//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.util;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.nio.charset.UnsupportedCharsetException;
  
  
  /** Fast B64 Encoder/Decoder as described in RFC 1421.
   * <p>Does not insert or interpret whitespace as described in RFC
   * 1521. If you require this you must pre/post process your data.
   * <p> Note that in a web context the usual case is to not want
   * linebreaks or other white space in the encoded output.
   *
   */
  public class B64Code
  {
      private static final char __pad='=';
      private static final char[] __rfc1421alphabet=
              {
                  'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
                  'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
                  'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
                  'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/'
              };
  
      private static final byte[] __rfc1421nibbles;
      static
      {
          __rfc1421nibbles=new byte[256];
          for (int i=0;i<256;i++)
              __rfc1421nibbles[i]=-1;
          for (byte b=0;b<64;b++)
              __rfc1421nibbles[(byte)__rfc1421alphabet[b]]=b;
          __rfc1421nibbles[(byte)__pad]=0;
      }
  
      private B64Code()
      {
      }
  
      /**
       * Base 64 encode as described in RFC 1421.
       * <p>Does not insert whitespace as described in RFC 1521.
       * @param s String to encode.
       * @return String containing the encoded form of the input.
       */
      public static String encode(String s)
      {
          return encode(s, (Charset)null);
      }
  
      /**
       * Base 64 encode as described in RFC 1421.
       * <p>Does not insert whitespace as described in RFC 1521.
       * @param s String to encode.
       * @param charEncoding String representing the name of
       *        the character encoding of the provided input String.
       * @return String containing the encoded form of the input.
       */
      public static String encode(String s,String charEncoding)
      {
          byte[] bytes;
          if (charEncoding==null)
              bytes=s.getBytes(StandardCharsets.ISO_8859_1);
          else
              bytes=s.getBytes(Charset.forName(charEncoding));
          return new String(encode(bytes));
      }
  
      /**
       * Base 64 encode as described in RFC 1421.
       * <p>Does not insert whitespace as described in RFC 1521.
       * @param s String to encode.
       * @param charEncoding The character encoding of the provided input String.
       * @return String containing the encoded form of the input.
       */
      public static String encode(String s, Charset charEncoding)
      {
          byte[] bytes=s.getBytes(charEncoding==null ? StandardCharsets.ISO_8859_1 : charEncoding);
         return new String(encode(bytes));
     }
 
     /**
      * Fast Base 64 encode as described in RFC 1421.
      * <p>Does not insert whitespace as described in RFC 1521.
      * <p> Avoids creating extra copies of the input/output.
      * @param b byte array to encode.
      * @return char array containing the encoded form of the input.
      */
     public static char[] encode(byte[] b)
     {
         if (b==null)
             return null;
 
         int bLen=b.length;
         int cLen=((bLen+2)/3)*4;
         char c[]=new char[cLen];
         int ci=0;
         int bi=0;
         byte b0, b1, b2;
         int stop=(bLen/3)*3;
         while (bi<stop)
         {
             b0=b[bi++];
             b1=b[bi++];
             b2=b[bi++];
             c[ci++]=__rfc1421alphabet[(b0>>>2)&0x3f];
             c[ci++]=__rfc1421alphabet[(b0<<4)&0x3f|(b1>>>4)&0x0f];
             c[ci++]=__rfc1421alphabet[(b1<<2)&0x3f|(b2>>>6)&0x03];
             c[ci++]=__rfc1421alphabet[b2&0x3f];
         }
 
         if (bLen!=bi)
         {
             switch (bLen%3)
             {
                 case 2:
                     b0=b[bi++];
                     b1=b[bi++];
                     c[ci++]=__rfc1421alphabet[(b0>>>2)&0x3f];
                     c[ci++]=__rfc1421alphabet[(b0<<4)&0x3f|(b1>>>4)&0x0f];
                     c[ci++]=__rfc1421alphabet[(b1<<2)&0x3f];
                     c[ci++]=__pad;
                     break;
 
                 case 1:
                     b0=b[bi++];
                     c[ci++]=__rfc1421alphabet[(b0>>>2)&0x3f];
                     c[ci++]=__rfc1421alphabet[(b0<<4)&0x3f];
                     c[ci++]=__pad;
                     c[ci++]=__pad;
                     break;
 
                 default:
                     break;
             }
         }
 
         return c;
     }
 
     /**
      * Fast Base 64 encode as described in RFC 1421 and RFC2045
      * <p>Does not insert whitespace as described in RFC 1521, unless rfc2045 is passed as true.
      * <p> Avoids creating extra copies of the input/output.
      * @param b byte array to encode.
      * @param rfc2045 If true, break lines at 76 characters with CRLF
      * @return char array containing the encoded form of the input.
      */
     public static char[] encode(byte[] b, boolean rfc2045)
     {
         if (b==null)
             return null;
         if (!rfc2045)
             return encode(b);
 
         int bLen=b.length;
         int cLen=((bLen+2)/3)*4;
         cLen+=2+2*(cLen/76);
         char c[]=new char[cLen];
         int ci=0;
         int bi=0;
         byte b0, b1, b2;
         int stop=(bLen/3)*3;
         int l=0;
         while (bi<stop)
         {
             b0=b[bi++];
             b1=b[bi++];
             b2=b[bi++];
             c[ci++]=__rfc1421alphabet[(b0>>>2)&0x3f];
             c[ci++]=__rfc1421alphabet[(b0<<4)&0x3f|(b1>>>4)&0x0f];
             c[ci++]=__rfc1421alphabet[(b1<<2)&0x3f|(b2>>>6)&0x03];
             c[ci++]=__rfc1421alphabet[b2&0x3f];
             l+=4;
             if (l%76==0)
             {
                 c[ci++]=13;
                 c[ci++]=10;
             }
         }
 
         if (bLen!=bi)
         {
             switch (bLen%3)
             {
                 case 2:
                     b0=b[bi++];
                     b1=b[bi++];
                     c[ci++]=__rfc1421alphabet[(b0>>>2)&0x3f];
                     c[ci++]=__rfc1421alphabet[(b0<<4)&0x3f|(b1>>>4)&0x0f];
                     c[ci++]=__rfc1421alphabet[(b1<<2)&0x3f];
                     c[ci++]=__pad;
                     break;
 
                 case 1:
                     b0=b[bi++];
                     c[ci++]=__rfc1421alphabet[(b0>>>2)&0x3f];
                     c[ci++]=__rfc1421alphabet[(b0<<4)&0x3f];
                     c[ci++]=__pad;
                     c[ci++]=__pad;
                     break;
 
                 default:
                     break;
             }
         }
 
         c[ci++]=13;
         c[ci++]=10;
         return c;
     }
 
     /**
      * Base 64 decode as described in RFC 2045.
      * <p>Unlike {@link #decode(char[])}, extra whitespace is ignored.
      * @param encoded String to decode.
      * @param charEncoding String representing the character encoding
      *        used to map the decoded bytes into a String.
      * @return String decoded byte array.
      * @throws UnsupportedCharsetException if the encoding is not supported
      * @throws IllegalArgumentException if the input is not a valid
      *         B64 encoding.
      */
     public static String decode(String encoded,String charEncoding)
     {
         byte[] decoded=decode(encoded);
         if (charEncoding==null)
             return new String(decoded);
         return new String(decoded,Charset.forName(charEncoding));
     }
 
     /**
      * Base 64 decode as described in RFC 2045.
      * <p>Unlike {@link #decode(char[])}, extra whitespace is ignored.
      * @param encoded String to decode.
      * @param charEncoding Character encoding
      *        used to map the decoded bytes into a String.
      * @return String decoded byte array.
      * @throws IllegalArgumentException if the input is not a valid
      *         B64 encoding.
      */
     public static String decode(String encoded, Charset charEncoding)
     {
         byte[] decoded=decode(encoded);
         if (charEncoding==null)
             return new String(decoded);
         return new String(decoded, charEncoding);
     }
 
     /**
      * Fast Base 64 decode as described in RFC 1421.
      *
      * <p>Unlike other decode methods, this does not attempt to
      * cope with extra whitespace as described in RFC 1521/2045.
      * <p> Avoids creating extra copies of the input/output.
      * <p> Note this code has been flattened for performance.
      * @param b char array to decode.
      * @return byte array containing the decoded form of the input.
      * @throws IllegalArgumentException if the input is not a valid
      *         B64 encoding.
      */
     public static byte[] decode(char[] b)
     {
         if (b==null)
             return null;
 
         int bLen=b.length;
         if (bLen%4!=0)
             throw new IllegalArgumentException("Input block size is not 4");
 
         int li=bLen-1;
         while (li>=0 && b[li]==(byte)__pad)
             li--;
 
         if (li<0)
             return new byte[0];
 
         // Create result array of exact required size.
         int rLen=((li+1)*3)/4;
         byte r[]=new byte[rLen];
         int ri=0;
         int bi=0;
         int stop=(rLen/3)*3;
         byte b0,b1,b2,b3;
         try
         {
             while (ri<stop)
             {
                 b0=__rfc1421nibbles[b[bi++]];
                 b1=__rfc1421nibbles[b[bi++]];
                 b2=__rfc1421nibbles[b[bi++]];
                 b3=__rfc1421nibbles[b[bi++]];
                 if (b0<0 || b1<0 || b2<0 || b3<0)
                     throw new IllegalArgumentException("Not B64 encoded");
 
                 r[ri++]=(byte)(b0<<2|b1>>>4);
                 r[ri++]=(byte)(b1<<4|b2>>>2);
                 r[ri++]=(byte)(b2<<6|b3);
             }
 
             if (rLen!=ri)
             {
                 switch (rLen%3)
                 {
                     case 2:
                         b0=__rfc1421nibbles[b[bi++]];
                         b1=__rfc1421nibbles[b[bi++]];
                         b2=__rfc1421nibbles[b[bi++]];
                         if (b0<0 || b1<0 || b2<0)
                             throw new IllegalArgumentException("Not B64 encoded");
                         r[ri++]=(byte)(b0<<2|b1>>>4);
                         r[ri++]=(byte)(b1<<4|b2>>>2);
                         break;
 
                     case 1:
                         b0=__rfc1421nibbles[b[bi++]];
                         b1=__rfc1421nibbles[b[bi++]];
                         if (b0<0 || b1<0)
                             throw new IllegalArgumentException("Not B64 encoded");
                         r[ri++]=(byte)(b0<<2|b1>>>4);
                         break;
 
                     default:
                         break;
                 }
             }
         }
         catch (IndexOutOfBoundsException e)
         {
             throw new IllegalArgumentException("char "+bi
                     +" was not B64 encoded");
         }
 
         return r;
     }
 
     /**
      * Base 64 decode as described in RFC 2045.
      * <p>Unlike {@link #decode(char[])}, extra whitespace is ignored.
      * @param encoded String to decode.
      * @return byte array containing the decoded form of the input.
      * @throws IllegalArgumentException if the input is not a valid
      *         B64 encoding.
      */
     public static byte[] decode(String encoded)
     {
         if (encoded==null)
             return null;
 
         ByteArrayOutputStream bout = new ByteArrayOutputStream(4*encoded.length()/3);        
         decode(encoded, bout);
         return bout.toByteArray();
     }
     
     /* ------------------------------------------------------------ */
     /**
      * Base 64 decode as described in RFC 2045.
      * <p>Unlike {@link #decode(char[])}, extra whitespace is ignored.
      * @param encoded String to decode.
      * @param output stream for decoded bytes
      * @return byte array containing the decoded form of the input.
      * @throws IllegalArgumentException if the input is not a valid
      *         B64 encoding.
      */
     static public void decode (String encoded, ByteArrayOutputStream bout)
     {
         if (encoded==null)
             return;
         
         if (bout == null)
             throw new IllegalArgumentException("No outputstream for decoded bytes");
         
         int ci=0;
         byte nibbles[] = new byte[4];
         int s=0;
   
         while (ci<encoded.length())
         {
             char c=encoded.charAt(ci++);
 
             if (c==__pad)
                 break;
 
             if (Character.isWhitespace(c))
                 continue;
 
             byte nibble=__rfc1421nibbles[c];
             if (nibble<0)
                 throw new IllegalArgumentException("Not B64 encoded");
 
             nibbles[s++]=__rfc1421nibbles[c];
 
             switch(s)
             {
                 case 1:
                     break;
                 case 2:
                     bout.write(nibbles[0]<<2|nibbles[1]>>>4);
                     break;
                 case 3:
                     bout.write(nibbles[1]<<4|nibbles[2]>>>2);
                     break;
                 case 4:
                     bout.write(nibbles[2]<<6|nibbles[3]);
                     s=0;
                     break;
             }
 
         }
 
         return;
     }
     
 
     public static void encode(int value,Appendable buf) throws IOException
     {
         buf.append(__rfc1421alphabet[0x3f&((0xFC000000&value)>>26)]);
         buf.append(__rfc1421alphabet[0x3f&((0x03F00000&value)>>20)]);
         buf.append(__rfc1421alphabet[0x3f&((0x000FC000&value)>>14)]);
         buf.append(__rfc1421alphabet[0x3f&((0x00003F00&value)>>8)]);
         buf.append(__rfc1421alphabet[0x3f&((0x000000FC&value)>>2)]);
         buf.append(__rfc1421alphabet[0x3f&((0x00000003&value)<<4)]);
         buf.append('=');
     }
 
     public static void encode(long lvalue,Appendable buf) throws IOException
     {
         int value=(int)(0xFFFFFFFC&(lvalue>>32));
         buf.append(__rfc1421alphabet[0x3f&((0xFC000000&value)>>26)]);
         buf.append(__rfc1421alphabet[0x3f&((0x03F00000&value)>>20)]);
         buf.append(__rfc1421alphabet[0x3f&((0x000FC000&value)>>14)]);
         buf.append(__rfc1421alphabet[0x3f&((0x00003F00&value)>>8)]);
         buf.append(__rfc1421alphabet[0x3f&((0x000000FC&value)>>2)]);
 
         buf.append(__rfc1421alphabet[0x3f&((0x00000003&value)<<4) + (0xf&(int)(lvalue>>28))]);
 
         value=0x0FFFFFFF&(int)lvalue;
         buf.append(__rfc1421alphabet[0x3f&((0x0FC00000&value)>>22)]);
         buf.append(__rfc1421alphabet[0x3f&((0x003F0000&value)>>16)]);
         buf.append(__rfc1421alphabet[0x3f&((0x0000FC00&value)>>10)]);
         buf.append(__rfc1421alphabet[0x3f&((0x000003F0&value)>>4)]);
         buf.append(__rfc1421alphabet[0x3f&((0x0000000F&value)<<2)]);
     }
 }