JwtAuthenticationFilter.java

package com.payflow.security;

import java.io.IOException;
import java.util.List;

import org.springframework.http.HttpHeaders;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.authentication.WebAuthenticationDetailsSource;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;

import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

@Component
public class JwtAuthenticationFilter extends OncePerRequestFilter {

	private static final String BEARER_PREFIX = "Bearer ";
	private static final List<SimpleGrantedAuthority> USER_ROLES = List.of(new SimpleGrantedAuthority("ROLE_USER"));

	private final JwtTokenProvider jwtTokenProvider;

	public JwtAuthenticationFilter(JwtTokenProvider jwtTokenProvider) {
		this.jwtTokenProvider = jwtTokenProvider;
	}

	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
			throws ServletException, IOException {

		String authHeader = request.getHeader(HttpHeaders.AUTHORIZATION);

		if (authHeader != null && authHeader.startsWith(BEARER_PREFIX)) {
			String token = authHeader.substring(BEARER_PREFIX.length()).trim();

			if (jwtTokenProvider.validateToken(token)) {
				String upiId = jwtTokenProvider.getUpiIdFromToken(token);

				var auth = new UsernamePasswordAuthenticationToken(upiId, null, USER_ROLES);
				auth.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));

				SecurityContextHolder.getContext().setAuthentication(auth);
			}
		}

		chain.doFilter(request, response);
	}
}