pub trait Device {
    fn auth_admin(&self) -> bool { true }
    fn auth_user(&self) -> bool { true }
}

pub struct NoAuth<D: Device>(D);

pub struct Device1(u32);
impl Device for Device1 {}
impl Device1 {
    pub fn new(arg: u32) -> NoAuth<Self> {
        NoAuth(Self(arg))
    }
}

pub struct Admin<'a, D: Device>(&'a mut D);
pub struct User<'a, D: Device>(&'a D);

impl<D: Device> NoAuth<D> {
    pub fn temp_auth<R, F: FnOnce(Admin<'_, D>) -> R>(&mut self, f: F) -> Option<R> {
        if self.0.auth_admin() {
            Some(f(Admin(&mut self.0)))
        } else {
            None
        }
    }

    pub fn auth(&mut self) -> Option<Admin<'_, D>> {
        if self.0.auth_admin() {
            Some(Admin(&mut self.0))
        } else {
            None
        }
    }
}

impl<D: Device> Admin<'_, D> {
    pub fn user(&self) -> Option<User<'_, D>> {
        if self.0.auth_user() {
            Some(User(self.0))
        } else {
            None
        }
    }
}