/*
    * 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.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.impl.MetadataGenerator;
  import org.eclipse.aether.installation.InstallRequest;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.util.ConfigUtils;
  
  /**
   * Maven local GAV level metadata generator.
   * <p>
   * Local snapshot metadata contains non-transformed snapshot version.
   */
  class LocalSnapshotMetadataGenerator implements MetadataGenerator {
  
      private final Map<Object, LocalSnapshotMetadata> snapshots;
  
      private final Instant timestamp;
  
      LocalSnapshotMetadataGenerator(RepositorySystemSession session, InstallRequest request) {
          timestamp = (Instant) ConfigUtils.getObject(session, MonotonicClock.now(), Constants.MAVEN_START_INSTANT);
  
          snapshots = new LinkedHashMap<>();
      }
  
      @Override
      public Collection<? extends Metadata> prepare(Collection<? extends Artifact> artifacts) {
          for (Artifact artifact : artifacts) {
              if (artifact.isSnapshot()) {
                  Object key = LocalSnapshotMetadata.getKey(artifact);
                  LocalSnapshotMetadata snapshotMetadata = snapshots.get(key);
                  if (snapshotMetadata == null) {
                      snapshotMetadata = new LocalSnapshotMetadata(artifact, timestamp);
                      snapshots.put(key, snapshotMetadata);
                  }
                  snapshotMetadata.bind(artifact);
              }
          }
  
          return Collections.emptyList();
      }
  
      @Override
      public Artifact transformArtifact(Artifact artifact) {
          return artifact;
      }
  
      @Override
      public Collection<? extends Metadata> finish(Collection<? extends Artifact> artifacts) {
          return snapshots.values();
      }
  }