//
   //  ========================================================================
   //  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.message;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteBuffer;
  
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.websocket.common.events.AnnotatedEventDriver;
  
  /**
   * Support class for reading binary message data as an InputStream.
   */
  public class MessageInputStream extends InputStream implements MessageAppender
  {
      private static final int BUFFER_SIZE = 65535;
      /**
       * Threshold (of bytes) to perform compaction at
       */
      private static final int COMPACT_THRESHOLD = 5;
      private final AnnotatedEventDriver driver;
      private final ByteBuffer buf;
      private int size;
      private boolean finished;
      private boolean needsNotification;
      private int readPosition;
  
      public MessageInputStream(AnnotatedEventDriver driver)
      {
          this.driver = driver;
          this.buf = ByteBuffer.allocate(BUFFER_SIZE);
          BufferUtil.clearToFill(this.buf);
          size = 0;
          readPosition = this.buf.position();
          finished = false;
          needsNotification = true;
      }
  
      @Override
      public void appendMessage(ByteBuffer payload) throws IOException
      {
          if (finished)
          {
              throw new IOException("Cannot append to finished buffer");
          }
  
          if (payload == null)
          {
              // empty payload is valid
              return;
          }
  
          driver.getPolicy().assertValidMessageSize(size + payload.remaining());
          size += payload.remaining();
  
          synchronized (buf)
          {
              // TODO: grow buffer till max binary message size?
              // TODO: compact this buffer to fit incoming buffer?
              // TODO: tell connection to suspend if buffer too full?
              BufferUtil.put(payload,buf);
          }
  
          if (needsNotification)
          {
              needsNotification = true;
              this.driver.onInputStream(this);
          }
      }
  
      @Override
      public void close() throws IOException
      {
          finished = true;
          super.close();
      }
  
      @Override
      public void messageComplete()
      {
          finished = true;
      }
 
     @Override
     public int read() throws IOException
     {
         synchronized (buf)
         {
             byte b = buf.get(readPosition);
             readPosition++;
             if (readPosition <= (buf.limit() - COMPACT_THRESHOLD))
             {
                 int curPos = buf.position();
                 buf.compact();
                 int offsetPos = buf.position() - curPos;
                 readPosition += offsetPos;
             }
             return b;
         }
     }
 }