/*
    * Copyright 2024 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.uring;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.socket.ServerSocketChannel;
  import io.netty.channel.socket.ServerSocketChannelConfig;
  
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  import java.nio.ByteBuffer;
  
  public final class IoUringServerSocketChannel extends AbstractIoUringServerChannel implements ServerSocketChannel {
      private final IoUringServerSocketChannelConfig config;
  
      public IoUringServerSocketChannel() {
          // We don't use a blocking fd for the server channel at the moment as
          // there is no support for IORING_CQE_F_SOCK_NONEMPTY and IORING_ACCEPT_DONTWAIT
          // at the moment. Once these land in the kernel we should check if we can use these and if so make
          // the fd blocking to get rid of POLLIN etc.
          // See:
          //
          //  - https://lore.kernel.org/netdev/[email protected]/
          //  - https://lore.kernel.org/io-uring/[email protected]/
          super(LinuxSocket.newSocketStream(), false);
          this.config = new IoUringServerSocketChannelConfig(this);
      }
  
      @Override
      public ServerSocketChannelConfig config() {
          return config;
      }
  
      @Override
      Channel newChildChannel(int fd, ByteBuffer acceptedAddressMemory) {
          IoUringIoHandler handler = registration().attachment();
          LinuxSocket socket = new LinuxSocket(fd);
          if (acceptedAddressMemory != null) {
              // We didnt use ACCEPT_MULTISHOT And so can depend on the addresses.
              final InetSocketAddress address;
              if (socket.isIpv6()) {
                  byte[] ipv6Array = handler.inet6AddressArray();
                  byte[] ipv4Array = handler.inet4AddressArray();
                  address = SockaddrIn.getIPv6(acceptedAddressMemory, ipv6Array, ipv4Array);
              } else {
                  byte[] addressArray = handler.inet4AddressArray();
                  address = SockaddrIn.getIPv4(acceptedAddressMemory, addressArray);
              }
              return new IoUringSocketChannel(this, new LinuxSocket(fd), address);
          }
          return new IoUringSocketChannel(this, new LinuxSocket(fd));
      }
  
      @Override
      public InetSocketAddress remoteAddress() {
          return (InetSocketAddress) super.remoteAddress();
      }
  
      @Override
      public InetSocketAddress localAddress() {
          return (InetSocketAddress) super.localAddress();
      }
  
      @Override
      public void doBind(SocketAddress localAddress) throws Exception {
          super.doBind(localAddress);
          if (IoUring.isTcpFastOpenServerSideAvailable()) {
              Integer fastOpen = config().getOption(ChannelOption.TCP_FASTOPEN);
              if (fastOpen != null && fastOpen > 0) {
                  socket.setTcpFastOpen(fastOpen);
              }
          }
          socket.listen(config.getBacklog());
          active = true;
      }
  }