/*
    * Copyright 2020 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.example.dns.dot;
  
  import io.netty5.bootstrap.Bootstrap;
  import io.netty5.buffer.BufferUtil;
  import io.netty5.channel.Channel;
  import io.netty5.channel.ChannelHandlerContext;
  import io.netty5.channel.ChannelInitializer;
  import io.netty5.channel.ChannelPipeline;
  import io.netty5.channel.EventLoopGroup;
  import io.netty5.channel.MultithreadEventLoopGroup;
  import io.netty5.channel.SimpleChannelInboundHandler;
  import io.netty5.channel.nio.NioHandler;
  import io.netty5.channel.socket.SocketChannel;
  import io.netty5.channel.socket.nio.NioSocketChannel;
  import io.netty5.handler.codec.dns.DefaultDnsQuery;
  import io.netty5.handler.codec.dns.DefaultDnsQuestion;
  import io.netty5.handler.codec.dns.DefaultDnsResponse;
  import io.netty5.handler.codec.dns.DnsOpCode;
  import io.netty5.handler.codec.dns.DnsQuery;
  import io.netty5.handler.codec.dns.DnsQuestion;
  import io.netty5.handler.codec.dns.DnsRawRecord;
  import io.netty5.handler.codec.dns.DnsRecord;
  import io.netty5.handler.codec.dns.DnsRecordType;
  import io.netty5.handler.codec.dns.DnsSection;
  import io.netty5.handler.codec.dns.TcpDnsQueryEncoder;
  import io.netty5.handler.codec.dns.TcpDnsResponseDecoder;
  import io.netty5.handler.ssl.SslContext;
  import io.netty5.handler.ssl.SslContextBuilder;
  import io.netty5.util.NetUtil;
  
  import java.util.Random;
  import java.util.concurrent.TimeUnit;
  
  public final class DoTClient {
      private static final String QUERY_DOMAIN = "www.example.com";
      private static final int DNS_SERVER_PORT = 853;
      private static final String DNS_SERVER_HOST = "8.8.8.8";
  
      private DoTClient() {
      }
  
      private static void handleQueryResp(DefaultDnsResponse msg) {
          if (msg.count(DnsSection.QUESTION) > 0) {
              DnsQuestion question = msg.recordAt(DnsSection.QUESTION, 0);
              System.out.printf("name: %s%n", question.name());
          }
          for (int i = 0, count = msg.count(DnsSection.ANSWER); i < count; i++) {
              DnsRecord record = msg.recordAt(DnsSection.ANSWER, i);
              if (record.type() == DnsRecordType.A) {
                  // Just print the IP after query
                  DnsRawRecord raw = (DnsRawRecord) record;
                  System.out.println(NetUtil.bytesToIpAddress(BufferUtil.getBytes(raw.content())));
              }
          }
      }
  
      public static void main(String[] args) throws Exception {
          EventLoopGroup group = new MultithreadEventLoopGroup(NioHandler.newFactory());
          try {
              final SslContext sslContext = SslContextBuilder.forClient()
                                                             .protocols("TLSv1.3", "TLSv1.2")
                                                             .build();
  
              Bootstrap b = new Bootstrap();
              b.group(group)
               .channel(NioSocketChannel.class)
               .handler(new ChannelInitializer<SocketChannel>() {
                   @Override
                   protected void initChannel(SocketChannel ch) {
                       ChannelPipeline p = ch.pipeline();
                       p.addLast(sslContext.newHandler(ch.bufferAllocator(), DNS_SERVER_HOST, DNS_SERVER_PORT))
                        .addLast(new TcpDnsQueryEncoder())
                        .addLast(new TcpDnsResponseDecoder())
                        .addLast(new SimpleChannelInboundHandler<DefaultDnsResponse>() {
                            @Override
                            protected void messageReceived(
                                    ChannelHandlerContext ctx, DefaultDnsResponse msg) {
                                try {
                                    handleQueryResp(msg);
                                } finally {
                                    ctx.close();
                                }
                            }
                        });
                  }
              });
             final Channel ch = b.connect(DNS_SERVER_HOST, DNS_SERVER_PORT).asStage().get();
 
             int randomID = new Random().nextInt(60000 - 1000) + 1000;
             DnsQuery query = new DefaultDnsQuery(randomID, DnsOpCode.QUERY)
                     .setRecord(DnsSection.QUESTION, new DefaultDnsQuestion(QUERY_DOMAIN, DnsRecordType.A));
             ch.writeAndFlush(query).asStage().sync();
             boolean success = ch.closeFuture().asStage().await(10, TimeUnit.SECONDS);
             if (!success) {
                 System.err.println("dns query timeout!");
                 ch.close().asStage().sync();
             }
         } finally {
             group.shutdownGracefully();
         }
     }
 }