/*
    * Copyright 2012 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.netty5.channel.local;
  
  import io.netty5.buffer.api.DefaultBufferAllocators;
  import io.netty5.channel.AbstractServerChannel;
  import io.netty5.channel.ChannelOption;
  import io.netty5.channel.ChannelPipeline;
  import io.netty5.channel.ChannelShutdownDirection;
  import io.netty5.channel.EventLoop;
  import io.netty5.channel.EventLoopGroup;
  import io.netty5.channel.RecvBufferAllocator;
  import io.netty5.channel.ServerChannel;
  import io.netty5.channel.ServerChannelRecvBufferAllocator;
  
  import java.net.SocketAddress;
  import java.util.ArrayDeque;
  import java.util.Queue;
  
  /**
   * A {@link ServerChannel} for the local transport which allows in VM communication.
   */
  public class LocalServerChannel extends AbstractServerChannel<LocalChannel, LocalAddress, LocalAddress>
          implements LocalChannelUnsafe {
  
      private final Queue<Object> inboundBuffer = new ArrayDeque<>();
      private volatile int state; // 0 - open, 1 - active, 2 - closed
      private volatile LocalAddress localAddress;
      private volatile boolean acceptInProgress;
  
      public LocalServerChannel(EventLoop eventLoop, EventLoopGroup childEventLoopGroup) {
          super(eventLoop, childEventLoopGroup, LocalChannel.class);
          setOption(ChannelOption.BUFFER_ALLOCATOR, DefaultBufferAllocators.onHeapAllocator());
      }
  
      @Override
      public boolean isOpen() {
          return state < 2;
      }
  
      @Override
      public boolean isActive() {
          return state == 1;
      }
  
      @Override
      protected LocalAddress localAddress0() {
          return localAddress;
      }
  
      @Override
      protected void doBind(SocketAddress localAddress) throws Exception {
          this.localAddress = LocalChannelRegistry.register(this, this.localAddress, localAddress);
          state = 1;
      }
  
      @Override
      protected void doClose() throws Exception {
          if (state <= 1) {
              // Update all internal state before the closeFuture is notified.
              if (localAddress != null) {
                  LocalChannelRegistry.unregister(localAddress);
                  localAddress = null;
              }
              state = 2;
          }
      }
  
      @Override
      protected void doBeginRead() throws Exception {
          if (acceptInProgress) {
              return;
          }
  
          Queue<Object> inboundBuffer = this.inboundBuffer;
          if (inboundBuffer.isEmpty()) {
              acceptInProgress = true;
              return;
          }
  
          readInbound();
      }
  
      LocalChannel serve(final LocalChannel peer) {
          final LocalChannel child = newLocalChannel(peer);
          if (executor().inEventLoop()) {
             serve0(child);
         } else {
             executor().execute(() -> serve0(child));
         }
         return child;
     }
 
     private void readInbound() {
         RecvBufferAllocator.Handle handle = recvBufAllocHandle();
         handle.reset();
         ChannelPipeline pipeline = pipeline();
         do {
             Object m = inboundBuffer.poll();
             if (m == null) {
                 break;
             }
             pipeline.fireChannelRead(m);
         } while (handle.continueReading(isAutoRead()) && !isShutdown(ChannelShutdownDirection.Inbound));
 
         pipeline.fireChannelReadComplete();
         readIfIsAutoRead();
     }
 
     /**
      * A factory method for {@link LocalChannel}s. Users may override it
      * to create custom instances of {@link LocalChannel}s.
      */
     protected LocalChannel newLocalChannel(LocalChannel peer) {
         return new LocalChannel(this, childEventLoopGroup().next(), peer);
     }
 
     private void serve0(final LocalChannel child) {
         inboundBuffer.add(child);
         if (acceptInProgress) {
             acceptInProgress = false;
 
             readInbound();
         }
     }
 
     @Override
     public void registerTransportNow() {
     }
 
     @Override
     public void deregisterTransportNow() {
     }
 
     @Override
     public void closeTransportNow() {
         closeTransport(newPromise());
     }
 }