/*
Copyright (c) 2007 Health Market Science, Inc.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License.

This library 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.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
USA

You can contact Health Market Science at info@healthmarketscience.com
or at the following address:

Health Market Science
2700 Horizon Drive
Suite 200
King of Prussia, PA 19406
*/

package com.healthmarketscience.rmiio;

import java.io.IOException;
import java.io.InputStream;
import java.util.zip.GZIPOutputStream;

import com.healthmarketscience.rmiio.util.InputStreamAdapter;
import com.healthmarketscience.rmiio.util.EncodingInputStream;


/**
 * Concrete implementation of a RemoteInputStreamServer which sends compressed
 * data in the GZIP format, which it will read from the underlying
 * InputStream.
 *
 * @see <a href="{@docRoot}/overview-summary.html#Usage_Notes">Usage Notes</a>
 * @see #writeReplace
 *
 * @author James Ahlborn
 */
public class GZIPRemoteInputStream extends RemoteInputStreamServer
{
  private static final long serialVersionUID = 20080212L;  

  /** input stream from which this class retrieves the gzip compressed data
      written to _packetOStream.  The OutputStream linked to this object will
      be used as the sink for the GZIPOutputStream. */
  private transient final GZIPEncodingInputStream _packetIStream;
  /** output stream which is used to compress the underlying data from the
      InputStream */
  private transient GZIPOutputStream _gzipOStream;
  /** manages reading from the underlying stream in a packet-like manner */
  private transient final InputStreamAdapter _inAdapter;
  
  public GZIPRemoteInputStream(InputStream in)
    throws IOException
  {
    this(in, DUMMY_MONITOR, DEFAULT_CHUNK_SIZE);
  }

  public GZIPRemoteInputStream(
    InputStream in,
    RemoteStreamMonitor<RemoteInputStreamServer> monitor)
    throws IOException
  {
    this(in, monitor, DEFAULT_CHUNK_SIZE);
  }

  public GZIPRemoteInputStream(
    InputStream in,
    RemoteStreamMonitor<RemoteInputStreamServer> monitor,
    int chunkSize)
    throws IOException
  {
    super(in, monitor, chunkSize);
    _packetIStream = new GZIPEncodingInputStream(_chunkSize);
    _inAdapter = InputStreamAdapter.create(in, _chunkSize);
  }

  public boolean usingGZIPCompression()
  {
    return true;
  }

  @Override
  protected int availableImpl()
    throws IOException
  {
    synchronized(getLock()) {
      return _packetIStream.available();
    }
  }

  @SuppressWarnings("PMD.UselessOverridingMethod")
  @Override
  protected void closeImpl(boolean readSuccess)
    throws IOException
  {
    // as much as we want to close the _gzipOStream here, we really can't.  if
    // this stream is closing prematurely, closing the _gzipOStream will cause
    // it to generate output, which can never make it over the remote stream
    // anyway (and could cause errors), and, if the stream was read
    // completely, the _gzipOStream will already be closed.  so, we'll just
    // let the stream die a natural death later whenever the garbage collector
    // gets to it
    
    // now close super
    super.closeImpl(readSuccess);
  }

  @Override
  protected byte[] readPacket()
    throws IOException
  {
    // will be called synchronized

    return _packetIStream.readPacket();
  }

  @Override
  protected long skip(long n)
    throws IOException
  {
    throw new IOException("Should not be called on compressed stream");
  }

  /**
   * Utility class which turns gzip output bytes into a sequence of byte[]'s.
   * The OutputStream of this class is used as the sink for data from the
   * GZIPOutputStream.
   */
  private class GZIPEncodingInputStream extends EncodingInputStream
  {
    private GZIPEncodingInputStream(int chunkSize) {
      super(chunkSize);
    }

    @Override
    protected void encode(int suggestedLength)
      throws IOException
    {
      if(_gzipOStream == null) {
        // cannot create GZIPOutputStream until first used (because its
        // constructor generates output!)
        _gzipOStream = new GZIPOutputStream(createOutputStream(),
                                            _chunkSize);
      }
        
      int numRead = _inAdapter.readTemp();
      if(numRead > 0) {

        _monitor.localBytesMoved(GZIPRemoteInputStream.this, numRead);
        
        // push data into the gzipper
        _gzipOStream.write(_inAdapter.getTempBuffer(), 0, numRead);
        
      } else {

        if(_gzipOStream != null) {
          // no more source data, finish it off
          _gzipOStream.close();
        }
      }
    }
  }
  
  
}