import { useEffect, useRef, useState } from 'react';
import { getNativeBalances, type OnChainBalance } from '../services/chain138';

export interface OnChainBalancesState {
  balances: Record<string, OnChainBalance>;
  loading: boolean;
  error: string | null;
  lastUpdated: Date | null;
}

/**
 * Fetches native Chain-138 balances for the given addresses and re-polls
 * every `pollMs` (default 30s). Addresses array must be stable — pass a
 * memoized list, or the hook will re-fetch on every render.
 */
export function useOnChainBalances(addresses: string[], pollMs = 30_000): OnChainBalancesState {
  const [balances, setBalances] = useState<Record<string, OnChainBalance>>({});
  const [loading, setLoading] = useState(addresses.length > 0);
  const [error, setError] = useState<string | null>(null);
  const [lastUpdated, setLastUpdated] = useState<Date | null>(null);
  const mounted = useRef(true);

  const key = addresses.join(',');

  useEffect(() => {
    mounted.current = true;
    if (addresses.length === 0) { setLoading(false); return; }
    let cancelled = false;

    const tick = async () => {
      try {
        const result = await getNativeBalances(addresses);
        if (cancelled || !mounted.current) return;
        setBalances(result);
        setError(null);
        setLastUpdated(new Date());
      } catch (e) {
        if (cancelled || !mounted.current) return;
        setError(e instanceof Error ? e.message : String(e));
      } finally {
        if (!cancelled && mounted.current) setLoading(false);
      }
    };
    void tick();
    const id = setInterval(tick, pollMs);
    return () => { cancelled = true; mounted.current = false; clearInterval(id); };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [key, pollMs]);

  return { balances, loading, error, lastUpdated };
}