effect-rs 0.1.0

use crate::core::{Cause, Clock, Ctx, Effect, EnvRef, Exit, FiberId, ScopeExit, ScopeHandle};
use crate::runtime::Runtime;
use futures::future::BoxFuture;
use std::cmp::Ordering;
use std::collections::{BinaryHeap, HashMap};
use std::sync::{Arc, Mutex as StdMutex};
use tokio::sync::Mutex as TokioMutex;
use tokio::time::{Duration, Instant};
use tokio_util::sync::CancellationToken;

struct Sleeper {
    wake_time: Instant,
    waker: tokio::sync::Notify,
}

impl PartialEq for Sleeper {
    fn eq(&self, other: &Self) -> bool {
        self.wake_time == other.wake_time
    }
}

impl Eq for Sleeper {}

impl PartialOrd for Sleeper {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Sleeper {
    fn cmp(&self, other: &Self) -> Ordering {
        // Reverse ordering for MinHeap behavior in BinaryHeap
        other.wake_time.cmp(&self.wake_time)
    }
}

#[derive(Clone)]
pub struct TestClock {
    state: Arc<StdMutex<TestClockState>>,
}

struct TestClockState {
    now: Instant,
    sleepers: BinaryHeap<Sleeper>,
    // Map of notifications to notify logic
}

impl Default for TestClock {
    fn default() -> Self {
        Self::new()
    }
}

impl TestClock {
    pub fn new() -> Self {
        Self {
            state: Arc::new(StdMutex::new(TestClockState {
                now: Instant::now(), // Base time
                sleepers: BinaryHeap::new(),
            })),
        }
    }

    pub fn adjust(&self, duration: Duration) {
        let mut state = self.state.lock().unwrap();
        state.now += duration;
        let now = state.now;

        // Wake up connected sleepers
        while let Some(sleeper) = state.sleepers.peek() {
            if sleeper.wake_time <= now {
                let sleeper = state.sleepers.pop().unwrap();
                sleeper.waker.notify_one();
            } else {
                break;
            }
        }
    }
}

impl Clock for TestClock {
    fn sleep(&self, duration: Duration) -> BoxFuture<'static, ()> {
        let state = self.state.clone();
        Box::pin(async move {
            let _notify = Arc::new(tokio::sync::Notify::new());

            {
                let mut guard = state.lock().unwrap();
                let wake_time = guard.now + duration;
                guard.sleepers.push(Sleeper {
                    wake_time,
                    waker: tokio::sync::Notify::new(), // We need a way to share the notify...
                                                       // Actually, Notify::new() cannot be cloned easily if we put it in struct.
                                                       // Let's change Sleeper to hold Arc<Notify>
                });
                // Re-implementing with Arc<Notify> below
            }
        })
    }

    fn now(&self) -> Instant {
        let guard = self.state.lock().unwrap();
        guard.now
    }
}

// Re-write wrapper for proper implementation
struct SharedSleeper {
    wake_time: Instant,
    notify: Arc<tokio::sync::Notify>,
}

impl PartialEq for SharedSleeper {
    fn eq(&self, other: &Self) -> bool {
        self.wake_time == other.wake_time
    }
}
impl Eq for SharedSleeper {}
#[allow(clippy::non_canonical_partial_ord_impl)]
impl PartialOrd for SharedSleeper {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(other.wake_time.cmp(&self.wake_time)) // Min-heap
    }
}
impl Ord for SharedSleeper {
    fn cmp(&self, other: &Self) -> Ordering {
        other.wake_time.cmp(&self.wake_time)
    }
}

#[derive(Clone)]
pub struct TestClockImpl {
    state: Arc<StdMutex<TestClockStateImpl>>,
}

struct TestClockStateImpl {
    now: Instant,
    sleepers: BinaryHeap<SharedSleeper>,
}

impl Default for TestClockImpl {
    fn default() -> Self {
        Self::new()
    }
}

impl TestClockImpl {
    pub fn new() -> Self {
        Self {
            state: Arc::new(StdMutex::new(TestClockStateImpl {
                now: Instant::now(),
                sleepers: BinaryHeap::new(),
            })),
        }
    }

    pub fn adjust(&self, duration: Duration) {
        let mut state = self.state.lock().unwrap();
        state.now += duration;
        let now = state.now;

        while let Some(sleeper) = state.sleepers.peek() {
            if sleeper.wake_time <= now {
                let sleeper = state.sleepers.pop().unwrap();
                sleeper.notify.notify_waiters();
            } else {
                break;
            }
        }
    }
}

impl Clock for TestClockImpl {
    fn sleep(&self, duration: Duration) -> BoxFuture<'static, ()> {
        let state = self.state.clone();
        Box::pin(async move {
            let notify = Arc::new(tokio::sync::Notify::new());
            {
                let mut guard = state.lock().unwrap();
                let wake_time = guard.now + duration;
                guard.sleepers.push(SharedSleeper {
                    wake_time,
                    notify: notify.clone(),
                });
            }
            notify.notified().await;
        })
    }

    fn now(&self) -> Instant {
        self.state.lock().unwrap().now
    }
}

pub struct TestRuntime {
    runtime: Runtime,
    pub clock: TestClockImpl,
}

impl Default for TestRuntime {
    fn default() -> Self {
        Self::new()
    }
}

impl TestRuntime {
    pub fn new() -> Self {
        Self {
            runtime: Runtime::new(),
            clock: TestClockImpl::new(),
        }
    }

    pub fn block_on<R, E, A>(&self, effect: Effect<R, E, A>, env: R) -> Exit<E, A>
    where
        R: Clone + Send + Sync + 'static,
        E: Send + Sync + Clone + 'static,
        A: Send + Sync + Clone + 'static,
    {
        // Inject TestClock into Ctx
        // Runtime::block_on uses default Ctx. We need to override it.
        // But Runtime::block_on abstracts Ctx creation.
        // We might need to expose a way to run with custom Ctx or modify Runtime.
        // For now, let's construct Ctx manually and run.

        let clock = Arc::new(self.clock.clone());
        let ctx = Ctx {
            token: CancellationToken::new(),
            scope: ScopeHandle::new(),
            fiber_id: FiberId(0),
            locals: Arc::new(TokioMutex::new(HashMap::new())),
            clock,
        };

        // We use the inner runtime's block_on but we need to pass our context.
        // Runtime::block_on creates a new Ctx. We should modify Runtime or copy logic.
        // Logic copy for MVP:

        self.runtime.rt.block_on(async move {
            let result = (effect.inner)(EnvRef { value: env }, ctx.clone()).await;
            let scope_exit = match &result {
                Exit::Success(_) => ScopeExit::Success,
                Exit::Failure(Cause::Interrupt) => ScopeExit::Interrupt,
                Exit::Failure(_) => ScopeExit::Failure,
            };
            ctx.scope.close(scope_exit).await;
            result
        })
    }

    pub fn spawn<R, E, A>(
        &self,
        effect: Effect<R, E, A>,
        env: R,
    ) -> tokio::task::JoinHandle<Exit<E, A>>
    where
        R: Clone + Send + Sync + 'static,
        E: Send + Sync + Clone + 'static,
        A: Send + Sync + Clone + 'static,
    {
        let clock = Arc::new(self.clock.clone());
        let ctx = Ctx {
            token: CancellationToken::new(),
            scope: ScopeHandle::new(),
            fiber_id: FiberId(0),
            locals: Arc::new(TokioMutex::new(HashMap::new())),
            clock,
        };

        self.runtime.rt.spawn(async move {
            let result = (effect.inner)(EnvRef { value: env }, ctx.clone()).await;
            let scope_exit = match &result {
                Exit::Success(_) => ScopeExit::Success,
                Exit::Failure(Cause::Interrupt) => ScopeExit::Interrupt,
                Exit::Failure(_) => ScopeExit::Failure,
            };
            ctx.scope.close(scope_exit).await;
            result
        })
    }

    pub async fn advance(&self, duration: Duration) {
        self.clock.adjust(duration);
        // Yield to allow fibers to process the wake-up?
        tokio::task::yield_now().await;
    }

    pub fn advance_blocking(&self, duration: Duration) {
        self.runtime.rt.block_on(async {
            self.advance(duration).await;
        })
    }

    pub fn block_on_future<F>(&self, future: F) -> F::Output
    where
        F: std::future::Future,
    {
        self.runtime.rt.block_on(future)
    }
}