/*
 * 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.common.requests;

import static org.apache.kafka.common.protocol.Protocol.REQUEST_HEADER;

import java.nio.ByteBuffer;

import org.apache.kafka.common.protocol.Protocol;
import org.apache.kafka.common.protocol.types.Field;
import org.apache.kafka.common.protocol.types.Struct;

/**
 * The header for a request in the Kafka protocol
 */
public class RequestHeader extends AbstractRequestResponse {

    private static final Field API_KEY_FIELD = REQUEST_HEADER.get("api_key");
    private static final Field API_VERSION_FIELD = REQUEST_HEADER.get("api_version");
    private static final Field CLIENT_ID_FIELD = REQUEST_HEADER.get("client_id");
    private static final Field CORRELATION_ID_FIELD = REQUEST_HEADER.get("correlation_id");

    private final short apiKey;
    private final short apiVersion;
    private final String clientId;
    private final int correlationId;

    public RequestHeader(Struct struct) {
        apiKey = struct.getShort(API_KEY_FIELD);
        apiVersion = struct.getShort(API_VERSION_FIELD);
        clientId = struct.getString(CLIENT_ID_FIELD);
        correlationId = struct.getInt(CORRELATION_ID_FIELD);
    }

    public RequestHeader(short apiKey, short version, String client, int correlation) {
        this.apiKey = apiKey;
        this.apiVersion = version;
        this.clientId = client;
        this.correlationId = correlation;
    }

    public Struct toStruct() {
        Struct struct = new Struct(Protocol.REQUEST_HEADER);
        struct.set(API_KEY_FIELD, apiKey);
        struct.set(API_VERSION_FIELD, apiVersion);
        struct.set(CLIENT_ID_FIELD, clientId);
        struct.set(CORRELATION_ID_FIELD, correlationId);
        return struct;
    }

    public short apiKey() {
        return apiKey;
    }

    public short apiVersion() {
        return apiVersion;
    }

    public String clientId() {
        return clientId;
    }

    public int correlationId() {
        return correlationId;
    }

    public ResponseHeader toResponseHeader() {
        return new ResponseHeader(correlationId);
    }

    public static RequestHeader parse(ByteBuffer buffer) {
        return new RequestHeader(Protocol.REQUEST_HEADER.read(buffer));
    }

    @Override
    public String toString() {
        return toStruct().toString();
    }
}