//! nampower's explicit spell queue: the three slots behind `QueueSpellByName`, `QueueScript` and
//! `ChannelStopCastingNextTick`.
//!
//! **What this is, and what it deliberately is not.** Upstream's queue has two halves. One is the
//! Lua surface — "remember this spell and send it when the client will accept it" — and that is
//! what is built here. The other intercepts **every ordinary press**, so a keypress during a cast
//! is held rather than refused; that half is governed by `NP_QueueCastTimeSpells`,
//! `NP_QueueInstantSpells`, `NP_QueueTargetingSpells` and friends, and it is **not** built. It is
//! not a binding: it changes how every key in the game feels, it is the one piece whose bugs are
//! double-casts and dropped casts, and it is not something to switch on as a side effect of
//! porting three function names. Those CVars stay stored-only in `cvars.rs`, which says so at
//! each row.
//!
//! So: a spell reaches a slot only because Lua asked, and leaves it the moment the client would
//! accept that press anyway.
//!
//! **Three slots, because upstream has three and its own event says so.** `SPELL_QUEUE_EVENT`'s
//! first argument is `0` on-swing queued, `1` on-swing popped, `2` normal queued, `3` normal
//! popped, `4` non-GCD queued, `5` non-GCD popped — so the queue is keyed by what *kind* of cast a
//! spell is, and one slot per kind is the shape a consumer reads. The kind comes off the spell's
//! own `Spell.dbc` row, the same three tests the send path makes.

use std::time::{Duration, Instant};

use bevy::prelude::*;

/// `SPELL_QUEUE_EVENT`'s first argument. Numbers, not an enum, because they cross to Lua as
/// numbers and an addon compares them against these literals.
pub(crate) mod queue_event {
    pub(crate) const ON_SWING_QUEUED: i64 = 0;
    pub(crate) const ON_SWING_POPPED: i64 = 1;
    pub(crate) const NORMAL_QUEUED: i64 = 2;
    pub(crate) const NORMAL_POPPED: i64 = 3;
    pub(crate) const NON_GCD_QUEUED: i64 = 4;
    pub(crate) const NON_GCD_POPPED: i64 = 5;
}

/// Which slot a spell belongs in, from its own `Spell.dbc` row.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub(crate) enum Kind {
    /// `Attributes & 0x404`: Heroic Strike, Cleave, Raptor Strike.
    OnSwing,
    /// `StartRecoveryTime == 0`: it costs no global cooldown, so it need not wait for one.
    NonGcd,
    /// Everything else.
    Normal,
}

impl Kind {
    /// The same three tests the send path makes, in the same order: the on-next-swing attribute
    /// first (it outranks everything, since such a spell never occupies the cast slot at all),
    /// then the GCD pair.
    pub(crate) fn of(spell: Option<&benilla_formats::SpellDisplay>) -> Self {
        match spell {
            Some(d) if d.on_next_swing() => Kind::OnSwing,
            Some(d) if d.start_recovery_ms == 0 => Kind::NonGcd,
            // An uncatalogued spell is Normal, which is the slot that waits for the most: a queue
            // that fires something early is worse than one that fires it late.
            _ => Kind::Normal,
        }
    }

    fn queued_code(self) -> i64 {
        match self {
            Kind::OnSwing => queue_event::ON_SWING_QUEUED,
            Kind::NonGcd => queue_event::NON_GCD_QUEUED,
            Kind::Normal => queue_event::NORMAL_QUEUED,
        }
    }

    fn popped_code(self) -> i64 {
        match self {
            Kind::OnSwing => queue_event::ON_SWING_POPPED,
            Kind::NonGcd => queue_event::NON_GCD_POPPED,
            Kind::Normal => queue_event::NORMAL_POPPED,
        }
    }
}

/// One occupied slot.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
struct Slot {
    spell_id: u32,
    /// Where the window is measured from: the latest guard end this entry has been told about.
    ///
    /// **It ratchets forward**, in [`SpellQueue::expire`], while something is still guarding.
    /// A fixed `expires` stamped at queue time looks right and has a hole in it: a cast pushed
    /// back twice (`SMSG_SPELL_DELAYED`) ends after the window a press made at its start was
    /// given, so the entry would time out while the thing it is waiting for is still running and
    /// the press would vanish with no packet and no error. The same hole swallows a press held
    /// through a cast whose global cooldown then outlasts the window.
    base: Instant,
    /// How long past [`Self::base`] this entry survives: one of nampower's four windows, picked
    /// by what guarded the press (`np_press.rs`'s `window_for`).
    window: Duration,
    /// The earliest [`SpellQueue::pop`] will take it. The moment it was queued for an ordinary
    /// entry, which is to say no constraint at all; later only for a retry
    /// (`NP_RetryServerRejectedSpells`), where the point is to not re-send inside the same
    /// millisecond the server just refused.
    not_before: Instant,
}

impl Slot {
    /// Whether the window has run out, `base` having already been brought up to date.
    fn expired(&self, now: Instant) -> bool {
        now >= self.base + self.window
    }
}

/// One queued script, with the priority that orders it.
#[derive(Clone, Debug, PartialEq, Eq)]
struct Script {
    priority: i64,
    chunk: String,
    expires: Instant,
}

/// What the press queue did in the reporting period, for the one line it prints at `info`.
///
/// **Every other line this half of the client writes is `debug!`, which the default filter drops**
/// — so without this a whole session says nothing about whether a press was held, popped, dropped
/// or refused, and the only evidence left is the player's own combat log. The period is long and
/// the line is skipped when nothing moved, so an idle session stays quiet.
#[derive(Default)]
pub(crate) struct Tally {
    /// Presses held by [`super::np_press::PressRules::admit`].
    pub(crate) held: u32,
    /// Held presses that reached the wire.
    pub(crate) sent: u32,
    /// Held presses that gave up: the window ran out, or the spell was cold with
    /// `NP_QueueSpellsOnCooldown` off. The failure mode a player cannot describe.
    pub(crate) dropped: u32,
    /// Casts re-sent after a server refusal (`NP_RetryServerRejectedSpells`).
    pub(crate) retried: u32,
    /// Presses the rules declined to hold while something still guarded — each one is an error
    /// line the player read. A high count beside a low `held` is the queue not doing its job.
    pub(crate) fell_through: u32,
    /// Presses that ended a channel instead (`NP_InterruptChannelsOutsideQueueWindow`).
    pub(crate) interrupted: u32,
    /// When the period began; `None` until the first event.
    since: Option<Instant>,
}

impl Tally {
    fn moved(&self) -> bool {
        self.held | self.sent | self.dropped | self.retried | self.fell_through | self.interrupted
            != 0
    }
}

/// The queue: one slot per [`Kind`], plus the scripts.
///
/// `pub(crate)` fields are avoided on purpose — every mutation goes through [`Self::queue`] or
/// [`Self::pop`], so the `SPELL_QUEUE_EVENT` rows cannot be forgotten by a caller that writes a
/// slot directly.
#[derive(Resource)]
pub(crate) struct SpellQueue {
    on_swing: Option<Slot>,
    non_gcd: Option<Slot>,
    normal: Option<Slot>,
    scripts: Vec<Script>,
    /// `(code, spellId)` rows for `SPELL_QUEUE_EVENT`, drained by the one system that holds the
    /// VM. A queue rather than a direct fire for the reason every producer here uses one: this
    /// resource is written from the send path, which holds no VM. (Naming the VM's type here —
    /// even in a comment — puts this file in `ui_script_wall.rs`'s gated family, which is the
    /// gate working as intended: this module really is gameplay state and not a feed.)
    events: Vec<(i64, u32)>,
    /// `NP_SpellQueueWindowMs`, the one window this half of the queue has a use for: how long an
    /// entry is held before it gives up. [`Default`] carries the registered 500, because a row
    /// the player never moved never reaches [`on_cvar`] — see [`super::np_press::PressRules`].
    window_ms: u32,
    /// `NP_QueueSpellsOnCooldown`: whether an entry may sit in the queue while the spell itself is
    /// on cooldown, or is dropped on the spot.
    allow_on_cooldown: bool,
    /// `ChannelStopCastingNextTick`: the channel is cancelled on the next frame, not this one.
    stop_channel: bool,
    /// The spell a server refusal has already been retried for. See [`Self::queue_retry`].
    retried: Option<u32>,
    /// The period's counters, reported by [`Self::take_report`].
    tally: Tally,
}

/// `NP_SpellQueueWindowMs` 500 and `NP_QueueSpellsOnCooldown` 1 — the values `cvars.rs` registers,
/// which is what a player who touched neither row runs. A derived `Default` gave a window of 0,
/// and an entry whose window is 0 expires on the frame it was queued.
impl Default for SpellQueue {
    fn default() -> Self {
        Self {
            on_swing: None,
            non_gcd: None,
            normal: None,
            scripts: Vec::new(),
            events: Vec::new(),
            window_ms: 500,
            allow_on_cooldown: true,
            stop_channel: false,
            retried: None,
            tally: Tally::default(),
        }
    }
}

impl SpellQueue {
    /// Put `spell_id` in the slot its `kind` implies, replacing whatever was there.
    ///
    /// **Replacing, not refusing**, which is upstream's own behaviour — its log line is
    /// `Replacing queued nonGcd spell X with Y`. The replaced entry raises no popped event: it was
    /// never sent, and a consumer counting pops against queues would see one too many.
    ///
    /// The expiry is `max(now, in_flight_until) + window`: an entry queued during a three-second
    /// cast is held until that cast's own end plus the window, so a player who queues early is not
    /// punished for it, and one that nothing ever pops gives up rather than firing minutes later
    /// out of nowhere. That last part is the whole reason the window exists here.
    pub(crate) fn queue(
        &mut self,
        spell_id: u32,
        kind: Kind,
        now: Instant,
        in_flight_until: Option<Instant>,
    ) {
        self.queue_with_window(spell_id, kind, now, in_flight_until, self.window_ms);
    }

    /// [`Self::queue`] with the window named by the caller, for the press-interception half: a
    /// held **press** gives up on one of four windows picked by what guarded it
    /// (`np_press.rs`'s `window_for`), where an explicit `QueueSpellByName` has only ever had the
    /// one. Both land in the same slot and raise the same event, because upstream has one queue.
    pub(crate) fn queue_with_window(
        &mut self,
        spell_id: u32,
        kind: Kind,
        now: Instant,
        in_flight_until: Option<Instant>,
        window_ms: u32,
    ) {
        let slot = Slot {
            spell_id,
            base: in_flight_until.unwrap_or(now).max(now),
            window: Duration::from_millis(u64::from(window_ms)),
            not_before: now,
        };
        *self.slot_mut(kind) = Some(slot);
        self.events.push((kind.queued_code(), spell_id));
    }

    /// Put `spell_id` back after the **server** refused it for a timing reason
    /// (`NP_RetryServerRejectedSpells`), held `delay_ms` before it may be sent again.
    ///
    /// **Once per spell, and that bound is the whole design.** An unbounded retry of a refusal
    /// that keeps arriving is a packet a second forever, which is worse than the dropped cast it
    /// was meant to save — upstream's own `Retry cast after cancel still failed` says it gives up
    /// too. [`Self::clear_retry`] forgets the memo on any cast the server accepts, so a second
    /// rejection later in the fight is retried again; what cannot happen is two retries of one
    /// press.
    ///
    /// Returns whether it was queued, for the caller's log line.
    pub(crate) fn queue_retry(
        &mut self,
        spell_id: u32,
        kind: Kind,
        now: Instant,
        delay_ms: u32,
        window_ms: u32,
    ) -> bool {
        if self.retried == Some(spell_id) {
            return false;
        }
        self.retried = Some(spell_id);
        self.tally.since.get_or_insert(now);
        self.tally.retried += 1;
        let not_before = now + Duration::from_millis(u64::from(delay_ms));
        *self.slot_mut(kind) = Some(Slot {
            spell_id,
            base: not_before,
            window: Duration::from_millis(u64::from(window_ms)),
            not_before,
        });
        self.events.push((kind.queued_code(), spell_id));
        true
    }

    /// The counter pokes. Each is one line at its site, so a new path that holds or drops a press
    /// cannot forget to be countable — see [`Tally`] for why counting matters at all.
    pub(crate) fn note_held(&mut self, now: Instant) {
        self.tally.since.get_or_insert(now);
        self.tally.held += 1;
    }

    pub(crate) fn note_fell_through(&mut self, now: Instant) {
        self.tally.since.get_or_insert(now);
        self.tally.fell_through += 1;
    }

    pub(crate) fn note_interrupted(&mut self, now: Instant) {
        self.tally.since.get_or_insert(now);
        self.tally.interrupted += 1;
    }

    /// The period's line, or `None` while it is too young or empty. Resets on the way out.
    ///
    /// 60 s, because the question it answers ("is the queue working at all") does not need a
    /// finer grain, and a line a minute is a size a session log can carry.
    pub(crate) fn take_report(&mut self, now: Instant) -> Option<Tally> {
        let since = self.tally.since?;
        if !self.tally.moved() || now.duration_since(since) < Duration::from_secs(60) {
            return None;
        }
        Some(std::mem::take(&mut self.tally))
    }

    /// Forget the retry memo: a cast the server accepted means the next refusal is a new one.
    pub(crate) fn clear_retry(&mut self) {
        self.retried = None;
    }

    /// Queue a chunk for [`Self::take_ready_scripts`].
    pub(crate) fn queue_script(&mut self, chunk: String, priority: i64, now: Instant) {
        self.scripts.push(Script {
            priority,
            chunk,
            expires: now + Duration::from_millis(u64::from(self.window_ms)),
        });
    }

    fn slot_mut(&mut self, kind: Kind) -> &mut Option<Slot> {
        match kind {
            Kind::OnSwing => &mut self.on_swing,
            Kind::NonGcd => &mut self.non_gcd,
            Kind::Normal => &mut self.normal,
        }
    }

    /// Take the spell in `kind`'s slot if it is still live, raising its popped event.
    ///
    /// `now` is read only to honour a retry's hold ([`Self::queue_retry`]); an ordinary entry is
    /// never held, so this is the same unconditional take it always was for one.
    pub(crate) fn pop(&mut self, kind: Kind, now: Instant) -> Option<u32> {
        if !self.ready(kind, now) {
            return None;
        }
        let spell_id = self.slot_mut(kind).take()?.spell_id;
        self.tally.since.get_or_insert(now);
        self.tally.sent += 1;
        self.events.push((kind.popped_code(), spell_id));
        Some(spell_id)
    }

    /// Take `kind`'s slot and count it as given up rather than sent — the queue's own decision to
    /// abandon an entry, as against [`Self::expire`]'s window running out. The `*_POPPED` row still
    /// goes out, because an addon tracking the slot has to see it empty either way.
    pub(crate) fn discard(&mut self, kind: Kind, now: Instant) -> Option<u32> {
        let spell_id = self.slot_mut(kind).take()?.spell_id;
        self.tally.since.get_or_insert(now);
        self.tally.dropped += 1;
        self.events.push((kind.popped_code(), spell_id));
        Some(spell_id)
    }

    /// What is in `kind`'s slot, without taking it.
    pub(crate) fn peek(&self, kind: Kind) -> Option<u32> {
        self.slot(kind).map(|s| s.spell_id)
    }

    /// Whether `kind`'s slot holds something [`Self::pop`] would take now.
    pub(crate) fn ready(&self, kind: Kind, now: Instant) -> bool {
        self.slot(kind).is_some_and(|s| now >= s.not_before)
    }

    fn slot(&self, kind: Kind) -> Option<Slot> {
        match kind {
            Kind::OnSwing => self.on_swing,
            Kind::NonGcd => self.non_gcd,
            Kind::Normal => self.normal,
        }
    }

    /// Drop every entry whose window has passed.
    ///
    /// **No popped event for an expiry**, and that is the point of the distinction: a consumer
    /// reads `*_POPPED` as "this spell was sent". An entry that timed out was not. Upstream has
    /// no code for it either.
    pub(crate) fn expire(&mut self, now: Instant, guard_until: Option<Instant>) {
        for kind in [Kind::OnSwing, Kind::NonGcd, Kind::Normal] {
            let Some(slot) = self.slot_mut(kind) else {
                continue;
            };
            // Ratchet the base forward while something still guards the press: the window is
            // "this long past the guard's end", and the guard's end can move — pushback stretches
            // a cast, and a global cooldown outlives the cast that armed it. See [`Slot::base`].
            if let Some(guard) = guard_until {
                slot.base = slot.base.max(guard);
            }
            if slot.expired(now) {
                let dropped = self.slot_mut(kind).take();
                if let Some(s) = dropped {
                    self.tally.since.get_or_insert(now);
                    self.tally.dropped += 1;
                    debug!(
                        "spell-queue: dropping {:?} spell {} — nothing popped it inside the window",
                        kind, s.spell_id
                    );
                }
            }
        }
        // The scripts keep a fixed deadline: their contract is "after queued spells", and a
        // script whose spells never fired has nothing left to run after.
        self.scripts.retain(|s| now < s.expires);
    }

    /// The queued scripts in priority order, taken.
    ///
    /// Ascending priority, which is the order `SuperCleveRoidMacros` assumes when it passes `3`
    /// for "after queued spells" (`Core.lua:312`) — a bigger number is later. Taken all at once
    /// because the caller runs them in one breath once the queue has drained.
    pub(crate) fn take_ready_scripts(&mut self) -> Vec<String> {
        let mut ready = std::mem::take(&mut self.scripts);
        // Stable, so two scripts at one priority keep the order they were queued in.
        ready.sort_by_key(|s| s.priority);
        ready.into_iter().map(|s| s.chunk).collect()
    }

    /// Whether every **spell** slot is empty — the gate the queued scripts wait behind, since
    /// their contract is "after queued spells" and not "after everything".
    pub(crate) fn no_spells_waiting(&self) -> bool {
        self.on_swing.is_none() && self.non_gcd.is_none() && self.normal.is_none()
    }

    /// Whether anything at all is waiting, spells or scripts. Tests only, for now: the drain's own
    /// gate is [`Self::no_spells_waiting`].
    #[cfg(test)]
    fn is_empty(&self) -> bool {
        self.no_spells_waiting() && self.scripts.is_empty()
    }

    /// Take the `SPELL_QUEUE_EVENT` rows.
    pub(crate) fn take_events(&mut self) -> Vec<(i64, u32)> {
        std::mem::take(&mut self.events)
    }

    /// `NP_QueueSpellsOnCooldown`'s applied value.
    pub(crate) fn allows_on_cooldown(&self) -> bool {
        self.allow_on_cooldown
    }

    /// Arm `ChannelStopCastingNextTick`.
    pub(crate) fn request_channel_stop(&mut self) {
        self.stop_channel = true;
    }

    /// Take the channel-stop request.
    pub(crate) fn take_channel_stop(&mut self) -> bool {
        std::mem::take(&mut self.stop_channel)
    }
}

/// `NP_SpellQueueWindowMs` and `NP_QueueSpellsOnCooldown`, the two rows this half of the queue
/// reads. Every other `NP_Queue*`/`NP_*BufferTimeMs` row tunes the press-interception half, which
/// is not built — `cvars.rs` says so at each.
pub(crate) const CVAR_QUEUE_WINDOW: &str = "NP_SpellQueueWindowMs";
pub(crate) const CVAR_QUEUE_ON_COOLDOWN: &str = "NP_QueueSpellsOnCooldown";

/// Apply a change of either row. The registry fires this at boot with the registered default, so
/// neither field is read before it has been seeded.
pub(crate) fn on_cvar(ev: On<crate::cvars::CvarChanged>, mut queue: ResMut<SpellQueue>) {
    if ev.is(CVAR_QUEUE_WINDOW) {
        // Clamped at 10 s: the window's whole job is to stop an entry firing out of nowhere, and
        // a player who types a huge number into the settings panel should not lose that.
        queue.window_ms = ev.num().clamp(0.0, 10_000.0) as u32;
    }
    if ev.is(CVAR_QUEUE_ON_COOLDOWN) {
        queue.allow_on_cooldown = ev.flag();
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use benilla_formats::SpellDisplay;

    fn display(attributes: u32, start_recovery_ms: u32) -> SpellDisplay {
        SpellDisplay {
            attributes,
            start_recovery_ms,
            ..Default::default()
        }
    }

    /// The period line counts what happened and holds its tongue until the period is up — and
    /// `Default` is the registry, which is the bug this file shipped with.
    #[test]
    fn the_tally_reports_once_a_period_and_only_when_something_moved() {
        let mut q = SpellQueue::default();
        assert_eq!(q.window_ms, 500, "the registered NP_SpellQueueWindowMs");
        assert!(
            q.allow_on_cooldown,
            "the registered NP_QueueSpellsOnCooldown"
        );

        let t0 = Instant::now();
        assert!(q.take_report(t0).is_none(), "nothing has happened yet");
        q.note_held(t0);
        q.note_fell_through(t0);
        assert!(
            q.take_report(t0).is_none(),
            "the period is a minute long: two events in the first millisecond print nothing"
        );
        let later = t0 + Duration::from_secs(61);
        let r = q.take_report(later).expect("the period is up and it moved");
        assert_eq!((r.held, r.fell_through), (1, 1));
        assert!(
            q.take_report(later + Duration::from_secs(61)).is_none(),
            "the counters reset, so a quiet minute stays out of the log"
        );
    }

    /// The three kinds, off the same tests the send path makes. `0x404` is the on-next-swing pair.
    #[test]
    fn a_spells_kind_is_its_own_dbc_row() {
        assert_eq!(Kind::of(Some(&display(0x404, 0))), Kind::OnSwing);
        assert_eq!(
            Kind::of(Some(&display(0x404, 1500))),
            Kind::OnSwing,
            "the on-swing attribute outranks a GCD pair: such a spell never occupies the cast slot"
        );
        assert_eq!(Kind::of(Some(&display(0, 0))), Kind::NonGcd);
        assert_eq!(Kind::of(Some(&display(0, 1500))), Kind::Normal);
        assert_eq!(
            Kind::of(None),
            Kind::Normal,
            "an uncatalogued spell waits for the most — firing early is worse than firing late"
        );
    }

    /// Queue, replace, pop — and the events each raises.
    #[test]
    fn a_replacement_raises_no_pop_and_an_expiry_raises_nothing() {
        let t0 = Instant::now();
        let mut q = SpellQueue {
            window_ms: 500,
            ..Default::default()
        };

        q.queue(133, Kind::Normal, t0, None);
        assert_eq!(q.peek(Kind::Normal), Some(133));
        q.queue(116, Kind::Normal, t0, None);
        assert_eq!(
            q.peek(Kind::Normal),
            Some(116),
            "a second queue replaces, as upstream's own log line says"
        );
        assert_eq!(
            q.take_events(),
            vec![
                (queue_event::NORMAL_QUEUED, 133),
                (queue_event::NORMAL_QUEUED, 116),
            ],
            "two queues, and NO pop for the replaced entry — it was never sent, and a consumer \
             counting pops against queues would see one too many"
        );

        assert_eq!(q.pop(Kind::Normal, t0), Some(116));
        assert_eq!(q.peek(Kind::Normal), None);
        assert_eq!(q.take_events(), vec![(queue_event::NORMAL_POPPED, 116)]);
        assert_eq!(q.pop(Kind::Normal, t0), None, "an empty slot pops nothing");
        assert!(q.take_events().is_empty());

        // The three slots are independent: a normal spell does not displace a strike.
        q.queue(78, Kind::OnSwing, t0, None);
        q.queue(133, Kind::Normal, t0, None);
        q.queue(2139, Kind::NonGcd, t0, None);
        assert_eq!(
            (
                q.peek(Kind::OnSwing),
                q.peek(Kind::Normal),
                q.peek(Kind::NonGcd)
            ),
            (Some(78), Some(133), Some(2139))
        );
        let codes: Vec<i64> = q.take_events().into_iter().map(|(c, _)| c).collect();
        assert_eq!(
            codes,
            vec![
                queue_event::ON_SWING_QUEUED,
                queue_event::NORMAL_QUEUED,
                queue_event::NON_GCD_QUEUED
            ]
        );

        // An expiry raises nothing: `*_POPPED` means "this was sent", and this was not.
        q.expire(t0 + Duration::from_millis(499), None);
        assert_eq!(q.peek(Kind::Normal), Some(133), "inside the window");
        q.expire(t0 + Duration::from_millis(500), None);
        assert!(q.is_empty(), "every slot gave up at the window");
        assert!(
            q.take_events().is_empty(),
            "and an expiry is not a pop — upstream has no code for one either"
        );
    }

    /// The expiry is measured from the **end of the cast in flight**, not from the moment of
    /// queueing: a player who queues early during a long cast is not punished for it.
    #[test]
    fn an_entry_queued_during_a_cast_is_held_until_that_casts_own_end() {
        let t0 = Instant::now();
        let mut q = SpellQueue {
            window_ms: 500,
            ..Default::default()
        };
        let cast_ends = t0 + Duration::from_secs(3);
        q.queue(133, Kind::Normal, t0, Some(cast_ends));

        q.expire(t0 + Duration::from_millis(600), None);
        assert_eq!(
            q.peek(Kind::Normal),
            Some(133),
            "600 ms in, the cast is still running — the window has not started"
        );
        q.expire(cast_ends + Duration::from_millis(499), None);
        assert_eq!(q.peek(Kind::Normal), Some(133));
        q.expire(cast_ends + Duration::from_millis(500), None);
        assert_eq!(q.peek(Kind::Normal), None);

        // A deadline already in the past is not a shorter window than a fresh queue's: the `max`
        // is what stops a lapsed cast making the entry expire instantly.
        q.queue(133, Kind::Normal, t0, Some(t0 - Duration::from_secs(10)));
        q.expire(t0 + Duration::from_millis(499), None);
        assert_eq!(q.peek(Kind::Normal), Some(133));
    }

    /// The window is measured from the **live** guard end, not the one stamped at queue time.
    ///
    /// A fixed deadline has a hole in it: a cast pushed back twice ends after the window a press
    /// made at its start was given, so the entry would time out while the thing it is waiting for
    /// is still running, and the press would vanish with no packet and no error line. The same
    /// hole swallows a press held through a cast whose global cooldown then outlasts the window.
    #[test]
    fn a_held_entry_cannot_time_out_while_something_still_guards_it() {
        let t0 = Instant::now();
        let mut q = SpellQueue {
            window_ms: 500,
            ..Default::default()
        };
        let cast_ends = t0 + Duration::from_secs(3);
        q.queue(133, Kind::Normal, t0, Some(cast_ends));

        // Two pushbacks of 500 ms each: the cast now ends at t0 + 4 s, well past the entry's
        // original t0 + 3.5 s deadline.
        let pushed = cast_ends + Duration::from_secs(1);
        q.expire(t0 + Duration::from_millis(3_600), Some(pushed));
        assert_eq!(
            q.peek(Kind::Normal),
            Some(133),
            "past where the window would have ended, but the cast is still running"
        );

        // And once it really ends, the window runs from there.
        q.expire(pushed + Duration::from_millis(499), None);
        assert_eq!(q.peek(Kind::Normal), Some(133));
        q.expire(pushed + Duration::from_millis(500), None);
        assert_eq!(q.peek(Kind::Normal), None, "500 ms past the real end");

        // The base only ever moves forward: a guard that reads *earlier* than the one already
        // recorded cannot shorten an entry's life.
        q.queue(133, Kind::Normal, t0, Some(cast_ends));
        q.expire(t0, Some(t0));
        q.expire(cast_ends + Duration::from_millis(499), None);
        assert_eq!(
            q.peek(Kind::Normal),
            Some(133),
            "a shorter guard end does not pull the deadline in"
        );
    }

    /// `NP_RetryServerRejectedSpells`: a refused cast goes back in its slot, held for the delay,
    /// and **once** — a retry that could itself be retried is a packet a second forever.
    #[test]
    fn a_retry_is_held_for_its_delay_and_happens_once() {
        let t0 = Instant::now();
        let mut q = SpellQueue {
            window_ms: 500,
            ..Default::default()
        };

        assert!(q.queue_retry(133, Kind::Normal, t0, 55, 500));
        assert_eq!(q.peek(Kind::Normal), Some(133));
        assert!(
            !q.ready(Kind::Normal, t0 + Duration::from_millis(40)),
            "inside the delay the entry is there but not sendable — re-sending inside the \
             millisecond the server refused it is the one thing a retry must not do"
        );
        assert_eq!(q.pop(Kind::Normal, t0 + Duration::from_millis(40)), None);
        assert!(q.ready(Kind::Normal, t0 + Duration::from_millis(55)));
        assert_eq!(
            q.pop(Kind::Normal, t0 + Duration::from_millis(55)),
            Some(133)
        );

        // The same spell refused again is not retried a second time.
        assert!(
            !q.queue_retry(133, Kind::Normal, t0, 55, 500),
            "once per rejection chain"
        );
        assert_eq!(q.peek(Kind::Normal), None, "and nothing was put back");

        // A cast the server accepted forgets the memo, so a later rejection is its own.
        q.clear_retry();
        assert!(q.queue_retry(133, Kind::Normal, t0, 55, 500));

        // An ordinary queue is never held: `ready` is about retries alone.
        let mut plain = SpellQueue {
            window_ms: 500,
            ..Default::default()
        };
        plain.queue(133, Kind::Normal, t0, None);
        assert!(plain.ready(Kind::Normal, t0));
    }

    /// Scripts come back in ascending priority, and two at one priority keep their order —
    /// `SuperCleveRoidMacros` passes `3` for "after queued spells", so a bigger number is later.
    #[test]
    fn queued_scripts_come_back_in_priority_order() {
        let t0 = Instant::now();
        let mut q = SpellQueue {
            window_ms: 500,
            ..Default::default()
        };
        q.queue_script("third".into(), 3, t0);
        q.queue_script("first".into(), 1, t0);
        q.queue_script("also-third".into(), 3, t0);
        q.queue_script("second".into(), 2, t0);
        assert_eq!(
            q.take_ready_scripts(),
            vec!["first", "second", "third", "also-third"]
        );
        assert!(q.is_empty(), "taking them empties the list");

        // And they expire on the same window as a spell does.
        q.queue_script("gone".into(), 1, t0);
        q.expire(t0 + Duration::from_millis(500), None);
        assert!(q.take_ready_scripts().is_empty());
    }
}