//
   //  ========================================================================
   //  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.client.io;
  
  import java.io.IOException;
  import java.net.URI;
  import java.nio.ByteBuffer;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.Executor;
  
  import org.eclipse.jetty.io.AbstractConnection;
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.FutureCallback;
  import org.eclipse.jetty.util.QuotedStringTokenizer;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.websocket.api.UpgradeException;
  import org.eclipse.jetty.websocket.api.WebSocketPolicy;
  import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;
  import org.eclipse.jetty.websocket.client.ClientUpgradeRequest;
  import org.eclipse.jetty.websocket.client.ClientUpgradeResponse;
  import org.eclipse.jetty.websocket.common.AcceptHash;
  import org.eclipse.jetty.websocket.common.SessionFactory;
  import org.eclipse.jetty.websocket.common.WebSocketSession;
  import org.eclipse.jetty.websocket.common.events.EventDriver;
  import org.eclipse.jetty.websocket.common.extensions.ExtensionStack;
  import org.eclipse.jetty.websocket.common.io.http.HttpResponseHeaderParser;
  import org.eclipse.jetty.websocket.common.io.http.HttpResponseHeaderParser.ParseException;
  
  /**
   * This is the initial connection handling that exists immediately after physical connection is established to destination server.
   * <p>
   * Eventually, upon successful Upgrade request/response, this connection swaps itself out for the WebSocektClientConnection handler.
   */
  public class UpgradeConnection extends AbstractConnection
  {
      public class SendUpgradeRequest extends FutureCallback implements Runnable
      {
          @Override
          public void run()
          {
              URI uri = connectPromise.getRequest().getRequestURI();
              request.setRequestURI(uri);
  
              UpgradeListener handshakeListener = connectPromise.getUpgradeListener();
              if (handshakeListener != null)
              {
                  handshakeListener.onHandshakeRequest(request);
              }
  
              String rawRequest = request.generate();
  
              ByteBuffer buf = BufferUtil.toBuffer(rawRequest, StandardCharsets.UTF_8);
              getEndPoint().write(this,buf);
          }
  
          @Override
          public void succeeded()
          {
              // Writing the request header is complete.
              super.succeeded();
              // start the interest in fill
              fillInterested();
          }
  
          @Override
          public void failed(Throwable cause)
          {
              super.failed(cause);
              // Fail the connect promise when a fundamental exception during connect occurs.
              connectPromise.failed(cause);
          }
      }
  
      /** HTTP Response Code: 101 Switching Protocols */
      private static final int SWITCHING_PROTOCOLS = 101;
  
      private static final Logger LOG = Log.getLogger(UpgradeConnection.class);
      private final ByteBufferPool bufferPool;
     private final ConnectPromise connectPromise;
     private final HttpResponseHeaderParser parser;
     private ClientUpgradeRequest request;
 
     public UpgradeConnection(EndPoint endp, Executor executor, ConnectPromise connectPromise)
     {
         super(endp,executor);
         this.connectPromise = connectPromise;
         this.bufferPool = connectPromise.getClient().getBufferPool();
         this.request = connectPromise.getRequest();
 
         // Setup the parser
         this.parser = new HttpResponseHeaderParser(new ClientUpgradeResponse());
     }
 
     public void disconnect(boolean onlyOutput)
     {
         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();
         }
     }
 
     private void notifyConnect(ClientUpgradeResponse response)
     {
         connectPromise.setResponse(response);
 
         UpgradeListener handshakeListener = connectPromise.getUpgradeListener();
         if (handshakeListener != null)
         {
             handshakeListener.onHandshakeResponse(response);
         }
     }
 
     @Override
     public void onFillable()
     {
         ByteBuffer buffer = bufferPool.acquire(getInputBufferSize(),false);
         BufferUtil.clear(buffer);
         boolean readMore = false;
         try
         {
             readMore = read(buffer);
         }
         finally
         {
             bufferPool.release(buffer);
         }
 
         if (readMore)
         {
             fillInterested();
         }
     }
 
     @Override
     public void onOpen()
     {
         super.onOpen();
         // TODO: handle timeout?
         getExecutor().execute(new SendUpgradeRequest());
     }
 
     /**
      * Read / Parse the waiting read/fill buffer
      * 
      * @param buffer
      *            the buffer to fill into from the endpoint
      * @return true if there is more to read, false if reading should stop
      */
     private boolean read(ByteBuffer buffer)
     {
         EndPoint endPoint = getEndPoint();
         try
         {
             while (true)
             {
                 int filled = endPoint.fill(buffer);
                 if (filled == 0)
                 {
                     return true;
                 }
                 else if (filled < 0)
                 {
                     LOG.debug("read - EOF Reached");
                     return false;
                 }
                 else
                 {
                     if (LOG.isDebugEnabled())
                     {
                         LOG.debug("Filled {} bytes - {}",filled,BufferUtil.toDetailString(buffer));
                     }
                     ClientUpgradeResponse resp = (ClientUpgradeResponse)parser.parse(buffer);
                     if (resp != null)
                     {
                         // Got a response!
                         validateResponse(resp);
                         notifyConnect(resp);
                         upgradeConnection(resp);
                         if (buffer.hasRemaining())
                         {
                             LOG.debug("Has remaining client bytebuffer of {}",buffer.remaining());
                         }
                         return false; // do no more reading
                     }
                 }
             }
         }
         catch (IOException | ParseException e)
         {
             UpgradeException ue = new UpgradeException(request.getRequestURI(),e);
             connectPromise.failed(ue);
             disconnect(false);
             return false;
         }
         catch (UpgradeException e)
         {
             connectPromise.failed(e);
             disconnect(false);
             return false;
         }
     }
 
     private void upgradeConnection(ClientUpgradeResponse response)
     {
         EndPoint endp = getEndPoint();
         Executor executor = getExecutor();
         
         EventDriver websocket = connectPromise.getDriver();
         WebSocketPolicy policy = websocket.getPolicy();
 
         WebSocketClientConnection connection = new WebSocketClientConnection(endp,executor,connectPromise,policy);
 
         SessionFactory sessionFactory = connectPromise.getClient().getSessionFactory();
         WebSocketSession session = sessionFactory.createSession(request.getRequestURI(),websocket,connection);
         session.setPolicy(policy);
         session.setUpgradeResponse(response);
 
         connection.setSession(session);
 
         // Initialize / Negotiate Extensions
         ExtensionStack extensionStack = new ExtensionStack(connectPromise.getClient().getExtensionFactory());
         extensionStack.negotiate(response.getExtensions());
 
         extensionStack.configure(connection.getParser());
         extensionStack.configure(connection.getGenerator());
 
         // Setup Incoming Routing
         connection.setNextIncomingFrames(extensionStack);
         extensionStack.setNextIncoming(session);
 
         // Setup Outgoing Routing
         session.setOutgoingHandler(extensionStack);
         extensionStack.setNextOutgoing(connection);
 
         // Now swap out the connection
         endp.setConnection(connection);
         connection.onOpen();
     }
 
     private void validateResponse(ClientUpgradeResponse response)
     {
         // Validate Response Status Code
         if (response.getStatusCode() != SWITCHING_PROTOCOLS)
         {
             throw new UpgradeException(request.getRequestURI(),response.getStatusCode(),"Didn't switch protocols");
         }
 
         // Validate Connection header
         String connection = response.getHeader("Connection");
         if (!"upgrade".equalsIgnoreCase(connection))
         {
             throw new UpgradeException(request.getRequestURI(),response.getStatusCode(),"Connection is " + connection + " (expected upgrade)");
         }
 
         // Check the Accept hash
         String reqKey = request.getKey();
         String expectedHash = AcceptHash.hashKey(reqKey);
         String respHash = response.getHeader("Sec-WebSocket-Accept");
 
         response.setSuccess(true);
         if (expectedHash.equalsIgnoreCase(respHash) == false)
         {
             response.setSuccess(false);
             throw new UpgradeException(request.getRequestURI(),response.getStatusCode(),"Invalid Sec-WebSocket-Accept hash");
         }
 
         // Parse extensions
         List<ExtensionConfig> extensions = new ArrayList<>();
         List<String> extValues = response.getHeaders("Sec-WebSocket-Extensions");
         if (extValues != null)
         {
             for (String extVal : extValues)
             {
                 QuotedStringTokenizer tok = new QuotedStringTokenizer(extVal,",");
                 while (tok.hasMoreTokens())
                 {
                     extensions.add(ExtensionConfig.parse(tok.nextToken()));
                 }
             }
         }
         response.setExtensions(extensions);
     }
 }