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() + "]";
      }
  }