lamellar 0.8.1

use crate::active_messaging::LamellarArcLocalAm;
use crate::array::iterator::distributed_iterator::DistributedIterator;
use crate::array::iterator::private::*;
use crate::array::iterator::{consumer::*, IterLockFuture};

use crate::array::r#unsafe::private::UnsafeArrayInner;
use crate::barrier::BarrierHandle;
use crate::darc::Darc;
use crate::darc::DarcMode;
use crate::lamellar_request::LamellarRequest;
use crate::lamellar_task_group::TaskGroupLocalAmHandle;
use crate::lamellar_team::LamellarTeamRT;
use crate::scheduler::LamellarTask;
use crate::warnings::RuntimeWarning;

use futures_util::{ready, Future};
use pin_project::{pin_project, pinned_drop};
use std::collections::VecDeque;
use std::pin::Pin;
use std::sync::{
    atomic::{AtomicUsize, Ordering},
    Arc,
};
use std::task::{Context, Poll};

#[derive(Clone, Debug)]
pub(crate) struct Count<I> {
    pub(crate) iter: I,
}

impl<I: InnerIter> InnerIter for Count<I> {
    fn lock_if_needed(&self, _s: Sealed) -> Option<IterLockFuture> {
        None
    }
    fn iter_clone(&self, _s: Sealed) -> Self {
        Count {
            iter: self.iter.iter_clone(Sealed),
        }
    }
}

impl<I> IterConsumer for Count<I>
where
    I: DistributedIterator,
{
    type AmOutput = usize;
    type Output = usize;
    type Item = I::Item;
    type Handle = InnerDistIterCountHandle;
    fn init(&self, start: usize, cnt: usize) -> Self {
        Count {
            iter: self.iter.init(start, cnt, Sealed),
        }
    }
    fn next(&mut self) -> Option<Self::Item> {
        self.iter.next()
    }
    fn into_am(&self, schedule: IterSchedule) -> LamellarArcLocalAm {
        Arc::new(CountAm {
            iter: self.iter_clone(Sealed),
            schedule,
        })
    }
    fn create_handle(
        self,
        team: Darc<LamellarTeamRT>,
        reqs: VecDeque<TaskGroupLocalAmHandle<Self::AmOutput>>,
    ) -> Self::Handle {
        InnerDistIterCountHandle {
            reqs,
            team,
            state: InnerState::ReqsPending(0),
            spawned: false,
        }
    }
    fn max_elems(&self, in_elems: usize) -> usize {
        self.iter.elems(in_elems)
    }
}

//#[doc(hidden)]
#[pin_project]
pub(crate) struct InnerDistIterCountHandle {
    pub(crate) reqs: VecDeque<TaskGroupLocalAmHandle<usize>>,
    team: Darc<LamellarTeamRT>,
    state: InnerState,
    spawned: bool,
}

enum InnerState {
    ReqsPending(usize),
    Counting(Pin<Box<dyn Future<Output = usize> + Send>>),
}

#[lamellar_impl::AmDataRT]
struct UpdateCntAm {
    remote_cnt: usize,
    cnt: Darc<AtomicUsize>,
}

#[lamellar_impl::rt_am]
impl LamellarAm for UpdateCntAm {
    async fn exec(self) {
        self.cnt.fetch_add(self.remote_cnt, Ordering::Relaxed);
    }
}

impl InnerDistIterCountHandle {
    async fn async_reduce_remote_counts(local_cnt: usize, team: Darc<LamellarTeamRT>) -> usize {
        let cnt = Darc::async_try_new_with_drop(&team, AtomicUsize::new(0), DarcMode::Darc, None)
            .await
            .unwrap();
        team.exec_am_all(UpdateCntAm {
            remote_cnt: local_cnt,
            cnt: cnt.clone(),
        })
        .await;
        team.async_barrier().await;
        cnt.load(Ordering::SeqCst)
    }

    // fn reduce_remote_counts(&self, local_cnt: usize, cnt: Darc<AtomicUsize>) -> usize {
    //     let _ = self
    //         .team
    //         .exec_am_all(UpdateCntAm {
    //             remote_cnt: local_cnt,
    //             cnt: cnt.clone(),
    //         })
    //         .spawn();
    //     self.team.wait_all();
    //     self.team.tasking_barrier();
    //     cnt.load(Ordering::SeqCst)
    // }
}

impl Future for InnerDistIterCountHandle {
    type Output = usize;
    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        if !self.spawned {
            for req in self.reqs.iter_mut() {
                req.ready_or_set_waker(cx.waker());
            }
            self.spawned = true;
        }
        let mut this = self.project();
        match &mut this.state {
            InnerState::ReqsPending(cnt) => {
                while let Some(mut req) = this.reqs.pop_front() {
                    if !req.ready_or_set_waker(cx.waker()) {
                        this.reqs.push_front(req);
                        return Poll::Pending;
                    }
                    *cnt += req.val();
                }
                let mut global_cnt =
                    Box::pin(Self::async_reduce_remote_counts(*cnt, this.team.clone()));
                match Future::poll(global_cnt.as_mut(), cx) {
                    Poll::Ready(count) => {
                        return Poll::Ready(count);
                    }
                    Poll::Pending => {
                        *this.state = InnerState::Counting(global_cnt);
                        Poll::Pending
                    }
                }
            }
            InnerState::Counting(global_cnt) => {
                let count = ready!(Future::poll(global_cnt.as_mut(), cx));
                Poll::Ready(count)
            }
        }
    }
}

/// This handle allows you to wait for the completion of a local iterator count operation
#[pin_project(PinnedDrop)]
pub struct DistIterCountHandle {
    array: UnsafeArrayInner,
    launched: bool,
    #[pin]
    state: State,
}

#[pinned_drop]
impl PinnedDrop for DistIterCountHandle {
    fn drop(self: Pin<&mut Self>) {
        if !self.launched {
            let mut this = self.project();
            RuntimeWarning::disable_warnings();
            *this.state = State::Dropped;
            RuntimeWarning::enable_warnings();
            RuntimeWarning::DroppedHandle("a DistIterCountHandle").print();
        }
    }
}

impl DistIterCountHandle {
    pub(crate) fn new(
        lock: Option<IterLockFuture>,
        inner: Pin<Box<dyn Future<Output = InnerDistIterCountHandle> + Send>>,
        array: &UnsafeArrayInner,
    ) -> Self {
        let state = match lock {
            Some(inner_lock) => State::Lock(inner_lock, Some(inner)),
            None => State::Barrier(array.barrier_handle(), inner),
        };
        Self {
            array: array.clone(),
            launched: false,
            state,
        }
    }

    /// This method will block until the associated Count operation completes and returns the result
    ///
    /// # Examples
    ///```no_run
    /// use lamellar::array::prelude::*;
    /// let world = LamellarWorldBuilder::new().build();
    /// let array: UnsafeArray<usize> = UnsafeArray::new(&world, 100, Distribution::Block).block();
    /// let handle = unsafe { array.dist_iter() }.count();
    /// let result = handle.block();
    ///```
    pub fn block(mut self) -> usize {
        self.launched = true;
        RuntimeWarning::BlockingCall(
            "DistIterCountHandle::block",
            "<handle>.spawn() or <handle>.await",
        )
        .print();
        self.array.clone().block_on(self)
    }

    /// This method will spawn the associated Count Operation on the work queue,
    /// initiating the remote operation.
    ///
    /// This function returns a handle that can be used to wait for the operation to complete
    ///
    /// # Examples
    ///```no_run
    /// use lamellar::array::prelude::*;
    /// let world = LamellarWorldBuilder::new().build();
    /// let array: UnsafeArray<usize> = UnsafeArray::new(&world, 100, Distribution::Block).block();
    /// let handle = unsafe { array.dist_iter() }.count();
    /// let task = handle.spawn();
    ///```
    #[must_use = "this function returns a future used to poll for completion and retrieve the result. Call '.await' on the future otherwise, if  it is ignored (via ' let _ = *.spawn()') or dropped the only way to ensure completion is calling 'wait_all()' on the world or array. Alternatively it may be acceptable to call '.block()' instead of 'spawn()'"]
    pub fn spawn(mut self) -> LamellarTask<usize> {
        self.launched = true;
        self.array.clone().spawn(self)
    }
}

#[pin_project(project = StateProj)]
enum State {
    Lock(
        #[pin] IterLockFuture,
        Option<Pin<Box<dyn Future<Output = InnerDistIterCountHandle> + Send>>>,
    ),
    Barrier(
        #[pin] BarrierHandle,
        Pin<Box<dyn Future<Output = InnerDistIterCountHandle> + Send>>,
    ),
    Reqs(#[pin] InnerDistIterCountHandle),
    Dropped,
}
impl Future for DistIterCountHandle {
    type Output = usize;
    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        self.launched = true;
        let mut this = self.project();
        match this.state.as_mut().project() {
            StateProj::Lock(lock, inner) => {
                ready!(lock.poll(cx));
                let barrier = this.array.barrier_handle();
                *this.state = State::Barrier(
                    barrier,
                    inner.take().expect("reqs should still be in this state"),
                );
                cx.waker().wake_by_ref();
                Poll::Pending
            }
            StateProj::Barrier(barrier, inner) => {
                ready!(barrier.poll(cx));
                let mut inner = ready!(Future::poll(inner.as_mut(), cx));
                match Pin::new(&mut inner).poll(cx) {
                    Poll::Ready(val) => Poll::Ready(val),
                    Poll::Pending => {
                        *this.state = State::Reqs(inner);
                        Poll::Pending
                    }
                }
            }
            StateProj::Reqs(inner) => {
                let val = ready!(inner.poll(cx));
                Poll::Ready(val)
            }
            StateProj::Dropped => panic!("should never be in dropped state"),
        }
    }
}

#[lamellar_impl::AmLocalDataRT(Clone)]
pub(crate) struct CountAm<I> {
    pub(crate) iter: Count<I>,
    pub(crate) schedule: IterSchedule,
}

impl<I> InnerIter for CountAm<I>
where
    I: InnerIter,
{
    fn lock_if_needed(&self, _s: Sealed) -> Option<IterLockFuture> {
        None
    }
    fn iter_clone(&self, _s: Sealed) -> Self {
        CountAm {
            iter: self.iter.iter_clone(Sealed),
            schedule: self.schedule.clone(),
        }
    }
}

#[lamellar_impl::rt_am_local]
impl<I> LamellarAm for CountAm<I>
where
    I: DistributedIterator + 'static,
{
    async fn exec(&self) -> usize {
        let mut iter = self.schedule.init_iter(self.iter.iter_clone(Sealed));
        let mut count: usize = 0;
        while let Some(_) = iter.next() {
            count += 1;
        }
        // println!("count: {} {:?}", count, std::thread::current().id());
        count
    }
}