use futures::future::poll_fn;
use tokio::sync::mpsc::channel;
use tokio_test::task::spawn;
use tokio_test::{assert_pending, assert_ready, assert_ready_err, assert_ready_ok};
use tokio_util::sync::PollSender;

#[tokio::test]
async fn simple() {
    let (send, mut recv) = channel(3);
    let mut send = PollSender::new(send);

    for i in 1..=3i32 {
        let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
        assert_ready_ok!(reserve.poll());
        send.send_item(i).unwrap();
    }

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_pending!(reserve.poll());

    assert_eq!(recv.recv().await.unwrap(), 1);
    assert!(reserve.is_woken());
    assert_ready_ok!(reserve.poll());

    drop(recv);

    send.send_item(42).unwrap();
}

#[tokio::test]
async fn repeated_poll_reserve() {
    let (send, mut recv) = channel::<i32>(1);
    let mut send = PollSender::new(send);

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
    assert_ready_ok!(reserve.poll());
    send.send_item(1).unwrap();

    assert_eq!(recv.recv().await.unwrap(), 1);
}

#[tokio::test]
async fn abort_send() {
    let (send, mut recv) = channel(3);
    let mut send = PollSender::new(send);
    let send2 = send.get_ref().cloned().unwrap();

    for i in 1..=3i32 {
        let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
        assert_ready_ok!(reserve.poll());
        send.send_item(i).unwrap();
    }

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_pending!(reserve.poll());
    assert_eq!(recv.recv().await.unwrap(), 1);
    assert!(reserve.is_woken());
    assert_ready_ok!(reserve.poll());

    let mut send2_send = spawn(send2.send(5));
    assert_pending!(send2_send.poll());
    assert!(send.abort_send());
    assert!(send2_send.is_woken());
    assert_ready_ok!(send2_send.poll());

    assert_eq!(recv.recv().await.unwrap(), 2);
    assert_eq!(recv.recv().await.unwrap(), 3);
    assert_eq!(recv.recv().await.unwrap(), 5);
}

#[tokio::test]
async fn close_sender_last() {
    let (send, mut recv) = channel::<i32>(3);
    let mut send = PollSender::new(send);

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    send.close();

    assert!(recv_task.is_woken());
    assert!(assert_ready!(recv_task.poll()).is_none());
}

#[tokio::test]
async fn close_sender_not_last() {
    let (send, mut recv) = channel::<i32>(3);
    let mut send = PollSender::new(send);
    let send2 = send.get_ref().cloned().unwrap();

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    send.close();

    assert!(!recv_task.is_woken());
    assert_pending!(recv_task.poll());

    drop(send2);

    assert!(recv_task.is_woken());
    assert!(assert_ready!(recv_task.poll()).is_none());
}

#[tokio::test]
async fn close_sender_before_reserve() {
    let (send, mut recv) = channel::<i32>(3);
    let mut send = PollSender::new(send);

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    send.close();

    assert!(recv_task.is_woken());
    assert!(assert_ready!(recv_task.poll()).is_none());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_err!(reserve.poll());
}

#[tokio::test]
async fn close_sender_after_pending_reserve() {
    let (send, mut recv) = channel::<i32>(1);
    let mut send = PollSender::new(send);

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
    send.send_item(1).unwrap();

    assert!(recv_task.is_woken());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_pending!(reserve.poll());
    drop(reserve);

    send.close();

    assert!(send.is_closed());
    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_err!(reserve.poll());
}

#[tokio::test]
async fn close_sender_after_successful_reserve() {
    let (send, mut recv) = channel::<i32>(3);
    let mut send = PollSender::new(send);

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
    drop(reserve);

    send.close();
    assert!(send.is_closed());
    assert!(!recv_task.is_woken());
    assert_pending!(recv_task.poll());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
}

#[tokio::test]
async fn abort_send_after_pending_reserve() {
    let (send, mut recv) = channel::<i32>(1);
    let mut send = PollSender::new(send);

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
    send.send_item(1).unwrap();

    assert_eq!(send.get_ref().unwrap().capacity(), 0);
    assert!(!send.abort_send());

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_pending!(reserve.poll());

    assert!(send.abort_send());
    assert_eq!(send.get_ref().unwrap().capacity(), 0);
}

#[tokio::test]
async fn abort_send_after_successful_reserve() {
    let (send, mut recv) = channel::<i32>(1);
    let mut send = PollSender::new(send);

    let mut recv_task = spawn(recv.recv());
    assert_pending!(recv_task.poll());

    assert_eq!(send.get_ref().unwrap().capacity(), 1);
    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
    assert_eq!(send.get_ref().unwrap().capacity(), 0);

    assert!(send.abort_send());
    assert_eq!(send.get_ref().unwrap().capacity(), 1);
}

#[tokio::test]
async fn closed_when_receiver_drops() {
    let (send, _) = channel::<i32>(1);
    let mut send = PollSender::new(send);

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_err!(reserve.poll());
}

#[should_panic]
#[test]
fn start_send_panics_when_idle() {
    let (send, _) = channel::<i32>(3);
    let mut send = PollSender::new(send);

    send.send_item(1).unwrap();
}

#[should_panic]
#[test]
fn start_send_panics_when_acquiring() {
    let (send, _) = channel::<i32>(1);
    let mut send = PollSender::new(send);

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_ready_ok!(reserve.poll());
    send.send_item(1).unwrap();

    let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
    assert_pending!(reserve.poll());
    send.send_item(2).unwrap();
}