import { useQuery } from '@tanstack/react-query';
import { useNostr } from '@nostrify/react';
import { useAppContext } from '@/hooks/useAppContext';

/** Parse the `relay` tags of a kind-10050 event (NIP-17) into URLs. */
export function dmRelaysFromEvent(tags: string[][]): string[] {
  return tags
    .filter(([name]) => name === 'relay')
    .map(([, url]) => url)
    .filter((url): url is string => Boolean(url));
}

/** The current user's own published DM relays (kind 10050), from config. */
export function useMyDmRelays(): string[] {
  const { config } = useAppContext();
  return config.relayMetadata.dmRelays ?? [];
}

/**
 * Fetch the NIP-17 DM relay lists (kind 10050) for the given pubkeys.
 * Returns a `pubkey → relayUrls` map (newest event per author wins).
 */
export function useDmRelays(pubkeys: string[]) {
  const { nostr } = useNostr();
  const unique = [...new Set(pubkeys.filter(Boolean))].sort();

  return useQuery<Record<string, string[]>>({
    queryKey: ['dm-relays', unique.join(',')],
    enabled: unique.length > 0,
    staleTime: 10 * 60 * 1000,
    queryFn: async (c) => {
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(8000)]);
      const events = await nostr.query(
        [{ kinds: [10050], authors: unique, limit: unique.length * 2 }],
        { signal },
      );
      const map: Record<string, string[]> = {};
      for (const ev of [...events].sort((a, b) => b.created_at - a.created_at)) {
        if (map[ev.pubkey]) continue;
        const urls = dmRelaysFromEvent(ev.tags);
        if (urls.length > 0) map[ev.pubkey] = urls;
      }
      return map;
    },
  });
}