package it.inaf.ia2.gms.authn;

import it.inaf.ia2.gms.persistence.LoggingDAO;
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 org.springframework.security.oauth2.common.OAuth2AccessToken;
import org.springframework.security.oauth2.provider.token.store.jwk.JwkTokenStore;

public class JWTFilter implements Filter {

    private final JwkTokenStore jwkTokenStore;
    private final LoggingDAO loggingDAO;

    public JWTFilter(JwkTokenStore jwkTokenStore, LoggingDAO loggingDAO) {
        this.jwkTokenStore = jwkTokenStore;
        this.loggingDAO = loggingDAO;
    }

    @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) {
            loggingDAO.logAction("Attempt to access WS without token", request);
            response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Missing Authorization token");
            return;
        }

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

        OAuth2AccessToken accessToken = jwkTokenStore.readAccessToken(authHeader);
        if (accessToken.isExpired()) {
            loggingDAO.logAction("Attempt to access WS with expired token", request);
            response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Access token is expired");
            return;
        }

        Map<String, Object> claims = accessToken.getAdditionalInformation();

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

        ServletRequestWithJWTPrincipal wrappedRequest = new ServletRequestWithJWTPrincipal(request, claims);
        loggingDAO.logAction("WS access from " + wrappedRequest.getUserPrincipal().getName(), request);

        fc.doFilter(wrappedRequest, res);
    }

    private static class ServletRequestWithJWTPrincipal extends HttpServletRequestWrapper {

        private final Principal principal;

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

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