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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.transport.impl;

import java.nio.ByteOrder;
import org.agrona.BitUtil;
import org.agrona.DirectBuffer;
import org.agrona.concurrent.UnsafeBuffer;

public class TransportHeaderDescriptor {
  public static final short REQUEST_RESPONSE = 0;
  public static final short FULL_DUPLEX_SINGLE_MESSAGE = 1;
  public static final short CONTROL_MESSAGE = 2;

  public static final int PROTOCOL_ID_OFFSET;
  public static final int HEADER_LENGTH;

  // do not change; must be stable for backwards/forwards compatibility
  public static final ByteOrder HEADER_BYTE_ORDER = ByteOrder.LITTLE_ENDIAN;

  static {
    int offset = 0;

    PROTOCOL_ID_OFFSET = offset;
    offset += BitUtil.SIZE_OF_SHORT;

    HEADER_LENGTH = offset;
  }

  public static int framedLength(int messageLength) {
    return HEADER_LENGTH + messageLength;
  }

  public static int headerLength() {
    return HEADER_LENGTH;
  }

  public static int protocolIdOffset(int offset) {
    return offset + PROTOCOL_ID_OFFSET;
  }

  protected final UnsafeBuffer buffer = new UnsafeBuffer(0, 0);

  public TransportHeaderDescriptor wrap(DirectBuffer buffer, int offset) {
    this.buffer.wrap(buffer, offset, HEADER_LENGTH);
    return this;
  }

  public TransportHeaderDescriptor protocolId(short protocolId) {
    buffer.putShort(PROTOCOL_ID_OFFSET, protocolId, HEADER_BYTE_ORDER);
    return this;
  }

  public TransportHeaderDescriptor putProtocolSingleMessage() {
    return protocolId(FULL_DUPLEX_SINGLE_MESSAGE);
  }

  public TransportHeaderDescriptor putProtocolRequestReponse() {
    return protocolId(REQUEST_RESPONSE);
  }

  public int protocolId() {
    return buffer.getShort(PROTOCOL_ID_OFFSET, HEADER_BYTE_ORDER);
  }
}