// Last-completed-review timestamp, local only — the review is a habit, not
// synced data.
import AsyncStorage from "@react-native-async-storage/async-storage";
import { useCallback, useEffect, useState } from "react";

const KEY = "review_last_v1";

export async function getLastReview(): Promise<string | null> {
  return AsyncStorage.getItem(KEY);
}

export async function markReviewed(): Promise<void> {
  await AsyncStorage.setItem(KEY, new Date().toISOString());
}

export function daysSince(iso: string | null): number | null {
  if (!iso) return null;
  return Math.floor((Date.now() - new Date(iso).getTime()) / 86_400_000);
}

/** [lastReviewIso, reload] — call reload on focus to pick up changes. */
export function useLastReview(): [string | null, () => void] {
  const [last, setLast] = useState<string | null>(null);
  const reload = useCallback(() => {
    void getLastReview().then(setLast);
  }, []);
  useEffect(reload, [reload]);
  return [last, reload];
}