/*
 * Copyright 2016 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:
 *
 * http://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.helloworld.multiplex.server;

import io.netty.channel.ChannelHandlerContext;
import io.netty.example.http2.helloworld.server.HelloWorldHttp1Handler;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http2.Http2FrameCodecBuilder;
import io.netty.handler.codec.http2.Http2MultiplexHandler;
import io.netty.handler.ssl.ApplicationProtocolNames;
import io.netty.handler.ssl.ApplicationProtocolNegotiationHandler;

/**
 * Negotiates with the browser if HTTP2 or HTTP is going to be used. Once decided, the Netty
 * pipeline is setup with the correct handlers for the selected protocol.
 */
public class Http2OrHttpHandler extends ApplicationProtocolNegotiationHandler {

    private static final int MAX_CONTENT_LENGTH = 1024 * 100;

    protected Http2OrHttpHandler() {
        super(ApplicationProtocolNames.HTTP_1_1);
    }

    @Override
    protected void configurePipeline(ChannelHandlerContext ctx, String protocol) throws Exception {
        if (ApplicationProtocolNames.HTTP_2.equals(protocol)) {
            ctx.pipeline().addLast(Http2FrameCodecBuilder.forServer().build());
            ctx.pipeline().addLast(new Http2MultiplexHandler(new HelloWorldHttp2Handler()));
            return;
        }

        if (ApplicationProtocolNames.HTTP_1_1.equals(protocol)) {
            ctx.pipeline().addLast(new HttpServerCodec(),
                                   new HttpObjectAggregator(MAX_CONTENT_LENGTH),
                                   new HelloWorldHttp1Handler("ALPN Negotiation"));
            return;
        }

        throw new IllegalStateException("unknown protocol: " + protocol);
    }
}
