/*
    * Copyright (c) 2014, Dienst Landelijk Gebied - Ministerie van Economische Zaken
    * 
    * Gepubliceerd onder de BSD 2-clause licentie, 
    * zie https://github.com/MinELenI/CBSviewer/blob/master/LICENSE.md voor de volledige licentie.
    */
   package nl.mineleni.cbsviewer.servlet;
   
   import java.io.IOException;
  import java.io.OutputStream;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.zip.GZIPOutputStream;
  
  import javax.servlet.ServletOutputStream;
  
  /**
   * comprimeert de output stream met gzip.
   * 
   * @author prinsmc
   *
   */
  public class ServletResponseGZIPOutputStream extends ServletOutputStream {
  	/** gzip output. */
  	GZIPOutputStream gzipStream;
  	/** vlag voor ststus van gzip output stream. */
  	final AtomicBoolean open = new AtomicBoolean(true);
  	/** output stream die gecomprimeerd wordt. */
  	OutputStream output;
  
  	/**
  	 * Instantiates a new servlet response gzip output stream.
  	 *
  	 * @param output
  	 *            the output
  	 * @throws IOException
  	 *             Signals that an I/O exception has occurred.
  	 */
  	public ServletResponseGZIPOutputStream(OutputStream output)
  			throws IOException {
  		this.output = output;
  		gzipStream = new GZIPOutputStream(output);
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see java.io.OutputStream#close()
  	 */
  	@Override
  	public void close() throws IOException {
  		if (open.compareAndSet(true, false)) {
  			gzipStream.close();
  		}
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see java.io.OutputStream#flush()
  	 */
  	@Override
  	public void flush() throws IOException {
  		gzipStream.flush();
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see java.io.OutputStream#write(byte[])
  	 */
  	@Override
  	public void write(byte b[]) throws IOException {
  		write(b, 0, b.length);
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see java.io.OutputStream#write(byte[], int, int)
  	 */
  	@Override
  	public void write(byte b[], int off, int len) throws IOException {
  		if (!open.get()) {
  			throw new IOException("Stream closed!");
  		}
  		gzipStream.write(b, off, len);
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see java.io.OutputStream#write(int)
  	 */
  	@Override
  	public void write(int b) throws IOException {
  		if (!open.get()) {
  			throw new IOException("Stream closed!");
  		}
  		gzipStream.write(b);
 	}
 
 }