/*
 * LinShare is an open source filesharing software, part of the LinPKI software
 * suite, developed by Linagora.
 * 
 * Copyright (C) 2013 LINAGORA
 * 
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any
 * later version, provided you comply with the Additional Terms applicable for
 * LinShare software by Linagora pursuant to Section 7 of the GNU Affero General
 * Public License, subsections (b), (c), and (e), pursuant to which you must
 * notably (i) retain the display of the “LinShare™” trademark/logo at the top
 * of the interface window, the display of the “You are using the Open Source
 * and free version of LinShare™, powered by Linagora © 2009–2013. Contribute to
 * Linshare R&D by subscribing to an Enterprise offer!” infobox and in the
 * e-mails sent with the Program, (ii) retain all hypertext links between
 * LinShare and linshare.org, between linagora.com and Linagora, and (iii)
 * refrain from infringing Linagora intellectual property rights over its
 * trademarks and commercial brands. Other Additional Terms apply, see
 * <http://www.linagora.com/licenses/> for more details.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Affero General Public License and
 * its applicable Additional Terms for LinShare along with this program. If not,
 * see <http://www.gnu.org/licenses/> for the GNU Affero General Public License
 * version 3 and <http://www.linagora.com/licenses/> for the Additional Terms
 * applicable to LinShare software.
 */
package org.linagora.linshare.core.utils;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


/**
 *
 *
 * <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/xmlizable">http://iharder.net/xmlizable</a>
 * periodically to check for updates or to contribute improvements.
 * </p>
 *
 * @author Robert Harder
 * @author rharder@usa.net
 * @version 1.3
 */
public class Base64Utils
{
	
	private static final Log LOGGER = LogFactory.getLog(Base64Utils.class);
    
    /** Specify encoding (value is <tt>true</tt>). */
    public final static boolean ENCODE = true;
    
    
    /** Specify decoding (value is <tt>false</tt>). */
    public final static boolean DECODE = false;
    
    
    /** Maximum line length (76) of Base64 output. */
    public 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';
    
    
    /** The 64 valid Base64 values. */
    private final static byte[] 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[] 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                                 // Decimal 123 - 126
        /*,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 127 - 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 */
    };
    
    private final static byte BAD_ENCODING    = -9; // Indicates error in encoding
    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
    
    
    /** Defeats instantiation. */
    private Base64Utils(){}
    
    
    
    /** Testing. */
    public static void main( String[] args )
    {
        String s = "Hello, world";
        s = "abcd";
        //s = System.getProperties().toString();
        //System.out.println( s + ": \n [" + encode( s ) + "]\n [" + decode(encode(s)) + "]" );
        
        byte[] b = encodeString(s).getBytes();
        byte[] c = decode( b, 0, b.length );
        
        if(LOGGER.isDebugEnabled()){
        	LOGGER.debug( "\n\n" + s + ":" + new String(b) + ":" + new String(c) );
        }
        
        try
        {
            java.io.FileInputStream fis = new java.io.FileInputStream( "c:\\abcd.txt" );
            Base64Utils.InputStream b64is = new Base64Utils.InputStream( fis, DECODE );
            int ib = 0;
            if(LOGGER.isDebugEnabled()){
	            while( (ib = b64is.read()) > 0 )
	            {   
	            	LOGGER.debug( new String( ""+(char)ib ) );
	            }
            }
        }   // end try
        catch( Exception e)
        {   e.printStackTrace();
        }
    }
    
    
/* ********  E N C O D I N G   M E T H O D S  ******** */    
    
    
    /**
     * Encodes the first three bytes of array <var>threeBytes</var>
     * and returns a four-byte array in Base64 notation.
     *
     * @param threeBytes the array to convert
     * @return four byte array in Base64 notation.
     * @since 1.3
     */
    public static byte[] encode3to4( byte[] threeBytes )
    {   return encode3to4( threeBytes, 3 );
    }   // end encodeToBytes
    
    
    
    /**
     * 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>.
     *
     * @param threeBytes the array to convert
     * @param numSigBytes the number of significant bytes in your array
     * @return four byte array in Base64 notation.
     * @since 1.3
     */
    public static byte[] encode3to4( byte[] threeBytes, int numSigBytes )
    {   byte[] dest = new byte[4];
        encode3to4( threeBytes, 0, numSigBytes, dest, 0 );
        return dest;
    }
    
    
    
    /**
     * 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>.
     *
     * @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
     */
    public static byte[] encode3to4( 
     byte[] source, int srcOffset, int numSigBytes,
     byte[] destination, int destOffset )
    {
        //           1         2         3  
        // 01234567890123456789012345678901 Bit position
        // --------000000001111111122222222 Array position from threeBytes
        // --------|    ||    ||    ||    | Six bit groups to index ALPHABET
        //          >>18  >>12  >> 6  >> 0  Right shift necessary
        //                0x3f  0x3f  0x3f  Additional AND
        
        // Create buffer with zero-padding if there are only one or two
        // significant bytes passed in the array.
        // We have to shift left 24 in order to flush out the 1's that appear
        // when Java treats a value as negative that is cast from a byte to an int.
        int inBuff =   ( numSigBytes > 0 ? ((source[ srcOffset     ] << 24) >>>  8) : 0 )
                     | ( numSigBytes > 1 ? ((source[ srcOffset + 1 ] << 24) >>> 16) : 0 )
                     | ( numSigBytes > 2 ? ((source[ srcOffset + 2 ] << 24) >>> 24) : 0 );

        switch( numSigBytes )
        {
            case 3:
                destination[ destOffset     ] = ALPHABET[ (inBuff >>> 18)        ];
                destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
                destination[ destOffset + 2 ] = ALPHABET[ (inBuff >>>  6) & 0x3f ];
                destination[ destOffset + 3 ] = ALPHABET[ (inBuff       ) & 0x3f ];
                return destination;
                
            case 2:
                destination[ destOffset     ] = ALPHABET[ (inBuff >>> 18)        ];
                destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
                destination[ destOffset + 2 ] = ALPHABET[ (inBuff >>>  6) & 0x3f ];
                destination[ destOffset + 3 ] = EQUALS_SIGN;
                return destination;
                
            case 1:
                destination[ destOffset     ] = ALPHABET[ (inBuff >>> 18)        ];
                destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
                destination[ destOffset + 2 ] = EQUALS_SIGN;
                destination[ destOffset + 3 ] = EQUALS_SIGN;
                return destination;
                
            default:
                return destination;
        }   // end switch
    }   // end encode3to4
    
    
    /**
     * Serializes an object and returns the Base64-encoded
     * version of that serialized object. If the object
     * cannot be serialized or there is another error,
     * the method will return <tt>null</tt>.
     *
     * @param serializableObject The object to encode
     * @return The Base64-encoded object
     * @since 1.4
     */
    public static String encodeObject( java.io.Serializable serializableObject )
    {
        java.io.ByteArrayOutputStream baos  = null; 
        java.io.OutputStream          b64os = null; 
        java.io.ObjectOutputStream    oos   = null; 
        
        try
        {
            baos  = new java.io.ByteArrayOutputStream();
            b64os = new Base64Utils.OutputStream( baos, Base64Utils.ENCODE );
            oos   = new java.io.ObjectOutputStream( b64os );
            
            oos.writeObject( serializableObject );
        }   // end try
        catch( java.io.IOException e )
        {
            e.printStackTrace();
            return null;
        }   // end catch
        finally
        {
            try{ oos.close();   } catch( Exception e ){}
            try{ b64os.close(); } catch( Exception e ){}
            try{ baos.close();  } catch( Exception e ){}
        }   // end finally
        
        return new String( baos.toByteArray() );
    }   // end encode
    
    
    /**
     * Encodes a byte array into Base64 notation.
     * Equivalen to calling
     * <code>encodeBytes( source, 0, source.length )</code>
     *
     * @param source The data to convert
     * @since 1.4
     */
    public static String encodeBytes( byte[] source )
    {   return encodeBytes( source, 0, source.length );
    }   // end encodeBytes
    
    
    
    
    /**
     * Encodes a byte array into Base64 notation.
     *
     * @param source The data to convert
     * @param off Offset in array where conversion should begin
     * @param len Length of data to convert
     * @since 1.4
     */
    public static String encodeBytes( byte[] source, int off, int len )
    {
        int    len43   = len * 4 / 3;
        byte[] outBuff = new byte[   ( len43 )                      // Main 4:3
                                   + ( (len % 3) > 0 ? 4 : 0 )      // Account for padding
                                   + ( len43 / MAX_LINE_LENGTH ) ]; // New lines      
        int d = 0;
        int e = 0;
        int len2 = len - 2;
        int lineLength = 0;
        for( ; d < len2; d+=3, e+=4 )
        {
            encode3to4( source, d, 3, outBuff, e );
            
            lineLength += 4;
            if( 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, len - d, outBuff, e );
            e += 4;
        }   // end if: some padding needed
        
        return new String( outBuff, 0, e );
    }   // end encodeBytes
    
    
    
    /**
     * Encodes a string in Base64 notation with line breaks
     * after every 75 Base64 characters.
     *
     * @param s the string to encode
     * @return the encoded string
     * @since 1.3
     */
    public static String encodeString( String s )
    {   return encodeBytes( s.getBytes() );
    }   // end encodeString
    
 
    
    
    
/* ********  D E C O D I N G   M E T H O D S  ******** */
    
    
    /**
     * Decodes the first four bytes of array <var>fourBytes</var>
     * and returns an array up to three bytes long with the
     * decoded values.
     *
     * @param fourBytes the array with Base64 content
     * @return array with decoded values
     * @since 1.3
     */
    public static byte[] decode4to3( byte[] fourBytes )
    {
        byte[] outBuff1 = new byte[3];
        int    count    = decode4to3( fourBytes, 0, outBuff1, 0 );
        byte[] outBuff2 = new byte[ count ];
        
        for( int i = 0; i < count; i++ )
            outBuff2[i] = outBuff1[i];
        
        return outBuff2;
    }
    
    
    
    
    /**
     * 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.
     * 
     *
     * @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
     * @return the number of decoded bytes converted
     * @since 1.3
     */
    public static int decode4to3( byte[] source, int srcOffset, byte[] destination, int destOffset )
    {
        // Example: Dk==
        if( source[ srcOffset + 2] == EQUALS_SIGN )
        {
            int outBuff =   ( ( DECODABET[ source[ srcOffset    ] ] << 24 ) >>>  6 )
                          | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
            
            destination[ destOffset ] = (byte)( outBuff >>> 16 );
            return 1;
        }
        
        // Example: DkL=
        else if( source[ srcOffset + 3 ] == EQUALS_SIGN )
        {
            int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] << 24 ) >>>  6 )
                          | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
                          | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
            
            destination[ destOffset     ] = (byte)( outBuff >>> 16 );
            destination[ destOffset + 1 ] = (byte)( outBuff >>>  8 );
            return 2;
        }
        
        // Example: DkLE
        else
        {
            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 );

            destination[ destOffset     ] = (byte)( outBuff >> 16 );
            destination[ destOffset + 1 ] = (byte)( outBuff >>  8 );
            destination[ destOffset + 2 ] = (byte)( outBuff       );
            return 3;
        }
    }   // end decodeToBytes
    
    
    
    /**
     * Decodes data from Base64 notation.
     *
     * @param s the string to decode
     * @return the decoded data
     * @since 1.4
     */
    public static byte[] decode( String s )
    {   
        byte[] bytes = s.getBytes();
        return decode( bytes, 0, bytes.length );
    }   // end decode
    
    
    /**
     * Decodes data from Base64 notation and
     * returns it as a string.
     * Equivlaent to calling
     * <code>new String( decode( s ) )</code>
     *
     * @param s the strind to decode
     * @return The data as a string
     * @since 1.4
     */
    public static String decodeToString( String s )
    {   return new String( decode( s ) );
    }   // end decodeToString
    
    
    /**
     * Attempts to decode Base64 data and deserialize a Java
     * Object within. Returns <tt>null if there was an error.
     *
     * @param encodedObject The Base64 data to decode
     * @return The decoded and deserialized object
     * @since 1.4
     */
    public static Object decodeToObject( String encodedObject )
    {
        byte[] objBytes = decode( encodedObject );
        
        java.io.ByteArrayInputStream bais = null;
        java.io.ObjectInputStream    ois  = null;
        
        try
        {
            bais = new java.io.ByteArrayInputStream( objBytes );
            ois  = new java.io.ObjectInputStream( bais );
        
            return ois.readObject();
        }   // end try
        catch( java.io.IOException e )
        {
            e.printStackTrace();
            return null;
        }   // end catch
        catch( java.lang.ClassNotFoundException e )
        {
            e.printStackTrace();
            return null;
        }   // end catch
        finally
        {
            try{ bais.close(); } catch( Exception e ){}
            try{ ois.close();  } catch( Exception e ){}
        }   // end finally
    }   // end decodeObject
    
    
    /**
     * Decodes Base64 content in byte array format and returns
     * the decoded byte array.
     *
     * @param source The Base64 encoded data
     * @param off    The offset of where to begin decoding
     * @param len    The length of characters to decode
     * @return decoded data
     * @since 1.3
     */
    public static byte[] decode( byte[] source, int off, int len )
    {
        int    len34   = len * 3 / 4;
        byte[] outBuff = new byte[ len34 ]; // Upper limit on size of output
        int    outBuffPosn = 0;
        
        byte[] b4        = new byte[4];
        int    b4Posn    = 0;
        int    i         = 0;
        byte   sbiCrop   = 0;
        byte   sbiDecode = 0;
        for( i = 0; i < len; i++ )
        {
            sbiCrop = (byte)(source[i] & 0x7f); // Only the low seven bits
            sbiDecode = DECODABET[ sbiCrop ];
            
            if( sbiDecode >= WHITE_SPACE_ENC ) // White space, Equals sign or better
            {
                if( sbiDecode >= EQUALS_SIGN_ENC )
                {
                    b4[ b4Posn++ ] = sbiCrop;
                    if( b4Posn > 3 )
                    {
                        outBuffPosn += decode4to3( b4, 0, outBuff, outBuffPosn );
                        b4Posn = 0;
                        
                        // If that was the equals sign, break out of 'for' loop
                        if( sbiCrop == EQUALS_SIGN )
                            break;
                    }   // end if: quartet built
                    
                }   // end if: equals sign or better
                
            }   // end if: white space, equals sign or better
            else
            {
            	LOGGER.error( "Bad Base64 input character at " + i + ": " + source[i] + "(decimal)" );
                return null;
            }   // end else: 
        }   // each input character
                                   
        byte[] out = new byte[ outBuffPosn ];
        System.arraycopy( outBuff, 0, out, 0, outBuffPosn ); 
        return out;
    }   // end decode
    
    
  
    
    /* ********  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
     * {@link java.io.InputStream}, given in the constructor,
     * and encode/decode to/from Base64 notation on the fly.
     *
     * @see Base64
     * @see java.io.FilterInputStream
     * @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
        
        
        /**
         * Constructs a {@link Base64#InputStream} in DECODE mode.
         *
         * @param in the {@link java.io.InputStream} from which to read data.
         * @since 1.3
         */
        public InputStream( java.io.InputStream in )
        {   this( in, Base64Utils.DECODE );
        }   // end constructor
        
        
        /**
         * Constructs a {@link Base64#InputStream} in
         * either ENCODE or DECODE mode.
         *
         * @param in the {@link java.io.InputStream} from which to read data.
         * @param encode Conversion direction
         * @see Base64#ENCODE
         * @see Base64#DECODE
         * @since 1.3
         */
        public InputStream( java.io.InputStream in, boolean encode )
        {   
            super( in );
            this.encode = encode;
            this.bufferLength = encode ? 4 : 3;
            this.buffer   = new byte[ bufferLength ];
            this.position = -1;
        }   // end constructor
        
        /**
         * Reads enough of the input stream to convert
         * to/from Base64 and returns the next byte.
         *
         * @return next byte
         * @since 1.3
         */
        public int read() throws java.io.IOException 
        { 
            // Do we need to get data?
            if( position < 0 )
            {
                if( encode )
                {
                    byte[] b3 = new byte[3];
                    numSigBytes = 0;
                    for( int i = 0; i < 3; i++ )
                    {
                        try
                        { 
                            int b = in.read();
                            
                            // If end of stream, b is -1.
                            if( b >= 0 )
                            {
                                b3[i] = (byte)b;
                                numSigBytes++;
                            }   // end if: not end of stream
                            
                        }   // end try: read
                        catch( java.io.IOException e )
                        {   
                            // Only a problem if we got no data at all.
                            if( i == 0 )
                                throw e;
                            
                        }   // end catch
                    }   // end for: each needed input byte
                    
                    if( numSigBytes > 0 )
                    {
                        encode3to4( b3, 0, numSigBytes, buffer, 0 );
                        position = 0;
                    }   // end if: got data
                }   // end if: encoding
                
                // Else decoding
                else
                {
                    byte[] b4 = new byte[4];
                    int i = 0;
                    for( i = 0; i < 4; i++ )
                    {
                        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
                        
                        b4[i] = (byte)b;
                    }   // end for: each needed input byte
                    
                    if( i == 4 )
                    {
                        numSigBytes = decode4to3( b4, 0, buffer, 0 );
                        position = 0;
                    }   // end if: got four characters
                    
                }   // end else: decode
            }   // end else: get data
            
            // Got data?
            if( position >= 0 )
            {
                // End of relevant data?
                if( position >= numSigBytes )
                    return -1;
                
                int b = buffer[ position++ ];
                
                if( position >= bufferLength )
                    position = -1;
                
                return b;
            }   // end if: position >= 0
            
            // Else error
            else
                return -1;
        }   // 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
         */
        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 )
                    return -1;
                
                dest[off + i] = (byte)b;
            }   // 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
     * {@link java.io.OutputStream}, given in the constructor,
     * and encode/decode to/from Base64 notation on the fly.
     *
     * @see Base64
     * @see java.io.FilterOutputStream
     * @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;
        
        
        /**
         * Constructs a {@link Base64#OutputStream} in ENCODE mode.
         *
         * @param out the {@link java.io.OutputStream} to which data will be written.
         * @since 1.3
         */
        public OutputStream( java.io.OutputStream out )
        {   this( out, Base64Utils.ENCODE );
        }   // end constructor
        
        
        
        /**
         * Constructs a {@link Base64#OutputStream} in
         * either ENCODE or DECODE mode.
         *
         * @param out the {@link java.io.OutputStream} to which data will be written.
         * @param encode Conversion direction
         * @see Base64#ENCODE
         * @see Base64#DECODE
         * @since 1.3
         */
        public OutputStream( java.io.OutputStream out, boolean encode )
        {   
            super( out );
            this.encode       = encode;
            this.bufferLength = encode ? 3 : 4;
            this.buffer       = new byte[ bufferLength ];
            this.position     = 0;
            this.lineLength   = 0;
        }   // 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
         */
        public void write(int theByte) throws java.io.IOException 
        {
            buffer[ position++ ] = (byte)theByte;
            if( position >= bufferLength )
            {   
                if( encode )
                {
                    out.write( Base64Utils.encode3to4( buffer, bufferLength ) );
                    
                    lineLength += 4;
                    if( lineLength >= MAX_LINE_LENGTH )
                    {
                        out.write( NEW_LINE );
                        lineLength = 0;
                    }   // end if: end o fline
                }   // end if: encoding
                else 
                    out.write( Base64Utils.decode4to3( buffer ) );
                
                position = 0;
            }   // end if: convert and flush
        }   // end write
        
        
        
        /**
         * Calls {@link #write} 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
         */
        public void write( byte[] theBytes, int off, int len ) throws java.io.IOException
        {
            for( int i = 0; i < len; i++ )
            {
                write( theBytes[ off + i ] );
            }   // end for: each byte written
            
        }   // end write
        
        
        /**
         * Appropriately pads Base64 notation when encoding
         * or throws an exception if Base64 input is not
         * properly padded when decoding.
         *
         * @since 1.3
         */
        public void flush() throws java.io.IOException
        {
            if( position > 0 )
            {
                if( encode )
                {
                    out.write( Base64Utils.encode3to4( buffer, position ) );
                }   // end if: encoding
                else
                {   
                    throw new java.io.IOException( "Base64 input not properly padded." );
                }   // end else: decoding
            }   // end if: buffer partially full
            
            super.flush();
            out.flush();
        }   // end flush
        
        
        /** 
         * Flushes and closes stream. 
         *
         * @since 1.3
         */
        public void close() throws java.io.IOException
        {
            this.flush();
            
            super.close();
            out.close();
            
            buffer = null;
            out    = null;
        }   // end close
        
    }   // end inner class OutputStream
    
    
}   // end class Base64
