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.jet;
  
  import com.hazelcast.jet.core.DAG;
  import java.util.function.Function;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.runners.TransformHierarchy;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.util.construction.PTransformTranslation;
  import org.apache.beam.sdk.values.PValue;
  
  /** Logic that specifies how to apply translations when traversing the nodes of a Beam pipeline. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class JetGraphVisitor extends Pipeline.PipelineVisitor.Defaults {
  
    private final JetTranslationContext translationContext;
    private final Function<PTransform<?, ?>, JetTransformTranslator<?>> translatorProvider;
  
    private boolean finalized = false;
  
    JetGraphVisitor(
        JetPipelineOptions options,
        Function<PTransform<?, ?>, JetTransformTranslator<?>> translatorProvider) {
      this.translationContext = new JetTranslationContext(options);
      this.translatorProvider = translatorProvider;
    }
  
    @Override
    public CompositeBehavior enterCompositeTransform(TransformHierarchy.Node node) {
      if (finalized) {
        throw new IllegalStateException("Attempting to traverse an already finalized pipeline!");
      }
  
      PTransform<?, ?> transform = node.getTransform();
      if (transform != null) {
        JetTransformTranslator<?> translator = translatorProvider.apply(transform);
        if (translator != null) {
          translate(node, translator);
          return CompositeBehavior.DO_NOT_ENTER_TRANSFORM;
        }
      }
      return CompositeBehavior.ENTER_TRANSFORM;
    }
  
    @Override
    public void leaveCompositeTransform(TransformHierarchy.Node node) {
      if (finalized) {
        throw new IllegalStateException("Attempting to traverse an already finalized pipeline!");
      }
      if (node.isRootNode()) {
        finalized = true;
      }
    }
  
    @Override
    public void visitPrimitiveTransform(TransformHierarchy.Node node) {
      PTransform<?, ?> transform = node.getTransform();
      JetTransformTranslator<?> translator = translatorProvider.apply(transform);
      if (translator == null) {
        String transformUrn = PTransformTranslation.urnForTransform(transform);
        throw new UnsupportedOperationException(
            "The transform " + transformUrn + " is currently not supported.");
      }
      translate(node, translator);
    }
  
    @Override
    public void visitValue(PValue value, TransformHierarchy.Node producer) {
      // do nothing here
    }
  
    DAG getDAG() {
      return translationContext.getDagBuilder().getDag();
    }
  
    private <T extends PTransform<?, ?>> void translate(
        TransformHierarchy.Node node, JetTransformTranslator<?> translator) {
      @SuppressWarnings("unchecked")
      JetTransformTranslator<T> typedTranslator = (JetTransformTranslator<T>) translator;
      Pipeline pipeline = getPipeline();
      AppliedPTransform<?, ?, ?> appliedTransform = node.toAppliedPTransform(pipeline);
      typedTranslator.translate(pipeline, appliedTransform, node, translationContext);
    }
  }
  