package org.eclipse.aether.internal.impl.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 javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.internal.impl.LocalPathComposer;
  import org.eclipse.aether.repository.ArtifactRepository;
  import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactory;
  import org.eclipse.aether.spi.io.FileProcessor;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Sparse file {@link FileTrustedChecksumsSourceSupport} implementation that use specified directory as base
   * directory, where it expects artifacts checksums on standard Maven2 "local" layout. This implementation uses Artifact
   * coordinates solely to form path from basedir, pretty much as Maven local repository does.
   * <p>
   * The source by default is "origin aware", it will factor in origin repository ID as well into base directory name
   * (for example ".checksums/central/...").
   * <p>
   * The checksums files are directly loaded from disk, so in-flight file changes during lifecycle of session are picked
   * up. This implementation can be simultaneously used to lookup and also write checksums. The written checksums
   * will become visible across all sessions right after the moment they were written.
   * <p>
   * The name of this implementation is "sparseDirectory".
   *
   * @see LocalPathComposer
   * @since 1.9.0
   */
  @Singleton
  @Named( SparseDirectoryTrustedChecksumsSource.NAME )
  public final class SparseDirectoryTrustedChecksumsSource
          extends FileTrustedChecksumsSourceSupport
  {
      public static final String NAME = "sparseDirectory";
  
      private static final Logger LOGGER = LoggerFactory.getLogger( SparseDirectoryTrustedChecksumsSource.class );
  
      private final FileProcessor fileProcessor;
  
      private final LocalPathComposer localPathComposer;
  
      @Inject
      public SparseDirectoryTrustedChecksumsSource( FileProcessor fileProcessor, LocalPathComposer localPathComposer )
      {
          super( NAME );
          this.fileProcessor = requireNonNull( fileProcessor );
          this.localPathComposer = requireNonNull( localPathComposer );
      }
  
      @Override
      protected Map<String, String> doGetTrustedArtifactChecksums(
              RepositorySystemSession session, Artifact artifact, ArtifactRepository artifactRepository,
              List<ChecksumAlgorithmFactory> checksumAlgorithmFactories )
      {
          final boolean originAware = isOriginAware( session );
          final HashMap<String, String> checksums = new HashMap<>();
          Path basedir = getBasedir( session, false );
          if ( Files.isDirectory( basedir ) )
          {
              for ( ChecksumAlgorithmFactory checksumAlgorithmFactory : checksumAlgorithmFactories )
              {
                  Path checksumPath = basedir.resolve(
                          calculateArtifactPath( originAware, artifact, artifactRepository, checksumAlgorithmFactory ) );
  
                  if ( !Files.isRegularFile( checksumPath ) )
                  {
                     LOGGER.debug( "Artifact '{}' trusted checksum '{}' not found on path '{}'",
                             artifact, checksumAlgorithmFactory.getName(), checksumPath );
                     continue;
                 }
 
                 try
                 {
                     String checksum = fileProcessor.readChecksum( checksumPath.toFile() );
                     if ( checksum != null )
                     {
                         checksums.put( checksumAlgorithmFactory.getName(), checksum );
                     }
                 }
                 catch ( IOException e )
                 {
                     // unexpected, log
                     LOGGER.warn( "Could not read artifact '{}' trusted checksum on path '{}'", artifact, checksumPath,
                             e );
                     throw new UncheckedIOException( e );
                 }
             }
         }
         return checksums;
     }
 
     @Override
     protected SparseDirectoryWriter doGetTrustedArtifactChecksumsWriter( RepositorySystemSession session )
     {
         return new SparseDirectoryWriter( getBasedir( session, true ), isOriginAware( session ) );
     }
 
     private String calculateArtifactPath( boolean originAware,
                                           Artifact artifact,
                                           ArtifactRepository artifactRepository,
                                           ChecksumAlgorithmFactory checksumAlgorithmFactory )
     {
         String path = localPathComposer.getPathForArtifact( artifact, false )
                 + "." + checksumAlgorithmFactory.getFileExtension();
         if ( originAware )
         {
             path = artifactRepository.getId() + "/" + path;
         }
         return path;
     }
 
     private class SparseDirectoryWriter implements Writer
     {
         private final Path basedir;
 
         private final boolean originAware;
 
         private SparseDirectoryWriter( Path basedir, boolean originAware )
         {
             this.basedir = basedir;
             this.originAware = originAware;
         }
 
         @Override
         public void addTrustedArtifactChecksums( Artifact artifact,
                                                  ArtifactRepository artifactRepository,
                                                  List<ChecksumAlgorithmFactory> checksumAlgorithmFactories,
                                                  Map<String, String> trustedArtifactChecksums ) throws IOException
         {
             for ( ChecksumAlgorithmFactory checksumAlgorithmFactory : checksumAlgorithmFactories )
             {
                 Path checksumPath = basedir.resolve( calculateArtifactPath(
                         originAware, artifact, artifactRepository, checksumAlgorithmFactory ) );
                 String checksum = requireNonNull(
                         trustedArtifactChecksums.get( checksumAlgorithmFactory.getName() ) );
                 fileProcessor.writeChecksum( checksumPath.toFile(), checksum );
             }
         }
    }
 }