package com.junmix.utilities.gzip;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
 * GZIPFilter
 * 
 * @author junmix
 * @version 1.0
 */
public class GZIPFilter implements Filter {
    /**
     * main process<br>
     * 
     * @param req
     *            ServletRequest(javax.servlet.ServletRequest)
     * @param res
     *            ServletResponse(javax.servlet.ServletResponse)
     * @return chain FilterChain(javax.servlet.Filter)
     * @throws Exception
     *             IOException, ServletException
     */
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException,
            ServletException {
        if (req instanceof HttpServletRequest) {
            HttpServletRequest request = (HttpServletRequest)req;
            HttpServletResponse response = (HttpServletResponse)res;
            String ae = request.getHeader("accept-encoding");
            // if Browser accepts gzip compression,
            if (ae != null && ae.indexOf("gzip") != -1) {
                // make new instance for Filter
                GZIPResponseWrapper wrappedResponse = new GZIPResponseWrapper(response);
                // execute
                chain.doFilter(req, wrappedResponse);
                // close writer, stream
                wrappedResponse.finishResponse();
                return;
            }
            // if Browser NOT accepts gzip compression,
            chain.doFilter(req, res);
        }
    }

    // no init parameters
    public void init(FilterConfig filterConfig) {
    }

    public void destroy() {
    }
}