content: /*
   * 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.beam.sdk.util.construction;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  import org.apache.beam.model.pipeline.v1.RunnerApi;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableMap;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
  
  /**
   * A default artifact resolver. This resolver applies {@link ResolutionFn} in the reversed order
   * they registered i.e. the function registered later overrides the earlier one if they resolve the
   * same artifact.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class DefaultArtifactResolver implements ArtifactResolver {
    public static final ArtifactResolver INSTANCE = new DefaultArtifactResolver();
  
    // Not threadsafe, access through register() and regesteredFns().
    private List<ResolutionFn> fns =
        Lists.newArrayList(
            (info) -> {
              if (BeamUrns.getUrn(RunnerApi.StandardArtifacts.Types.FILE).equals(info.getTypeUrn())) {
                return Optional.of(ImmutableList.of(info));
              } else {
                return Optional.empty();
              }
            });
  
    private synchronized List<ResolutionFn> regesteredFns() {
      return ImmutableList.copyOf(fns);
    }
  
    private Function<RunnerApi.ArtifactInformation, Stream<RunnerApi.ArtifactInformation>> resolver =
        (info) -> {
          for (ResolutionFn fn : Lists.reverse(regesteredFns())) {
            Optional<List<RunnerApi.ArtifactInformation>> resolved = fn.resolve(info);
            if (resolved.isPresent()) {
              return resolved.get().stream();
            }
          }
          throw new RuntimeException(String.format("Cannot resolve artifact information: %s", info));
        };
  
    @Override
    public synchronized void register(ResolutionFn fn) {
      fns.add(fn);
    }
  
    @Override
    public List<RunnerApi.ArtifactInformation> resolveArtifacts(
        List<RunnerApi.ArtifactInformation> artifacts) {
      for (ResolutionFn fn : Lists.reverse(regesteredFns())) {
        List<RunnerApi.ArtifactInformation> moreResolved = new ArrayList<>();
        for (RunnerApi.ArtifactInformation artifact : artifacts) {
          Optional<List<RunnerApi.ArtifactInformation>> resolved = fn.resolve(artifact);
          if (resolved.isPresent()) {
            moreResolved.addAll(resolved.get());
          } else {
            moreResolved.add(artifact);
          }
        }
        artifacts = moreResolved;
      }
      return artifacts;
    }
  
    @Override
    public RunnerApi.Pipeline resolveArtifacts(RunnerApi.Pipeline pipeline) {
      ImmutableMap.Builder<String, RunnerApi.Environment> environmentMapBuilder =
          ImmutableMap.builder();
      for (Map.Entry<String, RunnerApi.Environment> entry :
          pipeline.getComponents().getEnvironmentsMap().entrySet()) {
        List<RunnerApi.ArtifactInformation> resolvedDependencies =
            entry
                .getValue()
                .getDependenciesList()
                .parallelStream()
                .flatMap(resolver)
                .collect(Collectors.toList());
        environmentMapBuilder.put(
            entry.getKey(),
            entry
                .getValue()
                .toBuilder()
                .clearDependencies()
                .addAllDependencies(resolvedDependencies)
                .build());
      }
      return pipeline
          .toBuilder()
          .setComponents(
              pipeline.getComponents().toBuilder().putAllEnvironments(environmentMapBuilder.build()))
          .build();
    }
  }
  