/*
 * 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.rocketmq.remoting.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.PooledByteBufAllocator;
import io.netty.channel.Channel;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.epoll.EpollEventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
import io.netty.handler.timeout.IdleStateHandler;
import io.netty.util.concurrent.DefaultEventExecutorGroup;
import java.net.InetSocketAddress;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.rocketmq.remoting.ChannelEventListener;
import org.apache.rocketmq.remoting.InvokeCallback;
import org.apache.rocketmq.remoting.RPCHook;
import org.apache.rocketmq.remoting.RemotingServer;
import org.apache.rocketmq.remoting.common.Pair;
import org.apache.rocketmq.remoting.common.RemotingHelper;
import org.apache.rocketmq.remoting.common.RemotingUtil;
import org.apache.rocketmq.remoting.exception.RemotingSendRequestException;
import org.apache.rocketmq.remoting.exception.RemotingTimeoutException;
import org.apache.rocketmq.remoting.exception.RemotingTooMuchRequestException;
import org.apache.rocketmq.remoting.protocol.RemotingCommand;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * netty 服务端的server
 */
public class NettyRemotingServer extends NettyRemotingAbstract implements RemotingServer {
    private static final Logger log = LoggerFactory.getLogger(RemotingHelper.ROCKETMQ_REMOTING);
    private final ServerBootstrap serverBootstrap;
    private final EventLoopGroup eventLoopGroupSelector;
    private final EventLoopGroup eventLoopGroupBoss;
    private final NettyServerConfig nettyServerConfig;

    private final ExecutorService publicExecutor;
    private final ChannelEventListener channelEventListener;

    private final Timer timer = new Timer("ServerHouseKeepingService", true);
    private DefaultEventExecutorGroup defaultEventExecutorGroup;

    private RPCHook rpcHook;

    private int port = 0;

    public NettyRemotingServer(final NettyServerConfig nettyServerConfig) {
        this(nettyServerConfig, null);
    }

    public NettyRemotingServer(final NettyServerConfig nettyServerConfig, final ChannelEventListener channelEventListener) {
        super(nettyServerConfig.getServerOnewaySemaphoreValue(), nettyServerConfig.getServerAsyncSemaphoreValue());
        this.serverBootstrap = new ServerBootstrap();
        this.nettyServerConfig = nettyServerConfig;
        this.channelEventListener = channelEventListener;

        int publicThreadNums = nettyServerConfig.getServerCallbackExecutorThreads();
        if (publicThreadNums <= 0) {
            publicThreadNums = 4;
        }

        this.publicExecutor = Executors.newFixedThreadPool(publicThreadNums, new ThreadFactory() {
            private AtomicInteger threadIndex = new AtomicInteger(0);

            @Override
            public Thread newThread(Runnable r) {
                return new Thread(r, "NettyServerPublicExecutor_" + this.threadIndex.incrementAndGet());
            }
        });

        this.eventLoopGroupBoss = new NioEventLoopGroup(1, new ThreadFactory() {
            private AtomicInteger threadIndex = new AtomicInteger(0);

            @Override
            public Thread newThread(Runnable r) {
                return new Thread(r, String.format("NettyBoss_%d", this.threadIndex.incrementAndGet()));
            }
        });

        if (RemotingUtil.isLinuxPlatform() //
            && nettyServerConfig.isUseEpollNativeSelector()) {
            this.eventLoopGroupSelector = new EpollEventLoopGroup(nettyServerConfig.getServerSelectorThreads(), new ThreadFactory() {
                private AtomicInteger threadIndex = new AtomicInteger(0);
                private int threadTotal = nettyServerConfig.getServerSelectorThreads();

                @Override
                public Thread newThread(Runnable r) {
                    return new Thread(r, String.format("NettyServerEPOLLSelector_%d_%d", threadTotal, this.threadIndex.incrementAndGet()));
                }
            });
        } else {
            this.eventLoopGroupSelector = new NioEventLoopGroup(nettyServerConfig.getServerSelectorThreads(), new ThreadFactory() {
                private AtomicInteger threadIndex = new AtomicInteger(0);
                private int threadTotal = nettyServerConfig.getServerSelectorThreads();

                @Override
                public Thread newThread(Runnable r) {
                    return new Thread(r, String.format("NettyServerNIOSelector_%d_%d", threadTotal, this.threadIndex.incrementAndGet()));
                }
            });
        }
    }

    @Override
    public void start() {
        this.defaultEventExecutorGroup = new DefaultEventExecutorGroup(
            nettyServerConfig.getServerWorkerThreads(),
            new ThreadFactory() {

                private AtomicInteger threadIndex = new AtomicInteger(0);

                @Override
                public Thread newThread(Runnable r) {
                    return new Thread(r, "NettyServerCodecThread_" + this.threadIndex.incrementAndGet());
                }
            });

        ServerBootstrap childHandler =
            this.serverBootstrap.group(this.eventLoopGroupBoss, this.eventLoopGroupSelector).channel(NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG, 1024)
                .option(ChannelOption.SO_REUSEADDR, true)
                .option(ChannelOption.SO_KEEPALIVE, false)
                .childOption(ChannelOption.TCP_NODELAY, true)
                .option(ChannelOption.SO_SNDBUF, nettyServerConfig.getServerSocketSndBufSize())
                .option(ChannelOption.SO_RCVBUF, nettyServerConfig.getServerSocketRcvBufSize())
                .localAddress(new InetSocketAddress(this.nettyServerConfig.getListenPort()))
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch) throws Exception {
                        ch.pipeline().addLast(
                            defaultEventExecutorGroup,
                            new NettyEncoder(),
                            new NettyDecoder(),
                            new IdleStateHandler(0, 0, nettyServerConfig.getServerChannelMaxIdleTimeSeconds()),
                            new NettyConnetManageHandler(),
                            new NettyServerHandler());
                    }
                });

        if (nettyServerConfig.isServerPooledByteBufAllocatorEnable()) {
            childHandler.childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
        }

        try {
            ChannelFuture sync = this.serverBootstrap.bind().sync();
            InetSocketAddress addr = (InetSocketAddress) sync.channel().localAddress();
            this.port = addr.getPort();
        } catch (InterruptedException e1) {
            throw new RuntimeException("this.serverBootstrap.bind().sync() InterruptedException", e1);
        }

        if (this.channelEventListener != null) {
            this.nettyEventExecuter.start();
        }

        this.timer.scheduleAtFixedRate(new TimerTask() {

            @Override
            public void run() {
                try {
                    NettyRemotingServer.this.scanResponseTable();
                } catch (Exception e) {
                    log.error("scanResponseTable exception", e);
                }
            }
        }, 1000 * 3, 1000);
    }

    @Override
    public void shutdown() {
        try {
            if (this.timer != null) {
                this.timer.cancel();
            }

            this.eventLoopGroupBoss.shutdownGracefully();

            this.eventLoopGroupSelector.shutdownGracefully();

            if (this.nettyEventExecuter != null) {
                this.nettyEventExecuter.shutdown();
            }

            if (this.defaultEventExecutorGroup != null) {
                this.defaultEventExecutorGroup.shutdownGracefully();
            }
        } catch (Exception e) {
            log.error("NettyRemotingServer shutdown exception, ", e);
        }

        if (this.publicExecutor != null) {
            try {
                this.publicExecutor.shutdown();
            } catch (Exception e) {
                log.error("NettyRemotingServer shutdown exception, ", e);
            }
        }
    }

    @Override
    public void registerRPCHook(RPCHook rpcHook) {
        this.rpcHook = rpcHook;
    }

    /**
     * 注册处理器
     */
    @Override
    public void registerProcessor(int requestCode, NettyRequestProcessor processor, ExecutorService executor) {
        ExecutorService executorThis = executor;
        if (null == executor) {
            executorThis = this.publicExecutor;
        }

        Pair<NettyRequestProcessor, ExecutorService> pair = new Pair<NettyRequestProcessor, ExecutorService>(processor, executorThis);
        this.processorTable.put(requestCode, pair);
    }

    @Override
    public void registerDefaultProcessor(NettyRequestProcessor processor, ExecutorService executor) {
        this.defaultRequestProcessor = new Pair<NettyRequestProcessor, ExecutorService>(processor, executor);
    }

    @Override
    public int localListenPort() {
        return this.port;
    }

    @Override
    public Pair<NettyRequestProcessor, ExecutorService> getProcessorPair(int requestCode) {
        return processorTable.get(requestCode);
    }

    @Override
    public RemotingCommand invokeSync(final Channel channel, final RemotingCommand request, final long timeoutMillis)
        throws InterruptedException, RemotingSendRequestException, RemotingTimeoutException {
        return this.invokeSyncImpl(channel, request, timeoutMillis);
    }

    @Override
    public void invokeAsync(Channel channel, RemotingCommand request, long timeoutMillis, InvokeCallback invokeCallback)
        throws InterruptedException, RemotingTooMuchRequestException, RemotingTimeoutException, RemotingSendRequestException {
        this.invokeAsyncImpl(channel, request, timeoutMillis, invokeCallback);
    }

    @Override
    public void invokeOneway(Channel channel, RemotingCommand request, long timeoutMillis) throws InterruptedException,
        RemotingTooMuchRequestException, RemotingTimeoutException, RemotingSendRequestException {
        this.invokeOnewayImpl(channel, request, timeoutMillis);
    }

    @Override
    public ChannelEventListener getChannelEventListener() {
        return channelEventListener;
    }

    @Override
    public RPCHook getRPCHook() {
        return this.rpcHook;
    }

    @Override
    public ExecutorService getCallbackExecutor() {
        return this.publicExecutor;
    }

    /**
     * 简单的处理器,没有过于复杂的数据，前置的处理器已经处理好数据了
     */
    class NettyServerHandler extends SimpleChannelInboundHandler<RemotingCommand> {

        @Override
        protected void channelRead0(ChannelHandlerContext ctx, RemotingCommand msg) throws Exception {
            // 不用显示释放具体的数据
            processMessageReceived(ctx, msg);
        }
    }

    /**
     * netty 链接的处理，他处于倒数第二个个pipeline 上面
     */
    class NettyConnetManageHandler extends ChannelDuplexHandler {


        @Override // 当Channel已经注册到它的EventLoop并且能够处理I/O时被调用
        public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.info("NETTY SERVER PIPELINE: channelRegistered {}", remoteAddress);
            super.channelRegistered(ctx);
        }

        @Override // 当Channel从它的EventLoop注销并且无法处理任何I/O时被调用
        public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.info("NETTY SERVER PIPELINE: channelUnregistered, the channel[{}]", remoteAddress);
            super.channelUnregistered(ctx);
        }

        @Override //当Channel处于活动状态时被调用；Channel已经连接/绑定并且已经就绪
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.info("NETTY SERVER PIPELINE: channelActive, the channel[{}]", remoteAddress);
            super.channelActive(ctx);

            // 派发netty的事件 ==》 Channel处于活动状态（已经连接到它的远程节点）。它现在可以接收和发送数据了
            if (NettyRemotingServer.this.channelEventListener != null) {
                NettyRemotingServer.this.putNettyEvent(new NettyEvent(NettyEventType.CONNECT, remoteAddress.toString(), ctx.channel()));
            }
        }

        @Override // 当Channel离开活动状态并且不再连接它的远程节点时被调用
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.info("NETTY SERVER PIPELINE: channelInactive, the channel[{}]", remoteAddress);
            super.channelInactive(ctx);

            if (NettyRemotingServer.this.channelEventListener != null) {
                NettyRemotingServer.this.putNettyEvent(new NettyEvent(NettyEventType.CLOSE, remoteAddress.toString(), ctx.channel()));
            }
        }


        @Override // 调用ChannelPipeline中下一个ChannelInboundHandler的userEventTriggered(ChannelHandlerContext, Object)方法
        public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
            // 超时事件触发  --》是idle事件触发了
            if (evt instanceof IdleStateEvent) {
                IdleStateEvent evnet = (IdleStateEvent) evt;
                if (evnet.state().equals(IdleState.ALL_IDLE)) {
                    final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
                    log.warn("NETTY SERVER PIPELINE: IDLE exception [{}]", remoteAddress);

                    // 关闭channel
                    RemotingUtil.closeChannel(ctx.channel());
                    if (NettyRemotingServer.this.channelEventListener != null) {
                        NettyRemotingServer.this
                            .putNettyEvent(new NettyEvent(NettyEventType.IDLE, remoteAddress.toString(), ctx.channel()));
                    }
                }
            }

            // 当ChannelnboundHandler.fireUserEventTriggered() ==> 方法被调用时被调用，因为一个POJO被传经了 ChannelPipeline
            ctx.fireUserEventTriggered(evt);
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.warn("NETTY SERVER PIPELINE: exceptionCaught {}", remoteAddress);
            log.warn("NETTY SERVER PIPELINE: exceptionCaught exception.", cause);

            if (NettyRemotingServer.this.channelEventListener != null) {
                NettyRemotingServer.this.putNettyEvent(new NettyEvent(NettyEventType.EXCEPTION, remoteAddress.toString(), ctx.channel()));
            }

            // 关闭channel
            RemotingUtil.closeChannel(ctx.channel());
        }
    }
}
