//! Timer / sleep tests. These are time-sensitive and use generous
//! tolerances — we care about ordering and "didn't return instantly /
//! didn't take forever," not microsecond-precise scheduling.

use smarm::{run, sleep, spawn};
use std::sync::Arc;
use std::sync::Mutex;
use std::time::{Duration, Instant};

#[test]
fn sleep_returns_after_at_least_the_requested_duration() {
    run(|| {
        let t0 = Instant::now();
        sleep(Duration::from_millis(50));
        let elapsed = t0.elapsed();
        assert!(
            elapsed >= Duration::from_millis(45),
            "slept only {:?}, expected ≥ ~50ms",
            elapsed
        );
        // Loose upper bound — anything wildly slow indicates a bug.
        assert!(
            elapsed < Duration::from_millis(500),
            "slept {:?}, far longer than the 50ms request",
            elapsed
        );
    });
}

#[test]
fn shorter_sleep_wakes_first() {
    let log: Arc<Mutex<Vec<u8>>> = Arc::new(Mutex::new(Vec::new()));
    let l1 = log.clone();
    let l2 = log.clone();

    run(move || {
        let h1 = spawn(move || {
            sleep(Duration::from_millis(60));
            l1.lock().unwrap().push(1);
        });
        let h2 = spawn(move || {
            sleep(Duration::from_millis(20));
            l2.lock().unwrap().push(2);
        });
        h1.join().unwrap();
        h2.join().unwrap();
    });

    // 2 (shorter sleep) wakes before 1.
    assert_eq!(*log.lock().unwrap(), vec![2, 1]);
}

#[test]
fn one_sleeping_actor_does_not_block_other_runnable_actors() {
    let log: Arc<Mutex<Vec<u8>>> = Arc::new(Mutex::new(Vec::new()));
    let l1 = log.clone();
    let l2 = log.clone();

    run(move || {
        let h1 = spawn(move || {
            sleep(Duration::from_millis(100));
            l1.lock().unwrap().push(1);
        });
        let h2 = spawn(move || {
            // Doesn't sleep. Should be able to run while h1 is parked.
            for _ in 0..3 {
                l2.lock().unwrap().push(2);
                smarm::yield_now();
            }
        });
        h2.join().unwrap();
        h1.join().unwrap();
    });

    let v = log.lock().unwrap();
    // h2 finishes long before h1's 100ms timer.
    let h2_count = v.iter().filter(|&&x| x == 2).count();
    let h1_pos = v.iter().position(|&x| x == 1);
    assert_eq!(h2_count, 3);
    // h1's push should land after h2 is fully done.
    if let Some(p) = h1_pos {
        assert!(p >= h2_count, "h1 woke before h2 finished: log = {:?}", *v);
    }
}

#[test]
fn zero_duration_sleep_yields_but_does_not_park_forever() {
    // A zero-duration sleep should behave like yield_now: control returns
    // promptly without hanging.
    run(|| {
        let t0 = Instant::now();
        sleep(Duration::from_millis(0));
        assert!(t0.elapsed() < Duration::from_millis(100));
    });
}

#[test]
fn many_concurrent_sleepers_all_wake() {
    let counter = Arc::new(std::sync::atomic::AtomicU32::new(0));
    let c = counter.clone();
    run(move || {
        let mut handles = Vec::new();
        for i in 0..20u64 {
            let cc = c.clone();
            handles.push(spawn(move || {
                // Stagger so they don't all coalesce to the same wake.
                sleep(Duration::from_millis(5 + i * 2));
                cc.fetch_add(1, std::sync::atomic::Ordering::SeqCst);
            }));
        }
        for h in handles {
            h.join().unwrap();
        }
    });
    assert_eq!(counter.load(std::sync::atomic::Ordering::SeqCst), 20);
}

// ---------------------------------------------------------------------------
// Direct tests on the Timers data structure. No scheduler involved — these
// cover the new Reason machinery without needing a Mutex implementation.
// ---------------------------------------------------------------------------

use smarm::pid::Pid;
use smarm::timer::{Reason, TimerTarget, Timers};

struct RecordingTarget {
    calls: Mutex<Vec<(Pid, u32)>>,
}
impl TimerTarget for RecordingTarget {
    fn on_timeout(&self, pid: Pid, epoch: u32) {
        self.calls.lock().unwrap().push((pid, epoch));
    }
}

#[test]
fn timers_pop_due_returns_entries_in_deadline_order() {
    let mut t = Timers::new();
    let now = Instant::now();
    // Insert out of order; pop_due should hand them back sorted by deadline.
    t.insert_sleep(now + Duration::from_millis(30), Pid::new(0, 0), 1);
    t.insert_sleep(now + Duration::from_millis(10), Pid::new(1, 0), 1);
    t.insert_sleep(now + Duration::from_millis(20), Pid::new(2, 0), 1);

    // Advance past all of them.
    let due = t.pop_due(now + Duration::from_millis(50));
    let pids: Vec<u32> = due.iter().map(|e| e.pid.index()).collect();
    assert_eq!(pids, vec![1, 2, 0]);
    assert!(t.is_empty());
}

#[test]
fn timers_only_pop_entries_whose_deadline_has_passed() {
    let mut t = Timers::new();
    let now = Instant::now();
    t.insert_sleep(now + Duration::from_millis(5), Pid::new(0, 0), 1);
    t.insert_sleep(now + Duration::from_millis(100), Pid::new(1, 0), 1);

    let due = t.pop_due(now + Duration::from_millis(20));
    assert_eq!(due.len(), 1);
    assert_eq!(due[0].pid.index(), 0);
    assert!(!t.is_empty());
    // The unpopped entry's deadline is still visible.
    assert!(t.peek_deadline().is_some());
}

#[test]
fn timers_mix_sleep_and_wait_timeout_reasons() {
    let mut t = Timers::new();
    let target = Arc::new(RecordingTarget { calls: Mutex::new(Vec::new()) });
    let now = Instant::now();

    t.insert_sleep(now + Duration::from_millis(5), Pid::new(0, 0), 1);
    t.insert(
        now + Duration::from_millis(10),
        Pid::new(1, 0),
        Reason::WaitTimeout { target: target.clone(), epoch: 42 },
    );

    let due = t.pop_due(now + Duration::from_millis(20));
    assert_eq!(due.len(), 2);

    // Order: Sleep (5ms) first, WaitTimeout (10ms) second.
    match &due[0].reason {
        Reason::Sleep { .. } => {}
        _ => panic!("first entry should be a Sleep"),
    }
    match &due[1].reason {
        Reason::WaitTimeout { epoch, .. } => assert_eq!(*epoch, 42),
        _ => panic!("second entry should be a WaitTimeout"),
    }
}

#[test]
fn same_deadline_entries_pop_in_insertion_order() {
    // The `seq` tiebreaker means inserting two entries with the same
    // deadline preserves the order they were inserted.
    let mut t = Timers::new();
    let now = Instant::now();
    let d = now + Duration::from_millis(10);
    t.insert_sleep(d, Pid::new(0, 0), 1);
    t.insert_sleep(d, Pid::new(1, 0), 1);
    t.insert_sleep(d, Pid::new(2, 0), 1);

    let due = t.pop_due(now + Duration::from_millis(20));
    let pids: Vec<u32> = due.iter().map(|e| e.pid.index()).collect();
    assert_eq!(pids, vec![0, 1, 2]);
}

// ---------------------------------------------------------------------------
// send_after / cancel_timer — the message-delivery timer substrate.
//
// Unit tests drive `Timers` directly with a flag-flipping fire thunk (no
// runtime needed, mirroring RecordingTarget above). Integration tests drive
// the public scheduler API and assert real registry-resolved delivery.
// ---------------------------------------------------------------------------

use std::sync::atomic::{AtomicBool, Ordering};

// Pull the Send fire thunk out of a popped entry and run it.
fn run_fire(entry: smarm::timer::Entry) {
    match entry.reason {
        Reason::Send { fire } => fire(),
        _ => panic!("expected a Send entry"),
    }
}

#[test]
fn armed_send_timer_is_returned_and_fires() {
    let mut t = Timers::new();
    let now = Instant::now();
    let fired = Arc::new(AtomicBool::new(false));
    let f = fired.clone();
    let _id = t.insert_send(
        now + Duration::from_millis(10),
        Pid::new(0, 0),
        Box::new(move || f.store(true, Ordering::SeqCst)),
    );

    let mut due = t.pop_due(now + Duration::from_millis(20));
    assert_eq!(due.len(), 1, "an armed send timer should pop when due");
    assert!(!fired.load(Ordering::SeqCst), "pop must not fire on its own");
    run_fire(due.pop().unwrap());
    assert!(fired.load(Ordering::SeqCst), "running the thunk delivers");
    assert!(t.is_empty());
}

#[test]
fn cancelled_send_timer_is_discarded_not_returned() {
    let mut t = Timers::new();
    let now = Instant::now();
    let fired = Arc::new(AtomicBool::new(false));
    let f = fired.clone();
    let id = t.insert_send(
        now + Duration::from_millis(10),
        Pid::new(0, 0),
        Box::new(move || f.store(true, Ordering::SeqCst)),
    );

    assert!(t.cancel(id), "cancel before fire returns true");
    let due = t.pop_due(now + Duration::from_millis(20));
    assert!(due.is_empty(), "a cancelled send timer must not pop");
    assert!(!fired.load(Ordering::SeqCst));
}

#[test]
fn cancel_after_fire_returns_false() {
    // The race signal Mark wanted: cancelling a timer that already fired tells
    // you it was too late.
    let mut t = Timers::new();
    let now = Instant::now();
    let id = t.insert_send(
        now + Duration::from_millis(5),
        Pid::new(0, 0),
        Box::new(|| {}),
    );
    let due = t.pop_due(now + Duration::from_millis(10));
    assert_eq!(due.len(), 1);
    assert!(!t.cancel(id), "cancel after the timer fired returns false");
}

#[test]
fn cancel_unknown_id_returns_false() {
    let mut t = Timers::new();
    let now = Instant::now();
    let id = t.insert_send(now + Duration::from_millis(5), Pid::new(0, 0), Box::new(|| {}));
    assert!(t.cancel(id));
    // Second cancel of the same id: already gone.
    assert!(!t.cancel(id));
}

#[test]
fn send_timers_interleave_with_sleep_in_deadline_order() {
    let mut t = Timers::new();
    let now = Instant::now();
    t.insert_sleep(now + Duration::from_millis(30), Pid::new(0, 0), 1);
    let _id = t.insert_send(now + Duration::from_millis(10), Pid::new(1, 0), Box::new(|| {}));
    t.insert_sleep(now + Duration::from_millis(20), Pid::new(2, 0), 1);

    let due = t.pop_due(now + Duration::from_millis(50));
    assert_eq!(due.len(), 3);
    // 10ms Send, then 20ms Sleep, then 30ms Sleep.
    assert!(matches!(due[0].reason, Reason::Send { .. }));
    assert_eq!(due[1].pid.index(), 2);
    assert_eq!(due[2].pid.index(), 0);
}

#[test]
fn clear_drops_armed_send_timers() {
    let mut t = Timers::new();
    let now = Instant::now();
    let id = t.insert_send(now + Duration::from_millis(10), Pid::new(0, 0), Box::new(|| {}));
    t.clear();
    assert!(t.is_empty());
    // The arm record is gone too: cancelling reports nothing to cancel.
    assert!(!t.cancel(id));
}

// --- Integration: real delivery through the scheduler + registry. ---

use smarm::{cancel_timer, channel, register, send_after_named, Name};

#[test]
fn send_after_named_delivers_after_the_delay() {
    const PING: Name<u64> = Name::new("send_after_ping");
    run(|| {
        let (tx, rx) = channel::<u64>();
        register(PING, tx).unwrap();
        let t0 = Instant::now();
        let _id = send_after_named(Duration::from_millis(30), PING, 99);
        assert_eq!(rx.recv().unwrap(), 99);
        assert!(
            t0.elapsed() >= Duration::from_millis(25),
            "delivered too early: {:?}",
            t0.elapsed()
        );
    });
}

#[test]
fn cancel_timer_prevents_delivery() {
    const C: Name<u64> = Name::new("send_after_cancel");
    run(|| {
        let (tx, rx) = channel::<u64>();
        register(C, tx).unwrap();
        let id = send_after_named(Duration::from_millis(50), C, 7);
        assert!(cancel_timer(id), "cancel before fire returns true");
        sleep(Duration::from_millis(90));
        assert_eq!(rx.try_recv(), Ok(None), "cancelled timer delivered anyway");
    });
}

#[test]
fn send_after_to_unresolved_name_is_silent() {
    const NOPE: Name<u64> = Name::new("send_after_nobody_home");
    run(|| {
        // Nobody registered NOPE; firing resolves to nothing and is dropped.
        let _id = send_after_named(Duration::from_millis(10), NOPE, 1);
        sleep(Duration::from_millis(40)); // let it fire and no-op
        // Reaching here without a panic is the assertion.
    });
}

// --- Integration: typed Pid<A> delivery (exercises send_to on fire). ---

use smarm::{send_after, send_to, spawn_addr, Addressable, Receiver};

struct Sink;
impl Addressable for Sink {
    type Msg = u64;
}

#[test]
fn send_after_delivers_to_typed_pid() {
    run(|| {
        // A reply channel so the test actor learns what Sink received.
        let (report_tx, report_rx) = channel::<u64>();
        let sink: Pid<Sink> = spawn_addr::<Sink>(move |rx: Receiver<u64>| {
            if let Ok(v) = rx.recv() {
                let _ = report_tx.send(v);
            }
        });
        let _id = send_after(Duration::from_millis(25), sink, 1234);
        assert_eq!(report_rx.recv().unwrap(), 1234);
    });
}

#[test]
fn send_after_to_dead_typed_pid_is_silent() {
    run(|| {
        // Sink exits immediately after handling one message; arm a second
        // delivery for after it's gone. The fire-time send_to returns Dead and
        // is dropped — no panic.
        let (report_tx, report_rx) = channel::<u64>();
        let sink: Pid<Sink> = spawn_addr::<Sink>(move |rx: Receiver<u64>| {
            if let Ok(v) = rx.recv() {
                let _ = report_tx.send(v);
            }
            // body returns -> actor exits
        });
        send_to(sink, 1).unwrap();
        assert_eq!(report_rx.recv().unwrap(), 1); // sink has now exited
        let _id = send_after(Duration::from_millis(15), sink, 2);
        sleep(Duration::from_millis(45)); // let it fire against the dead pid
        // No panic; the sink is gone, so its report sender dropped with it —
        // closed+empty is Err (documented), which also proves nothing
        // further was delivered.
        assert!(report_rx.try_recv().is_err(), "nothing further delivered");
    });
}

// ---------------------------------------------------------------------------
// Wall-anchored send_after (RFC 007 user-facing opt-out). The API exists in
// both feature configs; featureless it is behaviourally identical to
// `send_after` — these tests pin exactly that.
// ---------------------------------------------------------------------------

#[test]
fn armed_wall_send_timer_is_returned_and_fires() {
    let mut t = Timers::new();
    let now = Instant::now();
    let fired = Arc::new(AtomicBool::new(false));
    let f = fired.clone();
    let _id = t.insert_send_wall(
        now + Duration::from_millis(10),
        Pid::new(0, 0),
        Box::new(move || f.store(true, Ordering::SeqCst)),
    );

    let mut due = t.pop_due(now + Duration::from_millis(20));
    assert_eq!(due.len(), 1, "an armed wall send timer should pop when due");
    run_fire(due.pop().unwrap());
    assert!(fired.load(Ordering::SeqCst), "running the thunk delivers");
    assert!(t.is_empty());
}

use smarm::send_after_named_wall;

#[test]
fn send_after_named_wall_delivers_after_the_delay() {
    const WPING: Name<u64> = Name::new("send_after_wall_ping");
    run(|| {
        let (tx, rx) = channel::<u64>();
        register(WPING, tx).unwrap();
        let t0 = Instant::now();
        let _id = send_after_named_wall(Duration::from_millis(30), WPING, 99);
        assert_eq!(rx.recv().unwrap(), 99);
        assert!(
            t0.elapsed() >= Duration::from_millis(25),
            "delivered too early: {:?}",
            t0.elapsed()
        );
    });
}

#[test]
fn send_after_named_wall_cancels() {
    const WC: Name<u64> = Name::new("send_after_wall_cancel");
    run(|| {
        let (tx, rx) = channel::<u64>();
        register(WC, tx).unwrap();
        let id = send_after_named_wall(Duration::from_millis(50), WC, 7);
        assert!(cancel_timer(id), "cancel before fire returns true");
        sleep(Duration::from_millis(90));
        assert_eq!(rx.try_recv(), Ok(None), "cancelled wall timer delivered");
    });
}