/**
 *
 * 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.hadoop.hbase.util;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilterInputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

/**
 * Encodes and decodes to and from Base64 notation.
 *
 * <p>
 * Homepage: <a href="http://iharder.net/base64">http://iharder.net/base64</a>.
 * </p>
 *
 * <p>
 * Change Log:
 * </p>
 * <ul>
 *   <li>v2.2.1 - Fixed bug using URL_SAFE and ORDERED encodings. Fixed bug
 *     when using very small files (~< 40 bytes).</li>
 *   <li>v2.2 - Added some helper methods for encoding/decoding directly from
 *     one file to the next. Also added a main() method to support command
 *     line encoding/decoding from one file to the next. Also added these
 *     Base64 dialects:
 *     <ol>
 *       <li>The default is RFC3548 format.</li>
 *       <li>Using Base64.URLSAFE generates URL and file name friendly format as
 *         described in Section 4 of RFC3548.
 *         http://www.faqs.org/rfcs/rfc3548.html</li>
 *       <li>Using Base64.ORDERED generates URL and file name friendly format
 *         that preserves lexical ordering as described in
 *         http://www.faqs.org/qa/rfcc-1940.html</li>
 *     </ol>
 *     <p>
 *     Special thanks to Jim Kellerman at <a href="http://www.powerset.com/">
 *     http://www.powerset.com/</a> for contributing the new Base64 dialects.
 *   </li>
 *
 *   <li>v2.1 - Cleaned up javadoc comments and unused variables and methods.
 *     Added some convenience methods for reading and writing to and from files.
 *   </li>
 *   <li>v2.0.2 - Now specifies UTF-8 encoding in places where the code fails on
 *     systems with other encodings (like EBCDIC).</li>
 *   <li>v2.0.1 - Fixed an error when decoding a single byte, that is, when the
 *     encoded data was a single byte.</li>
 *   <li>v2.0 - I got rid of methods that used booleans to set options. Now
 *     everything is more consolidated and cleaner. The code now detects when
 *     data that's being decoded is gzip-compressed and will decompress it
 *     automatically. Generally things are cleaner. You'll probably have to
 *     change some method calls that you were making to support the new options
 *     format (<tt>int</tt>s that you "OR" together).</li>
 *   <li>v1.5.1 - Fixed bug when decompressing and decoding to a byte[] using
 *     <tt>decode( String s, boolean gzipCompressed )</tt>. Added the ability to
 *     "suspend" encoding in the Output Stream so you can turn on and off the
 *     encoding if you need to embed base64 data in an otherwise "normal" stream
 *     (like an XML file).</li>
 *   <li>v1.5 - Output stream pases on flush() command but doesn't do anything
 *     itself. This helps when using GZIP streams. Added the ability to
 *     GZip-compress objects before encoding them.</li>
 *   <li>v1.4 - Added helper methods to read/write files.</li>
 *   <li>v1.3.6 - Fixed OutputStream.flush() so that 'position' is reset.</li>
 *   <li>v1.3.5 - Added flag to turn on and off line breaks. Fixed bug in input
 *     stream where last buffer being read, if not completely full, was not
 *     returned.</li>
 *   <li>v1.3.4 - Fixed when "improperly padded stream" error was thrown at the
 *     wrong time.</li>
 *   <li>v1.3.3 - Fixed I/O streams which were totally messed up.</li>
 * </ul>
 *
 * <p>
 * I am placing this code in the Public Domain. Do with it as you will. This
 * software comes with no guarantees or warranties but with plenty of
 * well-wishing instead!
 * <p>
 * Please visit <a href="http://iharder.net/base64">http://iharder.net/base64</a>
 * periodically to check for updates or to contribute improvements.
 * <p>
 * author: Robert Harder, rob@iharder.net
 * <br>
 * version: 2.2.1
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class Base64 {

  /* ******** P U B L I C   F I E L D S ******** */

  /** No options specified. Value is zero. */
  public final static int NO_OPTIONS = 0;

  /** Specify encoding. */
  public final static int ENCODE = 1;

  /** Specify decoding. */
  public final static int DECODE = 0;

  /** Specify that data should be gzip-compressed. */
  public final static int GZIP = 2;

  /** Don't break lines when encoding (violates strict Base64 specification) */
  public final static int DONT_BREAK_LINES = 8;

  /**
   * Encode using Base64-like encoding that is URL and Filename safe as
   * described in Section 4 of RFC3548:
   * <a href="http://www.faqs.org/rfcs/rfc3548.html">
   * http://www.faqs.org/rfcs/rfc3548.html</a>.
   * It is important to note that data encoded this way is <em>not</em>
   * officially valid Base64, or at the very least should not be called Base64
   * without also specifying that is was encoded using the URL and
   * Filename safe dialect.
   */
  public final static int URL_SAFE = 16;

  /**
   * Encode using the special "ordered" dialect of Base64 described here:
   * <a href="http://www.faqs.org/qa/rfcc-1940.html">
   * http://www.faqs.org/qa/rfcc-1940.html</a>.
   */
  public final static int ORDERED = 32;

  /* ******** P R I V A T E   F I E L D S ******** */

  private static final Log LOG = LogFactory.getLog(Base64.class);

  /** Maximum line length (76) of Base64 output. */
  private final static int MAX_LINE_LENGTH = 76;

  /** The equals sign (=) as a byte. */
  private final static byte EQUALS_SIGN = (byte) '=';

  /** The new line character (\n) as a byte. */
  private final static byte NEW_LINE = (byte) '\n';

  /** Preferred encoding. */
  private final static String PREFERRED_ENCODING = "UTF-8";

  private final static byte WHITE_SPACE_ENC = -5; // Indicates white space
  private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign

  /* ******** S T A N D A R D   B A S E 6 4   A L P H A B E T ******** */

  /** The 64 valid Base64 values. */

  /*
   * Host platform may be something funny like EBCDIC, so we hardcode these
   * values.
   */
  private final static byte[] _STANDARD_ALPHABET = { (byte) 'A', (byte) 'B',
    (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H',
    (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
    (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T',
    (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
    (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
    (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l',
    (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r',
    (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
    (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
    (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9',
    (byte) '+', (byte) '/'
  };

  /**
   * Translates a Base64 value to either its 6-bit reconstruction value or a
   * negative number indicating some other meaning.
   */
  private final static byte[] _STANDARD_DECODABET = {
    -9, -9, -9, -9, -9, -9, -9, -9, -9,             // Decimal 0 - 8
    -5, -5,                                         // Whitespace: Tab, Newline
    -9, -9,                                         // Decimal 11 - 12
    -5,                                             // Whitespace: Return
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
    -9, -9, -9, -9, -9,                             // Decimal 27 - 31
    -5,                                             // Whitespace: Space
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,         // Decimal 33 - 42
    62,                                             // Plus sign at decimal 43
    -9, -9, -9,                                     // Decimal 44 - 46
    63,                                             // Slash at decimal 47
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61,         // Numbers zero - nine
    -9, -9, -9,                                     // Decimal 58 - 60
    -1,                                             // Equals sign at decimal 61
    -9, -9, -9,                                     // Decimal 62 - 64
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,   // Letters 'A' - 'N'
    14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' - 'Z'
    -9, -9, -9, -9, -9, -9,                         // Decimal 91 - 96
    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' - 'm'
    39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' -'z'
    -9, -9, -9, -9                                  // Decimal 123 - 126
  };

  /* ******** U R L   S A F E   B A S E 6 4   A L P H A B E T ******** */

  /**
   * Used in the URL and Filename safe dialect described in Section 4 of RFC3548
   * <a href="http://www.faqs.org/rfcs/rfc3548.html">
   * http://www.faqs.org/rfcs/rfc3548.html</a>.
   * Notice that the last two bytes become "hyphen" and "underscore" instead of
   * "plus" and "slash."
   */
  private final static byte[] _URL_SAFE_ALPHABET = { (byte) 'A', (byte) 'B',
    (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H',
    (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
    (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T',
    (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
    (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
    (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l',
    (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r',
    (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
    (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
    (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9',
    (byte) '-', (byte) '_'
  };

  /**
   * Used in decoding URL and Filename safe dialects of Base64.
   */
  private final static byte[] _URL_SAFE_DECODABET = {
    -9, -9, -9, -9, -9, -9, -9, -9, -9,                 // Decimal 0 - 8
    -5, -5,                                             // Whitespace: Tab, Newline
    -9, -9,                                             // Decimal 11 - 12
    -5,                                                 // Whitespace: Return
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
    -9, -9, -9, -9, -9,                                 // Decimal 27 - 31
    -5,                                                 // Whitespace: Space
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,             // Decimal 33 - 42
    -9,                                                 // Plus sign at 43
    -9,                                                 // Decimal 44
    62,                                                 // Minus sign at 45
    -9,                                                 // Decimal 46
    -9,                                                 // Slash at 47
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61,             // Numbers 0 - 9
    -9, -9, -9,                                         // Decimal 58 - 60
    -1,                                                 // Equals sign at 61
    -9, -9, -9,                                         // Decimal 62 - 64
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,       // Letters 'A' - 'N'
    14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,     // Letters 'O' - 'Z'
    -9, -9, -9, -9,                                     // Decimal 91 - 94
    63,                                                 // Underscore at 95
    -9,                                                 // Decimal 96
    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' - 'm'
    39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' - 'z'
    -9, -9, -9, -9                                      // Decimal 123 - 126
  };

  /* ******** O R D E R E D   B A S E 6 4   A L P H A B E T ******** */

  /**
   * In addition to being URL and file name friendly, this encoding preserves
   * the sort order of encoded values. Whatever is input, be it string or
   * just an array of bytes, when you use this encoding, the encoded value sorts
   * exactly the same as the input value. It is described in the RFC change
   * request: <a href="http://www.faqs.org/qa/rfcc-1940.html">
   * http://www.faqs.org/qa/rfcc-1940.html</a>.
   *
   * It replaces "plus" and "slash" with "hyphen" and "underscore" and
   * rearranges the alphabet so that the characters are in their natural sort
   * order.
   */
  private final static byte[] _ORDERED_ALPHABET = { (byte) '-', (byte) '0',
    (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6',
    (byte) '7', (byte) '8', (byte) '9', (byte) 'A', (byte) 'B', (byte) 'C',
    (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I',
    (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O',
    (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U',
    (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) '_',
    (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
    (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l',
    (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r',
    (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
    (byte) 'y', (byte) 'z'
  };

  /**
   * Used in decoding the "ordered" dialect of Base64.
   */
  private final static byte[] _ORDERED_DECODABET = {
    -9, -9, -9, -9, -9, -9, -9, -9, -9,                 // Decimal 0 - 8
    -5, -5,                                             // Whitespace: Tab, Newline
    -9, -9,                                             // Decimal 11 - 12
    -5,                                                 // Whitespace: Return
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
    -9, -9, -9, -9, -9,                                 // Decimal 27 - 31
    -5,                                                 // Whitespace: Space
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,             // Decimal 33 - 42
    -9,                                                 // Plus sign at 43
    -9,                                                 // Decimal 44
    0,                                                  // Minus sign at 45
    -9,                                                 // Decimal 46
    -9,                                                 // Slash at decimal 47
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10,                      // Numbers 0 - 9
    -9, -9, -9,                                         // Decimal 58 - 60
    -1,                                                 // Equals sign at 61
    -9, -9, -9,                                         // Decimal 62 - 64
    11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, // Letters 'A' - 'M'
    24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, // Letters 'N' - 'Z'
    -9, -9, -9, -9,                                     // Decimal 91 - 94
    37,                                                 // Underscore at 95
    -9,                                                 // Decimal 96
    38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, // Letters 'a' - 'm'
    51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, // Letters 'n' - 'z'
    -9, -9, -9, -9                                      // Decimal 123 - 126
  };

  /* ******** D E T E R M I N E   W H I C H   A L H A B E T ******** */

  /**
   * Returns one of the _SOMETHING_ALPHABET byte arrays depending on the options
   * specified. It's possible, though silly, to specify ORDERED and URLSAFE in
   * which case one of them will be picked, though there is no guarantee as to
   * which one will be picked.
   *
   * @param options URL_SAFE or ORDERED
   * @return alphabet array to use
   */
  protected static byte[] getAlphabet(int options) {
    if ((options & URL_SAFE) == URL_SAFE) {
      return _URL_SAFE_ALPHABET;

    } else if ((options & ORDERED) == ORDERED) {
      return _ORDERED_ALPHABET;

    } else {
      return _STANDARD_ALPHABET;
    }
  } // end getAlphabet

  /**
   * Returns one of the _SOMETHING_DECODABET byte arrays depending on the
   * options specified. It's possible, though silly, to specify ORDERED and
   * URL_SAFE in which case one of them will be picked, though there is no
   * guarantee as to which one will be picked.
   * @param options URL_SAFE or ORDERED
   * @return alphabet array to use
   */
  protected static byte[] getDecodabet(int options) {
    if ((options & URL_SAFE) == URL_SAFE) {
      return _URL_SAFE_DECODABET;

    } else if ((options & ORDERED) == ORDERED) {
      return _ORDERED_DECODABET;

    } else {
      return _STANDARD_DECODABET;
    }
  } // end getDecodabet

  /** Defeats instantiation. */
  private Base64() {}

  /**
   * Main program. Used for testing.
   *
   * Encodes or decodes two files from the command line
   *
   * @param args command arguments
   */
  public static void main(String[] args) {
    if (args.length < 3) {
      usage("Not enough arguments.");

    } else {
      String flag = args[0];
      String infile = args[1];
      String outfile = args[2];
      if (flag.equals("-e")) {                          // encode
        encodeFileToFile(infile, outfile);

      } else if (flag.equals("-d")) {                   // decode
        decodeFileToFile(infile, outfile);

      } else {
        usage("Unknown flag: " + flag);
      }
    }
  } // end main

  /**
   * Prints command line usage.
   *
   * @param msg A message to include with usage info.
   */
  private static void usage(String msg) {
    System.err.println(msg);
    System.err.println("Usage: java Base64 -e|-d inputfile outputfile");
  } // end usage

  /* ******** E N C O D I N G   M E T H O D S ******** */

  /**
   * Encodes up to the first three bytes of array <var>threeBytes</var> and
   * returns a four-byte array in Base64 notation. The actual number of
   * significant bytes in your array is given by <var>numSigBytes</var>. The
   * array <var>threeBytes</var> needs only be as big as <var>numSigBytes</var>.
   * Code can reuse a byte array by passing a four-byte array as <var>b4</var>.
   *
   * @param b4 A reusable byte array to reduce array instantiation
   * @param threeBytes the array to convert
   * @param numSigBytes the number of significant bytes in your array
   * @param options options for get alphabet
   * @return four byte array in Base64 notation.
   * @since 1.5.1
   */
  protected static byte[] encode3to4(byte[] b4, byte[] threeBytes,
      int numSigBytes, int options) {
    encode3to4(threeBytes, 0, numSigBytes, b4, 0, options);
    return b4;
  } // end encode3to4

  /**
   * Encodes up to three bytes of the array <var>source</var> and writes the
   * resulting four Base64 bytes to <var>destination</var>. The source and
   * destination arrays can be manipulated anywhere along their length by
   * specifying <var>srcOffset</var> and <var>destOffset</var>. This method
   * does not check to make sure your arrays are large enough to accomodate
   * <var>srcOffset</var> + 3 for the <var>source</var> array or
   * <var>destOffset</var> + 4 for the <var>destination</var> array. The
   * actual number of significant bytes in your array is given by
   * <var>numSigBytes</var>.
   * <p>
   * This is the lowest level of the encoding methods with all possible
   * parameters.
   *
   * @param source the array to convert
   * @param srcOffset the index where conversion begins
   * @param numSigBytes the number of significant bytes in your array
   * @param destination the array to hold the conversion
   * @param destOffset the index where output will be put
   * @param options options for get alphabet
   * @return the <var>destination</var> array
   * @since 1.3
   */
  protected static byte[] encode3to4(byte[] source, int srcOffset,
      int numSigBytes, byte[] destination, int destOffset, int options) {
    byte[] ALPHABET = getAlphabet(options);

    //           1         2         3
    // 01234567890123456789012345678901 Bit position
    // --------000000001111111122222222 Array position from threeBytes
    // --------|    ||    ||    ||    | Six bit groups to index ALPHABET
    //          >>18  >>12  >> 6  >> 0  Right shift necessary
    //                0x3f  0x3f  0x3f  Additional AND

    // Create buffer with zero-padding if there are only one or two
    // significant bytes passed in the array.
    // We have to shift left 24 in order to flush out the 1's that appear
    // when Java treats a value as negative that is cast from a byte to an int.
    int inBuff =
        (numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0)
            | (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0)
            | (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0);

    switch (numSigBytes) {
    case 3:
      destination[destOffset] = ALPHABET[(inBuff >>> 18)];
      destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
      destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
      destination[destOffset + 3] = ALPHABET[(inBuff) & 0x3f];
      return destination;

    case 2:
      destination[destOffset] = ALPHABET[(inBuff >>> 18)];
      destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
      destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
      destination[destOffset + 3] = EQUALS_SIGN;
      return destination;

    case 1:
      destination[destOffset] = ALPHABET[(inBuff >>> 18)];
      destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
      destination[destOffset + 2] = EQUALS_SIGN;
      destination[destOffset + 3] = EQUALS_SIGN;
      return destination;

    default:
      return destination;
    } // end switch
  } // end encode3to4

  /**
   * Serializes an object and returns the Base64-encoded version of that
   * serialized object. If the object cannot be serialized or there is another
   * error, the method will return <tt>null</tt>. The object is not
   * GZip-compressed before being encoded.
   *
   * @param serializableObject The object to encode
   * @return The Base64-encoded object
   * @since 1.4
   */
  public static String encodeObject(Serializable serializableObject) {
    return encodeObject(serializableObject, NO_OPTIONS);
  } // end encodeObject

  /**
   * Serializes an object and returns the Base64-encoded version of that
   * serialized object. If the object cannot be serialized or there is another
   * error, the method will return <tt>null</tt>.
   * <p>
   * Valid options:
   * <ul>
   *   <li>GZIP: gzip-compresses object before encoding it.</li>
   *   <li>DONT_BREAK_LINES: don't break lines at 76 characters. <i>Note:
   *     Technically, this makes your encoding non-compliant.</i></li>
   * </ul>
   * <p>
   * Example: <code>encodeObject( myObj, Base64.GZIP )</code> or
   * <p>
   * Example:
   * <code>encodeObject( myObj, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
   *
   * @param serializableObject The object to encode
   * @param options Specified options
   * @see Base64#GZIP
   * @see Base64#DONT_BREAK_LINES
   * @return The Base64-encoded object
   * @since 2.0
   */
  @SuppressWarnings({"ConstantConditions"})
  public static String encodeObject(Serializable serializableObject,
      int options) {

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    OutputStream b64os = null;
    ObjectOutputStream oos = null;
    try {
      // ObjectOutputStream -> (GZIP) -> Base64 -> ByteArrayOutputStream
      b64os = new Base64OutputStream(baos, ENCODE | options);

      oos = ((options & GZIP) == GZIP) ?
          new ObjectOutputStream(new GZIPOutputStream(b64os)) :
            new ObjectOutputStream(b64os);

      oos.writeObject(serializableObject);
      return new String(baos.toByteArray(), PREFERRED_ENCODING);

    } catch (UnsupportedEncodingException uue) {
      return new String(baos.toByteArray());

    } catch (IOException e) {
      LOG.error("error encoding object", e);
      return null;

    } finally {
      if (oos != null) {
        try {
          oos.close();
        } catch (Exception e) {
          LOG.error("error closing ObjectOutputStream", e);
        }
      }
      if (b64os != null) {
        try {
          b64os.close();
        } catch (Exception e) {
          LOG.error("error closing Base64OutputStream", e);
        }
      }
      try {
        baos.close();
      } catch (Exception e) {
        LOG.error("error closing ByteArrayOutputStream", e);
      }
    } // end finally
  } // end encode

  /**
   * Encodes a byte array into Base64 notation. Does not GZip-compress data.
   *
   * @param source The data to convert
   * @return encoded byte array
   * @since 1.4
   */
  public static String encodeBytes(byte[] source) {
    return encodeBytes(source, 0, source.length, NO_OPTIONS);
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Valid options:
   * <ul>
   *   <li>GZIP: gzip-compresses object before encoding it.</li>
   *   <li>DONT_BREAK_LINES: don't break lines at 76 characters. <i>Note:
   *     Technically, this makes your encoding non-compliant.</i></li>
   * </ul>
   *
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example:
   * <code>encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
   *
   * @param source The data to convert
   * @param options Specified options
   * @see Base64#GZIP
   * @see Base64#DONT_BREAK_LINES
   * @see Base64#URL_SAFE
   * @see Base64#ORDERED
   * @return encoded byte array
   * @since 2.0
   */
  public static String encodeBytes(byte[] source, int options) {
    return encodeBytes(source, 0, source.length, options);
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation. Does not GZip-compress data.
   *
   * @param source The data to convert
   * @param off Offset in array where conversion should begin
   * @param len Length of data to convert
   * @return encoded byte array
   * @since 1.4
   */
  public static String encodeBytes(byte[] source, int off, int len) {
    return encodeBytes(source, off, len, NO_OPTIONS);
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Valid options:
   * <ul>
   *   <li>GZIP: gzip-compresses object before encoding it.</li>
   *   <li>DONT_BREAK_LINES: don't break lines at 76 characters. <i>Note:
   *     Technically, this makes your encoding non-compliant.</i></li>
   * </ul>
   *
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example:
   * <code>encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
   *
   * @param source The data to convert
   * @param off Offset in array where conversion should begin
   * @param len Length of data to convert
   * @param options Specified options
   * @see Base64#GZIP
   * @see Base64#DONT_BREAK_LINES
   * @see Base64#URL_SAFE
   * @see Base64#ORDERED
   * @return encoded byte array
   * @since 2.0
   */
  public static String encodeBytes(byte[] source, int off, int len, int options) {
    if ((options & GZIP) == GZIP) {                             // Compress?
      // GZip -> Base64 -> ByteArray
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      GZIPOutputStream gzos = null;

      try {
        gzos =
          new GZIPOutputStream(new Base64OutputStream(baos, ENCODE | options));

        gzos.write(source, off, len);
        gzos.close();
        gzos = null;
        return new String(baos.toByteArray(), PREFERRED_ENCODING);

      } catch (UnsupportedEncodingException uue) {
        return new String(baos.toByteArray());

      } catch (IOException e) {
        LOG.error("error encoding byte array", e);
        return null;

      } finally {
        if (gzos != null) {
          try {
            gzos.close();
          } catch (Exception e) {
            LOG.error("error closing GZIPOutputStream", e);
          }
        }
        try {
          baos.close();
        } catch (Exception e) {
          LOG.error("error closing ByteArrayOutputStream", e);
        }
      } // end finally

    } // end Compress

    // Don't compress. Better not to use streams at all then.

    boolean breakLines = ((options & DONT_BREAK_LINES) == 0);

    int len43 = len * 4 / 3;
    byte[] outBuff =
      new byte[(len43)                                          // Main 4:3
               + ((len % 3) > 0 ? 4 : 0)                        // padding
               + (breakLines ? (len43 / MAX_LINE_LENGTH) : 0)]; // New lines
    int d = 0;
    int e = 0;
    int len2 = len - 2;
    int lineLength = 0;
    for (; d < len2; d += 3, e += 4) {
      encode3to4(source, d + off, 3, outBuff, e, options);

      lineLength += 4;
      if (breakLines && lineLength == MAX_LINE_LENGTH) {
        outBuff[e + 4] = NEW_LINE;
        e++;
        lineLength = 0;
      } // end if: end of line
    } // end for: each piece of array

    if (d < len) {
      encode3to4(source, d + off, len - d, outBuff, e, options);
      e += 4;
    } // end if: some padding needed

    // Return value according to relevant encoding.
    try {
      return new String(outBuff, 0, e, PREFERRED_ENCODING);

    } catch (UnsupportedEncodingException uue) {
      return new String(outBuff, 0, e);
    }
  } // end encodeBytes

  /* ******** D E C O D I N G   M E T H O D S ******** */

  /**
   * Decodes four bytes from array <var>source</var> and writes the resulting
   * bytes (up to three of them) to <var>destination</var>. The source and
   * destination arrays can be manipulated anywhere along their length by
   * specifying <var>srcOffset</var> and <var>destOffset</var>. This method
   * does not check to make sure your arrays are large enough to accomodate
   * <var>srcOffset</var> + 4 for the <var>source</var> array or
   * <var>destOffset</var> + 3 for the <var>destination</var> array. This
   * method returns the actual number of bytes that were converted from the
   * Base64 encoding.
   * <p>
   * This is the lowest level of the decoding methods with all possible
   * parameters.
   * </p>
   *
   * @param source the array to convert
   * @param srcOffset the index where conversion begins
   * @param destination the array to hold the conversion
   * @param destOffset the index where output will be put
   * @param options options for getDecoabet
   * @see Base64#URL_SAFE
   * @see Base64#ORDERED
   * @return the number of decoded bytes converted
   * @since 1.3
   */
  @SuppressWarnings({"ConstantConditions"})
  protected static int decode4to3(byte[] source, int srcOffset,
      byte[] destination, int destOffset, int options) {
    byte[] DECODABET = getDecodabet(options);

    if (source[srcOffset + 2] == EQUALS_SIGN) {                 // Example: Dk==
      // Two ways to do the same thing. Don't know which way I like best.
      // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
      // | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
      int outBuff =
          ((DECODABET[source[srcOffset]] & 0xFF) << 18)
              | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12);

      destination[destOffset] = (byte) (outBuff >>> 16);
      return 1;

    } else if (source[srcOffset + 3] == EQUALS_SIGN) {          // Example: DkL=
      // Two ways to do the same thing. Don't know which way I like best.
      // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
      // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
      // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
      int outBuff =
          ((DECODABET[source[srcOffset]] & 0xFF) << 18)
              | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
              | ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6);

      destination[destOffset] = (byte) (outBuff >>> 16);
      destination[destOffset + 1] = (byte) (outBuff >>> 8);
      return 2;

    } else {                                                    // Example: DkLE
      try {
        // Two ways to do the same thing. Don't know which way I like best.
        // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
        // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
        // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
        // | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
        int outBuff =
            ((DECODABET[source[srcOffset]] & 0xFF) << 18)
                | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
                | ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6)
                | ((DECODABET[source[srcOffset + 3]] & 0xFF));

        destination[destOffset] = (byte) (outBuff >> 16);
        destination[destOffset + 1] = (byte) (outBuff >> 8);
        destination[destOffset + 2] = (byte) (outBuff);

        return 3;

      } catch (Exception e) {
        LOG.error("error decoding bytes at " + source[srcOffset] + ": " +
            (DECODABET[source[srcOffset]]) + ", " + source[srcOffset + 1] +
            ": " + (DECODABET[source[srcOffset + 1]]) + ", " +
            source[srcOffset + 2] + ": " + (DECODABET[source[srcOffset + 2]]) +
            ", " + source[srcOffset + 3] + ": " +
            (DECODABET[source[srcOffset + 3]]), e);
        return -1;
      } // end catch
    }
  } // end decodeToBytes

  /**
   * Very low-level access to decoding ASCII characters in the form of a byte
   * array. Does not support automatically gunzipping or any other "fancy"
   * features.
   *
   * @param source The Base64 encoded data
   * @param off The offset of where to begin decoding
   * @param len The length of characters to decode
   * @param options options for getDecodabet
   * @see Base64#URL_SAFE
   * @see Base64#ORDERED
   * @return decoded data
   * @since 1.3
   */
  public static byte[] decode(byte[] source, int off, int len, int options) {
    byte[] DECODABET = getDecodabet(options);

    int len34 = len * 3 / 4;
    byte[] outBuff = new byte[len34];           // Upper limit on size of output
    int outBuffPosn = 0;

    byte[] b4 = new byte[4];
    int b4Posn = 0;
    int i;
    byte sbiCrop;
    byte sbiDecode;
    for (i = off; i < off + len; i++) {
      sbiCrop = (byte) (source[i] & 0x7f);      // Only the low seven bits
      sbiDecode = DECODABET[sbiCrop];

      if (sbiDecode >= WHITE_SPACE_ENC) {       // Whitespace, Equals or better
        if (sbiDecode >= EQUALS_SIGN_ENC) {     // Equals or better
          b4[b4Posn++] = sbiCrop;
          if (b4Posn > 3) {
            outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, options);
            b4Posn = 0;

            // If that was the equals sign, break out of 'for' loop
            if (sbiCrop == EQUALS_SIGN)
              break;
          } // end if: quartet built
        } // end if: equals sign or better
      } else {
        LOG.error("Bad Base64 input character at " + i + ": " + source[i] +
            "(decimal)");
        return null;
      } // end else:
    } // each input character

    byte[] out = new byte[outBuffPosn];
    System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
    return out;
  } // end decode

  /**
   * Decodes data from Base64 notation, automatically detecting gzip-compressed
   * data and decompressing it.
   *
   * @param s the string to decode
   * @return the decoded data
   * @since 1.4
   */
  public static byte[] decode(String s) {
    return decode(s, NO_OPTIONS);
  }

  /**
   * Decodes data from Base64 notation, automatically detecting gzip-compressed
   * data and decompressing it.
   *
   * @param s the string to decode
   * @param options options for decode
   * @see Base64#URL_SAFE
   * @see Base64#ORDERED
   * @return the decoded data
   * @since 1.4
   */
  public static byte[] decode(String s, int options) {
    byte[] bytes;
    try {
      bytes = s.getBytes(PREFERRED_ENCODING);

    } catch (UnsupportedEncodingException uee) {
      bytes = s.getBytes();
    } // end catch

    // Decode

    bytes = decode(bytes, 0, bytes.length, options);

    // Check to see if it's gzip-compressed
    // GZIP Magic Two-Byte Number: 0x8b1f (35615)

    if (bytes != null && bytes.length >= 4) {
      int head = (bytes[0] & 0xff) | ((bytes[1] << 8) & 0xff00);
      if (GZIPInputStream.GZIP_MAGIC == head) {
        GZIPInputStream gzis = null;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
          gzis = new GZIPInputStream(new ByteArrayInputStream(bytes));

          byte[] buffer = new byte[2048];
          for (int length; (length = gzis.read(buffer)) >= 0; ) {
            baos.write(buffer, 0, length);
          } // end while: reading input

          // No error? Get new bytes.
          bytes = baos.toByteArray();

        } catch (IOException e) {
          // Just return originally-decoded bytes

        } finally {
          try {
            baos.close();
          } catch (Exception e) {
            LOG.error("error closing ByteArrayOutputStream", e);
          }
          if (gzis != null) {
            try {
              gzis.close();
            } catch (Exception e) {
              LOG.error("error closing GZIPInputStream", e);
            }
          }
        } // end finally
      } // end if: gzipped
    } // end if: bytes.length >= 2

    return bytes;
  } // end decode

  /**
   * Attempts to decode Base64 data and deserialize a Java Object within.
   * Returns <tt>null</tt> if there was an error.
   *
   * @param encodedObject The Base64 data to decode
   * @return The decoded and deserialized object
   * @since 1.5
   */
  public static Object decodeToObject(String encodedObject) {
    // Decode and gunzip if necessary
    byte[] objBytes = decode(encodedObject);

    Object obj = null;
    ObjectInputStream ois = null;
    try {
      ois = new ObjectInputStream(new ByteArrayInputStream(objBytes));
      obj = ois.readObject();

    } catch (IOException e) {
      LOG.error("error decoding object", e);

    } catch (ClassNotFoundException e) {
      LOG.error("error decoding object", e);

    } finally {
      if (ois != null) {
        try {
          ois.close();
        } catch (Exception e) {
          LOG.error("error closing ObjectInputStream", e);
        }
      }
    } // end finally

    return obj;
  } // end decodeObject

  /**
   * Convenience method for encoding data to a file.
   *
   * @param dataToEncode byte array of data to encode in base64 form
   * @param filename Filename for saving encoded data
   * @return <tt>true</tt> if successful, <tt>false</tt> otherwise
   *
   * @since 2.1
   */
  public static boolean encodeToFile(byte[] dataToEncode, String filename) {
    boolean success = false;
    Base64OutputStream bos = null;
    try {
      bos = new Base64OutputStream(new FileOutputStream(filename), ENCODE);
      bos.write(dataToEncode);
      success = true;

    } catch (IOException e) {
      LOG.error("error encoding file: " + filename, e);
      success = false;

    } finally {
      if (bos != null) {
        try {
          bos.close();
        } catch (Exception e) {
          LOG.error("error closing Base64OutputStream", e);
        }
      }
    } // end finally

    return success;
  } // end encodeToFile

  /**
   * Convenience method for decoding data to a file.
   *
   * @param dataToDecode Base64-encoded data as a string
   * @param filename Filename for saving decoded data
   * @return <tt>true</tt> if successful, <tt>false</tt> otherwise
   *
   * @since 2.1
   */
  public static boolean decodeToFile(String dataToDecode, String filename) {
    boolean success = false;
    Base64OutputStream bos = null;
    try {
      bos = new Base64OutputStream(new FileOutputStream(filename), DECODE);
      bos.write(dataToDecode.getBytes(PREFERRED_ENCODING));
      success = true;

    } catch (IOException e) {
      LOG.error("error decoding to file: " + filename, e);
      success = false;

    } finally {
      if (bos != null) {
        try {
          bos.close();
        } catch (Exception e) {
          LOG.error("error closing Base64OutputStream", e);
        }
      }
    } // end finally

    return success;
  } // end decodeToFile

  /**
   * Convenience method for reading a base64-encoded file and decoding it.
   *
   * @param filename Filename for reading encoded data
   * @return decoded byte array or null if unsuccessful
   *
   * @since 2.1
   */
  public static byte[] decodeFromFile(String filename) {
    byte[] decodedData = null;
    Base64InputStream bis = null;
    try {
      File file = new File(filename);
      byte[] buffer;

      // Check the size of file
      if (file.length() > Integer.MAX_VALUE) {
        LOG.fatal("File is too big for this convenience method (" +
            file.length() + " bytes).");
        return null;
      } // end if: file too big for int index

      buffer = new byte[(int) file.length()];

      // Open a stream

      bis = new Base64InputStream(new BufferedInputStream(
          new FileInputStream(file)), DECODE);

      // Read until done

      int length = 0;
      for (int numBytes; (numBytes = bis.read(buffer, length, 4096)) >= 0; ) {
        length += numBytes;
      }

      // Save in a variable to return

      decodedData = new byte[length];
      System.arraycopy(buffer, 0, decodedData, 0, length);

    } catch (IOException e) {
      LOG.error("Error decoding from file " + filename, e);

    } finally {
      if (bis != null) {
        try {
          bis.close();
        } catch (Exception e) {
          LOG.error("error closing Base64InputStream", e);
        }
      }
    } // end finally

    return decodedData;
  } // end decodeFromFile

  /**
   * Convenience method for reading a binary file and base64-encoding it.
   *
   * @param filename Filename for reading binary data
   * @return base64-encoded string or null if unsuccessful
   *
   * @since 2.1
   */
  public static String encodeFromFile(String filename) {
    String encodedData = null;
    Base64InputStream bis = null;
    try {
      File file = new File(filename);

      // Need max() for math on small files (v2.2.1)

      byte[] buffer = new byte[Math.max((int) (file.length() * 1.4), 40)];

      // Open a stream

      bis = new Base64InputStream(new BufferedInputStream(
              new FileInputStream(file)), ENCODE);

      // Read until done
      int length = 0;
      for (int numBytes; (numBytes = bis.read(buffer, length, 4096)) >= 0; ) {
        length += numBytes;
      }

      // Save in a variable to return

      encodedData = new String(buffer, 0, length, PREFERRED_ENCODING);

    } catch (IOException e) {
      LOG.error("Error encoding from file " + filename, e);

    } finally {
      if (bis != null) {
        try {
          bis.close();
        } catch (Exception e) {
          LOG.error("error closing Base64InputStream", e);
        }
      }
    } // end finally

    return encodedData;
  } // end encodeFromFile

  /**
   * Reads <tt>infile</tt> and encodes it to <tt>outfile</tt>.
   *
   * @param infile Input file
   * @param outfile Output file
   * @since 2.2
   */
  public static void encodeFileToFile(String infile, String outfile) {
    String encoded = encodeFromFile(infile);
    OutputStream out = null;
    try {
      out = new BufferedOutputStream(new FileOutputStream(outfile));
      out.write(encoded.getBytes("US-ASCII")); // Strict, 7-bit output.

    } catch (IOException e) {
      LOG.error("error encoding from file " + infile + " to " + outfile, e);

    } finally {
      if (out != null) {
        try {
          out.close();
        } catch (Exception e) {
          LOG.error("error closing " + outfile, e);
        }
      }
    } // end finally
  } // end encodeFileToFile

  /**
   * Reads <tt>infile</tt> and decodes it to <tt>outfile</tt>.
   *
   * @param infile Input file
   * @param outfile Output file
   * @since 2.2
   */
  public static void decodeFileToFile(String infile, String outfile) {
    byte[] decoded = decodeFromFile(infile);
    OutputStream out = null;
    try {
      out = new BufferedOutputStream(new FileOutputStream(outfile));
      out.write(decoded);

    } catch (IOException e) {
      LOG.error("error decoding from file " + infile + " to " + outfile, e);

    } finally {
      if (out != null) {
        try {
          out.close();
        } catch (Exception e) {
          LOG.error("error closing " + outfile, e);
        }
      }
    } // end finally
  } // end decodeFileToFile

  /* ******** I N N E R   C L A S S   I N P U T S T R E A M ******** */

  /**
   * A {@link Base64.Base64InputStream} will read data from another
   * <tt>InputStream</tt>, given in the constructor, and
   * encode/decode to/from Base64 notation on the fly.
   *
   * @see Base64
   * @since 1.3
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public static class Base64InputStream extends FilterInputStream {
    private boolean encode;                     // Encoding or decoding
    private int position;                       // Current position in the buffer
    private byte[] buffer;                      // Buffer holding converted data
    private int bufferLength;                   // Length of buffer (3 or 4)
    private int numSigBytes;                    // Meaningful bytes in the buffer
    private int lineLength;
    private boolean breakLines;                 // Break lines at < 80 characters
    private int options;                        // Record options
    private byte[] decodabet;                   // Local copy avoids method calls

    /**
     * Constructs a {@link Base64InputStream} in DECODE mode.
     *
     * @param in the <tt>InputStream</tt> from which to read data.
     * @since 1.3
     */
    public Base64InputStream(InputStream in) {
      this(in, DECODE);
    } // end constructor

    /**
     * Constructs a {@link Base64.Base64InputStream} in either ENCODE or DECODE mode.
     * <p>
     * Valid options:
     *
     * <pre>
     *   ENCODE or DECODE: Encode or Decode as data is read.
     *   DONT_BREAK_LINES: don't break lines at 76 characters
     *     (only meaningful when encoding)
     *     &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
     * </pre>
     *
     * <p>
     * Example: <code>new Base64.Base64InputStream( in, Base64.DECODE )</code>
     *
     *
     * @param in the <tt>InputStream</tt> from which to read data.
     * @param options Specified options
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DONT_BREAK_LINES
     * @since 2.0
     */
    public Base64InputStream(InputStream in, int options) {
      super(in);
      this.breakLines = (options & DONT_BREAK_LINES) != DONT_BREAK_LINES;
      this.encode = (options & ENCODE) == ENCODE;
      this.bufferLength = encode ? 4 : 3;
      this.buffer = new byte[bufferLength];
      this.position = -1;
      this.lineLength = 0;
      this.options = options; // Record for later, mostly to determine which
                              // alphabet to use
      this.decodabet = getDecodabet(options);
    } // end constructor

    /**
     * Reads enough of the input stream to convert to/from Base64 and returns
     * the next byte.
     *
     * @return next byte
     * @since 1.3
     */
    @Override
    public int read() throws IOException {
      // Do we need to get data?
      if (position < 0) {
        if (encode) {
          byte[] b3 = new byte[3];
          int numBinaryBytes = 0;
          for (int i = 0; i < 3; i++) {
            try {
              int b = in.read();

              // If end of stream, b is -1.
              if (b >= 0) {
                b3[i] = (byte) b;
                numBinaryBytes++;
              } // end if: not end of stream

            } catch (IOException e) {
              // Only a problem if we got no data at all.
              if (i == 0)
                throw e;

            } // end catch
          } // end for: each needed input byte

          if (numBinaryBytes > 0) {
            encode3to4(b3, 0, numBinaryBytes, buffer, 0, options);
            position = 0;
            numSigBytes = 4;

          } else {
            return -1;
          } // end else

        } else {
          byte[] b4 = new byte[4];
          int i;
          for (i = 0; i < 4; i++) {
            // Read four "meaningful" bytes:
            int b;
            do {
              b = in.read();
            } while (b >= 0 && decodabet[b & 0x7f] <= WHITE_SPACE_ENC);

            if (b < 0) {
              break; // Reads a -1 if end of stream
            }

            b4[i] = (byte) b;
          } // end for: each needed input byte

          if (i == 4) {
            numSigBytes = decode4to3(b4, 0, buffer, 0, options);
            position = 0;

          } else if (i == 0) {
            return -1;

          } else {
            // Must have broken out from above.
            throw new IOException("Improperly padded Base64 input.");
          } // end
        } // end else: decode
      } // end else: get data

      // Got data?
      if (position >= 0) {
        // End of relevant data?
        if ( /* !encode && */position >= numSigBytes) {
          return -1;
        }

        if (encode && breakLines && lineLength >= MAX_LINE_LENGTH) {
          lineLength = 0;
          return '\n';

        }
        lineLength++;                   // This isn't important when decoding
                                        // but throwing an extra "if" seems
                                        // just as wasteful.

        int b = buffer[position++];

        if (position >= bufferLength)
          position = -1;

        return b & 0xFF;                // This is how you "cast" a byte that's
                                        // intended to be unsigned.

      }

      // When JDK1.4 is more accepted, use an assertion here.
      throw new IOException("Error in Base64 code reading stream.");

    } // end read

    /**
     * Calls {@link #read()} repeatedly until the end of stream is reached or
     * <var>len</var> bytes are read. Returns number of bytes read into array
     * or -1 if end of stream is encountered.
     *
     * @param dest array to hold values
     * @param off offset for array
     * @param len max number of bytes to read into array
     * @return bytes read into array or -1 if end of stream is encountered.
     * @since 1.3
     */
    @Override
    public int read(byte[] dest, int off, int len) throws IOException {
      int i;
      int b;
      for (i = 0; i < len; i++) {
        b = read();
        if (b >= 0) {
          dest[off + i] = (byte) b;
        } else if (i == 0) {
          return -1;
        } else {
          break; // Out of 'for' loop
        }
      } // end for: each byte read
      return i;
    } // end read

  } // end inner class InputStream

  /* ******** I N N E R   C L A S S   O U T P U T S T R E A M ******** */

  /**
   * A {@link Base64.Base64OutputStream} will write data to another
   * <tt>OutputStream</tt>, given in the constructor, and
   * encode/decode to/from Base64 notation on the fly.
   *
   * @see Base64
   * @since 1.3
   */
  public static class Base64OutputStream extends FilterOutputStream {
    private boolean encode;
    private int position;
    private byte[] buffer;
    private int bufferLength;
    private int lineLength;
    private boolean breakLines;
    private byte[] b4;                          // Scratch used in a few places
    private boolean suspendEncoding;
    private int options;                        // Record for later
    private byte[] decodabet;                   // Local copy avoids method calls

    /**
     * Constructs a {@link Base64OutputStream} in ENCODE mode.
     *
     * @param out the <tt>OutputStream</tt> to which data will be written.
     * @since 1.3
     */
    public Base64OutputStream(OutputStream out) {
      this(out, ENCODE);
    } // end constructor

    /**
     * Constructs a {@link Base64OutputStream} in either ENCODE or DECODE mode.
     * <p>
     * Valid options:
     *
     * <ul>
     *   <li>ENCODE or DECODE: Encode or Decode as data is read.</li>
     *   <li>DONT_BREAK_LINES: don't break lines at 76 characters (only
     *     meaningful when encoding) <i>Note: Technically, this makes your
     *     encoding non-compliant.</i></li>
     * </ul>
     *
     * <p>
     * Example: <code>new Base64.Base64OutputStream( out, Base64.ENCODE )</code>
     *
     * @param out the <tt>OutputStream</tt> to which data will be written.
     * @param options Specified options.
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DONT_BREAK_LINES
     * @since 1.3
     */
    @InterfaceAudience.Public
    @InterfaceStability.Stable
    public Base64OutputStream(OutputStream out, int options) {
      super(out);
      this.breakLines = (options & DONT_BREAK_LINES) != DONT_BREAK_LINES;
      this.encode = (options & ENCODE) == ENCODE;
      this.bufferLength = encode ? 3 : 4;
      this.buffer = new byte[bufferLength];
      this.position = 0;
      this.lineLength = 0;
      this.suspendEncoding = false;
      this.b4 = new byte[4];
      this.options = options;
      this.decodabet = getDecodabet(options);
    } // end constructor

    /**
     * Writes the byte to the output stream after converting to/from Base64
     * notation. When encoding, bytes are buffered three at a time before the
     * output stream actually gets a write() call. When decoding, bytes are
     * buffered four at a time.
     *
     * @param theByte the byte to write
     * @since 1.3
     */
    @Override
    public void write(int theByte) throws IOException {
      // Encoding suspended?
      if (suspendEncoding) {
        super.out.write(theByte);
        return;
      } // end if: supsended

      // Encode?
      if (encode) {
        buffer[position++] = (byte) theByte;
        if (position >= bufferLength) {                 // Enough to encode.
          out.write(encode3to4(b4, buffer, bufferLength, options));
          lineLength += 4;
          if (breakLines && lineLength >= MAX_LINE_LENGTH) {
            out.write(NEW_LINE);
            lineLength = 0;
          } // end if: end of line

          position = 0;
        } // end if: enough to output

      } else {
        // Meaningful Base64 character?
        if (decodabet[theByte & 0x7f] > WHITE_SPACE_ENC) {
          buffer[position++] = (byte) theByte;
          if (position >= bufferLength) {               // Enough to output.
            int len = decode4to3(buffer, 0, b4, 0, options);
            out.write(b4, 0, len);
            position = 0;
          } // end if: enough to output

        } else if (decodabet[theByte & 0x7f] != WHITE_SPACE_ENC) {
          throw new IOException("Invalid character in Base64 data.");
        } // end else: not white space either
      } // end else: decoding
    } // end write

    /**
     * Calls {@link #write(int)} repeatedly until <var>len</var> bytes are
     * written.
     *
     * @param theBytes array from which to read bytes
     * @param off offset for array
     * @param len max number of bytes to read into array
     * @since 1.3
     */
    @Override
    public void write(byte[] theBytes, int off, int len) throws IOException {
      // Encoding suspended?
      if (suspendEncoding) {
        super.out.write(theBytes, off, len);
        return;
      } // end if: supsended

      for (int i = 0; i < len; i++) {
        write(theBytes[off + i]);
      } // end for: each byte written

    } // end write

    /**
     * Method added by PHIL. [Thanks, PHIL. -Rob] This pads the buffer without
     * closing the stream.
     *
     * @throws IOException e
     */
    public void flushBase64() throws IOException {
      if (position > 0) {
        if (encode) {
          out.write(encode3to4(b4, buffer, position, options));
          position = 0;

        } else {
          throw new IOException("Base64 input not properly padded.");
        } // end else: decoding
      } // end if: buffer partially full

    } // end flush

    /**
     * Flushes and closes (I think, in the superclass) the stream.
     *
     * @since 1.3
     */
    @Override
    public void close() throws IOException {
      // 1. Ensure that pending characters are written
      flushBase64();

      // 2. Actually close the stream
      // Base class both flushes and closes.
      super.close();

      buffer = null;
      out = null;
    } // end close

    /**
     * Suspends encoding of the stream. May be helpful if you need to embed a
     * piece of base640-encoded data in a stream.
     *
     * @throws IOException e
     * @since 1.5.1
     */
    public void suspendEncoding() throws IOException {
      flushBase64();
      this.suspendEncoding = true;
    } // end suspendEncoding

    /**
     * Resumes encoding of the stream. May be helpful if you need to embed a
     * piece of base640-encoded data in a stream.
     *
     * @since 1.5.1
     */
    public void resumeEncoding() {
      this.suspendEncoding = false;
    } // end resumeEncoding

  } // end inner class OutputStream

} // end class Base64
