/*

 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

 */

/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You 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 com.sun.org.apache.xerces.internal.impl.dv.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 Available at: http://www.ietf.org/rfc/rfc2045.txt

 * This class is used by XML Schema binary format validation

 *

 * This implementation does not encode/decode streaming

 * data. You need the data that you will encode/decode

 * already on a byte arrray.

 *

 * @xerces.internal

 *

 * @author Jeffrey Rodriguez

 * @author Sandy Gao

 * @LastModified: Nov 2017

 */

public final class  Base64 {

    static private final int  BASELENGTH         = 128;

    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  SIXBIT             = 6;

    static private final int  FOURBYTE           = 4;

    static private final int  SIGN               = -128;

    static private final char PAD                = '=';

    static private final boolean fDebug          = false;

    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] = '/';

    }

    protected static boolean isWhiteSpace(char octect) {

        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);

    }

    protected static boolean isPad(char octect) {

        return (octect == PAD);

    }

    protected static boolean isData(char octect) {

        return (octect < BASELENGTH && base64Alphabet[octect] != -1);

    }

    protected static boolean isBase64(char octect) {

        return (isWhiteSpace(octect) || isPad(octect) || isData(octect));

    }

    /**

     * Encodes hex octects into Base64

     *

     * @param binaryData Array containing binaryData

     * @return Encoded Base64 array

     */

    public static String encode(byte[] binaryData) {

        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;

        char     encodedData[]     = null;

        encodedData = new char[numberQuartet*4];

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

        int encodedIndex = 0;

        int dataIndex   = 0;

        if (fDebug) {

            System.out.println("number of triplets = " + numberTriplets );

        }

        for (int i=0; i<numberTriplets; i++) {

            b1 = binaryData[dataIndex++];

            b2 = binaryData[dataIndex++];

            b3 = binaryData[dataIndex++];

            if (fDebug) {

                System.out.println( "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 (fDebug) {

                System.out.println( "val2 = " + val2 );

                System.out.println( "k4   = " + (k<<4));

                System.out.println( "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 (fDebug) {

                System.out.println("b1=" + b1);

                System.out.println("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 containind decoded data.

     */

    public static byte[] decode(String encoded) {

        if (encoded == null)

            return null;

        char[] base64Data = encoded.toCharArray();

        // remove white spaces

        int len = removeWhiteSpace(base64Data);

        if (len%FOURBYTE != 0) {

            return null;//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;

        char     d1=0,d2=0,d3=0,d4=0;

        int i = 0;

        int encodedIndex = 0;

        int dataIndex    = 0;

        decodedData      = new byte[ (numberQuadruple)*3];

        for (; i<numberQuadruple-1; i++) {

            if (!isData( (d1 = base64Data[dataIndex++]) )||

                !isData( (d2 = base64Data[dataIndex++]) )||

                !isData( (d3 = base64Data[dataIndex++]) )||

                !isData( (d4 = base64Data[dataIndex++]) ))

                return null;//if found "no data" just return null

            b1 = base64Alphabet[d1];

            b2 = base64Alphabet[d2];

            b3 = base64Alphabet[d3];

            b4 = base64Alphabet[d4];

            decodedData[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 ) ;

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

            decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );

        }

        if (!isData( (d1 = base64Data[dataIndex++]) ) ||

            !isData( (d2 = base64Data[dataIndex++]) )) {

            return null;//if found "no data" just return null

        }

        b1 = base64Alphabet[d1];

        b2 = base64Alphabet[d2];

        d3 = base64Data[dataIndex++];

        d4 = base64Data[dataIndex++];

        if (!isData( (d3 ) ) ||

            !isData( (d4 ) )) {//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

                    return null;

                byte[] tmp = new byte[ i*3 + 1 ];

                System.arraycopy( decodedData, 0, tmp, 0, i*3 );

                tmp[encodedIndex]   = (byte)(  b1 <<2 | b2>>4 ) ;

                return tmp;

            } else if (!isPad( d3) && isPad(d4)) {               //One PAD  e.g. 3cQ[Pad]

                b3 = base64Alphabet[ d3 ];

                if ((b3 & 0x3 ) != 0)//last 2 bits should be zero

                    return null;

                byte[] tmp = new byte[ i*3 + 2 ];

                System.arraycopy( decodedData, 0, tmp, 0, i*3 );

                tmp[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 );

                tmp[encodedIndex]   = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );

                return tmp;

            } else {

                return null;//an error  like "3c[Pad]r", "3cdX", "3cXd", "3cXX" where X is non data

            }

        } else { //No PAD e.g 3cQl

            b3 = base64Alphabet[ d3 ];

            b4 = base64Alphabet[ d4 ];

            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(char[] 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++) {

            if (!isWhiteSpace(data[i]))

                data[newSize++] = data[i];

        }

        return newSize;

    }

}