use crate::Stream;

use core::future::Future;

use core::marker::PhantomPinned;

use core::pin::Pin;

use core::task::{ready, Context, Poll};

use pin_project_lite::pin_project;

pin_project! {

    /// Future for the [`all`](super::StreamExt::all) method.

    #[derive(Debug)]

    #[must_use = "futures do nothing unless you `.await` or poll them"]

    pub struct AllFuture<'a, St: ?Sized, F> {

        stream: &'a mut St,

        f: F,

        // Make this future `!Unpin` for compatibility with async trait methods.

        #[pin]

        _pin: PhantomPinned,

    }

}

impl<'a, St: ?Sized, F> AllFuture<'a, St, F> {

    pub(super) fn new(stream: &'a mut St, f: F) -> Self {

        Self {

            stream,

            f,

            _pin: PhantomPinned,

        }

    }

}

impl<St, F> Future for AllFuture<'_, St, F>

where

    St: ?Sized + Stream + Unpin,

    F: FnMut(St::Item) -> bool,

{

    type Output = bool;

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

        let me = self.project();

        let mut stream = Pin::new(me.stream);

        // Take a maximum of 32 items from the stream before yielding.

        for _ in 0..32 {

            match ready!(stream.as_mut().poll_next(cx)) {

                Some(v) => {

                    if !(me.f)(v) {

                        return Poll::Ready(false);

                    }

                }

                None => return Poll::Ready(true),

            }

        }

        cx.waker().wake_by_ref();

        Poll::Pending

    }

}