import { useCallback, useEffect, useRef, useState } from "react";
import { fetchDungeonReports, type DungeonReportSnapshot } from "../app/dungeonReports";

export function useDungeonReports() {
  const [snapshot, setSnapshot] = useState<DungeonReportSnapshot | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState("");
  const sequence = useRef(0);

  const refresh = useCallback(async () => {
    const request = ++sequence.current;
    setLoading(true);
    try {
      const next = await fetchDungeonReports();
      if (request !== sequence.current) return;
      setSnapshot(next);
      setError("");
    } catch (failure) {
      if (request === sequence.current) setError(failure instanceof Error ? failure.message : "Reports could not be loaded.");
    } finally {
      if (request === sequence.current) setLoading(false);
    }
  }, []);

  useEffect(() => {
    const refreshVisible = () => { if (document.visibilityState === "visible") void refresh(); };
    void refresh();
    const timer = window.setInterval(refreshVisible, 30_000);
    window.addEventListener("focus", refreshVisible);
    document.addEventListener("visibilitychange", refreshVisible);
    return () => {
      sequence.current += 1;
      window.clearInterval(timer);
      window.removeEventListener("focus", refreshVisible);
      document.removeEventListener("visibilitychange", refreshVisible);
    };
  }, [refresh]);

  return { snapshot, loading, error, refresh };
}