pollable-map 0.2.0

use crate::common::Timed;
use crate::error::TimedError;
use crate::futures::set::FutureSet;
use core::future::Future;
use core::ops::{Deref, DerefMut};
use core::pin::Pin;
use core::task::{Context, Poll};
use core::time::Duration;
use futures::stream::FusedStream;
use futures::{Stream, StreamExt};

pub struct TimeoutFutureSet<S> {
    duration: Duration,
    set: FutureSet<Timed<S>>,
}

impl<S> Deref for TimeoutFutureSet<S> {
    type Target = FutureSet<Timed<S>>;
    fn deref(&self) -> &Self::Target {
        &self.set
    }
}

impl<S> DerefMut for TimeoutFutureSet<S> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.set
    }
}

impl<F> TimeoutFutureSet<F>
where
    F: Future,
{
    /// Create an empty [`TimeoutFutureSet`]
    pub fn new(duration: Duration) -> Self {
        Self {
            duration,
            set: FutureSet::new(),
        }
    }

    /// Insert a future into the set of futures.
    pub fn insert(&mut self, future: F) -> bool {
        self.set.insert(Timed::new(future, self.duration))
    }
}

impl<F> Stream for TimeoutFutureSet<F>
where
    F: Future,
{
    type Item = Result<F::Output, TimedError>;
    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        self.set.poll_next_unpin(cx)
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.set.size_hint()
    }
}

impl<F> FusedStream for TimeoutFutureSet<F>
where
    F: Future,
{
    fn is_terminated(&self) -> bool {
        self.set.is_terminated()
    }
}

#[cfg(test)]
mod test {
    use crate::{error::TimedError, futures::timeout_set::TimeoutFutureSet};
    use futures::StreamExt;
    use std::time::Duration;

    #[test]
    fn timeout_set() {
        let mut list = TimeoutFutureSet::new(Duration::from_millis(100));
        assert!(list.insert(futures::future::pending::<()>()));

        futures::executor::block_on(async move {
            let result = list.next().await;
            let Some(Err(e)) = result else {
                unreachable!("result is err");
            };

            assert_eq!(e, TimedError);
        });
    }

    #[test]
    fn valid_stream() {
        let mut list = TimeoutFutureSet::new(Duration::from_secs(10));
        assert!(list.insert(futures::future::ready(0)));

        futures::executor::block_on(async move {
            let result = list.next().await;
            let Some(Ok(val)) = result else {
                unreachable!("result is err");
            };

            assert_eq!(val, 0);
        });
    }
}