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.runners.direct;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import org.apache.beam.runners.core.GroupByKeyViaGroupByKeyOnly;
  import org.apache.beam.runners.core.GroupByKeyViaGroupByKeyOnly.GroupByKeyOnly;
  import org.apache.beam.runners.core.KeyedWorkItem;
  import org.apache.beam.runners.core.KeyedWorkItems;
  import org.apache.beam.runners.direct.DirectGroupByKey.DirectGroupByKeyOnly;
  import org.apache.beam.runners.local.StructuralKey;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.coders.KvCoder;
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowedValues;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  
  /**
   * The {@link DirectRunner} {@link TransformEvaluatorFactory} for the {@link GroupByKeyOnly} {@link
   * PTransform}.
   */
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class GroupByKeyOnlyEvaluatorFactory implements TransformEvaluatorFactory {
    private final EvaluationContext evaluationContext;
  
    GroupByKeyOnlyEvaluatorFactory(EvaluationContext evaluationContext) {
      this.evaluationContext = evaluationContext;
    }
  
    @Override
    public <InputT> TransformEvaluator<InputT> forApplication(
        AppliedPTransform<?, ?, ?> application, CommittedBundle<?> inputBundle) {
      @SuppressWarnings({"cast", "unchecked", "rawtypes"})
      TransformEvaluator<InputT> evaluator = createEvaluator((AppliedPTransform) application);
      return evaluator;
    }
  
    @Override
    public void cleanup() {}
  
    private <K, V> TransformEvaluator<KV<K, V>> createEvaluator(
        final AppliedPTransform<
                PCollection<KV<K, V>>, PCollection<KeyedWorkItem<K, V>>, DirectGroupByKeyOnly<K, V>>
            application) {
      return new GroupByKeyOnlyEvaluator<>(evaluationContext, application);
    }
  
    /**
     * A transform evaluator for the pseudo-primitive {@link GroupByKeyOnly}. Windowing is ignored;
     * all input should be in the global window since all output will be as well.
     *
     * @see GroupByKeyViaGroupByKeyOnly
     */
    private static class GroupByKeyOnlyEvaluator<K, V> implements TransformEvaluator<KV<K, V>> {
      private final EvaluationContext evaluationContext;
  
      private final AppliedPTransform<
              PCollection<KV<K, V>>, PCollection<KeyedWorkItem<K, V>>, DirectGroupByKeyOnly<K, V>>
          application;
      private final Coder<K> keyCoder;
      private Map<StructuralKey<K>, List<WindowedValue<V>>> groupingMap;
  
      public GroupByKeyOnlyEvaluator(
          EvaluationContext evaluationContext,
          AppliedPTransform<
                  PCollection<KV<K, V>>, PCollection<KeyedWorkItem<K, V>>, DirectGroupByKeyOnly<K, V>>
              application) {
        this.evaluationContext = evaluationContext;
        this.application = application;
        this.keyCoder =
            getKeyCoder(
                ((PCollection<KV<K, V>>) Iterables.getOnlyElement(application.getInputs().values()))
                    .getCoder());
        this.groupingMap = new HashMap<>();
      }
  
      private Coder<K> getKeyCoder(Coder<KV<K, V>> coder) {
        checkState(
            coder instanceof KvCoder,
            "%s requires a coder of class %s."
                + " This is an internal error; this is checked during pipeline construction"
                + " but became corrupted.",
            getClass().getSimpleName(),
            KvCoder.class.getSimpleName());
        @SuppressWarnings("unchecked")
        Coder<K> keyCoder = ((KvCoder<K, V>) coder).getKeyCoder();
        return keyCoder;
      }
  
      @Override
      public void processElement(WindowedValue<KV<K, V>> element) {
        KV<K, V> kv = element.getValue();
        K key = kv.getKey();
        StructuralKey<K> groupingKey = StructuralKey.of(key, keyCoder);
        List<WindowedValue<V>> values =
            groupingMap.computeIfAbsent(groupingKey, k -> new ArrayList<>());
        values.add(element.withValue(kv.getValue()));
      }
  
      @Override
      public TransformResult<KV<K, V>> finishBundle() {
        StepTransformResult.Builder resultBuilder = StepTransformResult.withoutHold(application);
        for (Map.Entry<StructuralKey<K>, List<WindowedValue<V>>> groupedEntry :
            groupingMap.entrySet()) {
          K key = groupedEntry.getKey().getKey();
          KeyedWorkItem<K, V> groupedKv =
              KeyedWorkItems.elementsWorkItem(key, groupedEntry.getValue());
          UncommittedBundle<KeyedWorkItem<K, V>> bundle =
              evaluationContext.createKeyedBundle(
                  StructuralKey.of(key, keyCoder),
                  (PCollection<KeyedWorkItem<K, V>>)
                      Iterables.getOnlyElement(application.getOutputs().values()));
          bundle.add(WindowedValues.valueInGlobalWindow(groupedKv));
          resultBuilder.addOutput(bundle);
        }
        return resultBuilder.build();
      }
    }
  }
  