//
   //  ========================================================================
   //  Copyright (c) 1995-2015 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.client;
  
  import org.eclipse.jetty.client.api.Result;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  public abstract class HttpChannel
  {
      protected static final Logger LOG = Log.getLogger(HttpChannel.class);
  
      private final HttpDestination _destination;
      private HttpExchange _exchange;
  
      protected HttpChannel(HttpDestination destination)
      {
          this._destination = destination;
      }
  
      public HttpDestination getHttpDestination()
      {
          return _destination;
      }
  
      /**
       * <p>Associates the given {@code exchange} to this channel in order to be sent over the network.</p>
       * <p>If the association is successful, the exchange can be sent. Otherwise, the channel must be
       * disposed because whoever terminated the exchange did not do it - it did not have the channel yet.</p>
       *
       * @param exchange the exchange to associate
       * @return true if the association was successful, false otherwise
       */
      public boolean associate(HttpExchange exchange)
      {
          boolean result = false;
          boolean abort = true;
          synchronized (this)
          {
              if (_exchange == null)
              {
                  abort = false;
                  result = exchange.associate(this);
                  if (result)
                      _exchange = exchange;
              }
          }
  
          if (abort)
              exchange.getRequest().abort(new UnsupportedOperationException("Pipelined requests not supported"));
  
          if (LOG.isDebugEnabled())
              LOG.debug("{} associated {} to {}", exchange, result, this);
  
          return result;
      }
  
      public boolean disassociate(HttpExchange exchange)
      {
          boolean result = false;
          synchronized (this)
          {
              HttpExchange existing = _exchange;
              _exchange = null;
              if (existing == exchange)
              {
                  existing.disassociate(this);
                  result = true;
              }
          }
  
          if (LOG.isDebugEnabled())
              LOG.debug("{} disassociated {} from {}", exchange, result, this);
          return result;
      }
  
      public HttpExchange getHttpExchange()
      {
          synchronized (this)
          {
              return _exchange;
          }
      }
 
     protected abstract HttpSender getHttpSender();
 
     protected abstract HttpReceiver getHttpReceiver();
 
     public abstract void send();
 
     public abstract void release();
 
     public void proceed(HttpExchange exchange, Throwable failure)
     {
         getHttpSender().proceed(exchange, failure);
     }
 
     public boolean abort(HttpExchange exchange, Throwable requestFailure, Throwable responseFailure)
     {
         boolean requestAborted = false;
         if (requestFailure != null)
             requestAborted = getHttpSender().abort(exchange, requestFailure);
 
         boolean responseAborted = false;
         if (responseFailure != null)
             responseAborted = abortResponse(exchange, responseFailure);
 
         return requestAborted || responseAborted;
     }
 
     public boolean abortResponse(HttpExchange exchange, Throwable failure)
     {
         return getHttpReceiver().abort(exchange, failure);
     }
 
     public void exchangeTerminated(HttpExchange exchange, Result result)
     {
         disassociate(exchange);
     }
 
     @Override
     public String toString()
     {
         return String.format("%s@%x(exchange=%s)", getClass().getSimpleName(), hashCode(), getHttpExchange());
     }
 }