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.schemas.io;
  
  import java.io.ByteArrayOutputStream;
  import org.apache.beam.sdk.annotations.Internal;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.transforms.MapElements;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.transforms.SerializableFunction;
  import org.apache.beam.sdk.transforms.SimpleFunction;
  import org.apache.beam.sdk.transforms.WithFailures.Result;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PDone;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
  import org.apache.commons.lang3.exception.ExceptionUtils;
  
  @Internal
  public class DeadLetteredTransform<InputT, OutputT>
      extends PTransform<PCollection<? extends InputT>, PCollection<OutputT>> {
    private final SimpleFunction<InputT, OutputT> transform;
    private final PTransform<PCollection<Failure>, PDone> deadLetter;
  
    public DeadLetteredTransform(SimpleFunction<InputT, OutputT> transform, String deadLetterConfig) {
      this(transform, GenericDlq.getDlqTransform(deadLetterConfig));
    }
  
    @VisibleForTesting
    DeadLetteredTransform(
        SimpleFunction<InputT, OutputT> transform,
        PTransform<PCollection<Failure>, PDone> deadLetter) {
      this.transform = transform;
      this.deadLetter = deadLetter;
    }
  
    // Required to capture the generic type parameter of the PCollection.
    private <RealInputT extends InputT> PCollection<OutputT> expandInternal(
        PCollection<RealInputT> input) {
      Coder<RealInputT> coder = input.getCoder();
      SerializableFunction<RealInputT, OutputT> localTransform = transform::apply;
      MapElements.MapWithFailures<RealInputT, OutputT, Failure> mapWithFailures =
          MapElements.into(transform.getOutputTypeDescriptor())
              .via(localTransform)
              .exceptionsInto(TypeDescriptor.of(Failure.class))
              .exceptionsVia(
                  x -> {
                    try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {
                      coder.encode(x.element(), os);
                      return Failure.newBuilder()
                          .setPayload(os.toByteArray())
                          .setError(
                              String.format(
                                  "%s%n%n%s",
                                  x.exception().getMessage(),
                                  ExceptionUtils.getStackTrace(x.exception())))
                          .build();
                    }
                  });
      Result<PCollection<OutputT>, Failure> result = mapWithFailures.expand(input);
      result.failures().apply(deadLetter);
      return result.output();
    }
  
    @Override
    public PCollection<OutputT> expand(PCollection<? extends InputT> input) {
      return expandInternal(input);
    }
  }
  