/*
    * 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.
   */
  package org.eclipse.aether.internal.impl.checksum;
  
  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 java.util.function.Function;
  
  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.ChecksumProcessor;
  import org.eclipse.aether.util.ConfigUtils;
  import org.eclipse.aether.util.repository.RepositoryIdHelper;
  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 String CONFIG_PROPS_PREFIX =
              FileTrustedChecksumsSourceSupport.CONFIG_PROPS_PREFIX + NAME + ".";
  
      /**
       * Is checksum source enabled?
       *
       * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
       * @configurationType {@link java.lang.Boolean}
       * @configurationDefaultValue false
       */
      public static final String CONFIG_PROP_ENABLED = FileTrustedChecksumsSourceSupport.CONFIG_PROPS_PREFIX + NAME;
  
      /**
       * The basedir where checksums are. If relative, is resolved from local repository root.
       *
       * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
       * @configurationType {@link java.lang.String}
       * @configurationDefaultValue {@link #LOCAL_REPO_PREFIX_DIR}
       */
      public static final String CONFIG_PROP_BASEDIR = CONFIG_PROPS_PREFIX + "basedir";
  
      public static final String LOCAL_REPO_PREFIX_DIR = ".checksums";
  
      /**
       * Is source origin aware?
       *
       * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
       * @configurationType {@link java.lang.Boolean}
       * @configurationDefaultValue true
       */
      public static final String CONFIG_PROP_ORIGIN_AWARE = CONFIG_PROPS_PREFIX + "originAware";
 
     private static final Logger LOGGER = LoggerFactory.getLogger(SparseDirectoryTrustedChecksumsSource.class);
 
     private final ChecksumProcessor checksumProcessor;
 
     private final LocalPathComposer localPathComposer;
 
     @Inject
     public SparseDirectoryTrustedChecksumsSource(
             ChecksumProcessor checksumProcessor, LocalPathComposer localPathComposer) {
         this.checksumProcessor = requireNonNull(checksumProcessor);
         this.localPathComposer = requireNonNull(localPathComposer);
     }
 
     @Override
     protected boolean isEnabled(RepositorySystemSession session) {
         return ConfigUtils.getBoolean(session, false, CONFIG_PROP_ENABLED);
     }
 
     private boolean isOriginAware(RepositorySystemSession session) {
         return ConfigUtils.getBoolean(session, true, CONFIG_PROP_ORIGIN_AWARE);
     }
 
     @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, LOCAL_REPO_PREFIX_DIR, CONFIG_PROP_BASEDIR, false);
         if (Files.isDirectory(basedir)) {
             for (ChecksumAlgorithmFactory checksumAlgorithmFactory : checksumAlgorithmFactories) {
                 Path checksumPath = basedir.resolve(calculateArtifactPath(
                         originAware,
                         artifact,
                         RepositoryIdHelper.cachedIdToPathSegment(session).apply(artifactRepository),
                         checksumAlgorithmFactory));
 
                 if (!Files.isRegularFile(checksumPath)) {
                     LOGGER.debug(
                             "Artifact '{}' trusted checksum '{}' not found on path '{}'",
                             artifact,
                             checksumAlgorithmFactory.getName(),
                             checksumPath);
                     continue;
                 }
 
                 try {
                     String checksum = checksumProcessor.readChecksum(checksumPath);
                     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 Writer doGetTrustedArtifactChecksumsWriter(RepositorySystemSession session) {
         return new SparseDirectoryWriter(
                 getBasedir(session, LOCAL_REPO_PREFIX_DIR, CONFIG_PROP_BASEDIR, true),
                 isOriginAware(session),
                 RepositoryIdHelper.cachedIdToPathSegment(session));
     }
 
     private String calculateArtifactPath(
             boolean originAware,
             Artifact artifact,
             String safeRepositoryId,
             ChecksumAlgorithmFactory checksumAlgorithmFactory) {
         String path = localPathComposer.getPathForArtifact(artifact, false) + "."
                 + checksumAlgorithmFactory.getFileExtension();
         if (originAware) {
             path = safeRepositoryId + "/" + path;
         }
         return path;
     }
 
     private class SparseDirectoryWriter implements Writer {
         private final Path basedir;
 
         private final boolean originAware;
 
         private final Function<ArtifactRepository, String> idToPathSegmentFunction;
 
         private SparseDirectoryWriter(
                 Path basedir, boolean originAware, Function<ArtifactRepository, String> idToPathSegmentFunction) {
             this.basedir = basedir;
             this.originAware = originAware;
             this.idToPathSegmentFunction = idToPathSegmentFunction;
         }
 
         @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,
                         idToPathSegmentFunction.apply(artifactRepository),
                         checksumAlgorithmFactory));
                 String checksum = requireNonNull(trustedArtifactChecksums.get(checksumAlgorithmFactory.getName()));
                 checksumProcessor.writeChecksum(checksumPath, checksum);
             }
         }
     }
 }