/*
    *  Licensed to the Apache Software Foundation (ASF) under one
    *  or more contributor license agreements.  See the NOTICE file
    *  distributed with this work for additional information
    *  regarding copyright ownership.  The ASF 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 org.apache.mina.transport.vmpipe;
  
  import java.io.IOException;
  import java.net.SocketAddress;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.concurrent.Executor;
  
  import org.apache.mina.core.filterchain.IoFilterChain;
  import org.apache.mina.core.future.ConnectFuture;
  import org.apache.mina.core.future.DefaultConnectFuture;
  import org.apache.mina.core.future.IoFuture;
  import org.apache.mina.core.future.IoFutureListener;
  import org.apache.mina.core.service.AbstractIoConnector;
  import org.apache.mina.core.service.IoHandler;
  import org.apache.mina.core.service.TransportMetadata;
  import org.apache.mina.core.session.IdleStatusChecker;
  import org.apache.mina.core.session.IoSessionInitializer;
  import org.apache.mina.util.ExceptionMonitor;
  
  /**
   * Connects to {@link IoHandler}s which is bound on the specified
   * {@link VmPipeAddress}.
   *
   * @author The Apache MINA Project (dev@mina.apache.org)
   */
  public final class VmPipeConnector extends AbstractIoConnector {
  
      // object used for checking session idle
      private IdleStatusChecker idleChecker;
      
      /**
       * Creates a new instance.
       */
      public VmPipeConnector() {
          this(null);
      }
      
      /**
       * Creates a new instance.
       */
      public VmPipeConnector(Executor executor) {
          super(new DefaultVmPipeSessionConfig(), executor);
          idleChecker = new IdleStatusChecker();
          // we schedule the idle status checking task in this service exceutor
          // it will be woke up every seconds
          executeWorker(idleChecker.getNotifyingTask(), "idleStatusChecker");
      }
  
      public TransportMetadata getTransportMetadata() {
          return VmPipeSession.METADATA;
      }
  
      @Override
      public VmPipeSessionConfig getSessionConfig() {
          return (VmPipeSessionConfig) super.getSessionConfig();
      }
  
      @Override
      protected ConnectFuture connect0(SocketAddress remoteAddress,
                                        SocketAddress localAddress,
                                        IoSessionInitializer<? extends ConnectFuture> sessionInitializer) {
          VmPipe entry = VmPipeAcceptor.boundHandlers.get(remoteAddress);
          if (entry == null) {
              return DefaultConnectFuture.newFailedFuture(new IOException(
                      "Endpoint unavailable: " + remoteAddress));
          }
  
          DefaultConnectFuture future = new DefaultConnectFuture();
  
          // Assign the local address dynamically,
          VmPipeAddress actualLocalAddress;
          try {
              actualLocalAddress = nextLocalAddress();
          } catch (IOException e) {
              return DefaultConnectFuture.newFailedFuture(e);
          }
  
          VmPipeSession localSession = new VmPipeSession(this,
                  getListeners(), actualLocalAddress, getHandler(), entry);
 
         initSession(localSession, future, sessionInitializer);
 
         // and reclaim the local address when the connection is closed.
         localSession.getCloseFuture().addListener(LOCAL_ADDRESS_RECLAIMER);
 
         // initialize connector session
         try {
             IoFilterChain filterChain = localSession.getFilterChain();
             this.getFilterChainBuilder().buildFilterChain(filterChain);
 
             // The following sentences don't throw any exceptions.
             getListeners().fireSessionCreated(localSession);
             idleChecker.addSession(localSession);
         } catch (Throwable t) {
             future.setException(t);
             return future;
         }
 
         // initialize acceptor session
         VmPipeSession remoteSession = localSession.getRemoteSession();
         ((VmPipeAcceptor) remoteSession.getService()).doFinishSessionInitialization(remoteSession, null);
         try {
             IoFilterChain filterChain = remoteSession.getFilterChain();
             entry.getAcceptor().getFilterChainBuilder().buildFilterChain(
                     filterChain);
 
             // The following sentences don't throw any exceptions.
             entry.getListeners().fireSessionCreated(remoteSession);
             idleChecker.addSession(remoteSession);
         } catch (Throwable t) {
             ExceptionMonitor.getInstance().exceptionCaught(t);
             remoteSession.close(true);
         }
 
         // Start chains, and then allow and messages read/written to be processed. This is to ensure that
         // sessionOpened gets received before a messageReceived
         ((VmPipeFilterChain) localSession.getFilterChain()).start();
         ((VmPipeFilterChain) remoteSession.getFilterChain()).start();
 
         return future;
     }
 
     @Override
     protected IoFuture dispose0() throws Exception {
         // stop the idle checking task
         idleChecker.getNotifyingTask().cancel();
         return null;
     }
 
     private static final Set<VmPipeAddress> TAKEN_LOCAL_ADDRESSES = new HashSet<VmPipeAddress>();
 
     private static int nextLocalPort = -1;
 
     private static final IoFutureListener<IoFuture> LOCAL_ADDRESS_RECLAIMER = new LocalAddressReclaimer();
 
     private static VmPipeAddress nextLocalAddress() throws IOException {
         synchronized (TAKEN_LOCAL_ADDRESSES) {
             if (nextLocalPort >= 0) {
                 nextLocalPort = -1;
             }
             for (int i = 0; i < Integer.MAX_VALUE; i++) {
                 VmPipeAddress answer = new VmPipeAddress(nextLocalPort--);
                 if (!TAKEN_LOCAL_ADDRESSES.contains(answer)) {
                     TAKEN_LOCAL_ADDRESSES.add(answer);
                     return answer;
                 }
             }
         }
 
         throw new IOException("Can't assign a local VM pipe port.");
     }
 
     private static class LocalAddressReclaimer implements IoFutureListener<IoFuture> {
         public void operationComplete(IoFuture future) {
             synchronized (TAKEN_LOCAL_ADDRESSES) {
                 TAKEN_LOCAL_ADDRESSES.remove(future.getSession()
                         .getLocalAddress());
             }
         }
     }
 }