source: src/main/java/project/educatum/config/CustomAuthenticationProvider.java

package project.educatum.config;

import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.stereotype.Component;
import project.educatum.model.exceptions.InvalidUserCredentialsException;
import project.educatum.service.AuthService;

@Component
public class CustomAuthenticationProvider implements AuthenticationProvider {

    private final AuthService authService;
    private final PasswordEncoder passwordEncoder;

    public CustomAuthenticationProvider(AuthService authService, PasswordEncoder passwordEncoder) {
        this.authService = authService;
        this.passwordEncoder = passwordEncoder;
    }

    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        String username = authentication.getName();
        String password = authentication.getCredentials().toString();
        if ("".equals(username) || "".equals(password)) {
            throw new BadCredentialsException("Bad credentials!");
        }
        UserDetails userDetails = this.authService.loadUserByUsername(username);
        if (!passwordEncoder.matches(password, userDetails.getPassword())) {
            throw new BadCredentialsException("Bad credentials!");
        }
        return new UsernamePasswordAuthenticationToken(userDetails,
                userDetails.getPassword(), userDetails.getAuthorities());
    }

    @Override
    public boolean supports(Class<?> authentication) {
        return authentication.equals(CustomAuthenticationProvider.class);
    }
}