Custom AuthenticationFailureHandler

@Component
public class CustomAuthenticationHandler implements AuthenticationFailureHandler {

    @Autowired
    private UserRepository userRepository;
    private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(CustomAuthenticationHandler.class);

    @Override
    public void onAuthenticationFailure(HttpServletRequest request, HttpServletResponse response,
            AuthenticationException exception) throws IOException, ServletException {

        logger.info("CustomAuthenticationFailureHandler invoked");

        if (exception instanceof BadCredentialsException) {

            String email = request.getParameter("username");
            boolean emailExists = checkEmail(email);

            if (!emailExists) {
                logger.warn(" User not registered with email : {}", email);
                response.sendRedirect("/login?error=email");
            } else {
                logger.warn(" Incorrect password for email: {}", email);
                response.sendRedirect("/login?error=password");
            }
        } else {
            logger.error("Authentication failed due to: {}", exception.getMessage());
            response.sendRedirect("/login?error");
        }
    }

    private boolean checkEmail(String email) {
        Optional<User> user = userRepository.findByEmail(email);
        return user.isPresent();
    }

}