import { useQuery } from '@tanstack/react-query';
import { probeRelay, type RelayProbeResult } from '@/lib/relayProbe';

export type RelayStatus = 'connecting' | 'connected' | 'offline';

/**
 * useRelayStatus — live reachability of a single relay URL.
 *
 * Backed by react-query so every row that probes the same URL shares one result
 * and we don't open redundant sockets. Returns a coarse status the UI can map to
 * a coloured dot:
 *  - 'connecting': first probe in flight (no result yet).
 *  - 'connected':  the relay answered a Nostr handshake.
 *  - 'offline':    the probe finished and the relay did not answer.
 *
 * Reconnected relays are picked up because we keep polling while offline, and
 * stop polling once connected to avoid churn (a healthy relay rarely vanishes
 * silently, and any real read failure elsewhere is a separate concern).
 */
export function useRelayStatus(url: string): {
  status: RelayStatus;
  probing: boolean;
  reason: string | null;
  recheck: () => void;
} {
  const { data, isFetching, isFetched, refetch } = useQuery<RelayProbeResult>({
    queryKey: ['relay-status', url],
    queryFn: () => probeRelay(url),
    // Consider a result fresh for a minute so switching sub-screens doesn't
    // re-probe every relay each time.
    staleTime: 60_000,
    // Poll only while still offline so a relay that comes back is detected;
    // once connected, stop the background churn.
    refetchInterval: (query) => (query.state.data?.ok ? false : 30_000),
    refetchOnWindowFocus: (query) => !query.state.data?.ok,
    retry: false,
  });

  const status: RelayStatus = !isFetched
    ? 'connecting'
    : data?.ok
      ? 'connected'
      : isFetching
        ? 'connecting'
        : 'offline';

  return {
    status,
    probing: isFetching,
    reason: data?.reason ?? null,
    recheck: () => {
      refetch();
    },
  };
}