//
   //  ========================================================================
   //  Copyright (c) 1995-2012 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.extensions;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.ListIterator;
  import java.util.concurrent.Future;
  
  import javax.net.websocket.SendResult;
  
  import org.eclipse.jetty.util.annotation.ManagedAttribute;
  import org.eclipse.jetty.util.annotation.ManagedObject;
  import org.eclipse.jetty.util.component.ContainerLifeCycle;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.websocket.api.WebSocketException;
  import org.eclipse.jetty.websocket.api.extensions.Extension;
  import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;
  import org.eclipse.jetty.websocket.api.extensions.ExtensionFactory;
  import org.eclipse.jetty.websocket.api.extensions.Frame;
  import org.eclipse.jetty.websocket.api.extensions.IncomingFrames;
  import org.eclipse.jetty.websocket.api.extensions.OutgoingFrames;
  import org.eclipse.jetty.websocket.common.Generator;
  import org.eclipse.jetty.websocket.common.Parser;
  
  /**
   * Represents the stack of Extensions.
   */
  @ManagedObject("Extension Stack")
  public class ExtensionStack extends ContainerLifeCycle implements IncomingFrames, OutgoingFrames
  {
      private static final Logger LOG = Log.getLogger(ExtensionStack.class);
      private final ExtensionFactory factory;
      private List<Extension> extensions;
      private IncomingFrames nextIncoming;
      private OutgoingFrames nextOutgoing;
  
      public ExtensionStack(ExtensionFactory factory)
      {
          this.factory = factory;
      }
  
      public void configure(Generator generator)
      {
          generator.configureFromExtensions(extensions);
      }
  
      public void configure(Parser parser)
      {
          parser.configureFromExtensions(extensions);
      }
  
      @Override
      protected void doStart() throws Exception
      {
          super.doStart();
          LOG.debug("doStart");
  
          // Wire up Extensions
          if ((extensions != null) && (extensions.size() > 0))
          {
              ListIterator<Extension> eiter = extensions.listIterator();
  
              // Connect outgoings
              while (eiter.hasNext())
              {
                  Extension ext = eiter.next();
                  ext.setNextOutgoingFrames(nextOutgoing);
                  nextOutgoing = ext;
              }
  
              // Connect incomings
              while (eiter.hasPrevious())
              {
                  Extension ext = eiter.previous();
                  ext.setNextIncomingFrames(nextIncoming);
                  nextIncoming = ext;
              }
          }
      }
  
     @Override
     public void dump(Appendable out, String indent) throws IOException
     {
         super.dump(out,indent);
 
         IncomingFrames websocket = getLastIncoming();
         OutgoingFrames network = getLastOutgoing();
 
         out.append(indent).append(" +- Stack\n");
         out.append(indent).append("    +- Network  : ").append(network.toString()).append('\n');
         for (Extension ext : extensions)
         {
             out.append(indent).append("    +- Extension: ").append(ext.toString()).append('\n');
         }
         out.append(indent).append("    +- Websocket: ").append(websocket.toString()).append('\n');
     }
 
     @ManagedAttribute(name = "Extension List", readonly = true)
     public List<Extension> getExtensions()
     {
         return extensions;
     }
 
     private IncomingFrames getLastIncoming()
     {
         IncomingFrames last = nextIncoming;
         boolean done = false;
         while (!done)
         {
             if (last instanceof AbstractExtension)
             {
                 last = ((AbstractExtension)last).getNextIncoming();
             }
             else
             {
                 done = true;
             }
         }
         return last;
     }
 
     private OutgoingFrames getLastOutgoing()
     {
         OutgoingFrames last = nextOutgoing;
         boolean done = false;
         while (!done)
         {
             if (last instanceof AbstractExtension)
             {
                 last = ((AbstractExtension)last).getNextOutgoing();
             }
             else
             {
                 done = true;
             }
         }
         return last;
     }
 
     /**
      * Get the list of negotiated extensions, each entry being a full "name; params" extension configuration
      * 
      * @return list of negotiated extensions
      */
     public List<String> getNegotiatedExtensions()
     {
         List<String> ret = new ArrayList<>();
         if (extensions == null)
         {
             return ret;
         }
 
         for (Extension ext : extensions)
         {
             ret.add(ext.getConfig().getParameterizedName());
         }
         return ret;
     }
 
     @ManagedAttribute(name = "Next Incoming Frames Handler", readonly = true)
     public IncomingFrames getNextIncoming()
     {
         return nextIncoming;
     }
 
     @ManagedAttribute(name = "Next Outgoing Frames Handler", readonly = true)
     public OutgoingFrames getNextOutgoing()
     {
         return nextOutgoing;
     }
 
     @Override
     public void incomingError(WebSocketException e)
     {
         nextIncoming.incomingError(e);
     }
 
     @Override
     public void incomingFrame(Frame frame)
     {
         nextIncoming.incomingFrame(frame);
     }
 
     /**
      * Perform the extension negotiation.
      * <p>
      * For the list of negotiated extensions, use {@link #getNegotiatedExtensions()}
      * 
      * @param configs
      *            the configurations being requested
      */
     public void negotiate(List<ExtensionConfig> configs)
     {
         LOG.debug("Extension Configs={}",configs);
         this.extensions = new ArrayList<>();
         for (ExtensionConfig config : configs)
         {
             Extension ext = factory.newInstance(config);
             extensions.add(ext);
             LOG.debug("Adding Extension: {}",ext);
         }
 
         addBean(extensions);
     }
 
     @Override
     public Future<SendResult> outgoingFrame(Frame frame) throws IOException
     {
         return nextOutgoing.outgoingFrame(frame);
     }
 
     public void setNextIncoming(IncomingFrames nextIncoming)
     {
         this.nextIncoming = nextIncoming;
     }
 
     public void setNextOutgoing(OutgoingFrames nextOutgoing)
     {
         this.nextOutgoing = nextOutgoing;
     }
 
     @Override
     public String toString()
     {
         return String.format("ExtensionStack[extensions=%s]",extensions);
     }
 }