import { useEffect, useRef } from "react";
import { useRouter_UNSTABLE as useRouter } from "waku/router/client";

function scrollIntoView(hash: string) {
  const elementId = hash.slice(1);
  const element = document.getElementById(elementId);
  if (!element) {
    return false;
  }
  element.scrollIntoView({ behavior: "auto", block: "start" });
  return true;
}

export function useHashScroll() {
  const hashRef = useRef("");
  const router = useRouter();
  const path = router.path;
  hashRef.current = router.hash;
  useEffect(() => {
    path; // mark path as an effect dependency
    let cancel = false;
    const timeoutRef = { current: undefined };
    if (hashRef.current) {
      if (!scrollIntoView(hashRef.current)) {
        let attempt = 1;
        const retries = 4;
        const tryScroll = () => {
          if (cancel) return;
          const res = scrollIntoView(hashRef.current);
          if (res) {
            timeoutRef.current = undefined;
            return;
          }
          if (attempt < retries) {
            attempt++;
            timeoutRef.current = window.setTimeout(
              tryScroll,
              2 ** attempt * 200,
            );
          }
        };
        timeoutRef.current = window.setTimeout(tryScroll, 2 ** attempt * 200);
      }
    }
    return () => {
      cancel = true;
      if (timeoutRef.current) window.clearTimeout(timeoutRef.current);
    };
  }, [path]);
}