frontend/src/hooks/usePolling.ts

import { useState, useEffect, useCallback } from 'react';

const API_BASE = '/api';

export function usePolling<T>(
  fetchFn: () => Promise<T>,
  interval: number = 5000,
  enabled: boolean = true
) {
  const [data, setData] = useState<T | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const fetch = useCallback(async () => {
    try {
      const result = await fetchFn();
      setData(result);
      setError(null);
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Unknown error');
    } finally {
      setLoading(false);
    }
  }, [fetchFn]);

  useEffect(() => {
    if (!enabled) return;
    fetch();
    const id = setInterval(fetch, interval);
    return () => clearInterval(id);
  }, [fetch, interval, enabled]);

  return { data, loading, error, refetch: fetch };
}