/*
    * 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.apache.maven.impl.resolver;
  
  import java.time.Instant;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.Map;
  
  import org.apache.maven.api.Constants;
  import org.apache.maven.api.MonotonicClock;
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.deployment.DeployRequest;
  import org.eclipse.aether.impl.MetadataGenerator;
  import org.eclipse.aether.installation.InstallRequest;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.util.ConfigUtils;
  
  /**
   * Maven GA level metadata generator.
   *
   * Version metadata contains list of existing baseVersions within this GA.
   */
  class VersionsMetadataGenerator implements MetadataGenerator {
  
      private final Map<Object, VersionsMetadata> versions;
  
      private final Map<Object, VersionsMetadata> processedVersions;
  
      private final Instant timestamp;
  
      VersionsMetadataGenerator(RepositorySystemSession session, InstallRequest request) {
          this(session, request.getMetadata());
      }
  
      VersionsMetadataGenerator(RepositorySystemSession session, DeployRequest request) {
          this(session, request.getMetadata());
      }
  
      private VersionsMetadataGenerator(RepositorySystemSession session, Collection<? extends Metadata> metadatas) {
          versions = new LinkedHashMap<>();
          processedVersions = new LinkedHashMap<>();
          timestamp = (Instant) ConfigUtils.getObject(session, MonotonicClock.now(), Constants.MAVEN_START_INSTANT);
  
          /*
           * NOTE: This should be considered a quirk to support interop with Maven's legacy ArtifactDeployer which
           * processes one artifact at a time and hence cannot associate the artifacts from the same project to use the
           * same version index. Allowing the caller to pass in metadata from a previous deployment allows to re-establish
           * the association between the artifacts of the same project.
           */
          for (Iterator<? extends Metadata> it = metadatas.iterator(); it.hasNext(); ) {
              Metadata metadata = it.next();
              if (metadata instanceof VersionsMetadata versionsMetadata) {
                  it.remove();
                  processedVersions.put(versionsMetadata.getKey(), versionsMetadata);
              }
          }
      }
  
      @Override
      public Collection<? extends Metadata> prepare(Collection<? extends Artifact> artifacts) {
          return Collections.emptyList();
      }
  
      @Override
      public Artifact transformArtifact(Artifact artifact) {
          return artifact;
      }
  
      @Override
      public Collection<? extends Metadata> finish(Collection<? extends Artifact> artifacts) {
          for (Artifact artifact : artifacts) {
              Object key = VersionsMetadata.getKey(artifact);
              if (processedVersions.get(key) == null) {
                  VersionsMetadata versionsMetadata = versions.get(key);
                  if (versionsMetadata == null) {
                      versionsMetadata = new VersionsMetadata(artifact, timestamp);
                      versions.put(key, versionsMetadata);
                  }
              }
         }
 
         return versions.values();
     }
 }