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.kafka.connect.runtime;
  
  import org.apache.kafka.connect.connector.ConnectRecord;
  import org.apache.kafka.connect.runtime.errors.ProcessingContext;
  import org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator;
  import org.apache.kafka.connect.runtime.errors.Stage;
  import org.apache.kafka.connect.transforms.Transformation;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.List;
  import java.util.Objects;
  import java.util.StringJoiner;
  import java.util.stream.Collectors;
  
  /**
   * Represents a chain of {@link Transformation}s to be applied to a {@link ConnectRecord} serially.
   * @param <T> The type of record included in the {@link ProcessingContext} associated with each record
   * @param <R> The type of record (must be an implementation of {@link ConnectRecord})
   */
  public class TransformationChain<T, R extends ConnectRecord<R>> implements AutoCloseable {
      private static final Logger log = LoggerFactory.getLogger(TransformationChain.class);
  
      private final List<TransformationStage<R>> transformationStages;
      private final RetryWithToleranceOperator<T> retryWithToleranceOperator;
  
      public TransformationChain(List<TransformationStage<R>> transformationStages, RetryWithToleranceOperator<T> retryWithToleranceOperator) {
          this.transformationStages = transformationStages;
          this.retryWithToleranceOperator = retryWithToleranceOperator;
      }
  
      public R apply(ProcessingContext<T> context, R record) {
          if (transformationStages.isEmpty()) return record;
  
          for (final TransformationStage<R> transformationStage : transformationStages) {
              final R current = record;
  
              log.trace("Applying transformation {} to {}",
                  transformationStage.transformClass().getName(), record);
              // execute the operation
              record = retryWithToleranceOperator.execute(context, () -> transformationStage.apply(current), Stage.TRANSFORMATION, transformationStage.transformClass());
  
              if (record == null) break;
          }
  
          return record;
      }
  
      @Override
      public void close() {
          for (TransformationStage<R> transformationStage : transformationStages) {
              transformationStage.close();
          }
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
          TransformationChain<?, ?> that = (TransformationChain<?, ?>) o;
          return Objects.equals(transformationStages, that.transformationStages);
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(transformationStages);
      }
  
      public String toString() {
          StringJoiner chain = new StringJoiner(", ", getClass().getName() + "{", "}");
          for (TransformationStage<R> transformationStage : transformationStages) {
              chain.add(transformationStage.transformClass().getName());
          }
          return chain.toString();
      }
  
      public List<TransformationStage.StageInfo> transformationChainInfo() {
          return transformationStages.stream().map(TransformationStage::transformationStageInfo).collect(Collectors.toList());
      }
  }
  