/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *  http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package org.apache.geronimo.mail.util;
  
  import java.io.IOException;
  import java.io.OutputStream;
  
  public class HexEncoder
      implements Encoder
  {
      protected final byte[] encodingTable =
          {
              (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'
          };
  
      /*
       * set up the decoding table.
       */
      protected final byte[] decodingTable = new byte[128];
  
      protected void initialiseDecodingTable()
      {
          for (int i = 0; i < encodingTable.length; i++)
          {
              decodingTable[encodingTable[i]] = (byte)i;
          }
  
          decodingTable['A'] = decodingTable['a'];
          decodingTable['B'] = decodingTable['b'];
          decodingTable['C'] = decodingTable['c'];
          decodingTable['D'] = decodingTable['d'];
          decodingTable['E'] = decodingTable['e'];
          decodingTable['F'] = decodingTable['f'];
      }
  
      public HexEncoder()
      {
          initialiseDecodingTable();
      }
  
      /**
       * encode the input data producing a Hex output stream.
       *
       * @return the number of bytes produced.
       */
      public int encode(
          byte[]                data,
          int                    off,
          int                    length,
          OutputStream    out)
          throws IOException
      {
          for (int i = off; i < (off + length); i++)
          {
              int    v = data[i] & 0xff;
  
              out.write(encodingTable[(v >>> 4)]);
              out.write(encodingTable[v & 0xf]);
          }
  
          return length * 2;
      }
  
      private boolean ignore(
          char    c)
      {
          return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
      }
  
      /**
       * decode the Hex encoded byte data writing it to the given output stream,
       * whitespace characters will be ignored.
       *
       * @return the number of bytes produced.
       */
      public int decode(
          byte[]                data,
          int                    off,
          int                    length,
          OutputStream    out)
          throws IOException
     {
         byte[]    bytes;
         byte    b1, b2;
         int        outLen = 0;
 
         int        end = off + length;
 
         while (end > 0)
         {
             if (!ignore((char)data[end - 1]))
             {
                 break;
             }
 
             end--;
         }
 
         int i = off;
         while (i < end)
         {
             while (i < end && ignore((char)data[i]))
             {
                 i++;
             }
 
             b1 = decodingTable[data[i++]];
 
             while (i < end && ignore((char)data[i]))
             {
                 i++;
             }
 
             b2 = decodingTable[data[i++]];
 
             out.write((b1 << 4) | b2);
 
             outLen++;
         }
 
         return outLen;
     }
 
     /**
      * decode the Hex encoded String data writing it to the given output stream,
      * whitespace characters will be ignored.
      *
      * @return the number of bytes produced.
      */
     public int decode(
         String                data,
         OutputStream    out)
         throws IOException
     {
         byte[]    bytes;
         byte    b1, b2, b3, b4;
         int        length = 0;
 
         int        end = data.length();
 
         while (end > 0)
         {
             if (!ignore(data.charAt(end - 1)))
             {
                 break;
             }
 
             end--;
         }
 
         int i = 0;
         while (i < end)
         {
             while (i < end && ignore(data.charAt(i)))
             {
                 i++;
             }
 
             b1 = decodingTable[data.charAt(i++)];
 
             while (i < end && ignore(data.charAt(i)))
             {
                 i++;
             }
 
             b2 = decodingTable[data.charAt(i++)];
 
             out.write((b1 << 4) | b2);
 
             length++;
         }
 
         return length;
     }
 }