//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.websocket.common.io;
  
  import java.io.IOException;
  import java.net.InetSocketAddress;
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.Executor;
  import java.util.concurrent.RejectedExecutionException;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.eclipse.jetty.io.AbstractConnection;
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.io.Connection;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.Callback;
  import org.eclipse.jetty.util.ForkInvoker;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.thread.Scheduler;
  import org.eclipse.jetty.websocket.api.CloseException;
  import org.eclipse.jetty.websocket.api.StatusCode;
  import org.eclipse.jetty.websocket.api.SuspendToken;
  import org.eclipse.jetty.websocket.api.WebSocketException;
  import org.eclipse.jetty.websocket.api.WebSocketPolicy;
  import org.eclipse.jetty.websocket.api.WriteCallback;
  import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;
  import org.eclipse.jetty.websocket.api.extensions.Frame;
  import org.eclipse.jetty.websocket.common.CloseInfo;
  import org.eclipse.jetty.websocket.common.ConnectionState;
  import org.eclipse.jetty.websocket.common.Generator;
  import org.eclipse.jetty.websocket.common.LogicalConnection;
  import org.eclipse.jetty.websocket.common.Parser;
  import org.eclipse.jetty.websocket.common.WebSocketSession;
  
  /**
   * Provides the implementation of {@link WebSocketConnection} within the framework of the new {@link Connection} framework of jetty-io
   */
  public abstract class AbstractWebSocketConnection extends AbstractConnection implements LogicalConnection
  {
      private class FlushCallback implements Callback
      {
          @Override
          public void failed(Throwable x)
          {
              LOG.warn("Write flush failure",x);
          }
  
          @Override
          public void succeeded()
          {
              // Lets process the next set of bytes...
              AbstractWebSocketConnection.this.complete(writeBytes);
          }
      }
  
      private class FlushInvoker extends ForkInvoker<Callback>
      {
          private FlushInvoker()
          {
              super(4);
          }
  
          @Override
          public void call(Callback callback)
          {
              flush();
          }
  
          @Override
          public void fork(final Callback callback)
          {
              execute(new Runnable()
              {
                  @Override
                  public void run()
                  {
                      flush();
                  }
             });
         }
 
         @Override
         public String toString()
         {
             return String.format("%s@%x",FlushInvoker.class.getSimpleName(),hashCode());
         }
     }
 
     private class OnCloseCallback implements WriteCallback
     {
         @Override
         public void writeFailed(Throwable x)
         {
             disconnect();
         }
 
         @Override
         public void writeSuccess()
         {
             onWriteWebSocketClose();
         }
     }
 
     public static class Stats {
         private AtomicLong countFillInterestedEvents = new AtomicLong(0);
         private AtomicLong countOnFillableEvents = new AtomicLong(0);
         private AtomicLong countFillableErrors = new AtomicLong(0);
 
         public long getFillableErrorCount() {
             return countFillableErrors.get();
         }
 
         public long getFillInterestedCount() {
             return countFillInterestedEvents.get();
         }
 
         public long getOnFillableCount() {
             return countOnFillableEvents.get();
         }
     }
 
     private static final Logger LOG = Log.getLogger(AbstractWebSocketConnection.class);
 
     /**
      * Minimum size of a buffer is the determined to be what would be the maximum framing header size (not including payload)
      */
     private static final int MIN_BUFFER_SIZE = Generator.OVERHEAD;
 
     private final ForkInvoker<Callback> invoker = new FlushInvoker();
     private final ByteBufferPool bufferPool;
     private final Scheduler scheduler;
     private final Generator generator;
     private final Parser parser;
     private final WebSocketPolicy policy;
     private final WriteBytesProvider writeBytes;
     private final AtomicBoolean suspendToken;
     private WebSocketSession session;
     private List<ExtensionConfig> extensions;
     private boolean flushing;
     private boolean isFilling;
     private IOState ioState;
     private Stats stats = new Stats();
 
     public AbstractWebSocketConnection(EndPoint endp, Executor executor, Scheduler scheduler, WebSocketPolicy policy, ByteBufferPool bufferPool)
     {
         super(endp,executor,EXECUTE_ONFILLABLE); // TODO review if this is best. Specifically with MUX
         this.policy = policy;
         this.bufferPool = bufferPool;
         this.generator = new Generator(policy,bufferPool);
         this.parser = new Parser(policy,bufferPool);
         this.scheduler = scheduler;
         this.extensions = new ArrayList<>();
         this.suspendToken = new AtomicBoolean(false);
         this.ioState = new IOState();
         this.ioState.setState(ConnectionState.CONNECTING);
         this.writeBytes = new WriteBytesProvider(generator,new FlushCallback());
         this.setInputBufferSize(policy.getInputBufferSize());
     }
 
     @Override
     public void close()
     {
         close(StatusCode.NORMAL,null);
     }
 
     @Override
     public void close(int statusCode, String reason)
     {
         enqueClose(statusCode,reason);
     }
 
     public void complete(final Callback callback)
     {
         LOG.debug("complete({})",callback);
         synchronized (writeBytes)
         {
             flushing = false;
         }
 
         if (!ioState.isOpen() || (callback == null))
         {
             return;
         }
 
         invoker.invoke(callback);
     }
 
     @Override
     public void disconnect()
     {
         disconnect(false);
     }
 
     public void disconnect(boolean onlyOutput)
     {
         ioState.setState(ConnectionState.CLOSED);
         EndPoint endPoint = getEndPoint();
         // We need to gently close first, to allow
         // SSL close alerts to be sent by Jetty
         LOG.debug("Shutting down output {}",endPoint);
         endPoint.shutdownOutput();
         if (!onlyOutput)
         {
             LOG.debug("Closing {}",endPoint);
             endPoint.close();
         }
     }
 
     /**
      * Enqueue a close frame.
      * 
      * @param statusCode
      *            the WebSocket status code.
      * @param reason
      *            the (optional) reason string. (null is allowed)
      * @see StatusCode
      */
     private void enqueClose(int statusCode, String reason)
     {
         synchronized (writeBytes)
         {
             // It is possible to get close events from many different sources.
             // Make sure we only sent 1 over the network.
             if (writeBytes.isClosed())
             {
                 // already sent the close
                 return;
             }
         }
         CloseInfo close = new CloseInfo(statusCode,reason);
         // TODO: create DisconnectCallback?
         outgoingFrame(close.asFrame(),new OnCloseCallback());
     }
 
     private void execute(Runnable task)
     {
         try
         {
             getExecutor().execute(task);
         }
         catch (RejectedExecutionException e)
         {
             LOG.debug("Job not dispatched: {}",task);
         }
     }
 
     @Override
     public void fillInterested()
     {
         stats.countFillInterestedEvents.incrementAndGet();
         super.fillInterested();
     }
 
     public void flush()
     {
         ByteBuffer buffer = null;
 
         synchronized (writeBytes)
         {
             if (writeBytes.isFailed())
             {
                 LOG.debug(".flush() - queue is in failed state");
                 return;
             }
 
             if (flushing)
             {
                 return;
             }
 
             if (LOG.isDebugEnabled())
             {
                 LOG.debug(".flush() - flushing={} - writeBytes={}",flushing,writeBytes);
             }
 
             if (!isOpen())
             {
                 // No longer have an open connection, drop them all.
                 writeBytes.failAll(new WebSocketException("Connection closed"));
                 return;
             }
 
             buffer = writeBytes.getByteBuffer();
 
             if (buffer == null)
             {
                 return;
             }
 
             flushing = true;
 
             if (LOG.isDebugEnabled())
             {
                 LOG.debug("Flushing {} - {}",BufferUtil.toDetailString(buffer),writeBytes);
             }
         }
 
         write(buffer);
     }
 
     public ByteBufferPool getBufferPool()
     {
         return bufferPool;
     }
 
     /**
      * Get the list of extensions in use.
      * <p>
      * This list is negotiated during the WebSocket Upgrade Request/Response handshake.
      * 
      * @return the list of negotiated extensions in use.
      */
     public List<ExtensionConfig> getExtensions()
     {
         return extensions;
     }
 
     public Generator getGenerator()
     {
         return generator;
     }
 
     @Override
     public IOState getIOState()
     {
         return ioState;
     }
 
     public Parser getParser()
     {
         return parser;
     }
 
     @Override
     public WebSocketPolicy getPolicy()
     {
         return this.policy;
     }
 
     @Override
     public InetSocketAddress getRemoteAddress()
     {
         return getEndPoint().getRemoteAddress();
     }
 
     public Scheduler getScheduler()
     {
         return scheduler;
     }
 
     @Override
     public WebSocketSession getSession()
     {
         return session;
     }
 
     public Stats getStats()
     {
         return stats;
     }
 
     @Override
     public boolean isOpen()
     {
         return getIOState().isOpen() && getEndPoint().isOpen();
     }
 
     @Override
     public boolean isReading()
     {
         return isFilling;
     }
 
     @Override
     public void onClose()
     {
         super.onClose();
         this.getIOState().setState(ConnectionState.CLOSED);
     }
 
     @Override
     public void onFillable()
     {
         LOG.debug("{} onFillable()",policy.getBehavior());
         stats.countOnFillableEvents.incrementAndGet();
         ByteBuffer buffer = bufferPool.acquire(getInputBufferSize(),false);
         BufferUtil.clear(buffer);
         boolean readMore = false;
         try
         {
             isFilling = true;
             readMore = (read(buffer) != -1);
         }
         finally
         {
             bufferPool.release(buffer);
         }
 
         if (readMore && (suspendToken.get() == false))
         {
             fillInterested();
         }
         else
         {
             isFilling = false;
         }
     }
 
     @Override
     protected void onFillInterestedFailed(Throwable cause)
     {
         LOG.ignore(cause);
         stats.countFillInterestedEvents.incrementAndGet();
         super.onFillInterestedFailed(cause);
     }
 
     @Override
     public void onOpen()
     {
         super.onOpen();
         this.ioState.setState(ConnectionState.OPEN);
         LOG.debug("fillInterested");
         fillInterested();
     }
 
     @Override
     protected boolean onReadTimeout()
     {
         LOG.warn("Read Timeout");
 
         IOState state = getIOState();
         if ((state.getState() == ConnectionState.CLOSING) || (state.getState() == ConnectionState.CLOSED))
         {
             // close already initiated, extra timeouts not relevant
             // allow udnerlying connection and endpoint to disconnect on its own
             return true;
         }
 
         // Initiate close - politely send close frame.
         // Note: it is not possible in 100% of cases during read timeout to send this close frame.
         session.close(StatusCode.NORMAL,"Idle Timeout");
 
         return false;
     }
 
     public void onWriteWebSocketClose()
     {
         if (ioState.onCloseHandshake(false))
         {
             disconnect();
         }
     }
 
     /**
      * Frame from API, User, or Internal implementation destined for network.
      */
     @Override
     public void outgoingFrame(Frame frame, WriteCallback callback)
     {
         if (LOG.isDebugEnabled())
         {
             LOG.debug("outgoingFrame({}, {})",frame,callback);
         }
 
         if (!isOpen())
         {
             return;
         }
 
         synchronized (writeBytes)
         {
             writeBytes.enqueue(frame,WriteCallbackWrapper.wrap(callback));
         }
 
         flush();
     }
 
     private int read(ByteBuffer buffer)
     {
         EndPoint endPoint = getEndPoint();
         try
         {
             while (true)
             {
                 int filled = endPoint.fill(buffer);
                 if (filled == 0)
                 {
                     return 0;
                 }
                 else if (filled < 0)
                 {
                     LOG.debug("read - EOF Reached");
                     return -1;
                 }
                 else
                 {
                     if (LOG.isDebugEnabled())
                     {
                         LOG.debug("Filled {} bytes - {}",filled,BufferUtil.toDetailString(buffer));
                     }
                     parser.parse(buffer);
                 }
             }
         }
         catch (IOException e)
         {
             LOG.warn(e);
             enqueClose(StatusCode.PROTOCOL,e.getMessage());
             return -1;
         }
         catch (CloseException e)
         {
             LOG.warn(e);
             enqueClose(e.getStatusCode(),e.getMessage());
             return -1;
         }
     }
 
     @Override
     public void resume()
     {
         if (suspendToken.getAndSet(false))
         {
             fillInterested();
         }
     }
 
     /**
      * Get the list of extensions in use.
      * <p>
      * This list is negotiated during the WebSocket Upgrade Request/Response handshake.
      * 
      * @param extensions
      *            the list of negotiated extensions in use.
      */
     public void setExtensions(List<ExtensionConfig> extensions)
     {
         this.extensions = extensions;
     }
 
     @Override
     public void setInputBufferSize(int inputBufferSize)
     {
         if(inputBufferSize < MIN_BUFFER_SIZE) {
             throw new IllegalArgumentException("Cannot have buffer size less than " + MIN_BUFFER_SIZE);
         }
         super.setInputBufferSize(inputBufferSize);
     }
 
     @Override
     public void setSession(WebSocketSession session)
     {
         this.session = session;
     }
 
     @Override
     public SuspendToken suspend()
     {
         suspendToken.set(true);
         return this;
     }
 
     @Override
     public String toString()
     {
         return String.format("%s{g=%s,p=%s}",super.toString(),generator,parser);
     }
 
     private <C> void write(ByteBuffer buffer)
     {
         EndPoint endpoint = getEndPoint();
 
         if (!isOpen())
         {
             writeBytes.failAll(new IOException("Connection closed"));
             return;
         }
 
         try
         {
             endpoint.write(writeBytes,buffer);
         }
         catch (Throwable t)
         {
             writeBytes.failed(t);
         }
     }
 }