package org.apache.archiva.checksum;

 /*

  * 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.

  */

 import java.io.IOException;

 import java.io.InputStream;

 import java.security.DigestInputStream;

 import java.security.MessageDigest;

 import java.security.NoSuchAlgorithmException;

 import java.util.List;

 import org.apache.commons.io.IOUtils;

 import org.apache.commons.io.output.NullOutputStream;

 /**

  * Checksum - simple checksum hashing routines. 

  *

  * @version $Id: Checksum.java 718864 2008-11-19 06:33:35Z brett $

  */

 public class Checksum

 {

     private static final int BUFFER_SIZE = 32768;

     public static void update( List<Checksum> checksums, InputStream stream )

         throws IOException

     {

         byte[] buffer = new byte[BUFFER_SIZE];

         int size = stream.read( buffer, 0, BUFFER_SIZE );

         while ( size >= 0 )

         {

             for ( Checksum checksum : checksums )

             {

                 checksum.update( buffer, 0, size );

             }

             size = stream.read( buffer, 0, BUFFER_SIZE );

         }

     }

     protected final MessageDigest md;

     private ChecksumAlgorithm checksumAlgorithm;

     public Checksum( ChecksumAlgorithm checksumAlgorithm )

     {

         this.checksumAlgorithm = checksumAlgorithm;

         try

         {

             md = MessageDigest.getInstance( checksumAlgorithm.getAlgorithm() );

         }

         catch ( NoSuchAlgorithmException e )

         {

             // Not really possible, but here none-the-less

             throw new IllegalStateException( "Unable to initialize MessageDigest algorithm " + checksumAlgorithm.getAlgorithm()

                 + " : " + e.getMessage(), e );

         }

     }

     public String getChecksum()

     {

         return Hex.encode( md.digest() );

     }

     public ChecksumAlgorithm getAlgorithm()

     {

         return this.checksumAlgorithm;

     }

     public void reset()

     {

         md.reset();

     }

     public Checksum update( byte[] buffer, int offset, int size )

     {

         md.update( buffer, 0, size );

         return this;

     }

     public Checksum update( InputStream stream )

         throws IOException

     {

         DigestInputStream dig = new DigestInputStream( stream, md );

         IOUtils.copy( dig, new NullOutputStream() );

         return this;

     }

 }