66 lines
2.2 KiB
TypeScript
66 lines
2.2 KiB
TypeScript
import type { RealTime } from "@deadhead/sim";
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import type { GameEngine } from "./game/engine";
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/**
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* What the loop needs from the platform (CR-014 Step 14.6): a timer, and a way
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* to hear that the app is back in front (browser `visibilitychange`, Capacitor
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* `resume`). Injected so the engine stays testable.
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*/
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export interface LoopHost {
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setInterval(fn: () => void, ms: number): unknown;
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clearInterval(handle: unknown): void;
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/** Calls `fn` whenever the app comes back to the foreground; returns an unsubscribe. */
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onResume(fn: () => void): () => void;
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}
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export const RESOLUTION_INTERVAL_MS = 5_000;
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/**
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* Keeps the game current while it's open: on start (the app has just loaded),
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* on every resume, and every few seconds, it resolves due arrivals (the same
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* idempotent resolution every command runs first) and reports when anything
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* changed, including a rest or a shop job ending, so the screen can refresh.
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*/
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export class ResolutionLoop {
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#handle: unknown = null;
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#unsubscribe: (() => void) | null = null;
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#since: RealTime | null = null;
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#running: Promise<void> | null = null;
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constructor(
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private readonly engine: GameEngine,
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private readonly host: LoopHost,
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private readonly onChange: () => void,
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private readonly intervalMs = RESOLUTION_INTERVAL_MS,
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) {}
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/** Resolves once now, then keeps going until `stop`. */
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async start(): Promise<void> {
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this.stop();
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this.#handle = this.host.setInterval(() => void this.tick(), this.intervalMs);
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this.#unsubscribe = this.host.onResume(() => void this.tick());
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await this.tick();
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}
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stop(): void {
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if (this.#handle !== null) this.host.clearInterval(this.#handle);
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this.#handle = null;
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this.#unsubscribe?.();
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this.#unsubscribe = null;
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}
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/** One pass (ticks never overlap: a tick that is still running is reused). */
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tick(): Promise<void> {
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this.#running ??= (async () => {
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try {
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const result = await this.engine.resolveDue(this.#since);
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this.#since = result.now;
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if (result.resolved > 0 || result.eventsPassed > 0) this.onChange();
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} finally {
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this.#running = null;
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}
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})();
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return this.#running;
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}
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}
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