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A Kafka Connect Couchbase connector for copying data between Kafka and Couchbase Server.

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/*
 * Copyright 2019 Couchbase, Inc.
 *
 * Licensed 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 com.couchbase.connect.kafka.transform;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.kafka.common.config.ConfigDef;
import org.apache.kafka.common.utils.ByteBufferInputStream;
import org.apache.kafka.connect.connector.ConnectRecord;
import org.apache.kafka.connect.errors.DataException;
import org.apache.kafka.connect.transforms.Transformation;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Map;

public class DeserializeJson> implements Transformation {
  private static final ObjectMapper objectMapper = new ObjectMapper();

  static {
    objectMapper.enable(DeserializationFeature.FAIL_ON_TRAILING_TOKENS);
  }

  public static final String OVERVIEW_DOC =
      "Convert JSON values from a byte[] or ByteBuffer to a Map so downstream transforms can operate on the value." +
          " Any null values are passed through unmodified." +
          " The value schema is passed through unmodified (may be null).";

  @Override
  public R apply(R record) {
    final Object value = record.value();
    final Map newValue;

    try {
      if (value == null) {
        return record;

      } else if (value instanceof byte[]) {
        newValue = objectMapper.readValue((byte[]) value, Map.class);

      } else if (value instanceof ByteBuffer) {
        try (ByteBufferInputStream in = new ByteBufferInputStream((ByteBuffer) value)) {
          newValue = objectMapper.readValue(in, Map.class);
        }

      } else {
        throw new DataException(getClass().getSimpleName() + " transform expected value to be a byte array or ByteBuffer but got " + value.getClass().getName());
      }

      return record.newRecord(record.topic(), record.kafkaPartition(),
          record.keySchema(), record.key(),
          record.valueSchema(), newValue,
          record.timestamp());

    } catch (IOException e) {
      throw new DataException(getClass().getSimpleName() + " transform expected value to be JSON but got something else.", e);
    }
  }

  @Override
  public ConfigDef config() {
    return new ConfigDef();
  }

  @Override
  public void close() {
  }

  @Override
  public void configure(Map configs) {
  }
}