte[]");
        } 
        else {
            result = decode((byte[]) pObject);
        }

        return result;

    }

    //public byte[] decode(byte[] pArray) throws DecoderException {
    /**
	* @param pArray
	* @return @throws Exception
	*/
	public byte[] decode( byte[] pArray ) throws Exception {

        byte[] result;

        if (!isArrayByteBase64(pArray)) {
            throw new Exception(
                "Parameter supplied to "
                    + "Base64 "
                    + "decode is not a valid base64 data.");
        } 
        else {
            result = decodeBase64((byte[]) pArray);
        }

        return (result);
    }

    /**
	* Encodes hex octects into Base64.
	* 
	* @param binaryData Array containing binary data to encode.
	* @param isChunked
	* @return Base64-encoded data.
	*/
	public static byte[] encodeBase64( byte[] binaryData, boolean isChunked ) {
        int lengthDataBits = binaryData.length * EIGHTBIT;
        int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
        int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
        byte encodedData[] = null;
        int encodedDataLength = 0;
        int nbrChunks = 0;

        if (fewerThan24bits != 0) {
            //data not divisible by 24 bit
            encodedDataLength = (numberTriplets + 1) * 4;
        } 
        else {
            // 16 or 8 bit
            encodedDataLength = numberTriplets * 4;
        }

        // If the output is to be "chunked" into 76 character sections, 
        // for compliance with RFC 2045 MIME, then it is important to 
        // allow for extra length to account for the separator(s)
        if (isChunked) {

            nbrChunks =
                (CHUNK_SEPARATOR.length == 0
                    ? 0
                    : (int) Math.ceil((float) encodedDataLength / CHUNK_SIZE));
            encodedDataLength += nbrChunks * CHUNK_SEPARATOR.length;
        }

        encodedData = new byte[encodedDataLength];

        byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

        int encodedIndex = 0;
        int dataIndex = 0;
        int i = 0;
        int nextSeparatorIndex = CHUNK_SIZE;
        int chunksSoFar = 0;

        //log.debug("number of triplets = " + numberTriplets);
        for (i = 0; i < numberTriplets; i++) {
            dataIndex = i * 3;
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            b3 = binaryData[dataIndex + 2];

            //log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);

            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);

            byte val1 =
                ((b1 & SIGN) == 0)
                    ? (byte) (b1 >> 2)
                    : (byte) ((b1) >> 2 ^ 0xc0);
            byte val2 =
                ((b2 & SIGN) == 0)
                    ? (byte) (b2 >> 4)
                    : (byte) ((b2) >> 4 ^ 0xf0);
            byte val3 =
                ((b3 & SIGN) == 0)
                    ? (byte) (b3 >> 6)
                    : (byte) ((b3) >> 6 ^ 0xfc);

            encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
            //log.debug( "val2 = " + val2 );
            //log.debug( "k4   = " + (k<<4) );
            //log.debug(  "vak  = " + (val2 | (k<<4)) );
            encodedData[encodedIndex + 1] =
                lookUpBase64Alphabet[val2 | (k << 4)];
            encodedData[encodedIndex + 2] =
                lookUpBase64Alphabet[(l << 2) | val3];
            encodedData[encodedIndex + 3] = lookUpBase64Alphabet[b3 & 0x3f];

            encodedIndex += 4;

            // If we are chunking, let's put a chunk separator down.
            if (isChunked) {
                // this assumes that CHUNK_SIZE % 4 == 0
                if (encodedIndex == nextSeparatorIndex) {
                    System.arraycopy(
                        CHUNK_SEPARATOR,
                        0,
                        encodedData,
                        encodedIndex,
                        CHUNK_SEPARATOR.length);
                    chunksSoFar++;
                    nextSeparatorIndex =
                        (CHUNK_SIZE * (chunksSoFar + 1))
                            + (chunksSoFar * CHUNK_SEPARATOR.length);
                    encodedIndex += CHUNK_SEPARATOR.length;
                }
            }
        }

        // form integral number of 6-bit groups
        dataIndex = i * 3;

        if (fewerThan24bits == EIGHTBIT) {
            b1 = binaryData[dataIndex];
            k = (byte) (b1 & 0x03);
            //log.debug("b1=" + b1);
            //log.debug("b1<<2 = " + (b1>>2) );
            byte val1 =
                ((b1 & SIGN) == 0)
                    ? (byte) (b1 >> 2)
                    : (byte) ((b1) >> 2 ^ 0xc0);
            encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
            encodedData[encodedIndex + 1] = lookUpBase64Alphabet[k << 4];
            encodedData[encodedIndex + 2] = PAD;
            encodedData[encodedIndex + 3] = PAD;
        } 
        else if (fewerThan24bits == SIXTEENBIT) {

            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);

            byte val1 =
                ((b1 & SIGN) == 0)
                    ? (byte) (b1 >> 2)
                    : (byte) ((b1) >> 2 ^ 0xc0);
            byte val2 =
                ((b2 & SIGN) == 0)
                    ? (byte) (b2 >> 4)
                    : (byte) ((b2) >> 4 ^ 0xf0);

            encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
            encodedData[encodedIndex + 1] =
                lookUpBase64Alphabet[val2 | (k << 4)];
            encodedData[encodedIndex + 2] = lookUpBase64Alphabet[l << 2];
            encodedData[encodedIndex + 3] = PAD;
        }

        if (isChunked) {
            // we also add a separator to the end of the final chunk.
            if (chunksSoFar < nbrChunks) {
                System.arraycopy(
                    CHUNK_SEPARATOR,
                    0,
                    encodedData,
                    encodedDataLength - CHUNK_SEPARATOR.length,
                    CHUNK_SEPARATOR.length);
            }
        }

        return encodedData;
    }

    /**
	* Decodes Base64 data into octects
	* 
	* @param base64Data
	* @return Array containing decoded data.
	*/
	public static byte[] decodeBase64( byte[] base64Data ) {
        // RFC 2045 suggests line wrapping at (no more than) 76
        // characters -- we may have embedded whitespace.
        base64Data = discardWhitespace(base64Data);

        // handle the edge case, so we don't have to worry about it later
        if (base64Data.length == 0) {
            return new byte[0];
        }

        int numberQuadruple = base64Data.length / FOURBYTE;
        byte decodedData[] = null;
        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;

        // Throw away anything not in base64Data

        int encodedIndex = 0;
        int dataIndex = 0;
        {
            // this sizes the output array properly - rlw
            int lastData = base64Data.length;
            // ignore the '=' padding
            while (base64Data[lastData - 1] == PAD) {
                if (--lastData == 0) {
                    return new byte[0];
                }
            }
            decodedData = new byte[lastData - numberQuadruple];
        }

        for (int i = 0; i < numberQuadruple; i++) {
            dataIndex = i * 4;
            marker0 = base64Data[dataIndex + 2];
            marker1 = base64Data[dataIndex + 3];

            b1 = base64Alphabet[base64Data[dataIndex]];
            b2 = base64Alphabet[base64Data[dataIndex + 1]];

            if (marker0 != PAD && marker1 != PAD) {
                //No PAD e.g 3cQl
                b3 = base64Alphabet[marker0];
                b4 = base64Alphabet[marker1];

                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] =
                    (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex + 2] = (byte) (b3 << 6 | b4);
            } 
            else if (marker0 == PAD) {
                //Two PAD e.g. 3c[Pad][Pad]
                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
            } 
            else if (marker1 == PAD) {
                //One PAD e.g. 3cQ[Pad]
                b3 = base64Alphabet[marker0];

                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] =
                    (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            }
            encodedIndex += 3;
        }
        return decodedData;
    }

    /**
	* Discards any whitespace from a base-64 encoded block.
	* 
	* @param data The base-64 encoded data to discard the whitespace
	* from.
	* @return The data, less whitespace (see RFC 2045).
	*/
	static byte[] discardWhitespace( byte[] data ) {
        byte groomedData[] = new byte[data.length];
        int bytesCopied = 0;

        for (int i = 0; i < data.length; i++) {
            switch (data[i]) {
                case (byte) ' ' :
                case (byte) '\n' :
                case (byte) '\r' :
                case (byte) '\t' :
                    break;
                default:
                    groomedData[bytesCopied++] = data[i];
            }
        }

        byte packedData[] = new byte[bytesCopied];

        System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);

        return packedData;
    }

    // Implementation of the Encoder Interface

    /**
	* encode an Object
	* @param pObject
	* @return @throws Exception
	*/
	public Object encode( Object pObject ) throws Exception {

        Object result;

        if (!(pObject instanceof byte[])) {
            //throw new EncoderException(
            throw new Exception(
                "Parameter supplied to "
                    + "Base64 "
                    + "encode is not a byte[]");
        } 
        else {
            result = encode((byte[]) pObject);
        }

        return result;

    }

    //public byte[] encode(byte[] pArray) throws EncoderException {
    /**
	* @param pArray
	* @return @throws Exception
	*/
	public byte[] encode( byte[] pArray ) throws Exception {
        return (encodeBase64(pArray, false));
    }


	/**
	* @param args
	* @throws Exception
	*/
	public static void main( String[] args ) throws Exception
	{
		byte b[] = ByteUtil.fromHexString(args[0]);
		System.out.println("    Original: " + args[0]);
		System.out.println(" Back to hex: " + ByteUtil.toHexString(b));
		Base64 b64 = new Base64();
		byte [] ec = b64.encode(b);
		System.out.println("   To Base64: " + (new String(ec)));
		b = b64.decode(ec);
		System.out.println(" Back to hex: " + ByteUtil.toHexString(b));
	}

}