/*
    * 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.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import io.netty.channel.ChannelConfig;
  import io.netty.channel.RecvByteBufAllocator;
  import io.netty.channel.unix.PreferredDirectByteBufAllocator;
  import io.netty.util.UncheckedBooleanSupplier;
  
  final class IoUringRecvByteAllocatorHandle extends RecvByteBufAllocator.DelegatingHandle
          implements RecvByteBufAllocator.ExtendedHandle {
      private final PreferredDirectByteBufAllocator preferredDirectByteBufAllocator =
              new PreferredDirectByteBufAllocator();
  
      // We need to continue reading as long as we received something when using io_uring. Otherwise
      // we will not be able to batch things in an efficient way.
      private final UncheckedBooleanSupplier defaultSupplier = () -> lastBytesRead() > 0;
  
      IoUringRecvByteAllocatorHandle(RecvByteBufAllocator.ExtendedHandle handle) {
          super(handle);
      }
  
      private boolean firstRead;
      private boolean rdHupReceived;
      private boolean readComplete;
  
      @Override
      public void reset(ChannelConfig config) {
          super.reset(config);
          readComplete = false;
          firstRead = true;
      }
  
      void rdHupReceived() {
          this.rdHupReceived = true;
      }
  
      @Override
      public ByteBuf allocate(ByteBufAllocator alloc) {
          // We need to ensure we always allocate a direct ByteBuf as we can only use a direct buffer to read via JNI.
          preferredDirectByteBufAllocator.updateAllocator(alloc);
          return delegate().allocate(preferredDirectByteBufAllocator);
      }
  
      @Override
      public boolean continueReading() {
          // Ensure we use the our own supplier that will take care of reading data until there is nothing left.
          return continueReading(defaultSupplier);
      }
  
      @Override
      public boolean continueReading(UncheckedBooleanSupplier maybeMoreDataSupplier) {
          // If we received an POLLRDHUP we need to continue draining the input until there is nothing left.
          return ((RecvByteBufAllocator.ExtendedHandle) delegate()).continueReading(maybeMoreDataSupplier)
                  || rdHupReceived;
      }
  
      public boolean isFirstRead() {
          return firstRead;
      }
  
      @Override
      public void readComplete() {
          super.readComplete();
          readComplete = true;
      }
  
      boolean isReadComplete() {
          return readComplete;
      }
  
      @Override
      public void lastBytesRead(int bytes) {
          firstRead = false;
          super.lastBytesRead(bytes);
      }
  
      @Override
      public void incMessagesRead(int numMessages) {
          firstRead = false;
          super.incMessagesRead(numMessages);
      }
  }