/*
    * 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:
    *
    *   https://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.unix.DomainSocketAddress;
  import io.netty.channel.unix.DomainSocketChannel;
  import io.netty.channel.unix.FileDescriptor;
  import io.netty.channel.unix.PeerCredentials;
  
  import java.io.IOException;
  import java.net.SocketAddress;
  
  import static io.netty.channel.epoll.LinuxSocket.newSocketDomain;
  
  public final class EpollDomainSocketChannel extends AbstractEpollStreamChannel implements DomainSocketChannel {
      private final EpollDomainSocketChannelConfig config = new EpollDomainSocketChannelConfig(this);
  
      private volatile DomainSocketAddress local;
      private volatile DomainSocketAddress remote;
  
      public EpollDomainSocketChannel() {
          super(newSocketDomain(), false);
      }
  
      EpollDomainSocketChannel(Channel parent, FileDescriptor fd) {
          this(parent, new LinuxSocket(fd.intValue()));
      }
  
      public EpollDomainSocketChannel(int fd) {
          super(fd);
      }
  
      public EpollDomainSocketChannel(Channel parent, LinuxSocket fd) {
          super(parent, fd);
          local = fd.localDomainSocketAddress();
          remote = fd.remoteDomainSocketAddress();
      }
  
      public EpollDomainSocketChannel(int fd, boolean active) {
          super(new LinuxSocket(fd), active);
      }
  
      @Override
      protected AbstractEpollUnsafe newUnsafe() {
          return new EpollDomainUnsafe();
      }
  
      @Override
      protected DomainSocketAddress localAddress0() {
          return local;
      }
  
      @Override
      protected DomainSocketAddress remoteAddress0() {
          return remote;
      }
  
      @Override
      protected void doBind(SocketAddress localAddress) throws Exception {
          socket.bind(localAddress);
          local = (DomainSocketAddress) localAddress;
      }
  
      @Override
      public EpollDomainSocketChannelConfig config() {
          return config;
      }
  
      @Override
      protected boolean doConnect(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
          if (super.doConnect(remoteAddress, localAddress)) {
              local = localAddress != null ? (DomainSocketAddress) localAddress : socket.localDomainSocketAddress();
              remote = (DomainSocketAddress) remoteAddress;
              return true;
          }
          return false;
      }
  
      @Override
      public DomainSocketAddress remoteAddress() {
          return (DomainSocketAddress) super.remoteAddress();
      }
 
     @Override
     public DomainSocketAddress localAddress() {
         return (DomainSocketAddress) super.localAddress();
     }
 
     @Override
     protected int doWriteSingle(ChannelOutboundBuffer in) throws Exception {
         Object msg = in.current();
         if (msg instanceof FileDescriptor && socket.sendFd(((FileDescriptor) msg).intValue()) > 0) {
             // File descriptor was written, so remove it.
             in.remove();
             return 1;
         }
         return super.doWriteSingle(in);
     }
 
     @Override
     protected Object filterOutboundMessage(Object msg) {
         if (msg instanceof FileDescriptor) {
             return msg;
         }
         return super.filterOutboundMessage(msg);
     }
 
     /**
      * Returns the unix credentials (uid, gid, pid) of the peer
      * <a href=https://man7.org/linux/man-pages/man7/socket.7.html>SO_PEERCRED</a>
      */
     public PeerCredentials peerCredentials() throws IOException {
         return socket.getPeerCredentials();
     }
 
     private final class EpollDomainUnsafe extends EpollStreamUnsafe {
         @Override
         void epollInReady() {
             switch (config().getReadMode()) {
                 case BYTES:
                     super.epollInReady();
                     break;
                 case FILE_DESCRIPTORS:
                     epollInReadFd();
                     break;
                 default:
                     throw new Error();
             }
         }
 
         private void epollInReadFd() {
             if (socket.isInputShutdown()) {
                 clearEpollIn0();
                 return;
             }
             final ChannelConfig config = config();
             final EpollRecvByteAllocatorHandle allocHandle = recvBufAllocHandle();
 
             final ChannelPipeline pipeline = pipeline();
             allocHandle.reset(config);
 
             try {
                 readLoop: do {
                     // lastBytesRead represents the fd. We use lastBytesRead because it must be set so that the
                     // EpollRecvByteAllocatorHandle knows if it should try to read again or not when autoRead is
                     // enabled.
                     allocHandle.lastBytesRead(socket.recvFd());
                     switch(allocHandle.lastBytesRead()) {
                     case 0:
                         break readLoop;
                     case -1:
                         close(voidPromise());
                         return;
                     default:
                         allocHandle.incMessagesRead(1);
                         readPending = false;
                         pipeline.fireChannelRead(new FileDescriptor(allocHandle.lastBytesRead()));
                         break;
                     }
                 } while (allocHandle.continueReading());
 
                 allocHandle.readComplete();
                 pipeline.fireChannelReadComplete();
             } catch (Throwable t) {
                 allocHandle.readComplete();
                 pipeline.fireChannelReadComplete();
                 pipeline.fireExceptionCaught(t);
             } finally {
                 if (shouldStopReading(config)) {
                     clearEpollIn();
                 }
             }
         }
     }
 }