private void signInButton_Click(object sender, EventArgs e)
        {
            try
            {
                Validations();
                PasswordHashing passwordHashing = new PasswordHashing();
                UsersRepository usersRepository = new UsersRepository();

                if (usersRepository.UserLogin(usernameBox.Text, passwordBox.Text) != null)
                {
                    User user = usersRepository.UserLogin(usernameBox.Text, passwordBox.Text);
                    if (passwordHashing.comparePassword(passwordBox.Text, user.password) == true)
                    {
                        DialogResult dialog = MessageBox.Show("You signed in successfully!", "OK", MessageBoxButtons.OK);
                        if (dialog == DialogResult.OK)
                        {
                            MainWindow.loggedInUser = user;
                            LoggedIn loggedIn = new LoggedIn();
                            loggedIn.ShowDialog();
                        }
                    }
                    else
                    {
                        throw new Exception("Incorrect password! Please try again.");
                    }
                }
                else
                {
                    throw new Exception("User not found");
                }
            }
            catch (Exception exc)
            {
                MessageBox.Show(exc.Message);
            }
        }