/*
    * Copyright 2009 Red Hat, Inc.
    *
    * Red Hat 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.jboss.netty.channel.socket.nio;
  
  import static org.jboss.netty.channel.Channels.*;
  
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  import java.util.concurrent.Executor;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.jboss.netty.channel.AbstractChannelSink;
  import org.jboss.netty.channel.ChannelEvent;
  import org.jboss.netty.channel.ChannelFuture;
  import org.jboss.netty.channel.ChannelFutureListener;
  import org.jboss.netty.channel.ChannelPipeline;
  import org.jboss.netty.channel.ChannelState;
  import org.jboss.netty.channel.ChannelStateEvent;
  import org.jboss.netty.channel.MessageEvent;
  
  /**
   * Receives downstream events from a {@link ChannelPipeline}.  It contains
   * an array of I/O workers.
   *
   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
   * @author Daniel Bevenius (dbevenius@jboss.com)
   *
   * @version $Rev: 2340 $, $Date: 2010-07-07 13:37:10 +0900 (Wed, 07 Jul 2010) $
   */
  class NioDatagramPipelineSink extends AbstractChannelSink {
  
      private static final AtomicInteger nextId = new AtomicInteger();
  
      private final int id = nextId.incrementAndGet();
      private final NioDatagramWorker[] workers;
      private final AtomicInteger workerIndex = new AtomicInteger();
  
      /**
       * Creates a new {@link NioDatagramPipelineSink} with a the number of {@link NioDatagramWorker}s specified in workerCount.
       * The {@link NioDatagramWorker}s take care of reading and writing for the {@link NioDatagramChannel}.
       *
       * @param workerExecutor
       *        the {@link Executor} that will run the {@link NioDatagramWorker}s
       *        for this sink
       * @param workerCount
       *        the number of {@link NioDatagramWorker}s for this sink
       */
      NioDatagramPipelineSink(final Executor workerExecutor, final int workerCount) {
          workers = new NioDatagramWorker[workerCount];
          for (int i = 0; i < workers.length; i ++) {
              workers[i] = new NioDatagramWorker(id, i + 1, workerExecutor);
          }
      }
  
      /**
       * Handle downstream event.
       *
       * @param pipeline the {@link ChannelPipeline} that passes down the
       *                 downstream event.
       * @param e The downstream event.
       */
      public void eventSunk(final ChannelPipeline pipeline, final ChannelEvent e)
              throws Exception {
          final NioDatagramChannel channel = (NioDatagramChannel) e.getChannel();
          final ChannelFuture future = e.getFuture();
          if (e instanceof ChannelStateEvent) {
              final ChannelStateEvent stateEvent = (ChannelStateEvent) e;
              final ChannelState state = stateEvent.getState();
              final Object value = stateEvent.getValue();
              switch (state) {
              case OPEN:
                  if (Boolean.FALSE.equals(value)) {
                      channel.worker.close(channel, future);
                  }
                  break;
              case BOUND:
                  if (value != null) {
                      bind(channel, future, (InetSocketAddress) value);
                  } else {
                      channel.worker.close(channel, future);
                  }
                  break;
              case CONNECTED:
                  if (value != null) {
                      connect(channel, future, (InetSocketAddress) value);
                 } else {
                     NioDatagramWorker.disconnect(channel, future);
                 }
                 break;
             case INTEREST_OPS:
                 channel.worker.setInterestOps(channel, future, ((Integer) value).intValue());
                 break;
             }
         } else if (e instanceof MessageEvent) {
             final MessageEvent event = (MessageEvent) e;
             final boolean offered = channel.writeBufferQueue.offer(event);
             assert offered;
             channel.worker.writeFromUserCode(channel);
         }
     }
 
     private void close(NioDatagramChannel channel, ChannelFuture future) {
         try {
             channel.getDatagramChannel().socket().close();
             if (channel.setClosed()) {
                 future.setSuccess();
                 if (channel.isBound()) {
                     fireChannelUnbound(channel);
                 }
                 fireChannelClosed(channel);
             } else {
                 future.setSuccess();
             }
         } catch (final Throwable t) {
             future.setFailure(t);
             fireExceptionCaught(channel, t);
         }
     }
 
     /**
      * Will bind the DatagramSocket to the passed-in address.
      * Every call bind will spawn a new thread using the that basically in turn
      */
     private void bind(final NioDatagramChannel channel,
             final ChannelFuture future, final InetSocketAddress address) {
         boolean bound = false;
         boolean started = false;
         try {
             // First bind the DatagramSocket the specified port.
             channel.getDatagramChannel().socket().bind(address);
             bound = true;
 
             future.setSuccess();
             fireChannelBound(channel, address);
 
             channel.worker.register(channel, null);
             started = true;
         } catch (final Throwable t) {
             future.setFailure(t);
             fireExceptionCaught(channel, t);
         } finally {
             if (!started && bound) {
                 close(channel, future);
             }
         }
     }
 
     private void connect(
             NioDatagramChannel channel, ChannelFuture future,
             SocketAddress remoteAddress) {
 
         boolean bound = channel.isBound();
         boolean connected = false;
         boolean workerStarted = false;
 
         future.addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
 
         // Clear the cached address so that the next getRemoteAddress() call
         // updates the cache.
         channel.remoteAddress = null;
 
         try {
             channel.getDatagramChannel().connect(remoteAddress);
             connected = true;
 
             // Fire events.
             future.setSuccess();
             if (!bound) {
                 fireChannelBound(channel, channel.getLocalAddress());
             }
             fireChannelConnected(channel, channel.getRemoteAddress());
 
             if (!bound) {
                 channel.worker.register(channel, future);
             }
 
             workerStarted = true;
         } catch (Throwable t) {
             future.setFailure(t);
             fireExceptionCaught(channel, t);
         } finally {
             if (connected && !workerStarted) {
                 channel.worker.close(channel, future);
             }
         }
     }
 
     NioDatagramWorker nextWorker() {
         return workers[Math.abs(workerIndex.getAndIncrement() % workers.length)];
     }
 
 }