import { useEffect } from "react";

/**
 * Sets up a debounced scroll listener that calls `onSave(scrollY)` when the
 * user scrolls, but only while `enabled` is true (e.g. the page is loaded).
 */
export function useScrollSave(
  enabled: boolean,
  onSave: (scrollY: number) => void,
) {
  useEffect(() => {
    if (!enabled) return;
    let timer: ReturnType<typeof setTimeout>;
    const onScroll = () => {
      clearTimeout(timer);
      timer = setTimeout(() => onSave(globalThis.scrollY), 100);
    };
    globalThis.addEventListener("scroll", onScroll, { passive: true });
    return () => {
      globalThis.removeEventListener("scroll", onScroll);
      clearTimeout(timer);
    };
  }, [enabled, onSave]);
}