private void trsloginBtnClk(object sender, EventArgs e)
        {
            string id  = richTextBox1.Text;
            string pwd = richtextBox2.Text;



            var x = TeacherController.AuthenticateTeacher(id, pwd);

            if (x != null)
            {
                TeacherDashboard m = new TeacherDashboard();
                m.ShowDialog();
            }
            else
            {
                MessageBox.Show("✘ UserName / Password Error");
            }
        }
        private void buttonLogIn_Click(object sender, EventArgs e)
        {
            string userName = textBoxUserName.Text;
            string password = textBoxPassword.Text;
            string userType = comboBoxUserType.Text;

            if (userType == "Admin")
            {
                //AdminController.AuthenticateAdmin(userName, password);
                if (AdminController.AuthenticateAdmin(userName, password) != null)
                {
                    new FormAdmin().Show();
                }
                else
                {
                    MessageBox.Show("Invalid user name or password");
                }
            }
            else if (userType == "Teacher")
            {
                if (TeacherController.AuthenticateTeacher(userName, password) != null)
                {
                    Teacher t = TeacherController.AuthenticateTeacher(userName, password);
                    new FormTeacher(t).Show();
                }
                else
                {
                    MessageBox.Show("Invalid user name or password");
                }
            }
            else if (userType == "Student")
            {
                if (StudentController.AuthenticateStudent(userName, password) != null)
                {
                    Student s = StudentController.AuthenticateStudent(userName, password);
                    new FormStudent(s).Show();
                }
                else
                {
                    MessageBox.Show("Invalid user name or password");
                }
            }
        }