/*
 * 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.io.kafka;

import java.io.Serializable;
import org.apache.beam.sdk.transforms.DoFn;
import org.joda.time.Instant;

/** An interface for providing custom timestamp for elements written to Kafka. */
public interface KafkaPublishTimestampFunction<T> extends Serializable {

  /**
   * Returns timestamp for element being published to Kafka. See @{@link
   * org.apache.kafka.clients.producer.ProducerRecord}.
   *
   * @param element The element being published.
   * @param elementTimestamp Timestamp of the element from the context (i.e. @{@link
   *     DoFn.ProcessContext#timestamp()}
   */
  Instant getTimestamp(T element, Instant elementTimestamp);

  /**
   * Returns {@link KafkaPublishTimestampFunction} returns element timestamp from ProcessContext.
   */
  static <T> KafkaPublishTimestampFunction<T> withElementTimestamp() {
    return (element, elementTimestamp) -> elementTimestamp;
  }
}
