package org.codehaus.plexus.digest;

 /*

  * Copyright 2001-2006 The Codehaus.

  *

  * Licensed 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 org.codehaus.plexus.util.IOUtil;

 import org.codehaus.plexus.util.StringUtils;

 import java.io.File;

 import java.io.FileInputStream;

 import java.io.IOException;

 /**

  * Create a digest for a file.

  *

  * @author <a href="mailto:brett@apache.org">Brett Porter</a>

  */

 public abstract class AbstractDigester

     implements Digester

 {

     private final StreamingDigester streamingDigester;

     protected AbstractDigester( StreamingDigester streamingDigester )

     {

         this.streamingDigester = streamingDigester;

     }

     public String getAlgorithm()

     {

         return streamingDigester.getAlgorithm();

     }

     public String calc( File file )

         throws DigesterException

     {

         FileInputStream fis = null;

         try

         {

             fis = new FileInputStream( file );

             streamingDigester.reset();

             streamingDigester.update( fis );

             return streamingDigester.calc();

         }

         catch ( IOException e )

         {

             throw new DigesterException( "Unable to calculate the " + streamingDigester.getAlgorithm() +

                 " hashcode for " + file.getAbsolutePath() + ": " + e.getMessage(), e );

         }

         finally

         {

             IOUtil.close( fis );

         }

     }

     public void verify( File file, String checksum )

         throws DigesterException

     {

         String trimmedChecksum =

             DigestUtils.cleanChecksum( checksum, streamingDigester.getAlgorithm(), file.getName() );

         //Create checksum for file

         String sum = calc( file );

         if ( !StringUtils.equalsIgnoreCase( trimmedChecksum, sum ) )

         {

             throw new DigesterException( "Checksum failed (expected=" + trimmedChecksum + ", actual=" + sum + ")" );

         }

     }

     public String toString()

     {

         return "[Digester:" + streamingDigester.getAlgorithm() + "]";

     }

 }