55 lines
2 KiB
Rust
55 lines
2 KiB
Rust
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//! The mutation pipeline contracts (GameKernel §2.2, K1–K3):
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//! command → validate → events → infallible fold.
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use crate::ids::PlayerId;
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use serde::{Deserialize, Serialize};
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/// Who issued a command (GameKernel K2).
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#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
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pub enum Actor {
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Player(PlayerId),
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/// Runtime-driven steps (reveal, resolution ordering, round end).
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System,
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}
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/// Typed, testable command rejections (GameKernel K3). Game packages add
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/// specific rejection kinds via `Game`-typed payloads in their own enums;
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/// this kernel-level enum carries the cross-game cases.
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#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
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pub enum Rejection {
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/// The command's `CommandId` was already applied (idempotency, K2).
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DuplicateCommand,
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/// The actor may not issue this command now (turn/window gating).
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NotAllowedNow,
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/// Game-specific rejection, stable machine-readable code + human text.
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Game { code: String, detail: String },
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}
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impl core::fmt::Display for Rejection {
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fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
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match self {
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Rejection::DuplicateCommand => write!(f, "duplicate command"),
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Rejection::NotAllowedNow => write!(f, "not allowed now"),
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Rejection::Game { code, detail } => write!(f, "{code}: {detail}"),
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}
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}
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}
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/// An event-sourced aggregate (GameKernel K1): all validation happens in
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/// `validate`; `fold` is total and infallible for any logged event.
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pub trait Aggregate: Sized {
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type Command;
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type Event;
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/// Decide whether `command` is legal in the current state, producing
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/// the events it implies. Must not mutate state.
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fn validate(
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&self,
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actor: Actor,
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command: &Self::Command,
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) -> Result<Vec<Self::Event>, Rejection>;
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/// Apply one event. Infallible: every logged event must apply (K1).
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fn fold(&mut self, event: &Self::Event);
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}
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