/*
    * Copyright 2015 The Netty Project
    *
    * The Netty Project 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 io.netty.channel.epoll;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelConfig;
  import io.netty.channel.ChannelOutboundBuffer;
  import io.netty.channel.ChannelPipeline;
  import io.netty.channel.ChannelPromise;
  import io.netty.channel.EventLoop;
  import io.netty.channel.ServerChannel;
  import io.netty.channel.unix.FileDescriptor;
  import io.netty.channel.unix.Socket;
  
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  
  
  public abstract class AbstractEpollServerChannel extends AbstractEpollChannel implements ServerChannel {
  
      /**
       * @deprecated Use {@link #AbstractEpollServerChannel(Socket, boolean)}.
       */
      @Deprecated
      protected AbstractEpollServerChannel(int fd) {
          this(new Socket(fd), false);
      }
  
      /**
       * @deprecated Use {@link #AbstractEpollServerChannel(Socket, boolean)}.
       */
      @Deprecated
      protected AbstractEpollServerChannel(FileDescriptor fd) {
          this(new Socket(fd.intValue()));
      }
  
      /**
       * @deprecated Use {@link #AbstractEpollServerChannel(Socket, boolean)}.
       */
      @Deprecated
      protected AbstractEpollServerChannel(Socket fd) {
          this(fd, isSoErrorZero(fd));
      }
  
      protected AbstractEpollServerChannel(Socket fd, boolean active) {
          super(null, fd, Native.EPOLLIN, active);
      }
  
      @Override
      protected boolean isCompatible(EventLoop loop) {
          return loop instanceof EpollEventLoop;
      }
  
      @Override
      protected InetSocketAddress remoteAddress0() {
          return null;
      }
  
      @Override
      protected AbstractEpollUnsafe newUnsafe() {
          return new EpollServerSocketUnsafe();
      }
  
      @Override
      protected void doWrite(ChannelOutboundBuffer in) throws Exception {
          throw new UnsupportedOperationException();
      }
  
      @Override
      protected Object filterOutboundMessage(Object msg) throws Exception {
          throw new UnsupportedOperationException();
      }
  
      abstract Channel newChildChannel(int fd, byte[] remote, int offset, int len) throws Exception;
  
      final class EpollServerSocketUnsafe extends AbstractEpollUnsafe {
          // Will hold the remote address after accept(...) was sucesssful.
          // We need 24 bytes for the address as maximum + 1 byte for storing the length.
          // So use 26 bytes as it's a power of two.
          private final byte[] acceptedAddress = new byte[26];
  
          @Override
          public void connect(SocketAddress socketAddress, SocketAddress socketAddress2, ChannelPromise channelPromise) {
              // Connect not supported by ServerChannel implementations
              channelPromise.setFailure(new UnsupportedOperationException());
          }
 
         @Override
         void epollInReady() {
             assert eventLoop().inEventLoop();
             if (fd().isInputShutdown()) {
                 return;
             }
             boolean edgeTriggered = isFlagSet(Native.EPOLLET);
 
             final ChannelConfig config = config();
             if (!readPending && !edgeTriggered && !config.isAutoRead()) {
                 // ChannelConfig.setAutoRead(false) was called in the meantime
                 clearEpollIn0();
                 return;
             }
 
             final ChannelPipeline pipeline = pipeline();
             Throwable exception = null;
             try {
                 try {
                     // if edgeTriggered is used we need to read all messages as we are not notified again otherwise.
                     final int maxMessagesPerRead = edgeTriggered
                             ? Integer.MAX_VALUE : config.getMaxMessagesPerRead();
                     int messages = 0;
                     do {
                         int socketFd = fd().accept(acceptedAddress);
                         if (socketFd == -1) {
                             // this means everything was handled for now
                             break;
                         }
                         readPending = false;
 
                         try {
                             int len = acceptedAddress[0];
                             pipeline.fireChannelRead(newChildChannel(socketFd, acceptedAddress, 1, len));
                         } catch (Throwable t) {
                             // keep on reading as we use epoll ET and need to consume everything from the socket
                             pipeline.fireChannelReadComplete();
                             pipeline.fireExceptionCaught(t);
                         } finally {
                             if (!edgeTriggered && !config.isAutoRead()) {
                                 // This is not using EPOLLET so we can stop reading
                                 // ASAP as we will get notified again later with
                                 // pending data
                                 break;
                             }
                         }
                     } while (++ messages < maxMessagesPerRead || isRdHup());
                 } catch (Throwable t) {
                     exception = t;
                 }
                 pipeline.fireChannelReadComplete();
 
                 if (exception != null) {
                     pipeline.fireExceptionCaught(exception);
                 }
             } finally {
                 // Check if there is a readPending which was not processed yet.
                 // This could be for two reasons:
                 // * The user called Channel.read() or ChannelHandlerContext.read() in channelRead(...) method
                 // * The user called Channel.read() or ChannelHandlerContext.read() in channelReadComplete(...) method
                 //
                 // See https://github.com/netty/netty/issues/2254
                 if (!readPending && !config.isAutoRead()) {
                     clearEpollIn0();
                 }
             }
         }
     }
 
     @Override
     protected boolean doConnect(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
         throw new UnsupportedOperationException();
     }
 }