/*
    * 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 org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.channel.AbstractChannel;
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelFactory;
  import org.jboss.netty.channel.ChannelPipeline;
  import org.jboss.netty.channel.ChannelSink;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.channel.socket.nio.SocketSendBufferPool.SendBuffer;
  import org.jboss.netty.util.internal.ThreadLocalBoolean;
  
  import java.net.InetSocketAddress;
  import java.nio.channels.SelectableChannel;
  import java.nio.channels.WritableByteChannel;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import static org.jboss.netty.channel.Channels.*;
  
  abstract class AbstractNioChannel<C extends SelectableChannel & WritableByteChannel> extends AbstractChannel {
  
      /**
       * The {@link AbstractNioWorker}.
       */
      final AbstractNioWorker worker;
  
      /**
       * Monitor object for synchronizing access to the {@link WriteRequestQueue}.
       */
      final Object writeLock = new Object();
  
      /**
       * WriteTask that performs write operations.
       */
      final Runnable writeTask = new WriteTask();
  
      /**
       * Indicates if there is a {@link WriteTask} in the task queue.
       */
      final AtomicBoolean writeTaskInTaskQueue = new AtomicBoolean();
  
      /**
       * Queue of write {@link MessageEvent}s.
       */
      final Queue<MessageEvent> writeBufferQueue = new WriteRequestQueue();
  
      /**
       * Keeps track of the number of bytes that the {@link WriteRequestQueue} currently
       * contains.
       */
      final AtomicInteger writeBufferSize = new AtomicInteger();
  
      /**
       * Keeps track of the highWaterMark.
       */
      final AtomicInteger highWaterMarkCounter = new AtomicInteger();
  
      /**
       * The current write {@link MessageEvent}
       */
      MessageEvent currentWriteEvent;
      SendBuffer currentWriteBuffer;
  
      /**
       * Boolean that indicates that write operation is in progress.
       */
      boolean inWriteNowLoop;
      boolean writeSuspended;
  
      private volatile InetSocketAddress localAddress;
      volatile InetSocketAddress remoteAddress;
  
      final C channel;
  
      protected AbstractNioChannel(
              Integer id, Channel parent, ChannelFactory factory, ChannelPipeline pipeline,
              ChannelSink sink, AbstractNioWorker worker, C ch) {
          super(id, parent, factory, pipeline, sink);
          this.worker = worker;
         channel = ch;
     }
 
     protected AbstractNioChannel(
             Channel parent, ChannelFactory factory,
             ChannelPipeline pipeline, ChannelSink sink, AbstractNioWorker worker, C ch)  {
         super(parent, factory, pipeline, sink);
         this.worker = worker;
         channel = ch;
     }
 
     /**
      * Return the {@link AbstractNioWorker} that handle the IO of the
      * {@link AbstractNioChannel}
      *
      * @return worker
      */
     public AbstractNioWorker getWorker() {
         return worker;
     }
 
     public InetSocketAddress getLocalAddress() {
         InetSocketAddress localAddress = this.localAddress;
         if (localAddress == null) {
             try {
                 localAddress = getLocalSocketAddress();
                 if (localAddress.getAddress().isAnyLocalAddress()) {
                     // Don't cache on a wildcard address so the correct one
                     // will be cached once the channel is connected/bound
                     return localAddress;
                 }
                 this.localAddress = localAddress;
             } catch (Throwable t) {
                 // Sometimes fails on a closed socket in Windows.
                 return null;
             }
         }
         return localAddress;
     }
 
     public InetSocketAddress getRemoteAddress() {
         InetSocketAddress remoteAddress = this.remoteAddress;
         if (remoteAddress == null) {
             try {
                 this.remoteAddress = remoteAddress =
                     getRemoteSocketAddress();
             } catch (Throwable t) {
                 // Sometimes fails on a closed socket in Windows.
                 return null;
             }
         }
         return remoteAddress;
     }
 
     public abstract NioChannelConfig getConfig();
 
     int getRawInterestOps() {
         return super.getInterestOps();
     }
 
     void setRawInterestOpsNow(int interestOps) {
         setInterestOpsNow(interestOps);
     }
 
     @Override
     public int getInterestOps() {
         if (!isOpen()) {
             return Channel.OP_WRITE;
         }
 
         int interestOps = getRawInterestOps();
         int writeBufferSize = this.writeBufferSize.get();
         if (writeBufferSize != 0) {
             if (highWaterMarkCounter.get() > 0) {
                 int lowWaterMark = getConfig().getWriteBufferLowWaterMark();
                 if (writeBufferSize >= lowWaterMark) {
                     interestOps |= Channel.OP_WRITE;
                 } else {
                     interestOps &= ~Channel.OP_WRITE;
                 }
             } else {
                 int highWaterMark = getConfig().getWriteBufferHighWaterMark();
                 if (writeBufferSize >= highWaterMark) {
                     interestOps |= Channel.OP_WRITE;
                 } else {
                     interestOps &= ~Channel.OP_WRITE;
                 }
             }
         } else {
             interestOps &= ~Channel.OP_WRITE;
         }
 
         return interestOps;
     }
 
     @Override
     protected boolean setClosed() {
         return super.setClosed();
     }
 
     abstract InetSocketAddress getLocalSocketAddress() throws Exception;
 
     abstract InetSocketAddress getRemoteSocketAddress() throws Exception;
 
     private final class WriteRequestQueue implements Queue<MessageEvent> {
         private final ThreadLocalBoolean notifying = new ThreadLocalBoolean();
 
         private final Queue<MessageEvent> queue;
 
         public WriteRequestQueue() {
             queue = new ConcurrentLinkedQueue<MessageEvent>();
         }
 
         public MessageEvent remove() {
             return queue.remove();
         }
 
         public MessageEvent element() {
             return queue.element();
         }
 
         public MessageEvent peek() {
             return queue.peek();
         }
 
         public int size() {
             return queue.size();
         }
 
         public boolean isEmpty() {
             return queue.isEmpty();
         }
 
         public Iterator<MessageEvent> iterator() {
             return queue.iterator();
         }
 
         public Object[] toArray() {
             return queue.toArray();
         }
 
         public <T> T[] toArray(T[] a) {
             return queue.toArray(a);
         }
 
         public boolean containsAll(Collection<?> c) {
             return queue.containsAll(c);
         }
 
         public boolean addAll(Collection<? extends MessageEvent> c) {
             return queue.addAll(c);
         }
 
         public boolean removeAll(Collection<?> c) {
             return queue.removeAll(c);
         }
 
         public boolean retainAll(Collection<?> c) {
             return queue.retainAll(c);
         }
 
         public void clear() {
             queue.clear();
         }
 
         public boolean add(MessageEvent e) {
             return queue.add(e);
         }
 
         public boolean remove(Object o) {
             return queue.remove(o);
         }
 
         public boolean contains(Object o) {
             return queue.contains(o);
         }
 
         public boolean offer(MessageEvent e) {
             boolean success = queue.offer(e);
             assert success;
 
             int messageSize = getMessageSize(e);
             int newWriteBufferSize = writeBufferSize.addAndGet(messageSize);
             int highWaterMark =  getConfig().getWriteBufferHighWaterMark();
 
             if (newWriteBufferSize >= highWaterMark) {
                 if (newWriteBufferSize - messageSize < highWaterMark) {
                     highWaterMarkCounter.incrementAndGet();
                     if (!notifying.get()) {
                         notifying.set(Boolean.TRUE);
                         fireChannelInterestChanged(AbstractNioChannel.this);
                         notifying.set(Boolean.FALSE);
                     }
                 }
             }
             return true;
         }
 
         public MessageEvent poll() {
             MessageEvent e = queue.poll();
             if (e != null) {
                 int messageSize = getMessageSize(e);
                 int newWriteBufferSize = writeBufferSize.addAndGet(-messageSize);
                 int lowWaterMark = getConfig().getWriteBufferLowWaterMark();
 
                 if (newWriteBufferSize == 0 || newWriteBufferSize < lowWaterMark) {
                     if (newWriteBufferSize + messageSize >= lowWaterMark) {
                         highWaterMarkCounter.decrementAndGet();
                         if (isConnected() && !notifying.get()) {
                             notifying.set(Boolean.TRUE);
                             fireChannelInterestChanged(AbstractNioChannel.this);
                             notifying.set(Boolean.FALSE);
                         }
                     }
                 }
             }
             return e;
         }
 
         private int getMessageSize(MessageEvent e) {
             Object m = e.getMessage();
             if (m instanceof ChannelBuffer) {
                 return ((ChannelBuffer) m).readableBytes();
             }
             return 0;
         }
     }
 
     private final class WriteTask implements Runnable {
 
         WriteTask() {
         }
 
         public void run() {
             writeTaskInTaskQueue.set(false);
             worker.writeFromTaskLoop(AbstractNioChannel.this);
         }
     }
 
 }