/*
 * Base64.java
 * 
 * Light version of the Public Domain class available at http://iharder.net/base64 v2.3.7
 * 
 * This class and its modifications belong to Public Domain.
 */
package com.eteks.sweethome3d.io;

/**
 * <p>Encodes and decodes to and from Base64 notation.</p>
 * <p>Homepage: <a href="http://iharder.net/base64">http://iharder.net/base64</a>.</p>
 * 
 * <p>Example:</p>
 * 
 * <code>String encoded = Base64.encode( myByteArray );</code>
 * <br>
 * <code>byte[] myByteArray = Base64.decode( encoded );</code>
 *
 * <p>The <tt>options</tt> parameter, which appears in a few places, is used to pass 
 * several pieces of information to the encoder. In the "higher level" methods such as 
 * encodeBytes( bytes, options ) the options parameter can be used to indicate such 
 * things as first gzipping the bytes before encoding them, not inserting linefeeds,
 * and encoding using the URL-safe and Ordered dialects.</p>
 *
 * <p>Note, according to <a href="http://www.faqs.org/rfcs/rfc3548.html">RFC3548</a>,
 * Section 2.1, implementations should not add line feeds unless explicitly told
 * to do so. I've got Base64 set to this behavior now, although earlier versions
 * broke lines by default.</p>
 *
 * <p>The constants defined in Base64 can be OR-ed together to combine options, so you 
 * might make a call like this:</p>
 *
 * <code>String encoded = Base64.encodeBytes( mybytes, Base64.GZIP | Base64.DO_BREAK_LINES );</code>
 * <p>to compress the data before encoding it and then making the output have newline characters.</p>
 * <p>Also...</p>
 * <code>String encoded = Base64.encodeBytes( crazyString.getBytes() );</code>
 *
 * <p>
 * Change Log:
 * </p>
 * <ul>
 *  <li>v2.3.7 - Fixed subtle bug when base 64 input stream contained the
 *   value 01111111, which is an invalid base 64 character but should not
 *   throw an ArrayIndexOutOfBoundsException either. Led to discovery of
 *   mishandling (or potential for better handling) of other bad input
 *   characters. You should now get an IOException if you try decoding
 *   something that has bad characters in it.</li>
 *  <li>v2.3.6 - Fixed bug when breaking lines and the final byte of the encoded
 *   string ended in the last column; the buffer was not properly shrunk and
 *   contained an extra (null) byte that made it into the string.</li>
 *  <li>v2.3.5 - Fixed bug in <code>encodeFromFile</code> where estimated buffer size
 *   was wrong for files of size 31, 34, and 37 bytes.</li>
 *  <li>v2.3.4 - Fixed bug when working with gzipped streams whereby flushing
 *   the Base64.OutputStream closed the Base64 encoding (by padding with equals
 *   signs) too soon. Also added an option to suppress the automatic decoding
 *   of gzipped streams. Also added experimental support for specifying a
 *   class loader when using the <code>decodeToObject</code> method.</li>
 *  <li>v2.3.3 - Changed default char encoding to US-ASCII which reduces the internal Java
 *   footprint with its CharEncoders and so forth. Fixed some javadocs that were
 *   inconsistent. Removed imports and specified things like java.io.IOException
 *   explicitly inline.</li>
 *  <li>v2.3.2 - Reduced memory footprint! Finally refined the "guessing" of how big the
 *   final encoded data will be so that the code doesn't have to create two output
 *   arrays: an oversized initial one and then a final, exact-sized one. Big win
 *   when using the <code>encodeBytesToBytes(byte[])</code> family of methods (and not
 *   using the gzip options which uses a different mechanism with streams and stuff).</li>
 *  <li>v2.3.1 - Added {@link #encodeBytesToBytes(byte[], int, int, int)} and some
 *   similar helper methods to be more efficient with memory by not returning a
 *   String but just a byte array.</li>
 *  <li>v2.3 - <strong>This is not a drop-in replacement!</strong> This is two years of comments
 *   and bug fixes queued up and finally executed. Thanks to everyone who sent
 *   me stuff, and I'm sorry I wasn't able to distribute your fixes to everyone else.
 *   Much bad coding was cleaned up including throwing exceptions where necessary 
 *   instead of returning null values or something similar. Here are some changes
 *   that may affect you:
 *   <ul>
 *    <li><em>Does not break lines, by default.</em> This is to keep in compliance with
 *      <a href="http://www.faqs.org/rfcs/rfc3548.html">RFC3548</a>.</li>
 *    <li><em>Throws exceptions instead of returning null values.</em> Because some operations
 *      (especially those that may permit the GZIP option) use IO streams, there
 *      is a possiblity of an java.io.IOException being thrown. After some discussion and
 *      thought, I've changed the behavior of the methods to throw java.io.IOExceptions
 *      rather than return null if ever there's an error. I think this is more
 *      appropriate, though it will require some changes to your code. Sorry,
 *      it should have been done this way to begin with.</li>
 *    <li><em>Removed all references to System.out, System.err, and the like.</em>
 *      Shame on me. All I can say is sorry they were ever there.</li>
 *    <li><em>Throws NullPointerExceptions and IllegalArgumentExceptions</em> as needed
 *      such as when passed arrays are null or offsets are invalid.</li>
 *    <li>Cleaned up as much javadoc as I could to avoid any javadoc warnings.
 *      This was especially annoying before for people who were thorough in their
 *      own projects and then had gobs of javadoc warnings on this file.</li>
 *   </ul>
 *  <li>v2.2.1 - Fixed bug using URL_SAFE and ORDERED encodings. Fixed bug
 *   when using very small files (~&lt; 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>Calling Base64.setFormat(Base64.BASE64_FORMAT.URLSAFE_FORMAT) generates
 *   URL and file name friendly format as described in Section 4 of RFC3548.
 *   http://www.faqs.org/rfcs/rfc3548.html</li>
 *   <li>Calling Base64.setFormat(Base64.BASE64_FORMAT.ORDERED_FORMAT) generates
 *   URL and file name friendly format that preserves lexical ordering as described
 *   in http://www.faqs.org/qa/rfcc-1940.html</li>
 *   </ol>
 *   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!
 * 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
 * @author rob@iharder.net
 * @version 2.3.7
 */
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 in first bit. Value is one. */
  public final static int ENCODE = 1;
  
  /** Specify decoding in first bit. Value is zero. */
  public final static int DECODE = 0;
 
  /** Specify that data should be gzip-compressed in second bit. Value is two. */
  public final static int GZIP = 2;
  
  /** Specify that gzipped data should <em>not</em> be automatically gunzipped. */
  public final static int DONT_GUNZIP = 4;
  
  /** Do break lines when encoding. Value is 8. */
  public final static int DO_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  ******** */  
    
  /** 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 = "US-ASCII";
                
  private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
  private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding
                
  /* ********  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 me 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 and Linefeed
      -9,-9,                                      // Decimal 11 - 12
      -5,                                         // Whitespace: Carriage 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 through 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' through 'N'
      14,15,16,17,18,19,20,21,22,23,24,25,        // Letters 'O' through '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' through 'm'
      39,40,41,42,43,44,45,46,47,48,49,50,51,     // Letters 'n' through 'z'
      -9,-9,-9,-9,-9                              // Decimal 123 - 127
      ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,       // Decimal 128 - 139
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 140 - 152
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 153 - 165
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 166 - 178
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 179 - 191
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 192 - 204
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 205 - 217
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 218 - 230
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 231 - 243
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9         // Decimal 244 - 255 
  };
                
  /* ********  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 and Linefeed
      -9,-9,                                      // Decimal 11 - 12
      -5,                                         // Whitespace: Carriage 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 decimal 43
      -9,                                         // Decimal 44
      62,                                         // Minus sign at decimal 45
      -9,                                         // Decimal 46
      -9,                                         // Slash at decimal 47
      52,53,54,55,56,57,58,59,60,61,              // Numbers zero through 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' through 'N'
      14,15,16,17,18,19,20,21,22,23,24,25,        // Letters 'O' through 'Z'
      -9,-9,-9,-9,                                // Decimal 91 - 94
      63,                                         // Underscore at decimal 95
      -9,                                         // Decimal 96
      26,27,28,29,30,31,32,33,34,35,36,37,38,     // Letters 'a' through 'm'
      39,40,41,42,43,44,45,46,47,48,49,50,51,     // Letters 'n' through 'z'
      -9,-9,-9,-9,-9,                             // Decimal 123 - 127
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,        // Decimal 128 - 139
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 140 - 152
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 153 - 165
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 166 - 178
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 179 - 191
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 192 - 204
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 205 - 217
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 218 - 230
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 231 - 243
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9         // Decimal 244 - 255 
  };

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

  /**
   * I don't get the point of this technique, but someone requested it,
   * and it is described here:
   * <a href="http://www.faqs.org/qa/rfcc-1940.html">http://www.faqs.org/qa/rfcc-1940.html</a>.
   */
  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 and Linefeed
      -9,-9,                                      // Decimal 11 - 12
      -5,                                         // Whitespace: Carriage 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 decimal 43
      -9,                                         // Decimal 44
      0,                                          // Minus sign at decimal 45
      -9,                                         // Decimal 46
      -9,                                         // Slash at decimal 47
      1,2,3,4,5,6,7,8,9,10,                       // Numbers zero through nine
      -9,-9,-9,                                   // Decimal 58 - 60
      -1,                                         // Equals sign at decimal 61
      -9,-9,-9,                                   // Decimal 62 - 64
      11,12,13,14,15,16,17,18,19,20,21,22,23,     // Letters 'A' through 'M'
      24,25,26,27,28,29,30,31,32,33,34,35,36,     // Letters 'N' through 'Z'
      -9,-9,-9,-9,                                // Decimal 91 - 94
      37,                                         // Underscore at decimal 95
      -9,                                         // Decimal 96
      38,39,40,41,42,43,44,45,46,47,48,49,50,     // Letters 'a' through 'm'
      51,52,53,54,55,56,57,58,59,60,61,62,63,     // Letters 'n' through 'z'
      -9,-9,-9,-9,-9,                             // Decimal 123 - 127
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 128 - 139
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 140 - 152
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 153 - 165
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 166 - 178
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 179 - 191
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 192 - 204
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 205 - 217
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 218 - 230
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 231 - 243
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9         // Decimal 244 - 255 
  };

  /* ********  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 <b>and</b> URLSAFE
   * in which case one of them will be picked, though there is
   * no guarantee as to which one will be picked.
   */
  private final 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.
   */
  private final 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 getAlphabet

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

  /* ********  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
   * @return four byte array in Base64 notation.
   * @since 1.5.1
   */
  private static byte [] encode3to4(byte [] b4, byte [] threeBytes, int numSigBytes, int options) {
    encode3to4(threeBytes, 0, numSigBytes, b4, 0, options);
    return b4;
  } // end encode3to4
    
  /**
   * <p>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>
   * <p>This is the lowest level of the encoding methods with
   * all possible parameters.</p>
   *
   * @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
   * @return the <var>destination</var> array
   * @since 1.3
   */
  private 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
 
  /**
   * Encodes a byte array into Base64 notation.
   * Does not GZip-compress data.
   *  
   * @param source The data to convert
   * @return The data in Base64-encoded form
   * @throws NullPointerException if source array is null
   * @since 1.4
   */
  public static String encodeBytes(byte [] source) {
    // Since we're not going to have the GZIP encoding turned on,
    // we're not going to have an java.io.IOException thrown, so
    // we should not force the user to have to catch it.
    String encoded = null;
    try {
      encoded = encodeBytes(source, 0, source.length, NO_OPTIONS);
    } catch (java.io.IOException ex) {
      assert false : ex.getMessage();
    } // end catch
    assert encoded != null;
    return encoded;
  } // end encodeBytes  

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Example options:<pre>
   *   GZIP: gzip-compresses object before encoding it.
   *   DO_BREAK_LINES: break lines at 76 characters
   *     <i>Note: Technically, this makes your encoding non-compliant.</i>
   * </pre>
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
   *
   *  
   * <p>As of v 2.3, if there is an error with the GZIP stream,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned a null value, but
   * in retrospect that's a pretty poor way to handle it.</p>
   * 
   *
   * @param source The data to convert
   * @param options Specified options
   * @return The Base64-encoded data as a String
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if source array is null
   * @since 2.0
   */
  public static String encodeBytes(byte [] source, int options) throws java.io.IOException {
    return encodeBytes(source, 0, source.length, options);
  } // end encodeBytes  
  
  /**
   * Encodes a byte array into Base64 notation.
   * Does not GZip-compress data.
   *  
   * <p>As of v 2.3, if there is an error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned a null value, but
   * in retrospect that's a pretty poor way to handle it.</p>
   * 
   *
   * @param source The data to convert
   * @param off Offset in array where conversion should begin
   * @param len Length of data to convert
   * @return The Base64-encoded data as a String
   * @throws NullPointerException if source array is null
   * @throws IllegalArgumentException if source array, offset, or length are invalid
   * @since 1.4
   */
  public static String encodeBytes(byte [] source, int off, int len) {
    // Since we're not going to have the GZIP encoding turned on,
    // we're not going to have an java.io.IOException thrown, so
    // we should not force the user to have to catch it.
    String encoded = null;
    try {
      encoded = encodeBytes(source, off, len, NO_OPTIONS);
    } catch (java.io.IOException ex) {
      assert false : ex.getMessage();
    } // end catch
    assert encoded != null;
    return encoded;
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Example options:<pre>
   *   GZIP: gzip-compresses object before encoding it.
   *   DO_BREAK_LINES: break lines at 76 characters
   *     <i>Note: Technically, this makes your encoding non-compliant.</i>
   * </pre>
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
   *
   *  
   * <p>As of v 2.3, if there is an error with the GZIP stream,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned a null value, but
   * in retrospect that's a pretty poor way to handle it.</p>
   * 
   *
   * @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
   * @return The Base64-encoded data as a String
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if source array is null
   * @throws IllegalArgumentException if source array, offset, or length are invalid
   * @since 2.0
   */
  public static String encodeBytes(byte [] source, int off, int len, int options) throws java.io.IOException {
    byte [] encoded = encodeBytesToBytes(source, off, len, options);

    // Return value according to relevant encoding.
    try {
      return new String(encoded, PREFERRED_ENCODING);
    } // end try
    catch (java.io.UnsupportedEncodingException uue) {
      return new String(encoded);
    } // end catch
  } // end encodeBytes

  /**
   * Similar to {@link #encodeBytes(byte[], int, int, int)} but returns
   * a byte array instead of instantiating a String. This is more efficient
   * if you're working with I/O streams and have large data sets to encode.
   *
   *
   * @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
   * @return The Base64-encoded data as a String
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if source array is null
   * @throws IllegalArgumentException if source array, offset, or length are invalid
   * @since 2.3.1
   */
  private static byte [] encodeBytesToBytes(byte [] source, int off, int len, int options) throws java.io.IOException {
    if (source == null) {
      throw new NullPointerException("Cannot serialize a null array.");
    } // end if: null

    if (off < 0) {
      throw new IllegalArgumentException("Cannot have negative offset: " + off);
    } // end if: off < 0

    if (len < 0) {
      throw new IllegalArgumentException("Cannot have length offset: " + len);
    } // end if: len < 0

    if (off + len > source.length) {
      throw new IllegalArgumentException(String.format(
          "Cannot have offset of %d and length of %d with array of length %d", off, len, source.length));
    } // end if: off < 0

    // Compress?
    if ((options & GZIP) != 0) {
      java.io.ByteArrayOutputStream baos = null;
      java.util.zip.GZIPOutputStream gzos = null;
      Base64.OutputStream b64os = null;

      try {
        // GZip -> Base64 -> ByteArray
        baos = new java.io.ByteArrayOutputStream();
        b64os = new Base64.OutputStream(baos, ENCODE | options);
        gzos = new java.util.zip.GZIPOutputStream(b64os);

        gzos.write(source, off, len);
        gzos.close();
      } // end try
      catch (java.io.IOException e) {
        // Catch it and then throw it immediately so that
        // the finally{} block is called for cleanup.
        throw e;
      } // end catch
      finally {
        try {
          gzos.close();
        } catch (Exception e) {
        }
        try {
          b64os.close();
        } catch (Exception e) {
        }
        try {
          baos.close();
        } catch (Exception e) {
        }
      } // end finally

      return baos.toByteArray();
    } // end if: compress

    // Else, don't compress. Better not to use streams at all then.
    else {
      boolean breakLines = (options & DO_BREAK_LINES) != 0;

      // int len43 = len * 4 / 3;
      // byte[] outBuff = new byte[ ( len43 ) // Main 4:3
      // + ( (len % 3) > 0 ? 4 : 0 ) // Account for padding
      // + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines
      // Try to determine more precisely how big the array needs to be.
      // If we get it right, we don't have to do an array copy, and
      // we save a bunch of memory.
      int encLen = (len / 3) * 4 + (len % 3 > 0
          ? 4
          : 0); // Bytes needed for actual encoding
      if (breakLines) {
        encLen += encLen / MAX_LINE_LENGTH; // Plus extra newline characters
      }
      byte [] outBuff = new byte [encLen];

      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
      } // en dfor: each piece of array

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

      // Only resize array if we didn't guess it right.
      if (e <= outBuff.length - 1) {
        // If breaking lines and the last byte falls right at
        // the line length (76 bytes per line), there will be
        // one extra byte, and the array will need to be resized.
        // Not too bad of an estimate on array size, I'd say.
        byte [] finalOut = new byte [e];
        System.arraycopy(outBuff, 0, finalOut, 0, e);
        // System.err.println("Having to resize array from " + outBuff.length +
        // " to " + e );
        return finalOut;
      } else {
        // System.err.println("No need to resize array.");
        return outBuff;
      }
    } // end else: don't compress
  } // end encodeBytesToBytes  

  /* ********  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 alphabet type is pulled from this (standard, url-safe, ordered)
     * @return the number of decoded bytes converted
     * @throws NullPointerException if source or destination arrays are null
     * @throws IllegalArgumentException if srcOffset or destOffset are invalid
     *         or there is not enough room in the array.
     * @since 1.3
     */
  private static int decode4to3(byte [] source, int srcOffset, byte [] destination, int destOffset, int options) {
    // Lots of error checking and exception throwing
    if (source == null) {
      throw new NullPointerException("Source array was null.");
    } // end if
    if (destination == null) {
      throw new NullPointerException("Destination array was null.");
    } // end if
    if (srcOffset < 0 || srcOffset + 3 >= source.length) {
      throw new IllegalArgumentException(String.format(
          "Source array with length %d cannot have offset of %d and still process four bytes.", source.length,
          srcOffset));
    } // end if
    if (destOffset < 0 || destOffset + 2 >= destination.length) {
      throw new IllegalArgumentException(String.format(
          "Destination array with length %d cannot have offset of %d and still store three bytes.", destination.length,
          destOffset));
    } // end if
        
    byte [] DECODABET = getDecodabet(options);
        
    // Example: Dk==
    if (source [srcOffset + 2] == EQUALS_SIGN) {
      // 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;
    }
    // Example: DkL=
    else if( source[ srcOffset + 3 ] == EQUALS_SIGN ) {
      // 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;
    }
    // Example: DkLE
    else {
      // 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;
    }
  }   // end decodeToBytes

  /**
   * Low-level access to decoding ASCII characters in
   * the form of a byte array. <strong>Ignores GUNZIP option, if
   * it's set.</strong> This is not generally a recommended method,
   * although it is used internally as part of the decoding process.
   * Special case: if len = 0, an empty array is returned. Still,
   * if you need more speed and reduced memory footprint (and aren't
   * gzipping), consider this method.
   *
   * @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 Can specify options such as alphabet type to use
   * @return decoded data
   * @throws java.io.IOException If bogus characters exist in source data
   * @since 1.3
   */
  private static byte [] decode(byte [] source, int off, int len, int options) throws java.io.IOException {
    // Lots of error checking and exception throwing
    if (source == null) {
      throw new NullPointerException("Cannot decode null source array.");
    } // end if
    if (off < 0 || off + len > source.length) {
      throw new IllegalArgumentException(String.format(
          "Source array with length %d cannot have offset of %d and process %d bytes.", source.length, off, len));
    } // end if

    if (len == 0) {
      return new byte [0];
    } else if (len < 4) {
      throw new IllegalArgumentException(
          "Base64-encoded string must have at least four characters, but length specified was " + len);
    } // end if

    byte [] DECODABET = getDecodabet(options);
    
    int    len34   = len * 3 / 4;       // Estimate on array size
    byte[] outBuff = new byte[ len34 ]; // Upper limit on size of output
    int    outBuffPosn = 0;             // Keep track of where we're writing
      
    byte[] b4        = new byte[4];     // Four byte buffer from source, eliminating white space
    int    b4Posn    = 0;               // Keep track of four byte input buffer
    int    i         = 0;               // Source array counter
    byte   sbiDecode = 0;               // Special value from DECODABET
      
    for (i = off; i < off + len; i++) { // Loop through source
      sbiDecode = DECODABET [source [i] & 0xFF];

      // White space, Equals sign, or legit Base64 character
      // Note the values such as -5 and -9 in the
      // DECODABETs at the top of the file.
      if (sbiDecode >= WHITE_SPACE_ENC) {
        if (sbiDecode >= EQUALS_SIGN_ENC) {
          b4 [b4Posn++] = source [i]; // Save non-whitespace
          if (b4Posn > 3) { // Time to decode?
            outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, options);
            b4Posn = 0;

            // If that was the equals sign, break out of 'for' loop
            if (source [i] == EQUALS_SIGN) {
              break;
            } // end if: equals sign
          } // end if: quartet built
        } // end if: equals sign or better
      } // end if: white space, equals sign or better
      else {
        // There's a bad input character in the Base64 stream.
        throw new java.io.IOException(String.format("Bad Base64 input character decimal %d in array position %d",
            ((int)source [i]) & 0xFF, i));
      } // 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
   * @throws java.io.IOException If there is a problem
   * @since 1.4
   */
  public static byte [] decode(String s) throws java.io.IOException {
    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 encode options such as URL_SAFE
   * @return the decoded data
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if <tt>s</tt> is null
   * @since 1.4
   */
  public static byte [] decode(String s, int options) throws java.io.IOException {
    if (s == null) {
      throw new NullPointerException("Input string was null.");
    } // end if

    byte [] bytes;
    try {
      bytes = s.getBytes(PREFERRED_ENCODING);
    } // end try
    catch (java.io.UnsupportedEncodingException uee) {
      bytes = s.getBytes();
    } // end catch
    // </change>

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

    // Check to see if it's gzip-compressed
    // GZIP Magic Two-Byte Number: 0x8b1f (35615)
    boolean dontGunzip = (options & DONT_GUNZIP) != 0;
    if ((bytes != null) && (bytes.length >= 4) && (!dontGunzip)) {

      int head = ((int)bytes [0] & 0xff) | ((bytes [1] << 8) & 0xff00);
      if (java.util.zip.GZIPInputStream.GZIP_MAGIC == head) {
        java.io.ByteArrayInputStream bais = null;
        java.util.zip.GZIPInputStream gzis = null;
        java.io.ByteArrayOutputStream baos = null;
        byte [] buffer = new byte [2048];
        int length = 0;

        try {
          baos = new java.io.ByteArrayOutputStream();
          bais = new java.io.ByteArrayInputStream(bytes);
          gzis = new java.util.zip.GZIPInputStream(bais);

          while ((length = gzis.read(buffer)) >= 0) {
            baos.write(buffer, 0, length);
          } // end while: reading input

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

        } // end try
        catch (java.io.IOException e) {
          e.printStackTrace();
          // Just return originally-decoded bytes
        } // end catch
        finally {
          try {
            baos.close();
          } catch (Exception e) {
          }
          try {
            gzis.close();
          } catch (Exception e) {
          }
          try {
            bais.close();
          } catch (Exception e) {
          }
        } // end finally

      } // end if: gzipped
    } // end if: bytes.length >= 2

    return bytes;
  } // end decode

  
  /* ********  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.OutputStream} will write data to another
   * <tt>java.io.OutputStream</tt>, given in the constructor,
   * and encode/decode to/from Base64 notation on the fly.
   *
   * @see Base64
   * @since 1.3
   */
  private static class OutputStream extends java.io.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 copies to avoid extra method calls
    
    /**
     * Constructs a {@link Base64.OutputStream} in
     * either ENCODE or DECODE mode.
     * <p>
     * Valid options:<pre>
     *   ENCODE or DECODE: Encode or Decode as data is read.
     *   DO_BREAK_LINES: don't break lines at 76 characters
     *     (only meaningful when encoding)</i>
     * </pre>
     * <p>
     * Example: <code>new Base64.OutputStream( out, Base64.ENCODE )</code>
     *
     * @param out the <tt>java.io.OutputStream</tt> to which data will be written.
     * @param options Specified options.
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DO_BREAK_LINES
     * @since 1.3
     */
    public OutputStream(java.io.OutputStream out, int options) {
      super(out);
      this.breakLines   = (options & DO_BREAK_LINES) != 0;
      this.encode       = (options & ENCODE) != 0;
      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 java.io.IOException {
      // Encoding suspended?
      if (suspendEncoding) {
        this.out.write(theByte);
        return;
      } // end if: supsended

      // Encode?
      if (encode) {
        buffer [position++] = (byte)theByte;
        if (position >= bufferLength) { // Enough to encode.

          this.out.write(encode3to4(b4, buffer, bufferLength, options));

          lineLength += 4;
          if (breakLines && lineLength >= MAX_LINE_LENGTH) {
            this.out.write(NEW_LINE);
            lineLength = 0;
          } // end if: end of line

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

      // Else, Decoding
      else {
        // Meaningful Base64 character?
        if (decodabet [theByte & 0x7f] > WHITE_SPACE_ENC) {
          buffer [position++] = (byte)theByte;
          if (position >= bufferLength) { // Enough to output.

            int len = Base64.decode4to3(buffer, 0, b4, 0, options);
            out.write(b4, 0, len);
            position = 0;
          } // end if: enough to output
        } // end if: meaningful base64 character
        else if (decodabet [theByte & 0x7f] != WHITE_SPACE_ENC) {
          throw new java.io.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 java.io.IOException {
      // Encoding suspended?
      if (suspendEncoding) {
        this.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 java.io.IOException  if there's an error.
     */
    public void flushBase64() throws java.io.IOException  {
      if (position > 0) {
        if (encode) {
          out.write(encode3to4(b4, buffer, position, options));
          position = 0;
        } // end if: encoding
        else {
          throw new java.io.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 java.io.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
  }   // end inner class OutputStream
}   // end class Base64
