/*
    * 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 java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.file.Path;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  import org.eclipse.aether.ConfigurationProperties;
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.repository.ArtifactRepository;
  import org.eclipse.aether.repository.RemoteRepository;
  import org.eclipse.aether.spi.checksums.TrustedChecksumsSource;
  import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactory;
  import org.eclipse.aether.spi.remoterepo.RepositoryKeyFunctionFactory;
  import org.eclipse.aether.util.DirectoryUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Support class for implementing {@link TrustedChecksumsSource} backed by local filesystem. It implements basic support
   * like basedir calculation, "enabled" flag and "originAware" flag.
   * <p>
   * The configuration keys supported:
   * <ul>
   *     <li><pre>aether.trustedChecksumsSource.${name}</pre> (boolean) must be explicitly set to "true"
   *     to become enabled</li>
   *     <li><pre>aether.trustedChecksumsSource.${name}.basedir</pre> (string, path) directory from where implementation
   *     can use files. May be relative path (then is resolved against local repository basedir) or absolute. If unset,
   *     default value is ".checksums" and is resolved against local repository basedir.</li>
   *     <li><pre>aether.trustedChecksumsSource.${name}.originAware</pre> (boolean) whether to make implementation
   *     "originAware", to factor in origin repository ID as well or not.</li>
   * </ul>
   * <p>
   * This implementation ensures that implementations have "name" property, used in configuration properties above.
   *
   * @since 1.9.0
   */
  public abstract class FileTrustedChecksumsSourceSupport implements TrustedChecksumsSource {
      protected static final String CONFIG_PROPS_PREFIX =
              ConfigurationProperties.PREFIX_AETHER + "trustedChecksumsSource.";
  
      protected final Logger logger = LoggerFactory.getLogger(getClass());
  
      private final RepositoryKeyFunctionFactory repositoryKeyFunctionFactory;
  
      protected FileTrustedChecksumsSourceSupport(RepositoryKeyFunctionFactory repositoryKeyFunctionFactory) {
          this.repositoryKeyFunctionFactory = requireNonNull(repositoryKeyFunctionFactory);
      }
  
      /**
       * This implementation will call into underlying code only if enabled, and will enforce non-{@code null} return
       * value. In worst case, empty map should be returned, meaning "no trusted checksums available".
       */
      @Override
      public Map<String, String> getTrustedArtifactChecksums(
              RepositorySystemSession session,
              Artifact artifact,
              ArtifactRepository artifactRepository,
              List<ChecksumAlgorithmFactory> checksumAlgorithmFactories) {
          requireNonNull(session, "session is null");
          requireNonNull(artifact, "artifact is null");
          requireNonNull(artifactRepository, "artifactRepository is null");
          requireNonNull(checksumAlgorithmFactories, "checksumAlgorithmFactories is null");
          if (isEnabled(session)) {
              return requireNonNull(
                      doGetTrustedArtifactChecksums(session, artifact, artifactRepository, checksumAlgorithmFactories));
          }
          return null;
      }
  
      /**
       * This implementation will call into underlying code only if enabled, and will enforce non-{@code null} return
       * value. In worst case, empty map should be returned, meaning "no trusted checksums available".
       *
       * @since 2.0.23
      */
     @Override
     public Map<String, String> getTrustedMetadataChecksums(
             RepositorySystemSession session,
             Metadata metadata,
             ArtifactRepository artifactRepository,
             List<ChecksumAlgorithmFactory> checksumAlgorithmFactories) {
         requireNonNull(session, "session is null");
         requireNonNull(metadata, "metadata is null");
         requireNonNull(artifactRepository, "artifactRepository is null");
         requireNonNull(checksumAlgorithmFactories, "checksumAlgorithmFactories is null");
         if (isEnabled(session)) {
             return requireNonNull(
                     doGetTrustedMetadataChecksums(session, metadata, artifactRepository, checksumAlgorithmFactories));
         }
         return null;
     }
 
     /**
      * This implementation will call into underlying code only if enabled. Underlying implementation may still choose
      * to return {@code null}.
      */
     @Override
     public Writer getTrustedArtifactChecksumsWriter(RepositorySystemSession session) {
         requireNonNull(session, "session is null");
         if (isEnabled(session)) {
             return doGetTrustedArtifactChecksumsWriter(session);
         }
         return null;
     }
 
     /**
      * Implementors MUST NOT return {@code null} at this point, as this source is enabled.
      */
     protected abstract Map<String, String> doGetTrustedArtifactChecksums(
             RepositorySystemSession session,
             Artifact artifact,
             ArtifactRepository artifactRepository,
             List<ChecksumAlgorithmFactory> checksumAlgorithmFactories);
 
     /**
      * Implementors MUST NOT return {@code null} at this point, as this source is enabled. Metadata checksums are
      * looked up using the same file conventions as artifact checksums, with the metadata path composed from the
      * origin repository key (for example {@code g/a/v/maven-metadata-central.xml}).
      *
      * @since 2.0.23
      */
     protected abstract Map<String, String> doGetTrustedMetadataChecksums(
             RepositorySystemSession session,
             Metadata metadata,
             ArtifactRepository artifactRepository,
             List<ChecksumAlgorithmFactory> checksumAlgorithmFactories);
 
     /**
      * Implementors may override this method and return {@link Writer} instance.
      */
     protected Writer doGetTrustedArtifactChecksumsWriter(RepositorySystemSession session) {
         return null;
     }
 
     /**
      * Returns {@code true} if session configuration marks this instance as enabled.
      * <p>
      * Default value is {@code false}.
      */
     protected abstract boolean isEnabled(RepositorySystemSession session);
 
     /**
      * Uses utility {@link DirectoryUtils#resolveDirectory(RepositorySystemSession, String, String, boolean)} to
      * calculate (and maybe create) basedir for this implementation, never returns {@code null}. The returned
      * {@link Path} may not exist, if invoked with {@code mayCreate} being {@code false}.
      * <p>
      * Default value is {@code ${LOCAL_REPOSITORY}/.checksums}.
      *
      * @return The {@link Path} of basedir, never {@code null}.
      */
     protected Path getBasedir(
             RepositorySystemSession session, String defaultValue, String configPropKey, boolean mayCreate) {
         try {
             return DirectoryUtils.resolveDirectory(session, defaultValue, configPropKey, mayCreate);
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }
     }
 
     /**
      * Returns repository keys to be used on file system layout. Always returns a list with at least one element.
      * Elements are sorted from "most specific" to "least specific" keys.
      *
      * @since 2.0.14
      */
     protected List<String> repositoryKey(RepositorySystemSession session, ArtifactRepository artifactRepository) {
         ArrayList<String> keys = new ArrayList<>();
         if (artifactRepository instanceof RemoteRepository) {
             RemoteRepository rr = (RemoteRepository) artifactRepository;
             keys.add(repositoryKeyFunctionFactory
                     .trackingRepositoryKeyFunction(session)
                     .apply(rr, null));
             keys.add(repositoryKeyFunctionFactory
                     .systemRepositoryKeyFunction(session)
                     .apply(rr, null));
         } else {
             keys.add(artifactRepository.getId());
         }
         return keys;
     }
 }