package it.inaf.ia2.gms.authn;

import it.inaf.ia2.aa.UserManager;
import it.inaf.ia2.aa.data.User;
import it.inaf.ia2.gms.persistence.LoggingDAO;
import it.inaf.ia2.gms.persistence.model.ActionType;
import java.io.IOException;
import java.security.Principal;
import java.util.Map;
import javax.servlet.Filter;
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 javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class JWTFilter implements Filter {

    private final LoggingDAO loggingDAO;
    private final UserManager userManager;

    public JWTFilter(LoggingDAO loggingDAO, UserManager userManager) {
        this.loggingDAO = loggingDAO;
        this.userManager = userManager;
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain fc) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

        String authHeader = request.getHeader("Authorization");

        if (authHeader == null) {

            if (request.isRequestedSessionIdValid()) {
                HttpSession session = request.getSession(false);
                User user = (User) session.getAttribute("user_data");
                if (user != null) {
                    ServletRequestWithSessionPrincipal wrappedRequest = new ServletRequestWithSessionPrincipal(request, user);
                    fc.doFilter(wrappedRequest, res);
                    return;
                }
            }

            fc.doFilter(req, res);
            return;
        }

        String token = authHeader.replace("Bearer", "").trim();

        Map<String, Object> claims = userManager.parseIdTokenClaims(token);

        if (claims.get("sub") == null) {
            loggingDAO.logAction(ActionType.UNAUTHORIZED_ACCESS_ATTEMPT, "Attempt to access API with invalid token " + request.getRequestURI(), request);
            response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Invalid access token: missing sub claim");
            return;
        }

        ServletRequestWithJWTPrincipal wrappedRequest = new ServletRequestWithJWTPrincipal(request, token, claims);

        loggingDAO.logAction(ActionType.API_CALL, request.getRequestURI() + " called by " + wrappedRequest.getUserPrincipal().getName(), request);

        fc.doFilter(wrappedRequest, res);
    }

    private static class ServletRequestWithSessionPrincipal extends HttpServletRequestWrapper {

        private final User principal;

        public ServletRequestWithSessionPrincipal(HttpServletRequest request, User user) {
            super(request);
            this.principal = user;
        }

        @Override
        public Principal getUserPrincipal() {
            return principal;
        }
    }

    private static class ServletRequestWithJWTPrincipal extends HttpServletRequestWrapper {

        private final RapPrincipal principal;

        public ServletRequestWithJWTPrincipal(HttpServletRequest request, String token, Map<String, Object> jwtClaims) {
            super(request);
            this.principal = new RapPrincipal(token, jwtClaims);
        }

        @Override
        public Principal getUserPrincipal() {
            return principal;
        }
    }
}