dotzuki-rules 0.1.1

No-code RON authoring loader + closed primitive interpreter for dotzuki-engine's battle effect-stack. Parses a rules.ron into runtime Effects dispatched through ONE zero-capture interpreter-bridge fn keyed by source_effect (doc 11 Option A — zero engine change).
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193

//! The game binding seam (doc 11 §1, doc 12 §3.2).
//!
//! `dotzuki-rules` stays game-agnostic: it never names a concrete `P::Stat` /
//! `P::Status` / `P::Type`. The data uses **names**, interned to `usize` indices
//! at load. To actually apply a `Boost`/`InflictStatus`/`HasType`/`ApplyTypeChart`
//! against a [`BattlerState<P>`](dotzuki_engine::battle::BattlerState) the interpreter
//! asks the **game** to resolve those indices via this trait. This mirrors doc 12
//! §3.2's two defaulted provider seams (`defender_types`, `type_chart_mult`), but
//! lives game-side (no engine edit), keyed by the interned index the loader owns.
//!
//! All methods are **pure / RNG-free** (determinism, doc 11 §4.1): a binding may
//! read battler state and the interned chart but must never draw randomness. The
//! interpreter's only entropy is `ctx.rng`.

use dotzuki_engine::battle::stack::{BattleCtx, EffectProvider};
use dotzuki_engine::battle::{BattlerRef, BattlerState};

/// Resolves interned data-layer indices to concrete `P::Stat`/`P::Status` and
/// supplies the type-chart fold + defender-type membership, all pure.
///
/// A game implements this once for its provider; the loader carries it so the
/// zero-capture [`interpret`](crate::interpret) bridge can reach it. The trait is
/// generic over `P: EffectProvider`, so the engine learns nothing.
pub trait RuleBindings<P: EffectProvider + ?Sized>: 'static {
    /// Apply a signed stat-stage delta to `who` for the interned `stat_index`.
    /// Returns `false` if the index is unknown (a no-op; the loader validates
    /// names at compile, so this is defense-in-depth). Phase 1 applies directly;
    /// the nested-`TryBoost` veto is driver orchestration (doc 11 §3).
    fn apply_boost(&self, b: &mut BattlerState<P>, stat_index: usize, stages: i8) -> bool;

    /// Set `who`'s non-volatile status for the interned `status_index`. Returns
    /// `false` if the index is unknown.
    fn set_status(&self, b: &mut BattlerState<P>, status_index: usize) -> bool;

    /// Set `who`'s non-volatile status carrying a game-interpreted numeric
    /// `amount` (e.g. Gen-1 sleep turns). The engine resolves `amount` from the
    /// op's [`AmountSpec`](crate::AmountSpec) — drawing its OWN rng — and hands
    /// the pure number here. **Defaulted** to delegate to
    /// [`set_status`](Self::set_status) and ignore the amount, so a game whose
    /// statuses carry no duration is unaffected. Pure; no entropy.
    fn set_status_with_amount(
        &self,
        b: &mut BattlerState<P>,
        status_index: usize,
        _amount: u16,
    ) -> bool {
        self.set_status(b, status_index)
    }

    /// Build the game's OPAQUE `P::EffectStateKind` volatile for the vocabulary
    /// `name` + already-resolved `amount` (the [`InflictVolatile`](crate::Op::InflictVolatile)
    /// op). The engine installs whatever is returned generically (fresh arena
    /// id) and never learns what the volatile means — only the game does.
    /// **Defaulted to `None`** ⇒ a game with no volatiles (or that doesn't
    /// recognise `name`) makes the op inert. Pure — the engine already drew any
    /// rng needed for `amount`.
    fn make_volatile(&self, _name: &str, _amount: u16) -> Option<P::EffectStateKind> {
        None
    }

    /// Whether `who` has the type with interned chart `type_index` (the `HasType`
    /// predicate, doc 11 §1.1). Pure read.
    fn has_type(&self, b: &BattlerState<P>, type_index: usize) -> bool;

    /// The chart fold for the in-flight `move_type_index` against `defender`'s
    /// type(s), as ONE pre-combined integer rational `(num, den)` (doc 12 §3.2,
    /// §5.3 — one rational ⇒ exactly one `scale`, avoiding per-step truncation).
    /// Default `(1, 1)` ⇒ inert (no chart). Pure / RNG-free.
    fn type_chart_mult(
        &self,
        _ctx: &BattleCtx<'_, P>,
        _move_type_index: usize,
        _defender: BattlerRef,
    ) -> (u32, u32) {
        (1, 1)
    }

    /// The in-flight folded stat index, if the driver stashed one for a
    /// `StatIs` predicate (the Sandstorm `WeatherModifyStat` case, doc 11 §1).
    /// Default `None` ⇒ `StatIs` never matches. Pure.
    fn current_stat_index(&self, _ctx: &BattleCtx<'_, P>) -> Option<usize> {
        None
    }

    /// Whether `who` currently has the live volatile named by `name` (the
    /// `HasVolatile` predicate, blueprint `15` §2/§3 — the Substitute block on
    /// side-status). The game inspects its own `ctx.effects` arena (the engine
    /// treats `EffectStateKind` opaquely, so only the game can tell which arena
    /// entry IS "Substitute"). **Defaulted to `false`** so a game with no volatiles
    /// (every game built so far) is unaffected and the predicate never matches.
    /// Pure read; no entropy.
    fn has_volatile(&self, _ctx: &BattleCtx<'_, P>, _who: BattlerRef, _name: &str) -> bool {
        false
    }

    /// **Damage-redirection seam** for the DIRECT-MUTATE ops (`SetHp` / `DamageFraction`
    /// / `DamageCurrentHpFraction` / `RepeatHits`) that apply HP OUTSIDE the driver's
    /// `Event::Damage` fold. Before such an op subtracts `amount` HP from `who`
    /// (attributed to `source`), the interpreter asks the game whether a **damage sink**
    /// on `who` should swallow it instead — a monster Substitute doll, a cross-game
    /// shield/ward/decoy. Returning `true` means the game HANDLED the loss (it mutated
    /// its own sink via `ctx`); the interpreter then SKIPS the direct HP write. Returning
    /// `false` (the default) leaves the op to apply HP exactly as before.
    ///
    /// This is the ONLY binding permitted to MUTATE through `ctx` (every other is a pure
    /// read) — it is the redirect analogue of the `TryBoost`/`Event::Damage` interception
    /// the driver already fires for formula damage, extended to the ops the driver never
    /// routes. **Defaulted to `false`** so every existing game (and every op) is
    /// byte-identical: the loss applies unredirected, no `ctx` mutation, no entropy.
    /// `source` lets a game exempt self-inflicted loss (recoil / self-KO) from its own
    /// sink. Draws NO randomness.
    fn redirect_hp_loss(
        &self,
        _ctx: &mut BattleCtx<'_, P>,
        _who: BattlerRef,
        _source: BattlerRef,
        _amount: u16,
    ) -> bool {
        false
    }

    /// Whether the in-flight move's type (`move_type_index`, recovered from the
    /// record's `type:`) equals one of `who`'s types (the `MoveTypeIsDefenderType`
    /// predicate — Gen-1 burn/freeze/paralyze self-type-immunity quirk #23,
    /// blueprint `15` §2/§3). **Defaulted to `false`** ⇒ the quirk never fires for a
    /// game that does not implement it. Pure read; no entropy. The default body
    /// delegates to [`has_type`](Self::has_type) so a game whose `has_type` already
    /// answers chart membership gets the quirk for free by overriding nothing — but
    /// the engine has no `move_type_index` for a generic predicate, so the loader
    /// passes it through and the binding decides.
    fn move_type_is_defender_type(
        &self,
        ctx: &BattleCtx<'_, P>,
        move_type_index: usize,
        who: BattlerRef,
    ) -> bool {
        self.has_type(ctx.battler(who), move_type_index)
    }

    /// Whether `who` currently has the non-volatile status at interned
    /// `status_index` (the `TargetHasStatus` predicate — the Dream Eater sleep
    /// gate, blueprint `15` §2). The status index is the game's vocabulary (the same
    /// indices `set_status` consumes). **Defaulted to `false`** ⇒ a game that does
    /// not implement it never matches. Pure read; no entropy.
    fn has_status(&self, _b: &BattlerState<P>, _status_index: usize) -> bool {
        false
    }

    /// Whether `b` has ANY non-volatile status (the `TargetHasAnyStatus`
    /// predicate — the Toxic "already-statused ⇒ fail" guard). The engine knows
    /// no concrete status, so the game answers. **Defaulted to `false`** ⇒ a game
    /// that doesn't implement it never matches. Pure read; no entropy.
    fn has_any_status(&self, _b: &BattlerState<P>) -> bool {
        false
    }

    /// The level of battler `b` (the `LevelGE` predicate's gate + the level-based
    /// [`SetDamage`](crate::Op::SetDamage) sources — Seismic Toss / Night Shade /
    /// Psywave; blueprint `15` §2/§3). [`BattlerState<P>`](dotzuki_engine::battle::BattlerState)
    /// carries no `level` field (the engine is level-agnostic), so the game answers
    /// it here. **Defaulted to `0`** ⇒ a game that authors no level-gated op is
    /// unaffected (it never calls this) and `LevelGE` is `0 >= 0 == true`. Pure
    /// read; no entropy. Game-agnostic: "a number the binding supplies per battler".
    fn battler_level(&self, _b: &BattlerState<P>) -> u16 {
        0
    }

    /// Map an interned resource index (the ruleset's `resources:` order) to the
    /// engine's opaque resource id used in [`ResourcePool`](dotzuki_engine::battle::ResourcePool)
    /// / [`BattleProvider::move_cost`](dotzuki_engine::battle::BattleProvider::move_cost)
    /// (the MP/SP/mana cost gate, doc 13 §4). **Defaulted** so games with no
    /// resources need not implement it — they never reference a resource, so it is
    /// never called. Default: identity (`index as u16`). Pure.
    fn resource_id(&self, resource_index: usize) -> u16 {
        resource_index as u16
    }

    /// Whether `b` can pay `amount` of the resource at interned `resource_index`
    /// (the `PayResource` op's gate, doc 13 §4). Pure read. The default delegates
    /// to the engine's [`ResourcePool`](dotzuki_engine::battle::ResourcePool) via
    /// [`resource_id`](Self::resource_id) — a game that stores its pool on
    /// `BattlerState.resources` (the engine default) gets correct behavior for free.
    fn can_pay_resource(&self, b: &BattlerState<P>, resource_index: usize, amount: u16) -> bool {
        b.can_pay_resource(self.resource_id(resource_index), amount)
    }

    /// Deduct `amount` of the resource at interned `resource_index` from `b` (the
    /// `PayResource` op's deduction). **Pure arithmetic — no rng.** Default
    /// delegates to the engine `ResourcePool`.
    fn pay_resource(&self, b: &mut BattlerState<P>, resource_index: usize, amount: u16) {
        b.pay_resource(self.resource_id(resource_index), amount);
    }
}