package org.apache.archiva.transaction;
   
   /*
    * 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 org.apache.commons.io.FileUtils;
  import org.codehaus.plexus.digest.Digester;
  import org.codehaus.plexus.digest.DigesterException;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  /**
   * Abstract class for the TransactionEvents
   *
   *
   */
  public abstract class AbstractTransactionEvent
      implements TransactionEvent
  {
      private Map<File, File> backups = new HashMap<>();
  
      private List<File> createdDirs = new ArrayList<>();
  
      private List<File> createdFiles = new ArrayList<>();
  
      /**
       * {@link List}&lt;{@link Digester}&gt;
       */
      private List<? extends Digester> digesters;
  
      protected AbstractTransactionEvent()
      {
          this( new ArrayList<Digester>( 0 ) );
      }
  
      protected AbstractTransactionEvent( List<? extends Digester> digesters )
      {
          this.digesters = digesters;
      }
  
      protected List<? extends Digester> getDigesters()
      {
          return digesters;
      }
  
      /**
       * Method that creates a directory as well as all the parent directories needed
       *
       * @param dir The File directory to be created
       * @throws IOException when an unrecoverable error occurred
       */
      protected void mkDirs( File dir )
          throws IOException
      {
          List<File> createDirs = new ArrayList<>();
  
          File parent = dir;
          while ( !parent.exists() || !parent.isDirectory() )
          {
              createDirs.add( parent );
  
              parent = parent.getParentFile();
          }
  
          while ( !createDirs.isEmpty() )
          {
              File directory = createDirs.remove( createDirs.size() - 1 );
  
              if ( directory.mkdir() )
              {
                  createdDirs.add( directory );
              }
              else
              {
                  throw new IOException( "Failed to create directory: " + directory.getAbsolutePath() );
              }
         }
     }
 
     protected void revertMkDirs()
         throws IOException
     {
         if ( createdDirs != null )
         {
             Collections.reverse( createdDirs );
 
             while ( !createdDirs.isEmpty() )
             {
                 File dir = (File) createdDirs.remove( 0 );
 
                 if ( dir.isDirectory() && dir.list().length == 0 )
                 {
                     FileUtils.deleteDirectory( dir );
                 }
                 else
                 {
                     //cannot rollback created directory if it still contains files
                     break;
                 }
             }
         }
     }
 
     protected void revertFilesCreated()
         throws IOException
     {
         Iterator<File> it = createdFiles.iterator();
         while ( it.hasNext() )
         {
             File file = (File) it.next();
             file.delete();
             it.remove();
         }
     }
 
     protected void createBackup( File file )
         throws IOException
     {
         if ( file.exists() && file.isFile() )
         {
             File backup = File.createTempFile( "temp-", ".backup" );
 
             FileUtils.copyFile( file, backup );
 
             backup.deleteOnExit();
 
             backups.put( file, backup );
         }
     }
 
     protected void restoreBackups()
         throws IOException
     {
         for ( Map.Entry<File, File> entry : backups.entrySet() )
         {
             FileUtils.copyFile( entry.getValue(), entry.getKey() );
         }
     }
 
     protected void restoreBackup( File file )
         throws IOException
     {
         File backup = (File) backups.get( file );
         if ( backup != null )
         {
             FileUtils.copyFile( backup, file );
         }
     }
 
     /**
      * Create checksums of file using all digesters defined at construction time.
      *
      * @param file
      * @param force whether existing checksums should be overwritten or not
      * @throws IOException
      */
     protected void createChecksums( File file, boolean force )
         throws IOException
     {
         for ( Digester digester : getDigesters() )
         {
             File checksumFile = new File( file.getAbsolutePath() + "." + getDigesterFileExtension( digester ) );
             if ( checksumFile.exists() )
             {
                 if ( !force )
                 {
                     continue;
                 }
                 createBackup( checksumFile );
             }
             else
             {
                 createdFiles.add( checksumFile );
             }
 
             try
             {
                 writeStringToFile( checksumFile, digester.calc( file ) );
             }
             catch ( DigesterException e )
             {
                 throw (IOException) e.getCause();
             }
         }
     }
 
     /**
      * TODO: Remove in favor of using FileUtils directly.
      */
     protected void writeStringToFile( File file, String content )
         throws IOException
     {
         FileUtils.writeStringToFile( file, content );
     }
 
     /**
      * File extension for checksums
      * TODO should be moved to plexus-digester ?
      */
     protected String getDigesterFileExtension( Digester digester )
     {
         return digester.getAlgorithm().toLowerCase().replaceAll( "-", "" );
     }
 
 }