/*
    * 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.example.http2.tiles;
  
  import static io.netty.handler.codec.http2.Http2SecurityUtil.CIPHERS;
  import io.netty.bootstrap.ServerBootstrap;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelInitializer;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.socket.SocketChannel;
  import io.netty.channel.socket.nio.NioServerSocketChannel;
  import io.netty.handler.ssl.ApplicationProtocolConfig;
  import io.netty.handler.ssl.ApplicationProtocolConfig.Protocol;
  import io.netty.handler.ssl.ApplicationProtocolConfig.SelectedListenerFailureBehavior;
  import io.netty.handler.ssl.ApplicationProtocolConfig.SelectorFailureBehavior;
  import io.netty.handler.ssl.ApplicationProtocolNames;
  import io.netty.handler.ssl.SslContext;
  import io.netty.handler.ssl.SslContextBuilder;
  import io.netty.handler.ssl.SupportedCipherSuiteFilter;
  import io.netty.handler.ssl.util.SelfSignedCertificate;
  
  import java.security.cert.CertificateException;
  
  import javax.net.ssl.SSLException;
  
  /**
   * Demonstrates an Http2 server using Netty to display a bunch of images and
   * simulate latency. It is a Netty version of the <a href="https://http2.golang.org/gophertiles?latency=0">
   * Go lang HTTP2 tiles demo</a>.
   */
  public class Http2Server {
  
      public static final int PORT = Integer.parseInt(System.getProperty("http2-port", "8443"));
  
      private final EventLoopGroup group;
  
      public Http2Server(EventLoopGroup eventLoopGroup) {
          group = eventLoopGroup;
      }
  
      public ChannelFuture start() throws Exception {
          final SslContext sslCtx = configureTLS();
          ServerBootstrap b = new ServerBootstrap();
          b.option(ChannelOption.SO_BACKLOG, 1024);
          b.group(group).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() {
              @Override
              protected void initChannel(SocketChannel ch) throws Exception {
                  ch.pipeline().addLast(sslCtx.newHandler(ch.alloc()), new Http2OrHttpHandler());
              }
          });
  
          Channel ch = b.bind(PORT).sync().channel();
          return ch.closeFuture();
      }
  
      private static SslContext configureTLS() throws CertificateException, SSLException {
          SelfSignedCertificate ssc = new SelfSignedCertificate();
          ApplicationProtocolConfig apn = new ApplicationProtocolConfig(
                  Protocol.ALPN,
                  // NO_ADVERTISE is currently the only mode supported by both OpenSsl and JDK providers.
                  SelectorFailureBehavior.NO_ADVERTISE,
                  // ACCEPT is currently the only mode supported by both OpenSsl and JDK providers.
                  SelectedListenerFailureBehavior.ACCEPT,
                  ApplicationProtocolNames.HTTP_2,
                  ApplicationProtocolNames.HTTP_1_1);
  
          return SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey(), null)
                                  .ciphers(CIPHERS, SupportedCipherSuiteFilter.INSTANCE)
                                  .applicationProtocolConfig(apn).build();
      }
  }