/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/util/Attic/Base64.java,v 1.6.2.1 2004/02/22 18:21:16 olegk Exp $
 * $Revision: 1.6.2.1 $
 * $Date: 2004/02/22 18:21:16 $
 *
 * ====================================================================
 *
 *  Copyright 1999-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 * ====================================================================
 *
 * 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
 * .
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */

package org.apache.commons.httpclient.util;

import org.apache.commons.httpclient.HttpConstants;

/**
 * Base64 encoder and decoder.
 * 

 * This class provides encoding/decoding methods for the Base64 encoding 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. Available at: 
 * http://www.ietf.org/rfc/rfc2045.txt
 * 
 * 
 * @deprecated  The commons-codec Base64 class will be used in HttpClient 2.1
 * @author Jeffrey Rodriguez
 * @author Mike Bowler
 * @version $Revision: 1.6.2.1 $ $Date: 2004/02/22 18:21:16 $
 * 
 */
public final class Base64 {

    /** */
    private static final int  BASELENGTH = 255;

    /** */
    private static final int  LOOKUPLENGTH = 64;

    /** */
    private static final int  TWENTYFOURBITGROUP = 24;

    /** */
    private static final int  EIGHTBIT = 8;

    /** */
    private static final int  SIXTEENBIT = 16;

    /** */
    private static final int  SIXBIT = 6;

    /** */
    private static final int  FOURBYTE = 4;

    /** The sign bit as an int */
    private static final int  SIGN = -128;

    /** The padding character */
    private static final byte PAD = (byte) '=';

    /** The alphabet */
    private static final byte [] BASE64_ALPHABET = new byte[BASELENGTH];

    /** The lookup alphabet */
    private static final byte [] LOOKUP_BASE64_ALPHABET = new byte[LOOKUPLENGTH];

    static {

        for (int i = 0; i < BASELENGTH; i++) {
            BASE64_ALPHABET[i] = -1;
        }
        for (int i = 'Z'; i >= 'A'; i--) {
            BASE64_ALPHABET[i] = (byte) (i - 'A');
        }
        for (int i = 'z'; i >= 'a'; i--) {
            BASE64_ALPHABET[i] = (byte) (i - 'a' + 26);
        }

        for (int i = '9'; i >= '0'; i--) {
            BASE64_ALPHABET[i] = (byte) (i - '0' + 52);
        }

        BASE64_ALPHABET['+']  = 62;
        BASE64_ALPHABET['/']  = 63;

        for (int i = 0; i <= 25; i++) {
            LOOKUP_BASE64_ALPHABET[i] = (byte) ('A' + i);
        }

        for (int i = 26, j = 0; i <= 51; i++, j++) {
            LOOKUP_BASE64_ALPHABET[i] = (byte) ('a' + j);
        }

        for (int i = 52,  j = 0; i <= 61; i++, j++) {
            LOOKUP_BASE64_ALPHABET[i] = (byte) ('0' + j);
        }
        LOOKUP_BASE64_ALPHABET[62] = (byte) '+';
        LOOKUP_BASE64_ALPHABET[63] = (byte) '/';

    }

    /**
     * Create an instance.
     */
    private Base64() {
        // the constructor is intentionally private
    }

    /**
     * Return true if the specified string is base64 encoded.
     * @param isValidString The string to test.
     * @return boolean True if the string is base64.
     */
    public static boolean isBase64(String isValidString) {
        return isArrayByteBase64(HttpConstants.getAsciiBytes(isValidString));
    }


    /**
     * Return true if the specified octect is base64
     * @param octect The octet to test.
     * @return boolean True if the octect is base64.
     */
    static boolean isBase64(byte octect) {
        // Should we ignore white space?
        return (octect == PAD || BASE64_ALPHABET[octect] != -1);
    }

    /**
     * Return true if the specified byte array is base64
     * @param arrayOctect The array to test.
     * @return boolean true if the specified byte array is base64
     */
    public static boolean isArrayByteBase64(byte[] arrayOctect) {
        int length = arrayOctect.length;
        if (length == 0) {
            return true;
        }
        for (int i = 0; i < length; i++) {
            if (!Base64.isBase64(arrayOctect[i])) {
                return false;
            }
        }
        return true;
    }

    /**
     * Encodes hex octects into Base64
     *
     * @param binaryData Array containing binaryData
     * @return Base64-encoded array
     */
    public static byte[] encode(byte[] binaryData) {

        int      lengthDataBits    = binaryData.length * EIGHTBIT;
        int      fewerThan24bits   = lengthDataBits % TWENTYFOURBITGROUP;
        int      numberTriplets    = lengthDataBits / TWENTYFOURBITGROUP;
        byte     encodedData[]     = null;


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

        byte k = 0;
        byte l = 0;
        byte b1 = 0;
        byte b2 = 0;
        byte b3 = 0;
        int encodedIndex = 0;
        int dataIndex   = 0;
        int i           = 0;
        for (i = 0; i < numberTriplets; i++) {

            dataIndex = i * 3;
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            b3 = binaryData[dataIndex + 2];

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

            encodedIndex = i * 4;
            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]   = LOOKUP_BASE64_ALPHABET[val1];
            encodedData[encodedIndex + 1] = LOOKUP_BASE64_ALPHABET[val2
                | (k << 4)];
            encodedData[encodedIndex + 2] = LOOKUP_BASE64_ALPHABET[(l << 2)
                | val3];
            encodedData[encodedIndex + 3] = LOOKUP_BASE64_ALPHABET[b3 & 0x3f];
        }

        // form integral number of 6-bit groups
        dataIndex    = i * 3;
        encodedIndex = i * 4;
        if (fewerThan24bits == EIGHTBIT) {
            b1 = binaryData[dataIndex];
            k = (byte) (b1 & 0x03);
            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) 
                : (byte) ((b1) >> 2 ^ 0xc0);
            encodedData[encodedIndex]     = LOOKUP_BASE64_ALPHABET[val1];
            encodedData[encodedIndex + 1] = LOOKUP_BASE64_ALPHABET[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]     = LOOKUP_BASE64_ALPHABET[val1];
            encodedData[encodedIndex + 1] = LOOKUP_BASE64_ALPHABET[val2 
                | (k << 4)];
            encodedData[encodedIndex + 2] = LOOKUP_BASE64_ALPHABET[l << 2];
            encodedData[encodedIndex + 3] = PAD;
        }
        return encodedData;
    }


    /**
     * Decodes Base64 data into octects
     *
     * @param base64Data byte array containing Base64 data
     * @return Array containing decoded data.
     */
    public static byte[] decode(byte[] base64Data) {
        // Should we throw away anything not in 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;

        int encodedIndex = 0;
        int dataIndex    = 0;
        {
            // this block 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 = BASE64_ALPHABET[base64Data[dataIndex]];
            b2 = BASE64_ALPHABET[base64Data[dataIndex + 1]];

            if (marker0 != PAD && marker1 != PAD) {     //No PAD e.g 3cQl
                b3 = BASE64_ALPHABET[marker0];
                b4 = BASE64_ALPHABET[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 = BASE64_ALPHABET[marker0];
                decodedData[encodedIndex]   = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] = (byte) (((b2 & 0xf) << 4) 
                    | ((b3 >> 2) & 0xf));
            }
            encodedIndex += 3;
        }
        return decodedData;
    }
}