package org.keycloak.common.util;

import java.io.IOException;

/**
 * <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>v2.3.8 - Fixed automatic gzip decoding, based on the content,
 *  as this may lead to unexpected behaviour. Request either gzipped
 *  or non gzipped decoding as excepted. Automatic encoding is especially
 *  problematic with generated input (see KEYCLOAK-18914 for a detailed case).</li>
 *  <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 {@link #encodeFromFile} 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
 *   {@link #decodeToObject(java.lang.String, int, java.lang.ClassLoader)}
 *   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 {@link #encodeBytesToBytes(byte[])} 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 possibility 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 data should be gunzipped. */
    public final static int 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 it
     * 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 accommodate <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



    /**
     * Performs Base64 encoding on the <code>raw</code> ByteBuffer,
     * writing it to the <code>encoded</code> ByteBuffer.
     * This is an experimental feature. Currently it does not
     * pass along any options (such as {@link #DO_BREAK_LINES}
     * or {@link #GZIP}).
     *
     * @param raw input buffer
     * @param encoded output buffer
     * @since 2.3
     */
    public static void encode( java.nio.ByteBuffer raw, java.nio.ByteBuffer encoded ){
        byte[] raw3 = new byte[3];
        byte[] enc4 = new byte[4];

        while( raw.hasRemaining() ){
            int rem = Math.min(3,raw.remaining());
            raw.get(raw3,0,rem);
            Base64.encode3to4(enc4, raw3, rem, Base64.NO_OPTIONS);
            encoded.put(enc4);
        }   // end input remaining
    }


    /**
     * Performs Base64 encoding on the <code>raw</code> ByteBuffer,
     * writing it to the <code>encoded</code> CharBuffer.
     * This is an experimental feature. Currently it does not
     * pass along any options (such as {@link #DO_BREAK_LINES}
     * or {@link #GZIP}.
     *
     * @param raw input buffer
     * @param encoded output buffer
     * @since 2.3
     */
    public static void encode( java.nio.ByteBuffer raw, java.nio.CharBuffer encoded ){
        byte[] raw3 = new byte[3];
        byte[] enc4 = new byte[4];

        while( raw.hasRemaining() ){
            int rem = Math.min(3,raw.remaining());
            raw.get(raw3,0,rem);
            Base64.encode3to4(enc4, raw3, rem, Base64.NO_OPTIONS );
            for( int i = 0; i < 4; i++ ){
                encoded.put( (char)(enc4[i] & 0xFF) );
            }
        }   // end input remaining
    }




    /**
     * Serializes an object and returns the Base64-encoded
     * version of that serialized object.
     *
     * <p>As of v 2.3, if the object
     * cannot be serialized or there is another 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>
     *
     * The object is not GZip-compressed before being encoded.
     *
     * @param serializableObject The object to encode
     * @return The Base64-encoded object
     * @throws java.io.IOException if there is an error
     * @throws NullPointerException if serializedObject is null
     * @since 1.4
     */
    public static String encodeObject( java.io.Serializable serializableObject )
            throws java.io.IOException {
        return encodeObject( serializableObject, NO_OPTIONS );
    }   // end encodeObject



    /**
     * Serializes an object and returns the Base64-encoded
     * version of that serialized object.
     *
     * <p>As of v 2.3, if the object
     * cannot be serialized or there is another 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>
     *
     * The object is not GZip-compressed before being encoded.
     * <p>
     * Example options:<pre>
     *   GZIP: gzip-compresses object before encoding it.
     *   DO_BREAK_LINES: break lines at 76 characters
     * </pre>
     * <p>
     * Example: <code>encodeObject( myObj, Base64.GZIP )</code> or
     * <p>
     * Example: <code>encodeObject( myObj, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
     *
     * @param serializableObject The object to encode
     * @param options Specified options
     * @return The Base64-encoded object
     * @see Base64#GZIP
     * @see Base64#DO_BREAK_LINES
     * @throws java.io.IOException if there is an error
     * @since 2.0
     */
    public static String encodeObject( java.io.Serializable serializableObject, int options )
            throws java.io.IOException {

        if( serializableObject == null ){
            throw new NullPointerException( "Cannot serialize a null object." );
        }   // end if: null

        // Streams
        java.io.ByteArrayOutputStream  baos  = null;
        java.io.OutputStream           b64os = null;
        java.util.zip.GZIPOutputStream gzos  = null;
        java.io.ObjectOutputStream     oos   = null;


        try {
            // ObjectOutputStream -> (GZIP) -> Base64 -> ByteArrayOutputStream
            baos  = new java.io.ByteArrayOutputStream();
            b64os = new Base64.OutputStream( baos, ENCODE | options );
            if( (options & GZIP) != 0 ){
                // Gzip
                gzos = new java.util.zip.GZIPOutputStream(b64os);
                oos = new java.io.ObjectOutputStream( gzos );
            } else {
                // Not gzipped
                oos = new java.io.ObjectOutputStream( b64os );
            }
            oos.writeObject( serializableObject );
        }   // 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{ oos.close();   } catch( Exception e ){}
            try{ gzos.close();  } catch( Exception e ){}
            try{ b64os.close(); } catch( Exception e ){}
            try{ baos.close();  } catch( Exception e ){}
        }   // end finally

        // Return value according to relevant encoding.
        try {
            return new String( baos.toByteArray(), PREFERRED_ENCODING );
        }   // end try
        catch (java.io.UnsupportedEncodingException uue){
            // Fall back to some Java default
            return new String( baos.toByteArray() );
        }   // end catch

    }   // end encode



    /**
     * 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, without line break your encoding may become non-compliant (see rfc2045 and rfc4648).</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[])} 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
     * @return The Base64-encoded data as a byte[] (of ASCII characters)
     * @throws NullPointerException if source array is null
     * @since 2.3.1
     */
    public static byte[] encodeBytesToBytes( byte[] source ) {
        byte[] encoded = null;
        try {
            encoded = encodeBytesToBytes( source, 0, source.length, Base64.NO_OPTIONS );
        } catch( java.io.IOException ex ) {
            assert false : "IOExceptions only come from GZipping, which is turned off: " + ex.getMessage();
        }
        return encoded;
    }


    /**
     * 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
     */
    public 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
     * @return decoded data
     * @since 2.3.1
     */
    public static byte[] decode( byte[] source ) throws java.io.IOException {
        return decode( source, 0, source.length, Base64.NO_OPTIONS );
    }



    /**
     * 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
     */
    public 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 decode options such as URL_SAFE or GUNZIP
     * @return the decoded data
     * @throws java.io.IOException if there is an error (invalid character in source string or gunzip 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 doGunzip = (options & GUNZIP) != 0;
        if( (bytes != null) && (bytes.length >= 4) && doGunzip ) {

            int head = ((int)bytes[0] & 0xff) | ((bytes[1] << 8) & 0xff00);
            if( java.util.zip.GZIPInputStream.GZIP_MAGIC != head )  {
                throw new IOException("Provided data has no GZIP magic header.");
            }
            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 ) {
                throw new IOException("Failed to gunzip", e);
            }   // 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: bytes.length >= 2

        return bytes;
    }   // end decode

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

    /**
     * A {@link Base64.InputStream} will read data from another
     * <tt>java.io.InputStream</tt>, given in the constructor,
     * and encode/decode to/from Base64 notation on the fly.
     *
     * @see Base64
     * @since 1.3
     */
    public static class InputStream extends java.io.FilterInputStream {

        private boolean encode;         // Encoding or decoding
        private int     position;       // Current position in the buffer
        private byte[]  buffer;         // Small buffer holding converted data
        private int     bufferLength;   // Length of buffer (3 or 4)
        private int     numSigBytes;    // Number of meaningful bytes in the buffer
        private int     lineLength;
        private boolean breakLines;     // Break lines at less than 80 characters
        private int     options;        // Record options used to create the stream.
        private byte[]  decodabet;      // Local copies to avoid extra method calls


        /**
         * Constructs a {@link Base64.InputStream} in DECODE mode.
         *
         * @param in the <tt>java.io.InputStream</tt> from which to read data.
         * @since 1.3
         */
        public InputStream( java.io.InputStream in ) {
            this( in, DECODE );
        }   // end constructor


        /**
         * Constructs a {@link Base64.InputStream} in
         * either ENCODE or DECODE mode.
         * <p>
         * Valid options:<pre>
         *   ENCODE or DECODE: Encode or Decode as data is read.
         *   DO_BREAK_LINES: break lines at 76 characters
         *     (only meaningful when encoding)</i>
         * </pre>
         * <p>
         * Example: <code>new Base64.InputStream( in, Base64.DECODE )</code>
         *
         *
         * @param in the <tt>java.io.InputStream</tt> from which to read data.
         * @param options Specified options
         * @see Base64#ENCODE
         * @see Base64#DECODE
         * @see Base64#DO_BREAK_LINES
         * @since 2.0
         */
        public InputStream( java.io.InputStream in, int options ) {

            super( in );
            this.options      = options; // Record for later
            this.breakLines   = (options & DO_BREAK_LINES) > 0;
            this.encode       = (options & ENCODE) > 0;
            this.bufferLength = encode ? 4 : 3;
            this.buffer       = new byte[ bufferLength ];
            this.position     = -1;
            this.lineLength   = 0;
            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 java.io.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++ ) {
                        int b = in.read();

                        // If end of stream, b is -1.
                        if( b >= 0 ) {
                            b3[i] = (byte)b;
                            numBinaryBytes++;
                        } else {
                            break; // out of for loop
                        }   // end else: end of stream

                    }   // end for: each needed input byte

                    if( numBinaryBytes > 0 ) {
                        encode3to4( b3, 0, numBinaryBytes, buffer, 0, options );
                        position = 0;
                        numSigBytes = 4;
                    }   // end if: got data
                    else {
                        return -1;  // Must be end of stream
                    }   // end else
                }   // end if: encoding

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

                        if( b < 0 ) {
                            break; // Reads a -1 if end of stream
                        }   // end 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;
                    }   // end if: got four characters
                    else if( i == 0 ){
                        return -1;
                    }   // end else if: also padded correctly
                    else {
                        // Must have broken out from above.
                        throw new java.io.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;
                }   // end if: got data

                if( encode && breakLines && lineLength >= MAX_LINE_LENGTH ) {
                    lineLength = 0;
                    return '\n';
                }   // end if
                else {
                    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;
                    }   // end if: end

                    return b & 0xFF; // This is how you "cast" a byte that's
                    // intended to be unsigned.
                }   // end else
            }   // end if: position >= 0

            // Else error
            else {
                throw new java.io.IOException( "Error in Base64 code reading stream." );
            }   // end else
        }   // 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 java.io.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
                } // 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.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
     */
    public 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 ENCODE mode.
         *
         * @param out the <tt>java.io.OutputStream</tt> to which data will be written.
         * @since 1.3
         */
        public OutputStream( java.io.OutputStream out ) {
            this( out, ENCODE );
        }   // end constructor


        /**
         * 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



        /**
         * Suspends encoding of the stream.
         * May be helpful if you need to embed a piece of
         * base64-encoded data in a stream.
         *
         * @throws java.io.IOException  if there's an error flushing
         * @since 1.5.1
         */
        public void suspendEncoding() throws java.io.IOException  {
            flushBase64();
            this.suspendEncoding = true;
        }   // end suspendEncoding


        /**
         * Resumes encoding of the stream.
         * May be helpful if you need to embed a piece of
         * base64-encoded data in a stream.
         *
         * @since 1.5.1
         */
        public void resumeEncoding() {
            this.suspendEncoding = false;
        }   // end resumeEncoding



    }   // end inner class OutputStream


}   // end class Base64
