//
   //  ========================================================================
   //  Copyright (c) 1995-2016 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.http2.generator;
  
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  
  import org.eclipse.jetty.http2.Flags;
  import org.eclipse.jetty.http2.frames.Frame;
  import org.eclipse.jetty.http2.frames.FrameType;
  import org.eclipse.jetty.http2.frames.GoAwayFrame;
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.util.BufferUtil;
  
  public class GoAwayGenerator extends FrameGenerator
  {
      public GoAwayGenerator(HeaderGenerator headerGenerator)
      {
          super(headerGenerator);
      }
  
      @Override
      public void generate(ByteBufferPool.Lease lease, Frame frame)
      {
          GoAwayFrame goAwayFrame = (GoAwayFrame)frame;
          generateGoAway(lease, goAwayFrame.getLastStreamId(), goAwayFrame.getError(), goAwayFrame.getPayload());
      }
  
      public void generateGoAway(ByteBufferPool.Lease lease, int lastStreamId, int error, byte[] payload)
      {
          if (lastStreamId < 0)
              throw new IllegalArgumentException("Invalid last stream id: " + lastStreamId);
  
          // The last streamId + the error code.
          int fixedLength = 4 + 4;
  
          // Make sure we don't exceed the default frame max length.
          int maxPayloadLength = Frame.DEFAULT_MAX_LENGTH - fixedLength;
          if (payload != null && payload.length > maxPayloadLength)
              payload = Arrays.copyOfRange(payload, 0, maxPayloadLength);
  
          int length = fixedLength + (payload != null ? payload.length : 0);
          ByteBuffer header = generateHeader(lease, FrameType.GO_AWAY, length, Flags.NONE, 0);
  
          header.putInt(lastStreamId);
          header.putInt(error);
  
          if (payload != null)
          {
              header.put(payload);
          }
  
          BufferUtil.flipToFlush(header, 0);
          lease.append(header, true);
      }
  }