#![allow(dead_code)]
//! Various runtimes for hyper
use std::{
    future::Future,
    pin::Pin,
    task::{Context, Poll},
    time::{Duration, Instant},
};

use hyper::rt::{Sleep, Timer};
use pin_project_lite::pin_project;

#[derive(Clone)]
/// An Executor that uses the tokio runtime.
pub struct TokioExecutor;

impl<F> hyper::rt::Executor<F> for TokioExecutor
where
    F: std::future::Future + Send + 'static,
    F::Output: Send + 'static,
{
    fn execute(&self, fut: F) {
        tokio::task::spawn(fut);
    }
}

/// 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()),
        })
    }

    fn reset(&self, sleep: &mut Pin<Box<dyn Sleep>>, new_deadline: Instant) {
        if let Some(sleep) = sleep.as_mut().downcast_mut_pin::<TokioSleep>() {
            sleep.reset(new_deadline.into())
        }
    }
}

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)
    }
}

// Use TokioSleep to get tokio::time::Sleep to implement Unpin.
// see https://docs.rs/tokio/latest/tokio/time/struct.Sleep.html
pin_project! {
    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)
    }
}

impl Sleep for TokioSleep {}

impl TokioSleep {
    pub fn reset(self: Pin<&mut Self>, deadline: Instant) {
        self.project().inner.as_mut().reset(deadline.into());
    }
}

pin_project! {
    #[derive(Debug)]
    pub struct TokioIo<T> {
        #[pin]
        inner: T,
    }
}

impl<T> TokioIo<T> {
    pub fn new(inner: T) -> Self {
        Self { inner }
    }

    pub fn inner(self) -> T {
        self.inner
    }
}

impl<T> hyper::rt::Read for TokioIo<T>
where
    T: tokio::io::AsyncRead,
{
    fn poll_read(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        mut buf: hyper::rt::ReadBufCursor<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        let n = unsafe {
            let mut tbuf = tokio::io::ReadBuf::uninit(buf.as_mut());
            match tokio::io::AsyncRead::poll_read(
                self.project().inner,
                cx,
                &mut tbuf,
            ) {
                Poll::Ready(Ok(())) => tbuf.filled().len(),
                other => return other,
            }
        };

        unsafe {
            buf.advance(n);
        }
        Poll::Ready(Ok(()))
    }
}

impl<T> hyper::rt::Write for TokioIo<T>
where
    T: tokio::io::AsyncWrite,
{
    fn poll_write(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<Result<usize, std::io::Error>> {
        tokio::io::AsyncWrite::poll_write(self.project().inner, cx, buf)
    }

    fn poll_flush(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        tokio::io::AsyncWrite::poll_flush(self.project().inner, cx)
    }

    fn poll_shutdown(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        tokio::io::AsyncWrite::poll_shutdown(self.project().inner, cx)
    }

    fn is_write_vectored(&self) -> bool {
        tokio::io::AsyncWrite::is_write_vectored(&self.inner)
    }

    fn poll_write_vectored(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        bufs: &[std::io::IoSlice<'_>],
    ) -> Poll<Result<usize, std::io::Error>> {
        tokio::io::AsyncWrite::poll_write_vectored(self.project().inner, cx, bufs)
    }
}

impl<T> tokio::io::AsyncRead for TokioIo<T>
where
    T: hyper::rt::Read,
{
    fn poll_read(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        tbuf: &mut tokio::io::ReadBuf<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        //let init = tbuf.initialized().len();
        let filled = tbuf.filled().len();
        let sub_filled = unsafe {
            let mut buf = hyper::rt::ReadBuf::uninit(tbuf.unfilled_mut());

            match hyper::rt::Read::poll_read(
                self.project().inner,
                cx,
                buf.unfilled(),
            ) {
                Poll::Ready(Ok(())) => buf.filled().len(),
                other => return other,
            }
        };

        let n_filled = filled + sub_filled;
        // At least sub_filled bytes had to have been initialized.
        let n_init = sub_filled;
        unsafe {
            tbuf.assume_init(n_init);
            tbuf.set_filled(n_filled);
        }

        Poll::Ready(Ok(()))
    }
}

impl<T> tokio::io::AsyncWrite for TokioIo<T>
where
    T: hyper::rt::Write,
{
    fn poll_write(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<Result<usize, std::io::Error>> {
        hyper::rt::Write::poll_write(self.project().inner, cx, buf)
    }

    fn poll_flush(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        hyper::rt::Write::poll_flush(self.project().inner, cx)
    }

    fn poll_shutdown(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        hyper::rt::Write::poll_shutdown(self.project().inner, cx)
    }

    fn is_write_vectored(&self) -> bool {
        hyper::rt::Write::is_write_vectored(&self.inner)
    }

    fn poll_write_vectored(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        bufs: &[std::io::IoSlice<'_>],
    ) -> Poll<Result<usize, std::io::Error>> {
        hyper::rt::Write::poll_write_vectored(self.project().inner, cx, bufs)
    }
}