import { useCallback, useEffect, useRef, useState } from 'react';
import { getChainHealth, getLatestBlock, type ChainHealth, type LatestBlock } from '../services/chain138';
import { getExplorerStats, type ExplorerStats } from '../services/explorer';

export interface LiveChainState {
  health: ChainHealth | null;
  latestBlock: LatestBlock | null;
  stats: ExplorerStats | null;
  loading: boolean;
  error: string | null;
  lastUpdated: Date | null;
  refresh: () => void;
}

/**
 * Polls chain-138 RPC + SolaceScan explorer every `pollMs` (default 12s).
 * Returns `null` values while loading the first time; never throws.
 */
export function useLiveChain(pollMs = 12_000): LiveChainState {
  const [health, setHealth] = useState<ChainHealth | null>(null);
  const [latestBlock, setLatestBlock] = useState<LatestBlock | null>(null);
  const [stats, setStats] = useState<ExplorerStats | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [lastUpdated, setLastUpdated] = useState<Date | null>(null);
  const mounted = useRef(true);

  const tick = useCallback(async () => {
    try {
      const [h, b, s] = await Promise.allSettled([getChainHealth(), getLatestBlock(), getExplorerStats()]);
      if (!mounted.current) return;
      if (h.status === 'fulfilled') setHealth(h.value);
      if (b.status === 'fulfilled') setLatestBlock(b.value);
      if (s.status === 'fulfilled') setStats(s.value);
      const anyError = [h, b, s].find(r => r.status === 'rejected') as PromiseRejectedResult | undefined;
      setError(anyError ? String(anyError.reason?.message ?? anyError.reason) : null);
      setLastUpdated(new Date());
    } catch (e) {
      if (!mounted.current) return;
      setError(e instanceof Error ? e.message : String(e));
    } finally {
      if (mounted.current) setLoading(false);
    }
  }, []);

  useEffect(() => {
    mounted.current = true;
    void tick();
    const id = setInterval(tick, pollMs);
    return () => { mounted.current = false; clearInterval(id); };
  }, [tick, pollMs]);

  return { health, latestBlock, stats, loading, error, lastUpdated, refresh: () => { void tick(); } };
}