/*
    * Copyright (c) 2012 the original author or authors.
    *
    * Licensed 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.eclipse.jetty.spdy.parser;
  
  import java.nio.ByteBuffer;
  import java.util.EventListener;
  import java.util.List;
  import java.util.concurrent.CopyOnWriteArrayList;
  
  import org.eclipse.jetty.spdy.CompressionFactory;
  import org.eclipse.jetty.spdy.SessionException;
  import org.eclipse.jetty.spdy.StreamException;
  import org.eclipse.jetty.spdy.api.SessionStatus;
  import org.eclipse.jetty.spdy.frames.ControlFrame;
  import org.eclipse.jetty.spdy.frames.DataFrame;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class Parser
  {
      private static final Logger logger = LoggerFactory.getLogger(Parser.class);
      private final List<Listener> listeners = new CopyOnWriteArrayList<>();
      private final ControlFrameParser controlFrameParser;
      private final DataFrameParser dataFrameParser;
      private State state = State.CONTROL_BIT;
  
      public Parser(CompressionFactory.Decompressor decompressor)
      {
          // It is important to allocate one decompression context per
          // SPDY session for the control frames (to decompress the headers)
          controlFrameParser = new ControlFrameParser(decompressor)
          {
              @Override
              protected void onControlFrame(ControlFrame frame)
              {
                  logger.debug("Parsed {}", frame);
                  notifyControlFrame(frame);
              }
          };
          dataFrameParser = new DataFrameParser()
          {
              @Override
              protected void onDataFrame(DataFrame frame, ByteBuffer data)
              {
                  logger.debug("Parsed {}, {} data bytes", frame, data.remaining());
                  notifyDataFrame(frame, data);
              }
          };
      }
  
      public void addListener(Listener listener)
      {
          listeners.add(listener);
      }
  
      public void removeListener(Listener listener)
      {
          listeners.remove(listener);
      }
  
      protected void notifyControlFrame(ControlFrame frame)
      {
          for (Listener listener : listeners)
          {
              try
              {
                  listener.onControlFrame(frame);
              }
              catch (Exception x)
              {
                  logger.info("Exception while notifying listener " + listener, x);
              }
          }
      }
  
      protected void notifyDataFrame(DataFrame frame, ByteBuffer data)
      {
          for (Listener listener : listeners)
          {
              try
              {
                  listener.onDataFrame(frame, data);
              }
              catch (Exception x)
              {
                 logger.info("Exception while notifying listener " + listener, x);
             }
         }
     }
 
     protected void notifyStreamException(StreamException x)
     {
         for (Listener listener : listeners)
         {
             listener.onStreamException(x);
         }
     }
 
     protected void notifySessionException(SessionException x)
     {
         logger.debug("SPDY session exception", x);
         for (Listener listener : listeners)
         {
             try
             {
                 listener.onSessionException(x);
             }
             catch (Exception xx)
             {
                 logger.debug("Could not notify listener " + listener, xx);
             }
         }
     }
 
     public void parse(ByteBuffer buffer)
     {
         try
         {
             logger.debug("Parsing {} bytes", buffer.remaining());
             while (buffer.hasRemaining())
             {
                 switch (state)
                 {
                     case CONTROL_BIT:
                     {
                         // We must only peek the first byte and not advance the buffer
                         // because the 7 least significant bits may be relevant in data frames
                         int currByte = buffer.get(buffer.position());
                         boolean isControlFrame = (currByte & 0x80) == 0x80;
                         state = isControlFrame ? State.CONTROL_FRAME : State.DATA_FRAME;
                         break;
                     }
                     case CONTROL_FRAME:
                     {
                         if (controlFrameParser.parse(buffer))
                             reset();
                         break;
                     }
                     case DATA_FRAME:
                     {
                         if (dataFrameParser.parse(buffer))
                             reset();
                         break;
                     }
                     default:
                     {
                         throw new IllegalStateException();
                     }
                 }
             }
         }
         catch (SessionException x)
         {
             notifySessionException(x);
         }
         catch (StreamException x)
         {
             notifyStreamException(x);
         }
         catch (Throwable x)
         {
             notifySessionException(new SessionException(SessionStatus.PROTOCOL_ERROR, x));
         }
         finally
         {
             // Be sure to consume after exceptions
             buffer.position(buffer.limit());
         }
     }
 
     private void reset()
     {
         state = State.CONTROL_BIT;
     }
 
     public interface Listener extends EventListener
     {
         public void onControlFrame(ControlFrame frame);
 
         public void onDataFrame(DataFrame frame, ByteBuffer data);
 
         public void onStreamException(StreamException x);
 
         public void onSessionException(SessionException x);
 
         public static class Adapter implements Listener
         {
             @Override
             public void onControlFrame(ControlFrame frame)
             {
             }
 
             @Override
             public void onDataFrame(DataFrame frame, ByteBuffer data)
             {
             }
 
             @Override
             public void onStreamException(StreamException x)
             {
             }
 
             @Override
             public void onSessionException(SessionException x)
             {
             }
         }
     }
 
     private enum State
     {
         CONTROL_BIT, CONTROL_FRAME, DATA_FRAME
     }
 
 }