import 'dart:async';

import 'nip99.dart';
import 'nostr_connection.dart';
import 'offer.dart';
import 'offer_transport.dart';

/// Nostr NIP-99 backend for [OfferTransport], on a shared [NostrConnection]
/// (Q2/Q3). Signs offers with the derived key (Q1) and publishes them as
/// kind-30402 classified listings; discovery is a REQ filtered by kind + `#g`.
class NostrOfferTransport implements OfferTransport {
  NostrOfferTransport(this._conn);

  final NostrConnection _conn;
  final Nip99Codec _codec = Nip99Codec();

  /// Convenience: open a dedicated connection for this transport.
  static Future<NostrOfferTransport> connect(
    String relayUrl, {
    required String privateKeyHex,
    required String pubkeyHex,
  }) async =>
      NostrOfferTransport(await NostrConnection.connect(
        relayUrl,
        privateKeyHex: privateKeyHex,
        publicKeyHex: pubkeyHex,
      ));

  Map<String, dynamic> _filter(DiscoveryQuery q) => {
        'kinds': [Nip99Codec.kindActive],
        '#g': [q.geohashPrefix],
        'limit': q.limit,
      };

  @override
  Future<PublishResult> publish(Offer offer) async {
    final event = _codec.encode(
      offer,
      createdAt: DateTime.now().millisecondsSinceEpoch ~/ 1000,
    )..signWith(_conn.privateKeyHex);
    final r = await _conn.publish(event);
    return PublishResult(
      accepted: r.accepted,
      transportRef: event.id,
      message: r.message,
    );
  }

  @override
  Stream<Offer> discover(DiscoveryQuery query) => _conn.subscribe(_filter(query)).map(_codec.decode).where(
        (o) => query.types.isEmpty || query.types.contains(o.type),
      );

  /// Collect matches up to EOSE (for tests/metrics).
  Future<List<Offer>> discoverUntilEose(DiscoveryQuery query) async {
    final events = await _conn.reqOnce(_filter(query));
    return events
        .map(_codec.decode)
        .where((o) => query.types.isEmpty || query.types.contains(o.type))
        .toList();
  }

  @override
  Future<void> retract(String offerId) async {
    // A NIP-09 deletion of the addressable coordinate would go here; the OK-path
    // is identical to publish. Omitted from the spike surface.
  }

  @override
  Future<void> close() => _conn.close();
}