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use std::{
    cell::RefCell,
    hash::Hash,
    ops::{Deref, DerefMut},
    rc::Rc,
    sync::{Arc, RwLock},
};

use crate::{
    core::{
        self,
        pipes::{self, Receiver, Sender},
        TrackingIndex,
    },
    Input, InputRelation,
};

use self::{
    input_change_tracker::{InputChangeTracker, IsInputChangeTracker},
    pq_receiver::PQReceiver,
};

use super::op::{Instruct, IsFeedback, IsFeeder};

pub use self::tracker::ContextTracker;

mod input_change_tracker;
mod pq_receiver;
mod tracker;

pub struct CreationContext<'a, I = ()> {
    inner: core::CreationContext<'a>,
    feeders: Vec<Box<dyn IsFeeder<'a, I> + 'a>>,
    input_trackers: Vec<Rc<RefCell<dyn IsInputChangeTracker<I> + 'a>>>,
    extra_edges: Arc<RwLock<Vec<(TrackingIndex, TrackingIndex)>>>,
    dirty_send: Sender<usize>,
    dirty_receive: Receiver<usize>,
}

impl<I> Default for CreationContext<'_, I> {
    fn default() -> Self {
        let (dirty_send, dirty_receive) = pipes::new();
        Self {
            inner: Default::default(),
            feeders: Default::default(),
            input_trackers: Default::default(),
            extra_edges: Default::default(),
            dirty_send,
            dirty_receive,
        }
    }
}

pub struct ExecutionContext<'a, I = ()> {
    inner: core::ExecutionContext<'a>,
    feeders: Vec<Box<dyn IsFeeder<'a, I> + 'a>>,
    input_trackers: Vec<Rc<RefCell<dyn IsInputChangeTracker<I> + 'a>>>,
    extra_edges: Arc<RwLock<Vec<(TrackingIndex, TrackingIndex)>>>,
    dirty: PQReceiver,
}

impl<'a, I> ExecutionContext<'a, I> {
    pub fn commit(&mut self) -> Option<I> {
        loop {
            self.inner.commit();
            match self.dirty.pop_min() {
                Some(feeder_index) => match self.feeders[feeder_index].feed(&self.inner) {
                    Instruct::Unchanged => (),
                    Instruct::Changed => self.dirty.insert(feeder_index),
                    Instruct::Interrupt(interrupted) => return Some(interrupted),
                },
                None => return None,
            }
        }
    }
    pub fn tracker(&self) -> ContextTracker {
        ContextTracker::new(self.inner.tracker().clone(), self.extra_edges.clone())
    }
    pub fn in_frame<R>(&mut self, f: impl FnOnce(&mut Self) -> R) -> R {
        for input_tracker in self.input_trackers.iter() {
            input_tracker.borrow_mut().push_frame();
        }
        let result = f(self);
        for input_tracker in self.input_trackers.iter() {
            input_tracker.borrow_mut().pop_frame(self);
        }
        result
    }
}

impl<'a, I> CreationContext<'a, I> {
    pub fn new_() -> Self {
        Default::default()
    }
    pub fn new_trackable_input<D: Eq + Hash + Clone + 'a>(
        &mut self,
    ) -> (Input<'a, D>, InputRelation<D>) {
        let (mut input, relation) = self.inner.new_input_::<(D, isize)>();
        let tracker: Rc<RefCell<InputChangeTracker<D>>> =
            Rc::new(RefCell::new(InputChangeTracker::new(input.clone())));
        {
            let tracker = Rc::clone(&tracker);
            input.add_listener(&self.inner, move |kvs| {
                tracker.borrow_mut().add_changes(kvs)
            });
        }
        self.input_trackers.push(tracker);
        (input, relation)
    }
    pub fn begin(self) -> ExecutionContext<'a, I> {
        ExecutionContext {
            inner: self.inner.begin(),
            feeders: self.feeders,
            input_trackers: self.input_trackers,
            extra_edges: self.extra_edges,
            dirty: PQReceiver::new(self.dirty_receive),
        }
    }
    pub(super) fn add_feeder(
        &mut self,
        mut feeder: impl IsFeedback<'a, I> + 'a,
        extra_edge: Option<(TrackingIndex, TrackingIndex)>,
    ) {
        let mut dirty_send = self.dirty_send.clone();
        let i = self.feeders.len();
        feeder.add_listener(self, move || dirty_send.send(i));
        self.feeders.push(Box::new(feeder));
        if let Some(edge) = extra_edge {
            self.extra_edges.write().unwrap().push(edge);
        }
    }
    pub fn tracker(&self) -> ContextTracker {
        ContextTracker::new(self.inner.tracker().clone(), self.extra_edges.clone())
    }
}

impl<'a, I> Deref for CreationContext<'a, I> {
    type Target = core::CreationContext<'a>;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl<'a, I> DerefMut for CreationContext<'a, I> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}

impl<'a, I> Deref for ExecutionContext<'a, I> {
    type Target = core::ExecutionContext<'a>;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl<'a, I> DerefMut for ExecutionContext<'a, I> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}