/*
    * Copyright (c) 2012 the original author or authors.
    *
    * Licensed 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 org.eclipse.jetty.spdy;
  
  import java.nio.channels.SocketChannel;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.Executor;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicReference;
  import javax.net.ssl.SSLEngine;
  import javax.net.ssl.SSLException;
  
  import org.eclipse.jetty.io.AsyncEndPoint;
  import org.eclipse.jetty.io.nio.AsyncConnection;
  import org.eclipse.jetty.io.nio.SslConnection;
  import org.eclipse.jetty.npn.NextProtoNego;
  import org.eclipse.jetty.server.nio.SelectChannelConnector;
  import org.eclipse.jetty.spdy.api.SPDY;
  import org.eclipse.jetty.spdy.api.Session;
  import org.eclipse.jetty.spdy.api.server.ServerSessionFrameListener;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.ssl.SslContextFactory;
  import org.eclipse.jetty.util.thread.ThreadPool;
  
  public class SPDYServerConnector extends SelectChannelConnector
  {
      private static final Logger logger = Log.getLogger(SPDYServerConnector.class);
  
      // Order is important on server side, so we use a LinkedHashMap
      private final Map<String, AsyncConnectionFactory> factories = new LinkedHashMap<>();
      private final Queue<Session> sessions = new ConcurrentLinkedQueue<>();
      private final ByteBufferPool bufferPool = new StandardByteBufferPool();
      private final ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
      private final ServerSessionFrameListener listener;
      private final SslContextFactory sslContextFactory;
      private AsyncConnectionFactory defaultConnectionFactory;
  
      public SPDYServerConnector(ServerSessionFrameListener listener)
      {
          this(listener, null);
      }
  
      public SPDYServerConnector(ServerSessionFrameListener listener, SslContextFactory sslContextFactory)
      {
          this.listener = listener;
          this.sslContextFactory = sslContextFactory;
          if (sslContextFactory != null)
              addBean(sslContextFactory);
      }
  
      public ByteBufferPool getByteBufferPool()
      {
          return bufferPool;
      }
  
      public Executor getExecutor()
      {
          final ThreadPool threadPool = getThreadPool();
          if (threadPool instanceof Executor)
              return (Executor)threadPool;
          return new Executor()
          {
              @Override
              public void execute(Runnable command)
              {
                  threadPool.dispatch(command);
              }
          };
      }
  
      public ScheduledExecutorService getScheduler()
      {
          return scheduler;
      }
  
     public SslContextFactory getSslContextFactory()
     {
         return sslContextFactory;
     }
 
     @Override
     protected void doStart() throws Exception
     {
         super.doStart();
         defaultConnectionFactory = new ServerSPDYAsyncConnectionFactory(SPDY.V2, getByteBufferPool(), getExecutor(), scheduler, listener);
         putAsyncConnectionFactory("spdy/2", defaultConnectionFactory);
         logger.info("SPDY support is experimental. Please report feedback at jetty-dev@eclipse.org");
     }
 
     @Override
     protected void doStop() throws Exception
     {
         closeSessions();
         scheduler.shutdown();
         super.doStop();
     }
 
     @Override
     public void join() throws InterruptedException
     {
         scheduler.awaitTermination(0, TimeUnit.MILLISECONDS);
         super.join();
     }
 
     public AsyncConnectionFactory getAsyncConnectionFactory(String protocol)
     {
         synchronized (factories)
         {
             return factories.get(protocol);
         }
     }
 
     public AsyncConnectionFactory putAsyncConnectionFactory(String protocol, AsyncConnectionFactory factory)
     {
         synchronized (factories)
         {
             return factories.put(protocol, factory);
         }
     }
 
     public AsyncConnectionFactory removeAsyncConnectionFactory(String protocol)
     {
         synchronized (factories)
         {
             return factories.remove(protocol);
         }
     }
 
     public Map<String, AsyncConnectionFactory> getAsyncConnectionFactories()
     {
         synchronized (factories)
         {
             return new LinkedHashMap<>(factories);
         }
     }
 
     protected List<String> provideProtocols()
     {
         synchronized (factories)
         {
             return new ArrayList<>(factories.keySet());
         }
     }
 
     protected AsyncConnectionFactory getDefaultAsyncConnectionFactory()
     {
         return defaultConnectionFactory;
     }
 
     @Override
     protected AsyncConnection newConnection(final SocketChannel channel, AsyncEndPoint endPoint)
     {
         if (sslContextFactory != null)
         {
             SSLEngine engine = newSSLEngine(sslContextFactory, channel);
             final AtomicReference<AsyncEndPoint> sslEndPointRef = new AtomicReference<>();
             SslConnection sslConnection = new SslConnection(engine, endPoint)
             {
                 @Override
                 public void onClose()
                 {
                     sslEndPointRef.set(null);
                     super.onClose();
                 }
             };
             endPoint.setConnection(sslConnection);
             AsyncEndPoint sslEndPoint = sslConnection.getSslEndPoint();
             sslEndPointRef.set(sslEndPoint);
 
             // Instances of the ServerProvider inner class strong reference the
             // SslEndPoint (via lexical scoping), which strong references the SSLEngine.
             // Since NextProtoNego stores in a WeakHashMap the SSLEngine as key
             // and this instance as value, we are in the situation where the value
             // of a WeakHashMap refers indirectly to the key, which is bad because
             // the entry will never be removed from the WeakHashMap.
             // We use AtomicReferences to be captured via lexical scoping,
             // and we null them out above when the connection is closed.
             NextProtoNego.put(engine, new NextProtoNego.ServerProvider()
             {
                 @Override
                 public void unsupported()
                 {
                     AsyncConnectionFactory connectionFactory = getDefaultAsyncConnectionFactory();
                     AsyncEndPoint sslEndPoint = sslEndPointRef.get();
                     AsyncConnection connection = connectionFactory.newAsyncConnection(channel, sslEndPoint, SPDYServerConnector.this);
                     sslEndPoint.setConnection(connection);
                 }
 
                 @Override
                 public List<String> protocols()
                 {
                     return provideProtocols();
                 }
 
                 @Override
                 public void protocolSelected(String protocol)
                 {
                     AsyncConnectionFactory connectionFactory = getAsyncConnectionFactory(protocol);
                     AsyncEndPoint sslEndPoint = sslEndPointRef.get();
                     AsyncConnection connection = connectionFactory.newAsyncConnection(channel, sslEndPoint, SPDYServerConnector.this);
                     sslEndPoint.setConnection(connection);
                 }
             });
 
             AsyncConnection connection = new EmptyAsyncConnection(sslEndPoint);
             sslEndPoint.setConnection(connection);
 
             startHandshake(engine);
 
             return sslConnection;
         }
         else
         {
             AsyncConnectionFactory connectionFactory = getDefaultAsyncConnectionFactory();
             AsyncConnection connection = connectionFactory.newAsyncConnection(channel, endPoint, this);
             endPoint.setConnection(connection);
             return connection;
         }
     }
 
     protected SSLEngine newSSLEngine(SslContextFactory sslContextFactory, SocketChannel channel)
     {
         String peerHost = channel.socket().getInetAddress().getHostAddress();
         int peerPort = channel.socket().getPort();
         SSLEngine engine = sslContextFactory.newSslEngine(peerHost, peerPort);
         engine.setUseClientMode(false);
         return engine;
     }
 
     private void startHandshake(SSLEngine engine)
     {
         try
         {
             engine.beginHandshake();
         }
         catch (SSLException x)
         {
             throw new RuntimeException(x);
         }
     }
 
     protected boolean sessionOpened(Session session)
     {
         // Add sessions only if the connector is not stopping
         return isRunning() && sessions.offer(session);
     }
 
     protected boolean sessionClosed(Session session)
     {
         // Remove sessions only if the connector is not stopping
         // to avoid concurrent removes during iterations
         return isRunning() && sessions.remove(session);
     }
 
     private void closeSessions()
     {
         for (Session session : sessions)
             session.goAway();
         sessions.clear();
     }
 
     protected Collection<Session> getSessions()
     {
         return Collections.unmodifiableCollection(sessions);
     }
 }