/*
    * 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.OutputStreamWriter;
  import java.io.PrintWriter;
  
  import javax.servlet.ServletOutputStream;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpServletResponseWrapper;
  
  import org.apache.http.HttpHeaders;
  
  /**
   * The Class GZIPHttpServletResponseWrapper.
   */
  public class GZIPHttpServletResponseWrapper extends HttpServletResponseWrapper {
  	/** gecomprimeerde output. */
  	private ServletResponseGZIPOutputStream gzipStream;
  	/** te comprimeren output. */
  	private ServletOutputStream outputStream;
  	/** output. */
  	private PrintWriter printWriter;
  
  	/**
  	 * Instantiates a new GZIP http servlet response wrapper.
  	 *
  	 * @param response
  	 *            the response
  	 * @throws IOException
  	 *             Signals that an I/O exception has occurred.
  	 */
  	public GZIPHttpServletResponseWrapper(HttpServletResponse response)
  			throws IOException {
  		super(response);
  		response.addHeader(HttpHeaders.CONTENT_ENCODING, "gzip");
  	}
  
  	/**
  	 * Finish.
  	 *
  	 * @throws IOException
  	 *             Signals that an I/O exception has occurred.
  	 */
  	public void finish() throws IOException {
  		if (printWriter != null) {
  			printWriter.close();
  		}
  		if (outputStream != null) {
  			outputStream.close();
  		}
  		if (gzipStream != null) {
  			gzipStream.close();
  		}
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see javax.servlet.ServletResponseWrapper#flushBuffer()
  	 */
  	@Override
  	public void flushBuffer() throws IOException {
  		if (printWriter != null) {
  			printWriter.flush();
  		}
  		if (outputStream != null) {
  			outputStream.flush();
  		}
  		super.flushBuffer();
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see javax.servlet.ServletResponseWrapper#getOutputStream()
  	 */
  	@Override
  	public ServletOutputStream getOutputStream() throws IOException {
  		if (printWriter != null) {
  			throw new IllegalStateException("printWriter already defined");
  		}
  		if (outputStream == null) {
  			initGzip();
  			outputStream = gzipStream;
  		}
  		return outputStream;
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see javax.servlet.ServletResponseWrapper#getWriter()
  	 */
 	@Override
 	public PrintWriter getWriter() throws IOException {
 		if (outputStream != null) {
 			throw new IllegalStateException("printWriter already defined");
 		}
 		if (printWriter == null) {
 			initGzip();
 			printWriter = new PrintWriter(new OutputStreamWriter(gzipStream,
 					getResponse().getCharacterEncoding()));
 		}
 		return printWriter;
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see javax.servlet.ServletResponseWrapper#setContentLength(int)
 	 */
 	@Override
 	public void setContentLength(int len) {
 	}
 
 	/**
 	 * Inits the gzip.
 	 *
 	 * @throws IOException
 	 *             Signals that an I/O exception has occurred.
 	 */
 	private void initGzip() throws IOException {
 		gzipStream = new ServletResponseGZIPOutputStream(getResponse()
 				.getOutputStream());
 	}
 
 }