/*
    * Copyright 2021 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.handler.codec.quic;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.epoll.SegmentedDatagramPacket;
  import io.netty.channel.socket.DatagramPacket;
  import io.netty.util.internal.ObjectUtil;
  
  import java.net.InetSocketAddress;
  
  /**
   * Class that provides utility methods to setup {@code QUIC} when using the {@code EPOLL} transport.
   */
  public final class EpollQuicUtils {
  
      private EpollQuicUtils() { }
  
      /**
       * Return a new {@link SegmentedDatagramPacketAllocator} that can be used while using
       * {@link io.netty.channel.epoll.EpollDatagramChannel}.
       *
       * @param maxNumSegments the maximum number of segments that we try to send in one packet.
       * @return a allocator.
       */
      public static SegmentedDatagramPacketAllocator newSegmentedAllocator(int maxNumSegments) {
          ObjectUtil.checkInRange(maxNumSegments, 1, 64, "maxNumSegments");
          if (SegmentedDatagramPacket.isSupported()) {
              return new EpollSegmentedDatagramPacketAllocator(maxNumSegments);
          }
          return SegmentedDatagramPacketAllocator.NONE;
      }
  
      private static final class EpollSegmentedDatagramPacketAllocator implements SegmentedDatagramPacketAllocator {
  
          private final int maxNumSegments;
  
          EpollSegmentedDatagramPacketAllocator(int maxNumSegments) {
              this.maxNumSegments = maxNumSegments;
          }
  
          @Override
          public int maxNumSegments() {
              return maxNumSegments;
          }
  
          @Override
          public DatagramPacket newPacket(ByteBuf buffer, int segmentSize, InetSocketAddress remoteAddress) {
              return new io.netty.channel.unix.SegmentedDatagramPacket(buffer, segmentSize, remoteAddress);
          }
      }
  }