/*
    *  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.socket.nio;
  
  import java.net.Inet4Address;
  import java.net.Inet6Address;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  import java.nio.channels.DatagramChannel;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.Selector;
  import java.util.Set;
  import java.util.concurrent.Executor;
  
  import org.apache.mina.core.buffer.IoBuffer;
  import org.apache.mina.core.polling.AbstractPollingConnectionlessIoAcceptor;
  import org.apache.mina.core.service.IoAcceptor;
  import org.apache.mina.core.service.IoProcessor;
  import org.apache.mina.core.service.TransportMetadata;
  import org.apache.mina.transport.socket.DatagramAcceptor;
  import org.apache.mina.transport.socket.DatagramSessionConfig;
  import org.apache.mina.transport.socket.DefaultDatagramSessionConfig;
  
  /**
   * {@link IoAcceptor} for datagram transport (UDP/IP).
   *
   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
   * @org.apache.xbean.XBean
   */
  public final class NioDatagramAcceptor extends AbstractPollingConnectionlessIoAcceptor<NioSession, DatagramChannel>
          implements DatagramAcceptor {
  
      private volatile Selector selector;
  
      /**
       * Creates a new instance.
       */
      public NioDatagramAcceptor() {
          super(new DefaultDatagramSessionConfig());
      }
  
      /**
       * Creates a new instance.
       */
      public NioDatagramAcceptor(Executor executor) {
          super(new DefaultDatagramSessionConfig(), executor);
      }
  
      @Override
      protected void init() throws Exception {
          this.selector = Selector.open();
      }
  
      @Override
      protected void destroy() throws Exception {
          if (selector != null) {
              selector.close();
          }
      }
  
      public TransportMetadata getTransportMetadata() {
          return NioDatagramSession.METADATA;
      }
  
      @Override
      public DatagramSessionConfig getSessionConfig() {
          return (DatagramSessionConfig) super.getSessionConfig();
      }
  
      @Override
      public InetSocketAddress getLocalAddress() {
          return (InetSocketAddress) super.getLocalAddress();
      }
  
      @Override
      public InetSocketAddress getDefaultLocalAddress() {
          return (InetSocketAddress) super.getDefaultLocalAddress();
      }
  
      public void setDefaultLocalAddress(InetSocketAddress localAddress) {
          setDefaultLocalAddress((SocketAddress) localAddress);
     }
 
     @Override
     protected DatagramChannel open(SocketAddress localAddress) throws Exception {
         final DatagramChannel c = DatagramChannel.open();
         boolean success = false;
         try {
             new NioDatagramSessionConfig(c).setAll(getSessionConfig());
             c.configureBlocking(false);
             c.socket().bind(localAddress);
             c.register(selector, SelectionKey.OP_READ);
             success = true;
         } finally {
             if (!success) {
                 close(c);
             }
         }
 
         return c;
     }
 
     @Override
     protected boolean isReadable(DatagramChannel handle) {
         SelectionKey key = handle.keyFor(selector);
 
         if ((key == null) || (!key.isValid())) {
             return false;
         }
 
         return key.isReadable();
     }
 
     @Override
     protected boolean isWritable(DatagramChannel handle) {
         SelectionKey key = handle.keyFor(selector);
 
         if ((key == null) || (!key.isValid())) {
             return false;
         }
 
         return key.isWritable();
     }
 
     @Override
     protected SocketAddress localAddress(DatagramChannel handle) throws Exception {
         InetSocketAddress inetSocketAddress = (InetSocketAddress) handle.socket().getLocalSocketAddress();
         InetAddress inetAddress = inetSocketAddress.getAddress();
 
         if ((inetAddress instanceof Inet6Address) && (((Inet6Address) inetAddress).isIPv4CompatibleAddress())) {
             // Ugly hack to workaround a problem on linux : the ANY address is always converted to IPV6
             // even if the original address was an IPV4 address. We do store the two IPV4 and IPV6
             // ANY address in the map.
             byte[] ipV6Address = ((Inet6Address) inetAddress).getAddress();
             byte[] ipV4Address = new byte[4];
 
             for (int i = 0; i < 4; i++) {
                 ipV4Address[i] = ipV6Address[12 + i];
             }
 
             InetAddress inet4Adress = Inet4Address.getByAddress(ipV4Address);
             return new InetSocketAddress(inet4Adress, inetSocketAddress.getPort());
         } else {
             return inetSocketAddress;
         }
     }
 
     @Override
     protected NioSession newSession(IoProcessor<NioSession> processor, DatagramChannel handle,
             SocketAddress remoteAddress) {
         SelectionKey key = handle.keyFor(selector);
 
         if ((key == null) || (!key.isValid())) {
             return null;
         }
 
         NioDatagramSession newSession = new NioDatagramSession(this, handle, processor, remoteAddress);
         newSession.setSelectionKey(key);
 
         return newSession;
     }
 
     @Override
     protected SocketAddress receive(DatagramChannel handle, IoBuffer buffer) throws Exception {
         return handle.receive(buffer.buf());
     }
 
     @Override
     protected int select() throws Exception {
         return selector.select();
     }
 
     @Override
     protected int select(long timeout) throws Exception {
         return selector.select(timeout);
     }
 
     @Override
     protected Set<SelectionKey> selectedHandles() {
         return selector.selectedKeys();
     }
 
     @Override
     protected int send(NioSession session, IoBuffer buffer, SocketAddress remoteAddress) throws Exception {
         return ((DatagramChannel) session.getChannel()).send(buffer.buf(), remoteAddress);
     }
 
     @Override
     protected void setInterestedInWrite(NioSession session, boolean isInterested) throws Exception {
         SelectionKey key = session.getSelectionKey();
 
         if (key == null) {
             return;
         }
 
         int newInterestOps = key.interestOps();
 
         if (isInterested) {
             newInterestOps |= SelectionKey.OP_WRITE;
             //newInterestOps &= ~SelectionKey.OP_READ;
         } else {
             newInterestOps &= ~SelectionKey.OP_WRITE;
             //newInterestOps |= SelectionKey.OP_READ;
         }
 
         key.interestOps(newInterestOps);
     }
 
     @Override
     protected void close(DatagramChannel handle) throws Exception {
         SelectionKey key = handle.keyFor(selector);
 
         if (key != null) {
             key.cancel();
         }
 
         handle.disconnect();
         handle.close();
     }
 
     @Override
     protected void wakeup() {
         selector.wakeup();
     }
 }