/*
 * 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.hadoop.ozone.om.ratis;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Strings;
import java.io.File;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.SocketAddress;
import java.util.Collections;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.StorageUnit;
import org.apache.hadoop.hdds.scm.HddsServerUtil;
import org.apache.hadoop.ozone.om.OMConfigKeys;
import org.apache.ratis.RaftConfigKeys;
import org.apache.ratis.client.RaftClientConfigKeys;
import org.apache.ratis.conf.RaftProperties;
import org.apache.ratis.grpc.GrpcConfigKeys;
import org.apache.ratis.netty.NettyConfigKeys;
import org.apache.ratis.protocol.RaftGroupId;
import org.apache.ratis.protocol.RaftPeerId;
import org.apache.ratis.rpc.RpcType;
import org.apache.ratis.rpc.SupportedRpcType;
import org.apache.ratis.server.RaftServer;
import org.apache.ratis.server.RaftServerConfigKeys;
import org.apache.ratis.statemachine.impl.BaseStateMachine;
import org.apache.ratis.util.LifeCycle;
import org.apache.ratis.util.SizeInBytes;
import org.apache.ratis.util.TimeDuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Creates a Ratis server endpoint for OM.
 */
public final class OzoneManagerRatisServer {
  private static final Logger LOG = LoggerFactory
      .getLogger(OzoneManagerRatisServer.class);

  private final int port;
  private final RaftServer server;

  private OzoneManagerRatisServer(String omId, int port, Configuration conf)
      throws IOException {
    Objects.requireNonNull(omId, "omId == null");
    this.port = port;
    RaftProperties serverProperties = newRaftProperties(conf);

    this.server = RaftServer.newBuilder()
        .setServerId(RaftPeerId.valueOf(omId))
        .setProperties(serverProperties)
        .setStateMachineRegistry(this::getStateMachine)
        .build();
  }

  public static OzoneManagerRatisServer newOMRatisServer(String omId,
      Configuration ozoneConf) throws IOException {
    int localPort = ozoneConf.getInt(
        OMConfigKeys.OZONE_OM_RATIS_PORT_KEY,
        OMConfigKeys.OZONE_OM_RATIS_PORT_DEFAULT);

    // Get an available port on current node and
    // use that as the container port
    if (ozoneConf.getBoolean(
        OMConfigKeys.OZONE_OM_RATIS_RANDOM_PORT_KEY,
        OMConfigKeys.OZONE_OM_RATIS_RANDOM_PORT_KEY_DEFAULT)) {
      try (ServerSocket socket = new ServerSocket()) {
        socket.setReuseAddress(true);
        SocketAddress address = new InetSocketAddress(0);
        socket.bind(address);
        localPort = socket.getLocalPort();
        LOG.info("Found a free port for the OM Ratis server : {}", localPort);
      } catch (IOException e) {
        LOG.error("Unable find a random free port for the server, "
            + "fallback to use default port {}", localPort, e);
      }
    }
    return new OzoneManagerRatisServer(omId, localPort, ozoneConf);
  }

  /**
   * Return a dummy StateMachine.
   * TODO: Implement a state machine on OM.
   */
  private BaseStateMachine getStateMachine(RaftGroupId gid) {
    return new BaseStateMachine();
  }

  public void start() throws IOException {
    LOG.info("Starting {} {} at port {}", getClass().getSimpleName(),
        server.getId(), port);
    server.start();
  }

  public void stop() {
    try {
      server.close();
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }

  private RaftProperties newRaftProperties(Configuration conf) {
    final RaftProperties properties = new RaftProperties();

    // Set RPC type
    final String rpcType = conf.get(
        OMConfigKeys.OZONE_OM_RATIS_RPC_TYPE_KEY,
        OMConfigKeys.OZONE_OM_RATIS_RPC_TYPE_DEFAULT);
    final RpcType rpc = SupportedRpcType.valueOfIgnoreCase(rpcType);
    RaftConfigKeys.Rpc.setType(properties, rpc);

    // Set the ratis port number
    if (rpc == SupportedRpcType.GRPC) {
      GrpcConfigKeys.Server.setPort(properties, port);
    } else if (rpc == SupportedRpcType.NETTY) {
      NettyConfigKeys.Server.setPort(properties, port);
    }

    // Set Ratis storage directory
    String storageDir = getOMRatisDirectory(conf);
    RaftServerConfigKeys.setStorageDirs(properties,
        Collections.singletonList(new File(storageDir)));

    // Set RAFT segment size
    final int raftSegmentSize = (int) conf.getStorageSize(
        OMConfigKeys.OZONE_OM_RATIS_SEGMENT_SIZE_KEY,
        OMConfigKeys.OZONE_OM_RATIS_SEGMENT_SIZE_DEFAULT,
        StorageUnit.BYTES);
    RaftServerConfigKeys.Log.setSegmentSizeMax(properties,
        SizeInBytes.valueOf(raftSegmentSize));

    // Set RAFT segment pre-allocated size
    final int raftSegmentPreallocatedSize = (int) conf.getStorageSize(
        OMConfigKeys.OZONE_OM_RATIS_SEGMENT_PREALLOCATED_SIZE_KEY,
        OMConfigKeys.OZONE_OM_RATIS_SEGMENT_PREALLOCATED_SIZE_DEFAULT,
        StorageUnit.BYTES);
    int logAppenderQueueNumElements = conf.getInt(
        OMConfigKeys.OZONE_OM_RATIS_LOG_APPENDER_QUEUE_NUM_ELEMENTS,
        OMConfigKeys.OZONE_OM_RATIS_LOG_APPENDER_QUEUE_NUM_ELEMENTS_DEFAULT);
    final int logAppenderQueueByteLimit = (int) conf.getStorageSize(
        OMConfigKeys.OZONE_OM_RATIS_LOG_APPENDER_QUEUE_BYTE_LIMIT,
        OMConfigKeys.OZONE_OM_RATIS_LOG_APPENDER_QUEUE_BYTE_LIMIT_DEFAULT,
        StorageUnit.BYTES);
    RaftServerConfigKeys.Log.Appender
        .setBufferElementLimit(properties, logAppenderQueueNumElements);
    RaftServerConfigKeys.Log.Appender.setBufferByteLimit(properties,
        SizeInBytes.valueOf(logAppenderQueueByteLimit));
    RaftServerConfigKeys.Log.setPreallocatedSize(properties,
        SizeInBytes.valueOf(raftSegmentPreallocatedSize));

    // For grpc set the maximum message size
    // TODO: calculate the max message size based on the max size of a
    // PutSmallFileRequest's file size limit
    GrpcConfigKeys.setMessageSizeMax(properties,
        SizeInBytes.valueOf(logAppenderQueueByteLimit));

    // Set the server request timeout
    TimeUnit serverRequestTimeoutUnit =
        OMConfigKeys.OZONE_OM_RATIS_SERVER_REQUEST_TIMEOUT_DEFAULT.getUnit();
    long serverRequestTimeoutDuration = conf.getTimeDuration(
        OMConfigKeys.OZONE_OM_RATIS_SERVER_REQUEST_TIMEOUT_KEY,
        OMConfigKeys.OZONE_OM_RATIS_SERVER_REQUEST_TIMEOUT_DEFAULT
            .getDuration(), serverRequestTimeoutUnit);
    final TimeDuration serverRequestTimeout = TimeDuration.valueOf(
        serverRequestTimeoutDuration, serverRequestTimeoutUnit);
    RaftServerConfigKeys.Rpc.setRequestTimeout(properties,
        serverRequestTimeout);

    // Set timeout for server retry cache entry
    TimeUnit retryCacheTimeoutUnit = OMConfigKeys
        .OZONE_OM_RATIS_SERVER_RETRY_CACHE_TIMEOUT_DEFAULT.getUnit();
    long retryCacheTimeoutDuration = conf.getTimeDuration(
        OMConfigKeys.OZONE_OM_RATIS_SERVER_RETRY_CACHE_TIMEOUT_KEY,
        OMConfigKeys.OZONE_OM_RATIS_SERVER_RETRY_CACHE_TIMEOUT_DEFAULT
            .getDuration(), retryCacheTimeoutUnit);
    final TimeDuration retryCacheTimeout = TimeDuration.valueOf(
        retryCacheTimeoutDuration, retryCacheTimeoutUnit);
    RaftServerConfigKeys.RetryCache
        .setExpiryTime(properties, retryCacheTimeout);

    // Set the server min and max timeout
    TimeUnit serverMinTimeoutUnit =
        OMConfigKeys.OZONE_OM_RATIS_MINIMUM_TIMEOUT_DEFAULT.getUnit();
    long serverMinTimeoutDuration = conf.getTimeDuration(
        OMConfigKeys.OZONE_OM_RATIS_MINIMUM_TIMEOUT_KEY,
        OMConfigKeys.OZONE_OM_RATIS_MINIMUM_TIMEOUT_DEFAULT
            .getDuration(), serverMinTimeoutUnit);
    final TimeDuration serverMinTimeout = TimeDuration.valueOf(
        serverMinTimeoutDuration, serverMinTimeoutUnit);
    long serverMaxTimeoutDuration =
        serverMinTimeout.toLong(TimeUnit.MILLISECONDS) + 200;
    final TimeDuration serverMaxTimeout = TimeDuration.valueOf(
        serverMaxTimeoutDuration, serverMinTimeoutUnit);
    RaftServerConfigKeys.Rpc.setTimeoutMin(properties,
        serverMinTimeout);
    RaftServerConfigKeys.Rpc.setTimeoutMax(properties,
        serverMaxTimeout);

    // Set the number of maximum cached segments
    RaftServerConfigKeys.Log.setMaxCachedSegmentNum(properties, 2);

    // Set the client request timeout
    TimeUnit clientRequestTimeoutUnit =
        OMConfigKeys.OZONE_OM_RATIS_CLIENT_REQUEST_TIMEOUT_DEFAULT.getUnit();
    long clientRequestTimeoutDuration = conf.getTimeDuration(
        OMConfigKeys.OZONE_OM_RATIS_CLIENT_REQUEST_TIMEOUT_KEY,
        OMConfigKeys.OZONE_OM_RATIS_CLIENT_REQUEST_TIMEOUT_DEFAULT
            .getDuration(), clientRequestTimeoutUnit);
    final TimeDuration clientRequestTimeout = TimeDuration.valueOf(
        clientRequestTimeoutDuration, clientRequestTimeoutUnit);
    RaftClientConfigKeys.Rpc.setRequestTimeout(properties,
        clientRequestTimeout);

    // TODO: set max write buffer size

    /**
     * TODO: when state machine is implemented, enable StateMachineData sync
     * and set sync timeout and number of sync retries.
     */

    /**
     * TODO: set following ratis leader election related configs when
     * replicated ratis server is implemented.
     * 1. leader election timeout
     * 2. node failure timeout
     * 3.
     */

    /**
     * TODO: when ratis snapshots are implemented, set snapshot threshold and
     * queue size.
     */

    return properties;
  }

  public int getServerPort() {
    return port;
  }

  @VisibleForTesting
  public LifeCycle.State getServerState() {
    return server.getLifeCycleState();
  }

  /**
   * Get the local directory where ratis logs will be stored.
   */
  public static String getOMRatisDirectory(Configuration conf) {
    String storageDir = conf.get(OMConfigKeys.OZONE_OM_RATIS_STORAGE_DIR);

    if (Strings.isNullOrEmpty(storageDir)) {
      storageDir = HddsServerUtil.getDefaultRatisDirectory(conf);
    }
    return storageDir;
  }

}
