/**
 * Watchdog — simple per-room timeout detector.
 *
 * `start()` begins a countdown. `heartbeat()` resets it. If the
 * countdown elapses without a heartbeat, `onTimeout` fires once
 * (subsequent heartbeats are no-ops after firing, unless `start()`
 * is called again). `stop()` cancels any pending timer.
 *
 * Used by the runner to detect stuck rooms: one watchdog per room,
 * scenarios call ctx.heartbeat(roomId) at each progress point, and
 * a firing watchdog logs + aborts the run.
 */

export class Watchdog {
  private timer: NodeJS.Timeout | null = null;
  private fired = false;

  constructor(
    private timeoutMs: number,
    private onTimeout: () => void,
  ) {}

  start(): void {
    this.stop();
    this.fired = false;
    this.timer = setTimeout(() => {
      if (this.fired) return;
      this.fired = true;
      this.onTimeout();
    }, this.timeoutMs);
  }

  heartbeat(): void {
    if (this.fired) return;
    this.start();
  }

  stop(): void {
    if (this.timer) {
      clearTimeout(this.timer);
      this.timer = null;
    }
  }
}