investor-flow/app/src/lib/useVisibilityAwarePoll.ts

"use client";

import { useEffect, useRef } from "react";

/**
 * Run `tick` on an interval, but pause while the document is hidden
 * (background Safari tab / phone locked). Resumes with an immediate tick
 * when the page becomes visible again.
 */
export function useVisibilityAwarePoll(
  tick: () => void | Promise<void>,
  intervalMs: number,
  enabled = true,
): void {
  const tickRef = useRef(tick);
  tickRef.current = tick;

  useEffect(() => {
    if (!enabled || intervalMs <= 0) return;

    let id: ReturnType<typeof setInterval> | null = null;

    const run = () => {
      void tickRef.current();
    };

    const start = () => {
      if (id != null) return;
      id = setInterval(run, intervalMs);
    };

    const stop = () => {
      if (id != null) {
        clearInterval(id);
        id = null;
      }
    };

    const onVisibility = () => {
      if (document.hidden) {
        stop();
      } else {
        run();
        start();
      }
    };

    if (!document.hidden) start();

    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      stop();
      document.removeEventListener("visibilitychange", onVisibility);
    };
  }, [intervalMs, enabled]);
}