/*
    *  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 org.apache.mina.util;
  
  import java.security.InvalidParameterException;
  
  /**
   * Provides Base64 encoding and decoding as defined by RFC 2045.
   * 
   * <p>
   * This class implements section <cite>6.8. Base64
   * Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose Internet
   * Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by
   * Freed and Borenstein.
   * </p>
   * 
   * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
   * 
   * 
   * @author Apache Software Foundation commons codec
   *         (http://commons.apache.org/codec/)
   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
   */
  public class Base64 {
  
      /**
       * Chunk size per RFC 2045 section 6.8.
       * 
       * <p>The {@value} character limit does not count the trailing CRLF, but counts
       * all other characters, including any equal signs.</p>
       * 
       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
       */
      static final int CHUNK_SIZE = 76;
  
      /**
       * Chunk separator per RFC 2045 section 2.1.
       * 
       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
       */
      static final byte[] CHUNK_SEPARATOR = "\r\n".getBytes();
  
      /**
       * The base length.
       */
      static final int BASELENGTH = 255;
  
      /**
       * Lookup length.
       */
      static final int LOOKUPLENGTH = 64;
  
      /**
       * Used to calculate the number of bits in a byte.
       */
      static final int EIGHTBIT = 8;
  
      /**
       * Used when encoding something which has fewer than 24 bits.
       */
      static final int SIXTEENBIT = 16;
  
      /**
       * Used to determine how many bits data contains.
       */
      static final int TWENTYFOURBITGROUP = 24;
  
      /**
       * Used to get the number of Quadruples.
       */
      static final int FOURBYTE = 4;
  
      /**
       * Used to test the sign of a byte.
       */
      static final int SIGN = -128;
  
      /**
       * Byte used to pad output.
       */
      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) '/';
     }
 
     private static boolean isBase64(byte octect) {
         if (octect == PAD) {
             return true;
         } else if (base64Alphabet[octect] == -1) {
             return false;
         } else {
             return true;
         }
     }
 
     /**
      * Tests a given byte array to see if it contains
      * only valid characters within the Base64 alphabet.
      *
      * @param arrayOctect byte array to test
      * @return true if all bytes are valid characters in the Base64
      *         alphabet or if the byte array is empty; false, otherwise
      */
     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 true;
         }
         for (int i = 0; i < length; i++) {
             if (!isBase64(arrayOctect[i])) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Encodes binary data using the base64 algorithm but
      * does not chunk the output.
      *
      * @param binaryData binary data to encode
      * @return Base64 characters
      */
     public static byte[] encodeBase64(byte[] binaryData) {
         return encodeBase64(binaryData, false);
     }
 
     /**
      * Encodes binary data using the base64 algorithm and chunks
      * the encoded output into 76 character blocks
      *
      * @param binaryData binary data to encode
      * @return Base64 characters chunked in 76 character blocks
      */
     public static byte[] encodeBase64Chunked(byte[] binaryData) {
         return encodeBase64(binaryData, true);
     }
 
     /**
      * Decodes an Object using the base64 algorithm.  This method
      * is provided in order to satisfy the requirements of the
      * Decoder interface, and will throw a DecoderException if the
      * supplied object is not of type byte[].
      *
      * @param pObject Object to decode
      * @return An object (of type byte[]) containing the
      *         binary data which corresponds to the byte[] supplied.
      * @throws InvalidParameterException if the parameter supplied is not
      *                          of type byte[]
      */
     public Object decode(Object pObject) {
         if (!(pObject instanceof byte[])) {
             throw new InvalidParameterException("Parameter supplied to Base64 decode is not a byte[]");
         }
         return decode((byte[]) pObject);
     }
 
     /**
      * Decodes a byte[] containing containing
      * characters in the Base64 alphabet.
      *
      * @param pArray A byte array containing Base64 character data
      * @return a byte array containing binary data
      */
     public byte[] decode(byte[] pArray) {
         return decodeBase64(pArray);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally
      * chunking the output into 76 character blocks.
      *
      * @param binaryData Array containing binary data to encode.
      * @param isChunked if isChunked is true this encoder will chunk
      *                  the base64 output into 76 character blocks
      * @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;
 
         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);
 
             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];
             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);
             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 Byte array containing Base64 data
      * @return Array containing decoded data.
      */
     public static byte[] decodeBase64(byte[] base64Data) {
         // RFC 2045 requires that we discard ALL non-Base64 characters
         base64Data = discardNonBase64(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;
     }
 
     /**
      * Discards any characters outside of the base64 alphabet, per
      * the requirements on page 25 of RFC 2045 - "Any characters
      * outside of the base64 alphabet are to be ignored in base64
      * encoded data."
      *
      * @param data The base-64 encoded data to groom
      * @return The data, less non-base64 characters (see RFC 2045).
      */
     static byte[] discardNonBase64(byte[] data) {
         byte groomedData[] = new byte[data.length];
         int bytesCopied = 0;
 
         for (int i = 0; i < data.length; i++) {
             if (isBase64(data[i])) {
                 groomedData[bytesCopied++] = data[i];
             }
         }
 
         byte packedData[] = new byte[bytesCopied];
 
         System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
 
         return packedData;
     }
 
     // Implementation of the Encoder Interface
 
     /**
      * Encodes an Object using the base64 algorithm.  This method
      * is provided in order to satisfy the requirements of the
      * Encoder interface, and will throw an EncoderException if the
      * supplied object is not of type byte[].
      *
      * @param pObject Object to encode
      * @return An object (of type byte[]) containing the
      *         base64 encoded data which corresponds to the byte[] supplied.
      * @throws InvalidParameterException if the parameter supplied is not
      *                          of type byte[]
      */
     public Object encode(Object pObject) {
         if (!(pObject instanceof byte[])) {
             throw new InvalidParameterException("Parameter supplied to Base64 encode is not a byte[]");
         }
         return encode((byte[]) pObject);
     }
 
     /**
      * Encodes a byte[] containing binary data, into a byte[] containing
      * characters in the Base64 alphabet.
      *
      * @param pArray a byte array containing binary data
      * @return A byte array containing only Base64 character data
      */
     public byte[] encode(byte[] pArray) {
         return encodeBase64(pArray, false);
     }
 
 }