// ========================================================================
   // Copyright (c) 2009-2009 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.http.gzip;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.OutputStreamWriter;
  import java.io.PrintWriter;
  import java.io.UnsupportedEncodingException;
  import java.util.zip.DeflaterOutputStream;
  
  import javax.servlet.ServletOutputStream;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.util.ByteArrayOutputStream2;
  
  /* ------------------------------------------------------------ */
  /**
   * Skeletal implementation of a CompressedStream. This class adds compression features to a ServletOutputStream and takes care of setting response headers, etc.
   * Major work and configuration is done here. Subclasses using different kinds of compression only have to implement the abstract methods doCompress() and
   * setContentEncoding() using the desired compression and setting the appropriate Content-Encoding header string.
   */
  public abstract class AbstractCompressedStream extends ServletOutputStream 
  {
      private final String _encoding;
      protected HttpServletRequest _request;
      protected HttpServletResponse _response;
      protected OutputStream _out;
      protected ByteArrayOutputStream2 _bOut;
      protected DeflaterOutputStream _compressedOutputStream;
      protected boolean _closed;
      protected int _bufferSize;
      protected int _minCompressSize;
      protected long _contentLength;
      protected boolean _doNotCompress;
  
      /**
       * Instantiates a new compressed stream.
       * 
       * @param request
       *            the request
       * @param response
       *            the response
       * @param contentLength
       *            the content length
       * @param bufferSize
       *            the buffer size
       * @param minCompressSize
       *            the min compress size
       * @throws IOException
       *             Signals that an I/O exception has occurred.
       */
      public AbstractCompressedStream(String encoding,HttpServletRequest request, HttpServletResponse response, long contentLength, int bufferSize, int minCompressSize)
              throws IOException
      {
          _encoding=encoding;
          _request = request;
          _response = response;
          _contentLength = contentLength;
          _bufferSize = bufferSize;
          _minCompressSize = minCompressSize;
          if (minCompressSize == 0)
              doCompress();
      }
  
      /**
       * Reset buffer.
       */
      public void resetBuffer()
      {
          if (_response.isCommitted())
              throw new IllegalStateException("Committed");
          _closed = false;
          _out = null;
          _bOut = null;
          if (_compressedOutputStream != null)
              _response.setHeader("Content-Encoding",null);
          _compressedOutputStream = null;
          _doNotCompress = false;
      }
  
      /**
       * Sets the content length.
       * 
       * @param length
       *            the new content length
       */
     public void setContentLength(long length)
     {
         _contentLength = length;
         if (_doNotCompress && length >= 0)
         {
             if (_contentLength < Integer.MAX_VALUE)
                 _response.setContentLength((int)_contentLength);
             else
                 _response.setHeader("Content-Length",Long.toString(_contentLength));
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see java.io.OutputStream#flush()
      */
     @Override
     public void flush() throws IOException
     {
         if (_out == null || _bOut != null)
         {
             if (_contentLength > 0 && _contentLength < _minCompressSize)
                 doNotCompress();
             else
                 doCompress();
         }
 
         _out.flush();
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see java.io.OutputStream#close()
      */
     @Override
     public void close() throws IOException
     {
         if (_closed)
             return;
 
         if (_request.getAttribute("javax.servlet.include.request_uri") != null)
             flush();
         else
         {
             if (_bOut != null)
             {
                 if (_contentLength < 0)
                     _contentLength = _bOut.getCount();
                 if (_contentLength < _minCompressSize)
                     doNotCompress();
                 else
                     doCompress();
             }
             else if (_out == null)
             {
                 doNotCompress();
             }
 
             if (_compressedOutputStream != null)
                 _compressedOutputStream.close();
             else
                 _out.close();
             _closed = true;
         }
     }
 
     /**
      * Finish.
      * 
      * @throws IOException
      *             Signals that an I/O exception has occurred.
      */
     public void finish() throws IOException
     {
         if (!_closed)
         {
             if (_out == null || _bOut != null)
             {
                 if (_contentLength > 0 && _contentLength < _minCompressSize)
                     doNotCompress();
                 else
                     doCompress();
             }
 
             if (_compressedOutputStream != null && !_closed)
             {
                 _closed = true;
                 _compressedOutputStream.close();
             }
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see java.io.OutputStream#write(int)
      */
     @Override
     public void write(int b) throws IOException
     {
         checkOut(1);
         _out.write(b);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see java.io.OutputStream#write(byte[])
      */
     @Override
     public void write(byte b[]) throws IOException
     {
         checkOut(b.length);
         _out.write(b);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see java.io.OutputStream#write(byte[], int, int)
      */
     @Override
     public void write(byte b[], int off, int len) throws IOException
     {
         checkOut(len);
         _out.write(b,off,len);
     }
     
     /**
      * Do compress.
      *
      * @throws IOException Signals that an I/O exception has occurred.
      */
     public void doCompress() throws IOException
     {
         if (_compressedOutputStream==null) 
         {
             if (_response.isCommitted())
                 throw new IllegalStateException();
             
             setHeader("Content-Encoding", _encoding);
             
             if (_response.containsHeader("Content-Encoding"))
             {
                 _out=_compressedOutputStream=createStream();
 
                 if (_bOut!=null)
                 {
                     _out.write(_bOut.getBuf(),0,_bOut.getCount());
                     _bOut=null;
                 }
             }
             else 
                 doNotCompress();
         }
     }
 
     /**
      * Do not compress.
      * 
      * @throws IOException
      *             Signals that an I/O exception has occurred.
      */
     public void doNotCompress() throws IOException
     {
         if (_compressedOutputStream != null)
             throw new IllegalStateException("Compressed output stream is already assigned.");
         if (_out == null || _bOut != null)
         {
             _doNotCompress = true;
 
             _out = _response.getOutputStream();
             setContentLength(_contentLength);
 
             if (_bOut != null)
                 _out.write(_bOut.getBuf(),0,_bOut.getCount());
             _bOut = null;
         }
     }
 
     /**
      * Check out.
      * 
      * @param length
      *            the length
      * @throws IOException
      *             Signals that an I/O exception has occurred.
      */
     private void checkOut(int length) throws IOException
     {
         if (_closed)
             throw new IOException("CLOSED");
 
         if (_out == null)
         {
             if (_response.isCommitted() || (_contentLength >= 0 && _contentLength < _minCompressSize))
                 doNotCompress();
             else if (length > _minCompressSize)
                 doCompress();
             else
                 _out = _bOut = new ByteArrayOutputStream2(_bufferSize);
         }
         else if (_bOut != null)
         {
             if (_response.isCommitted() || (_contentLength >= 0 && _contentLength < _minCompressSize))
                 doNotCompress();
             else if (length >= (_bOut.getBuf().length - _bOut.getCount()))
                 doCompress();
         }
     }
 
     /**
      * @see org.eclipse.jetty.http.gzip.CompressedStream#getOutputStream()
      */
     public OutputStream getOutputStream()
     {
         return _out;
     }
 
     /**
      * @see org.eclipse.jetty.http.gzip.CompressedStream#isClosed()
      */
     public boolean isClosed()
     {
         return _closed;
     }
     
     /**
      * Allows derived implementations to replace PrintWriter implementation.
      */
     protected PrintWriter newWriter(OutputStream out, String encoding) throws UnsupportedEncodingException
     {
         return encoding == null?new PrintWriter(out):new PrintWriter(new OutputStreamWriter(out,encoding));
     }
 
     protected void setHeader(String name,String value)
     {
         _response.setHeader(name, value);
     }
     
     /**
      * Create the stream fitting to the underlying compression type.
      * 
      * @throws IOException
      *             Signals that an I/O exception has occurred.
      */
     protected abstract DeflaterOutputStream createStream() throws IOException;
 
 }