/*
    * 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 javax.servlet.Filter;
  import javax.servlet.FilterChain;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.http.HttpHeaders;
  
  /**
   * Eenvoudige GZip compressie filter ter optimalisatie van bandbreedte.
   * 
   * @author prinsmc
   *
   */
  public class GZipFilter implements Filter {
  
  	/**
  	 * Comprimeert de response met GZip mits de clinet aangeeft dat die gzip
  	 * accepteert.
  	 * 
  	 * {@inheritDoc}
  	 * 
  	 * @param request
  	 *            het request
  	 * @param response
  	 *            de response
  	 * @param chain
  	 *            de filter chain
  	 * @throws IOException
  	 *             Signals that an I/O exception has occurred.
  	 * @throws ServletException
  	 *             the servlet exception
  	 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
  	 *      javax.servlet.ServletResponse, javax.servlet.FilterChain)
  	 * 
  	 * 
  	 */
  	@Override
  	public void doFilter(final ServletRequest request,
  			final ServletResponse response, final FilterChain chain)
  			throws IOException, ServletException {
  		HttpServletRequest httpRequest = (HttpServletRequest) request;
  		HttpServletResponse httpResponse = (HttpServletResponse) response;
  		String acceptEncoding = httpRequest
  				.getHeader(HttpHeaders.ACCEPT_ENCODING);
  		if (acceptEncoding != null) {
  			if (acceptEncoding.indexOf("gzip") >= 0) {
  				GZIPHttpServletResponseWrapper gzipResponse = new GZIPHttpServletResponseWrapper(
  						httpResponse);
  				chain.doFilter(request, gzipResponse);
  				gzipResponse.finish();
  				return;
  			}
  		}
  		chain.doFilter(request, response);
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
  	 */
  	@Override
  	public void init(final FilterConfig filterConfig) throws ServletException {
  		// do nothing
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see javax.servlet.Filter#destroy()
  	 */
  	@Override
  	public void destroy() {
  		// do nothing
  	}
  }