Function createClock

src/ink/components/ClockContext.tsx:10–68

(tickIntervalMs: number)

  setTickInterval: (ms: number) => void;
};
export function createClock(tickIntervalMs: number): Clock {
  const subscribers = new Map<() => void, boolean>();
  let interval: ReturnType<typeof setInterval> | null = null;
  let currentTickIntervalMs = tickIntervalMs;
  let startTime = 0;
  // Snapshot of the current tick's time, ensuring all subscribers in the same
  // tick see the same value (keeps animations synchronized)
  let tickTime = 0;
  function tick(): void {
    tickTime = Date.now() - startTime;
    for (const onChange of subscribers.keys()) {
      onChange();
    }
  }
  function updateInterval(): void {
    const anyKeepAlive = [...subscribers.values()].some(Boolean);
    if (anyKeepAlive) {
      if (interval) {
        clearInterval(interval);
        interval = null;
      }
      if (startTime === 0) {
        startTime = Date.now();
      }
      interval = setInterval(tick, currentTickIntervalMs);
    } else if (interval) {
      clearInterval(interval);
      interval = null;
    }
  }
  return {
    subscribe(onChange, keepAlive) {
      subscribers.set(onChange, keepAlive);
      updateInterval();
      return () => {
        subscribers.delete(onChange);
        updateInterval();
      };
    },
    now() {
      if (startTime === 0) {
        startTime = Date.now();
      }
      // When the clock interval is running, return the synchronized tickTime
      // so all subscribers in the same tick see the same value.
      // When paused (no keepAlive subscribers), return real-time to avoid
      // returning a stale tickTime from the last tick before the pause.
      if (interval && tickTime) {
        return tickTime;
      }
      return Date.now() - startTime;
    },
    setTickInterval(ms) {
      if (ms === currentTickIntervalMs) return;
      currentTickIntervalMs = ms;
      updateInterval();
    }
  };