/*
    * Copyright 2012 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 org.jboss.netty.channel.socket.nio;
  
  import static org.jboss.netty.channel.Channels.*;
  
  import java.net.InetSocketAddress;
  import java.util.concurrent.Executor;
  
  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.
   */
  class NioDatagramPipelineSink extends AbstractNioChannelSink {
  
      private final WorkerPool<NioDatagramWorker> workerPool;
  
      /**
       * 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 WorkerPool<NioDatagramWorker> workerPool) {
          this.workerPool = workerPool;
      }
  
      /**
       * 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 static 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 static 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 static void connect(
             NioDatagramChannel channel, ChannelFuture future,
             InetSocketAddress 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 workerPool.nextWorker();
     }
 
 }