swarm/test/fake_relay_connection.dart

import 'dart:async';
import 'dart:convert';
import 'package:swarm/swarm.dart';

final class FakeRelayConnection implements RelayConnection {
  final _controller = StreamController<String>.broadcast();
  final sentMessages = <String>[];
  final queuedResponses = <String>[];
  bool isConnected = false;
  bool autoRespond = true;
  bool throwOnConnect = false;
  // When set, connect() never completes — simulates a handshake that hangs
  // (accepted socket, no WebSocket upgrade).
  bool hangOnConnect = false;
  void Function(String subId)? onReq;

  @override
  Future<void> connect() async {
    if (throwOnConnect) throw Exception('connection failed');
    if (hangOnConnect) await Completer<void>().future;
    isConnected = true;
  }

  @override
  Future<void> send(String message) async {
    sentMessages.add(message);
    if (queuedResponses.isNotEmpty) {
      final response = queuedResponses.removeAt(0);
      Future(() => _controller.add(response));
      return;
    }
    _tryAutoRespond(message);
  }

  @override
  Stream<String> get messages => _controller.stream;

  @override
  Future<void> close() async => isConnected = false;

  void push(String message) => _controller.add(message);

  Future<void> dispose() => _controller.close();

  void _tryAutoRespond(String message) {
    if (!autoRespond) return;
    try {
      final list = jsonDecode(message) as List;
      if (list[0] == 'EVENT') {
        final event = list[1] as Map<String, dynamic>;
        final id = event['id'] as String;
        Future(() => _controller.add(jsonEncode(['OK', id, true, ''])));
      } else if (list[0] == 'REQ') {
        final subId = list[1] as String;
        Future(() => onReq?.call(subId));
      }
    } catch (_) {
      // malformed, ignore
    }
  }
}