source: jobvista-backend/src/main/java/mk/ukim/finki/predmeti/internettehnologii/jobvistabackend/config/JwtAuthFilter.java

package mk.ukim.finki.predmeti.internettehnologii.jobvistabackend.config;

import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import mk.ukim.finki.predmeti.internettehnologii.jobvistabackend.service.intef.JwtService;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.web.authentication.WebAuthenticationDetailsSource;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;

import java.io.IOException;

@Component
@RequiredArgsConstructor
public class JwtAuthFilter extends OncePerRequestFilter {

    private final JwtService jwtService;
    private final UserDetailsService userDetailsService;

    @Override
    protected void doFilterInternal(@NonNull HttpServletRequest request, @NonNull HttpServletResponse response, @NonNull FilterChain filterChain) throws ServletException, IOException {
        final String authHeader = request.getHeader("Authorization");

        if (authHeader == null ||!authHeader.startsWith("Bearer ")) {
            filterChain.doFilter(request, response);
            return;
        }

        final String jwt = authHeader.substring(7);
        final String userEmail = jwtService.extractUsername(jwt);

        if (userEmail != null && SecurityContextHolder.getContext().getAuthentication() == null) {
            UserDetails userDetails = userDetailsService.loadUserByUsername(userEmail);

            if(jwtService.isTokenValid(jwt, userDetails)) {
                UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(userDetails, null, userDetails.getAuthorities());
                token.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));

                SecurityContextHolder.getContext().setAuthentication(token);
            }
        }
        filterChain.doFilter(request, response);
    }
}