import 'dart:async';

import 'package:multicast_dns/multicast_dns.dart';

import '../../../domain/models/server_config.dart';

class MdnsDiscovery {
  static const String serviceType = '_localiserd._tcp';

  MDnsClient? _client;

  Stream<ServerConfig> discover() async* {
    _client?.stop();
    final client = MDnsClient();
    _client = client;
    await client.start();
    try {
      await for (final ptr in client.lookup<PtrResourceRecord>(
        ResourceRecordQuery.serverPointer(serviceType),
      )) {
        await for (final srv in client.lookup<SrvResourceRecord>(
          ResourceRecordQuery.service(ptr.domainName),
        )) {
          await for (final ip in client.lookup<IPAddressResourceRecord>(
            ResourceRecordQuery.addressIPv4(srv.target),
          )) {
            yield ServerConfig(host: ip.address.address, port: srv.port);
          }
        }
      }
    } finally {
      client.stop();
      if (_client == client) _client = null;
    }
  }

  Future<void> stop() async {
    _client?.stop();
    _client = null;
  }
}