// ========================================================================
   // Copyright (c) 2010 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;
  
  import java.io.IOException;
  import java.security.SecureRandom;
  import java.util.Random;
  
  import org.eclipse.jetty.io.Buffer;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.io.EofException;
  import org.eclipse.jetty.util.TypeUtil;
  
  
  /* ------------------------------------------------------------ */
  /** WebSocketGenerator.
   * This class generates websocket packets.
   * It is fully synchronized because it is likely that async
   * threads will call the addMessage methods while other
   * threads are flushing the generator.
   */
  public class WebSocketGeneratorD06 implements WebSocketGenerator
  {
      final private WebSocketBuffers _buffers;
      final private EndPoint _endp;
      private Buffer _buffer;
      private final byte[] _mask=new byte[4];
      private int _m;
      private boolean _opsent;
      private final MaskGen _maskGen;
  
      public interface MaskGen
      {
          void genMask(byte[] mask);
      }
      
      public static class NullMaskGen implements MaskGen
      {
          public void genMask(byte[] mask)
          {
              mask[0]=mask[1]=mask[2]=mask[3]=0;
          }
      }
      
      public static class FixedMaskGen implements MaskGen
      {
          final byte[] _mask;
          public FixedMaskGen()
          {
              _mask=new byte[]{(byte)0xff,(byte)0xff,(byte)0xff,(byte)0xff};
          }
          
          public FixedMaskGen(byte[] mask)
          {
              _mask=mask;
          }
          
          public void genMask(byte[] mask)
          {
              mask[0]=_mask[0];
              mask[1]=_mask[1];
              mask[2]=_mask[2];
              mask[3]=_mask[3];
          }
      }
  
      public static class RandomMaskGen implements MaskGen
      {
          final Random _random;
          public RandomMaskGen()
          {
              _random=new SecureRandom(); 
          }
          
          public RandomMaskGen(Random random)
          {
              _random=random;
          }
          
          public void genMask(byte[] mask)
          {
              _random.nextBytes(mask);
          }
      }
  
      
      public WebSocketGeneratorD06(WebSocketBuffers buffers, EndPoint endp)
      {
         _buffers=buffers;
         _endp=endp;
         _maskGen=null;
     }
     
     public WebSocketGeneratorD06(WebSocketBuffers buffers, EndPoint endp, MaskGen maskGen)
     {
         _buffers=buffers;
         _endp=endp;
         _maskGen=maskGen;
     }
 
     public synchronized void addFrame(byte flags, byte opcode, byte[] content, int offset, int length, int blockFor) throws IOException
     {
         // System.err.printf("<< %s %s %s\n",TypeUtil.toHexString(flags),TypeUtil.toHexString(opcode),length);
         
         if (_buffer==null)
             _buffer=(_maskGen!=null)?_buffers.getBuffer():_buffers.getDirectBuffer();
             
         boolean last=WebSocketConnectionD06.isLastFrame(flags);
         opcode=(byte)(((0xf&flags)<<4)+0xf&opcode);
         
         int space=(_maskGen!=null)?14:10;
         
         do
         {
             opcode = _opsent?WebSocketConnectionD06.OP_CONTINUATION:opcode;
             _opsent=true;
             
             int payload=length;
             if (payload+space>_buffer.capacity())
             {
                 // We must fragement, so clear FIN bit
                 opcode&=(byte)0x7F; // Clear the FIN bit
                 payload=_buffer.capacity()-space;
             }
             else if (last)
                 opcode|=(byte)0x80; // Set the FIN bit
 
             // ensure there is space for header
             if (_buffer.space() <= space)
                 expelBuffer(blockFor);
             
             // write mask
             if ((_maskGen!=null))
             {
                 _maskGen.genMask(_mask);
                 _m=0;
                 _buffer.put(_mask);
             }
 
             // write the opcode and length
             if (payload>0xffff)
             {
                 bufferPut(new byte[]{
                         opcode,
                         (byte)0x7f,
                         (byte)((payload>>56)&0x7f),
                         (byte)((payload>>48)&0xff), 
                         (byte)((payload>>40)&0xff), 
                         (byte)((payload>>32)&0xff),
                         (byte)((payload>>24)&0xff),
                         (byte)((payload>>16)&0xff),
                         (byte)((payload>>8)&0xff),
                         (byte)(payload&0xff)});
             }
             else if (payload >=0x7e)
             {
                 bufferPut(new byte[]{
                         opcode,
                         (byte)0x7e,
                         (byte)(payload>>8),
                         (byte)(payload&0xff)});
             }
             else
             {
                 bufferPut(opcode);
                 bufferPut((byte)payload);
             }
 
             // write payload
             int remaining = payload;
             while (remaining > 0)
             {
                 _buffer.compact();
                 int chunk = remaining < _buffer.space() ? remaining : _buffer.space();
                 
                 if ((_maskGen!=null))
                 {
                     for (int i=0;i<chunk;i++)
                         bufferPut(content[offset+ (payload-remaining)+i]);
                 }
                 else
                     _buffer.put(content, offset + (payload - remaining), chunk);
                 
                 remaining -= chunk;
                 if (_buffer.space() > 0)
                 {
                     // Gently flush the data, issuing a non-blocking write
                     flushBuffer();
                 }
                 else
                 {
                     // Forcibly flush the data, issuing a blocking write
                     expelBuffer(blockFor);
                     if (remaining == 0)
                     {
                         // Gently flush the data, issuing a non-blocking write
                         flushBuffer();
                     }
                 }
             }
             offset+=payload;
             length-=payload;
         }
         while (length>0);
         _opsent=!last;
     }
 
     private synchronized void bufferPut(byte[] data) throws IOException
     {
         if (_maskGen!=null)
             for (int i=0;i<data.length;i++)
                 data[i]^=_mask[+_m++%4];
         _buffer.put(data);
     }
     
     private synchronized void bufferPut(byte data) throws IOException
     {
         _buffer.put((byte)(data^_mask[+_m++%4]));
     }
 
     public synchronized int flush(int blockFor) throws IOException
     {
         return expelBuffer(blockFor);
     }
 
     public synchronized int flush() throws IOException
     {
         int flushed = flushBuffer();
         if (_buffer!=null && _buffer.length()==0)
         {
             _buffers.returnBuffer(_buffer);
             _buffer=null;
         }
         return flushed;
     }
 
     private synchronized int flushBuffer() throws IOException
     {
         if (!_endp.isOpen())
             throw new EofException();
 
         if (_buffer!=null)
             return _endp.flush(_buffer);
 
         return 0;
     }
 
     private synchronized int expelBuffer(long blockFor) throws IOException
     {
         if (_buffer==null)
             return 0;
         int result = flushBuffer();
         _buffer.compact();
         if (!_endp.isBlocking())
         {
             while (_buffer.space()==0)
             {
                 // TODO: in case the I/O system signals write ready, but when we attempt to write we cannot
                 // TODO: we should decrease the blockFor timeout instead of waiting again the whole timeout
                 boolean ready = _endp.blockWritable(blockFor);
                 if (!ready)
                     throw new IOException("Write timeout");
 
                 result += flushBuffer();
                 _buffer.compact();
             }
         }
         return result;
     }
 
     public synchronized boolean isBufferEmpty()
     {
         return _buffer==null || _buffer.length()==0;
     }
 
 }