/*
 * 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.
 *
 */

package org.apache.ws.security.util;

import org.apache.ws.security.WSSecurityException;

public class Base64 {
    /**
     * Implementation of MIME's Base64 encoding and decoding conversions.
     * Optimized code. (raw version taken from oreilly.jonathan.util,
     * and currently org.apache.xerces.ds.util.Base64)
     *
     * @author Raul Benito(Of the xerces copy, and little adaptations).
     * @author Anli Shundi
     * @author Christian Geuer-Pollmann
     * @see <A HREF="ftp://ftp.isi.edu/in-notes/rfc2045.txt">RFC 2045</A>
     * @see org.apache.xml.security.transforms.implementations.TransformBase64Decode
     */

    /**
     * {@link org.apache.commons.logging} logging facility
     */
    static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory
            .getLog(Base64.class.getName());

    /**
     * Field BASE64DEFAULTLENGTH
     */
    public static final int BASE64DEFAULTLENGTH = 76;

    /**
     * Field _base64length
     */
    static int _base64length = Base64.BASE64DEFAULTLENGTH;

    static private final int BASELENGTH = 255;

    static private final int LOOKUPLENGTH = 64;

    static private final int TWENTYFOURBITGROUP = 24;

    static private final int EIGHTBIT = 8;

    static private final int SIXTEENBIT = 16;

    static private final int FOURBYTE = 4;

    static private final int SIGN = -128;

    static private final char PAD = '=';

    static private final boolean IS_DEBUG = log.isDebugEnabled();

    static final private byte[] base64Alphabet = new byte[BASELENGTH];

    static final private char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];

    static {

        for (int i = 0; i < BASELENGTH; i++) {
            base64Alphabet[i] = -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] = (char) ('A' + i);

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

        for (int i = 52, j = 0; i <= 61; i++, j++)
            lookUpBase64Alphabet[i] = (char) ('0' + j);
        lookUpBase64Alphabet[62] = '+';
        lookUpBase64Alphabet[63] = '/';

    }

    private Base64() {
        // we don't allow instantiation
    }

    /**
     * Encode a byte array and fold lines at the standard 76th character.
     *
     * @param binaryData <code>byte[]<code> to be base64 encoded
     * @return the <code>String<code> with encoded data
     */
    public static String encode(byte[] binaryData) {
        return encode(binaryData, BASE64DEFAULTLENGTH, false);
    }

    protected static boolean isWhiteSpace(byte octect) {
        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
    }

    protected static boolean isPad(byte octect) {
        return (octect == PAD);
    }

    /**
     * Encode a byte array in Base64 format and return an optionally
     * wrapped line.
     *
     * @param binaryData <code>byte[]</code> data to be encoded
     * @param length     <code>int<code> length of wrapped lines; No wrapping if less than 4.
     * @return a <code>String</code> with encoded data
     */
    public static String encode(byte[] binaryData, int length, boolean wrap) {

        if (length < 4) {
            length = Integer.MAX_VALUE;
        }

        if (binaryData == null)
            return null;

        int lengthDataBits = binaryData.length * EIGHTBIT;
        if (lengthDataBits == 0) {
            return "";
        }

        int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
        int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
        int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1
                : numberTriplets;
        int quartesPerLine = length / 4;
        int numberLines = (numberQuartet - 1) / quartesPerLine;
        char encodedData[];

        encodedData = new char[(numberQuartet * 4) + (wrap ? numberLines : 0)];

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

        int encodedIndex = 0;
        int dataIndex = 0;
        int tripletsDone = 0;
        if (IS_DEBUG) {
            log.debug("number of triplets = " + numberTriplets);
        }

        for (int line = 0; line < numberLines; line++) {
            for (int quartet = 0; quartet < quartesPerLine; quartet++) {
                b1 = binaryData[dataIndex++];
                b2 = binaryData[dataIndex++];
                b3 = binaryData[dataIndex++];

                if (IS_DEBUG) {
                    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);

                if (IS_DEBUG) {
                    log.debug("val2 = " + val2);
                    log.debug("k4   = " + (k << 4));
                    log.debug("vak  = " + (val2 | (k << 4)));
                }

                encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[val2
                        | (k << 4)];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2)
                        | val3];
                encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];

                tripletsDone++;
            }
            if (wrap) {
                encodedData[encodedIndex++] = 0xa;
            }
        }

        for (; tripletsDone < numberTriplets; tripletsDone++) {
            b1 = binaryData[dataIndex++];
            b2 = binaryData[dataIndex++];
            b3 = binaryData[dataIndex++];

            if (IS_DEBUG) {
                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);

            if (IS_DEBUG) {
                log.debug("val2 = " + val2);
                log.debug("k4   = " + (k << 4));
                log.debug("vak  = " + (val2 | (k << 4)));
            }

            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
        }

        // form integral number of 6-bit groups
        if (fewerThan24bits == EIGHTBIT) {
            b1 = binaryData[dataIndex];
            k = (byte) (b1 & 0x03);
            if (IS_DEBUG) {
                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++] = lookUpBase64Alphabet[k << 4];
            encodedData[encodedIndex++] = PAD;
            encodedData[encodedIndex++] = 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++] = lookUpBase64Alphabet[val2 | (k << 4)];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
            encodedData[encodedIndex++] = PAD;
        }
        return new String(encodedData);
    }

    /**
     * Decodes Base64 data into octects
     *
     * @param encoded String containing Base64 data
     * @return Array containing decoded data.
     */
    public static byte[] decode(String encoded) throws WSSecurityException {
        byte[] base64Data = encoded.getBytes();
        // remove white spaces
        int len = removeWhiteSpace(base64Data);

        if (len % FOURBYTE != 0) {
            throw new WSSecurityException("decoding.divisible.four");
            //should be divisible by four
        }

        int numberQuadruple = (len / FOURBYTE);

        if (numberQuadruple == 0)
            return new byte[0];

        byte decodedData[] = null;
        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;

        int i = 0;
        int encodedIndex = 0;
        int dataIndex = 0;

        //decodedData      = new byte[ (numberQuadruple)*3];
        dataIndex = (numberQuadruple - 1) * 4;
        encodedIndex = (numberQuadruple - 1) * 3;
        //first last bits.
        b1 = base64Alphabet[base64Data[dataIndex++]];
        b2 = base64Alphabet[base64Data[dataIndex++]];
        if ((b1 == -1) || (b2 == -1)) {
            throw new WSSecurityException("decoding.general");//if found "no data" just return null
        }

        byte d3, d4;
        b3 = base64Alphabet[d3 = base64Data[dataIndex++]];
        b4 = base64Alphabet[d4 = base64Data[dataIndex++]];
        if ((b3 == -1) || (b4 == -1)) {
            //Check if they are PAD characters
            if (isPad(d3) && isPad(d4)) { //Two PAD e.g. 3c[Pad][Pad]
                if ((b2 & 0xf) != 0)//last 4 bits should be zero
                    throw new WSSecurityException("decoding.general");
                decodedData = new byte[encodedIndex + 1];
                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
            } else if (!isPad(d3) && isPad(d4)) { //One PAD  e.g. 3cQ[Pad]
                if ((b3 & 0x3) != 0)//last 2 bits should be zero
                    throw new WSSecurityException("decoding.general");
                decodedData = new byte[encodedIndex + 2];
                decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            } else {
                throw new WSSecurityException("decoding.general");//an error  like "3c[Pad]r", "3cdX", "3cXd", "3cXX" where X is non data
            }
        } else {
            //No PAD e.g 3cQl
            decodedData = new byte[encodedIndex + 3];
            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
        }
        encodedIndex = 0;
        dataIndex = 0;
        //the begin
        for (i = numberQuadruple - 1; i > 0; i--) {
            b1 = base64Alphabet[base64Data[dataIndex++]];
            b2 = base64Alphabet[base64Data[dataIndex++]];
            b3 = base64Alphabet[base64Data[dataIndex++]];
            b4 = base64Alphabet[base64Data[dataIndex++]];

            if ((b1 == -1) || (b2 == -1) || (b3 == -1) || (b4 == -1)) {
                throw new WSSecurityException("decoding.general");//if found "no data" just return null
            }

            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
        }
        return decodedData;
    }

    /**
     * remove WhiteSpace from MIME containing encoded Base64 data.
     *
     * @param data the byte array of base64 data (with WS)
     * @return the new length
     */
    protected static int removeWhiteSpace(byte[] data) {
        if (data == null)
            return 0;

        // count characters that's not whitespace
        int newSize = 0;
        int len = data.length;
        for (int i = 0; i < len; i++) {
            byte dataS = data[i];
            if (!isWhiteSpace(dataS))
                data[newSize++] = dataS;
        }
        return newSize;
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

    }
}