import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
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.HttpServletResponse;
import java.io.IOException;

public class JwtFilter extends GenericFilterBean {

	@Override
	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
			throws IOException, ServletException {

		final HttpServletRequest request = (HttpServletRequest) servletRequest;
		final HttpServletResponse response = (HttpServletResponse) servletResponse;
		final String authHeader = request.getHeader("authorization");

		if ("OPTIONS".equals(request.getMethod())) {
			response.setStatus(HttpServletResponse.SC_OK);
			filterChain.doFilter(request, response);
		} else {
			if (authHeader == null || !authHeader.startsWith("Bearer ")) {
				throw new ServletException("An exception occurred");
			}
		}

		final String token = authHeader.substring(7);

		Claims claims = Jwts.parser().setSigningKey("secret").parseClaimsJws(token).getBody();

		request.setAttribute("claims", claims);
		request.setAttribute("blog", servletRequest.getParameter("id"));

		filterChain.doFilter(request, response);

	}
}