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use pin_project_lite::pin_project;

use super::*;
use std::{
    pin::Pin,
    task::{Context, Poll},
    time::{Duration, Instant},
};

/// A Timer that uses the tokio runtime.
#[derive(Clone, Debug)]
pub struct TokioTimer;

impl Timer for TokioTimer {
    fn sleep(&self, duration: Duration) -> Pin<Box<dyn Sleep>> {
        Box::pin(TokioSleep {
            inner: tokio::time::sleep(duration),
        })
    }

    fn sleep_until(&self, deadline: Instant) -> Pin<Box<dyn Sleep>> {
        Box::pin(TokioSleep {
            inner: tokio::time::sleep_until(deadline.into()),
        })
    }
}

pub(crate) struct TokioTimeout<T> {
    inner: Pin<Box<tokio::time::Timeout<T>>>,
}

impl<T> Future for TokioTimeout<T>
where
    T: Future,
{
    type Output = Result<T::Output, tokio::time::error::Elapsed>;

    fn poll(mut self: Pin<&mut Self>, context: &mut Context<'_>) -> Poll<Self::Output> {
        self.inner.as_mut().poll(context)
    }
}

pin_project! {
    /// Use TokioSleep to get tokio::time::Sleep to implement Unpin.
    /// see https://docs.rs/tokio/latest/tokio/time/struct.Sleep.html
    pub(crate) struct TokioSleep {
        #[pin]
        pub(crate) inner: tokio::time::Sleep,
    }
}

impl Future for TokioSleep {
    type Output = ();

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        self.project().inner.poll(cx)
    }
}

/// Use HasSleep to get tokio::time::Sleep to implement Unpin.
/// see https://docs.rs/tokio/latest/tokio/time/struct.Sleep.html
impl Sleep for TokioSleep {}