AuthService.java

package banking.service;

import banking.model.User;
import java.sql.*;

public class AuthService {
    private Connection conn;

    public AuthService(Connection conn) {
        this.conn = conn;
    }

    public boolean registerUser(String username, String password) {
        try {
            String query = "INSERT INTO users (username, password) VALUES (?, ?)";
            PreparedStatement stmt = conn.prepareStatement(query);
            stmt.setString(1, username);
            stmt.setString(2, password);
            stmt.executeUpdate();
            return true;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    public User login(String username, String password) {
        try {
            String sql = "SELECT * FROM users WHERE username=? AND password=?";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, username);
            ps.setString(2, password);
            ResultSet rs = ps.executeQuery();

            if (rs.next()) {
                return new User(
                        rs.getInt("user_id"),
                        rs.getString("username"),
                        rs.getString("role")
                );
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null; // login failed
    }
}