CannonGame.menuSplash.Update C# (CSharp) Метод

        public override void Update()
        {
            mouse = new Point(Mouse.GetState().X, Mouse.GetState().Y);

            if ((Frameinfo.PreviousMouseState.LeftButton == ButtonState.Pressed) &&
                (Frameinfo.MouseState.LeftButton == ButtonState.Released))

                if (button1.Contains(mouse))
                {
                    if (CurrentGameStateIndex == 1)
                      CannonGame.ChangeState(4);
                    else if (CurrentGameStateIndex == 5)
                       CannonGame.ChangeState(CannonGame.PreviousLevel);
                    else if (CurrentGameStateIndex == 6)
                       CannonGame.ChangeState(CannonGame.PreviousLevel);
                }

                else if (button2.Contains(mouse))
                {
                    if (CurrentGameStateIndex == 1)
                        CannonGame.ChangeState(2);
                    else if (CurrentGameStateIndex == 5)
                        CannonGame.ChangeState(CannonGame.PreviousLevel + 1);
                    else if (CurrentGameStateIndex == 6)
                        CannonGame.ChangeState(4);
                }

                else if (button3.Contains(mouse))
                {
                    if (CurrentGameStateIndex == 1)
                        CannonGame.ChangeState(3);
                    else if (CurrentGameStateIndex == 5)
                        CannonGame.ChangeState(4);
                    else if (CurrentGameStateIndex == 6)
                        CannonGame.ChangeState(1);
                }

                else if (button4.Contains(mouse))
                {
                    if (CurrentGameStateIndex == 1)
                        CannonGame.ExitGame = true;
                    else if (CurrentGameStateIndex == 5)
                        CannonGame.ChangeState(1);
                    else if (CurrentGameStateIndex == 6)
                        CannonGame.ExitGame = true;
                }
        }