/*
    * 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.handler.codec.dns;
  
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.socket.DatagramPacket;
  import io.netty.handler.codec.CorruptedFrameException;
  import io.netty.handler.codec.MessageToMessageDecoder;
  import io.netty.util.internal.UnstableApi;
  
  import java.net.InetSocketAddress;
  import java.util.List;
  
  /**
   * Decodes a {@link DatagramPacket} into a {@link DatagramDnsResponse}.
   */
  @UnstableApi
  @ChannelHandler.Sharable
  public class DatagramDnsResponseDecoder extends MessageToMessageDecoder<DatagramPacket> {
  
      private final DnsResponseDecoder<InetSocketAddress> responseDecoder;
  
      /**
       * Creates a new decoder with {@linkplain DnsRecordDecoder#DEFAULT the default record decoder}.
       */
      public DatagramDnsResponseDecoder() {
          this(DnsRecordDecoder.DEFAULT);
      }
  
      /**
       * Creates a new decoder with the specified {@code recordDecoder}.
       */
      public DatagramDnsResponseDecoder(DnsRecordDecoder recordDecoder) {
          this.responseDecoder = new DnsResponseDecoder<InetSocketAddress>(recordDecoder) {
              @Override
              protected DnsResponse newResponse(InetSocketAddress sender, InetSocketAddress recipient,
                                                int id, DnsOpCode opCode, DnsResponseCode responseCode) {
                  return new DatagramDnsResponse(sender, recipient, id, opCode, responseCode);
              }
          };
      }
  
      @Override
      protected void decode(ChannelHandlerContext ctx, DatagramPacket packet, List<Object> out) throws Exception {
          try {
              out.add(decodeResponse(ctx, packet));
          } catch (IndexOutOfBoundsException e) {
              throw new CorruptedFrameException("Unable to decode response", e);
          }
      }
  
      protected DnsResponse decodeResponse(ChannelHandlerContext ctx, DatagramPacket packet) throws Exception {
          return responseDecoder.decode(packet.sender(), packet.recipient(), packet.content());
      }
  }