/*
 * 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.servicecomb.zeroconfig.multicast;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.MulticastSocket;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.concurrent.TimeUnit;

import org.apache.servicecomb.registry.lightweight.Message;
import org.apache.servicecomb.registry.lightweight.MessageType;
import org.apache.servicecomb.zeroconfig.Config;
import org.apache.servicecomb.zeroconfig.ZeroConfigConst;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import com.google.common.net.HostAndPort;

@Component
//@Conditional(ConditionOnMulticast.class)
public class Multicast {
  private static final Logger LOGGER = LoggerFactory.getLogger(Multicast.class);

  private final InetSocketAddress bindAddress;

  // (224.0.0.0, 239.255.255.255]
  private final InetAddress group;

  private final MulticastSocket multicastSocket;

  private final byte[] recvBuffer = new byte[ZeroConfigConst.MAX_PACKET_SIZE];

  private final DatagramPacket recvPacket = new DatagramPacket(recvBuffer, recvBuffer.length);

  public Multicast(Config config) throws IOException {
    this.bindAddress = initBindAddress(config);
    this.group = initGroup(config);
    LOGGER.info("zero config, address: {}", bindAddress);
    LOGGER.info("zero config, group: {}", group);

    // delete after support @Conditional
    if (!config.isMulticast()) {
      multicastSocket = null;
      return;
    }

    this.multicastSocket = new MulticastSocket(bindAddress);
    this.multicastSocket.joinGroup(group);
    this.multicastSocket.setSoTimeout((int) TimeUnit.SECONDS.toMillis(5));
  }

  public Multicast setSendBufferSize(int size) throws SocketException {
    multicastSocket.setSendBufferSize(size);
    return this;
  }

  public Multicast setReceiveBufferSize(int size) throws SocketException {
    multicastSocket.setReceiveBufferSize(size);
    return this;
  }

  @SuppressWarnings("UnstableApiUsage")
  private InetSocketAddress initBindAddress(Config config) {
    HostAndPort hostAndPort = HostAndPort.fromString(config.getMulticastAddress());
    return new InetSocketAddress(hostAndPort.getHost(), hostAndPort.getPort());
  }

  private InetAddress initGroup(Config config) throws UnknownHostException {
    return InetAddress.getByName(config.getMulticastGroup());
  }

  public <T> void send(MessageType type, T body) throws IOException {
    byte[] buffer = Message.of(type, body).encode();
    DatagramPacket packet = new DatagramPacket(buffer, buffer.length, group, bindAddress.getPort());
    multicastSocket.send(packet);
  }

  public Message<?> recv() throws IOException {
    multicastSocket.receive(recvPacket);

    return Message.decode(recvPacket.getData(), recvPacket.getLength());
  }
}
