// package

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.GenericFilterBean;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;

@Component
public final class IEFixerFilter extends GenericFilterBean {
    private final Logger log = LoggerFactory.getLogger(this.getClass());

    private class IEFixerRequestWrapper extends HttpServletRequestWrapper {
        private IEFixerRequestWrapper(HttpServletRequest request) {
            super(request);
        }

        @Override
        public String getHeader(String name) {
            if (name.toLowerCase().equals("authorization")) {
                return null;
            }
            return super.getHeader(name);
        }

        @Override
        public Enumeration<String> getHeaderNames() {
            List<String> list = new ArrayList<>();
            HttpServletRequest request = (HttpServletRequest)getRequest();
            Enumeration e = request.getHeaderNames();
            while (e.hasMoreElements()) {
                String n = (String)e.nextElement();
                if (!n.equals("authorization") && !n.equals("Authorization")) {
                    list.add(n);
                }
            }
            return Collections.enumeration(list);
        }
    }

    @Override
    public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain) throws IOException, ServletException {
        if (request instanceof HttpServletRequest) {
            HttpServletRequest req = (HttpServletRequest) request;
            if (req.getCookies() != null &&
                    (req.getHeader("authorization") != null || req.getHeader("Authorization") != null)) {
                IEFixerRequestWrapper alteredReq = new IEFixerRequestWrapper(req);
                chain.doFilter(alteredReq, response);
            }
            else {
                chain.doFilter(req, response);
            }
        }
        else {
            chain.doFilter(request, response);
        }
    }
}