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/*
 * Copyright © 2017 camunda services GmbH ([email protected])
 *
 * 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 io.zeebe.logstreams.log;

import io.zeebe.util.buffer.BufferReader;
import org.agrona.DirectBuffer;

/** Represents an event on the log stream. */
public interface LoggedEvent {
  /** @return the event's position in the log. */
  long getPosition();

  /** @return the raft term this event was committed in */
  int getRaftTerm();

  /**
   * @return the position of the event which causes this event. Returns a negative value if no such
   *     an event exists.
   */
  long getSourceEventPosition();

  /** @return the id of the producer which produced this event */
  int getProducerId();

  /** @return the key of the event */
  long getKey();

  /** @return the timestamp of the event, the ActorClock current time when the event was written */
  long getTimestamp();

  /**
   * @return a buffer containing the event's metadata at offset {@link #getMetadataOffset()} and
   *     with length {@link #getMetadataLength()}.
   */
  DirectBuffer getMetadata();

  /** @return the offset of the event's metadata */
  int getMetadataOffset();

  /** @return the length of the event's metadata */
  short getMetadataLength();

  /** @return the maximum possible length of the event's value */
  int getMaxValueLength();

  /**
   * Wraps the given buffer to read the event's metadata
   *
   * @param reader the reader to read into
   */
  void readMetadata(BufferReader reader);

  /**
   * @return a buffer containing the value of the event at offset {@link #getValueOffset()} ()} and
   *     with length {@link #getValueLength()} ()}.
   */
  DirectBuffer getValueBuffer();

  /** @return the buffer offset where the event's value can read from */
  int getValueOffset();

  /** @return the length of the event's value */
  int getValueLength();

  /**
   * Wraps the given buffer to read the event's value.
   *
   * @param reader the buffer to read from
   */
  void readValue(BufferReader reader);
}