use crate::prelude::*;

pub struct Terminator {
    signal: Promise<()>,
    completion: JoinHandle<Result<()>>,
}
impl Terminator {
    pub async fn terminate(self) -> Result<()> {
        match self.signal.send(()) {
            Ok(()) => {}
            Err(_) => log::warn!("Termination channel is dropped"),
        }
        self.completion.await??;
        Ok(())
    }

    /// Used to spawn managed tasks with support for graceful shutdown
    pub fn spawn<Fun, Fut>(launcher: Fun) -> Terminator
    where
        Fun: FnOnce(Deferred<()>) -> Fut,
        Fut: Future<Output = Result<()>> + Send + 'static,
    {
        let (signal, rx) = oneshot();
        let future = launcher(rx);
        let completion = tokio::task::spawn(future);
        Terminator { signal, completion }
    }
}