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/*
 * Copyright (c) 1998-2018 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.remote.websocket;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;

/**
 * WebSocketOutputStream writes a single WebSocket packet.
 *
 *  * 
 */
public class WebSocketWriter extends Writer
  implements WebSocketConstants
{
  private final OutputStream _os;
  private byte []_buffer;
  private int _offset;
  
  private MessageState _state = MessageState.IDLE;
  private boolean _isAutoFlush = true;
  
  private char _savedPair;

  public WebSocketWriter(OutputStream os, byte []buffer)
    throws IOException
  {
    if (os == null) {
      throw new NullPointerException();
    }
    
    _os = os;
    _buffer = buffer;
  }
  
  public void init()
    throws IOException
  {
    if (_state != MessageState.IDLE)
      throw new IllegalStateException(String.valueOf(_state));
    
    _state = MessageState.FIRST;
    
    _savedPair = 0;
    
    if (_buffer.length <= _offset) {
      _os.flush();
    }
    
    _offset = 4;
  }

  @Override
  public void write(int ch)
    throws IOException
  {
    if (! _state.isActive())
      throw new IllegalStateException(String.valueOf(_state));
    
    byte []buffer = _buffer;

    if (_offset == buffer.length) {
      complete(false);
    }

    if (ch < 0x80) {
      buffer[_offset++] = (byte) ch;
    }
    else if (ch < 0x800) {
      if (buffer.length <= _offset + 1) {
        complete(false);
      }
      
      buffer[_offset++] = (byte) (0xc0 + (ch >> 6)); 
      buffer[_offset++] = (byte) (0x80 + (ch & 0x3f));
    }
    else if (0xd800 <= ch && ch <= 0xdbff) {
      _savedPair = (char) ch;
    }
    else if (0xdc00 <= ch && ch <= 0xdfff) {
      int cp = ((_savedPair & 0x3ff) << 10) + (ch & 0x3ff);
      _savedPair = 0;
      
      if (buffer.length <= _offset + 4) { 
        complete(false);
      }
      
      cp += 0x10000;
      
      buffer[_offset++] = (byte) (0xf0 + (cp >> 18));
      buffer[_offset++] = (byte) (0x80 + ((cp >> 12) & 0x3f));
      buffer[_offset++] = (byte) (0x80 + ((cp >> 6) & 0x3f));
      buffer[_offset++] = (byte) (0x80 + (cp & 0x3f));
    }
    else {
      if (buffer.length <= _offset + 2) { 
        complete(false);
      }
      
      buffer[_offset++] = (byte) (0xe0 + (ch >> 12)); 
      buffer[_offset++] = (byte) (0x80 + ((ch >> 6) & 0x3f));
      buffer[_offset++] = (byte) (0x80 + (ch & 0x3f));
    }
  }

  @Override
  public void write(char []buffer, int offset, int length)
    throws IOException
  {
    if (! _state.isActive())
      throw new IllegalStateException(String.valueOf(_state));
    
    byte []wsBuffer = _buffer;
    int wsOffset = _offset;

    for (; length > 0; length--) {
      if (wsBuffer.length <= wsOffset + 2) {
        _offset = wsOffset;
        complete(false);
        wsOffset = _offset;
      }
      
      char ch = buffer[offset++];

      if (ch < 0x80)
        wsBuffer[wsOffset++] = (byte) ch;
      else if (ch < 0x800) {
        wsBuffer[wsOffset++] = (byte) (0xc0 + (ch >> 6)); 
        wsBuffer[wsOffset++] = (byte) (0x80 + (ch & 0x3f));
      }
      else if (0xd800 <= ch && ch <= 0xdbff) {
        _savedPair = ch;
      }
      else if (0xdc00 <= ch && ch <= 0xdfff) {
        int cp = ((_savedPair & 0x3ff) << 10) + (ch & 0x3ff);
        _savedPair = 0;
        
        if (buffer.length <= _offset + 4) { 
          complete(false);
        }
        
        cp += 0x10000;
        
        wsBuffer[wsOffset++] = (byte) (0xf0 + (cp >> 18));
        wsBuffer[wsOffset++] = (byte) (0x80 + ((cp >> 12) & 0x3f));
        wsBuffer[wsOffset++] = (byte) (0x80 + ((cp >> 6) & 0x3f));
        wsBuffer[wsOffset++] = (byte) (0x80 + (cp & 0x3f));
      }
      else {
        wsBuffer[wsOffset++] = (byte) (0xe0 + (ch >> 12)); 
        wsBuffer[wsOffset++] = (byte) (0x80 + ((ch >> 6) & 0x3f));
        wsBuffer[wsOffset++] = (byte) (0x80 + (ch & 0x3f));
      }
    }
    
    _offset = wsOffset;
  }

  @Override
  public void flush()
    throws IOException
  {
    complete(false);

    _os.flush();
  }

  @Override
  public void close()
    throws IOException
  {
    if (_state == MessageState.IDLE) {
      return;
    }

    complete(true);
    
    _state = MessageState.IDLE;
    
    if (_isAutoFlush) {
      _os.flush();
    }
  }

  private void complete(boolean isFinal)
    throws IOException
  {
    byte []buffer = _buffer;

    int offset = _offset;
    _offset = 4;
    int length = offset - 4;

    // don't flush empty chunk
    if (length == 0 && ! isFinal) {
      return;
    }

    int code1;

    if (_state == MessageState.FIRST) {
      code1 = OP_TEXT;
    }
    else {
      code1 = OP_CONT;
    }

    _state = MessageState.CONT;

    if (isFinal)
      code1 |= FLAG_FIN;

    //System.out.println(Thread.currentThread().getName() + ": code=" + 
    //    Integer.toHexString(code1) + " len=" + length);

    if (length < 0x7e) {
      buffer[2] = (byte) code1;
      buffer[3] = (byte) length;

      _os.write(buffer, 2, offset - 2);
    }
    else {
      buffer[0] = (byte) code1;
      buffer[1] = (byte) 0x7e;
      buffer[2] = (byte) (length >> 8);
      buffer[3] = (byte) (length);

      _os.write(buffer, 0, offset);
    }
  }
  
  public void destroy()
    throws IOException
  {
    _state = MessageState.DESTROYED;
  }
  
  enum MessageState {
    IDLE,
    FIRST {
      @Override
      public boolean isActive() { return true; } 
    },
    CONT {
      @Override
      public boolean isActive() { return true; }
    },
    DESTROYED;
    
    public boolean isActive()
    {
      return false;
    }
  };
  
  static class DummyWriter extends Writer {
    public void write(int ch) throws IOException
    {
      
    }
    
    public void write(char []data, int offset, int length) throws IOException
    {
      
    }
    
    public void flush()
    {
      
    }
    
    public void close()
    {
    }
  }
}