Future _startLocalDebugService()

in dwds/lib/src/handlers/dev_handler.dart [129:214]
72 lines of code
12 McCabe index (conditional complexity)

  Future<DebugService> _startLocalDebugService(
      ChromeConnection chromeConnection, AppConnection appConnection) async {
    ChromeTab appTab;
    ExecutionContext executionContext;
    WipConnection tabConnection;
    var appInstanceId = appConnection.request.instanceId;
    for (var tab in await chromeConnection.getTabs()) {
      if (tab.isChromeExtension || tab.isBackgroundPage) continue;

      tabConnection = await tab.connect();
      if (_enableLogging) {
        tabConnection.onSend.listen((message) {
          _log('  wip', '==> $message');
        });
        tabConnection.onReceive.listen((message) {
          _log('  wip', '<== $message');
        });
        tabConnection.onNotification.listen((message) {
          _log('  wip', '<== $message');
        });
      }
      var contextIds = tabConnection.runtime.onExecutionContextCreated
          .map((context) => context.id)
          // There is no way to calculate the number of existing execution
          // contexts so keep receiving them until there is a 50ms gap after
          // receiving the last one.
          .takeUntilGap(const Duration(milliseconds: 50));
      // We enqueue this work as we need to begin listening (`.hasNext`)
      // before events are received.
      unawaited(Future.microtask(() => tabConnection.runtime.enable()));

      await for (var contextId in contextIds) {
        var result = await tabConnection.sendCommand('Runtime.evaluate', {
          'expression': r'window["$dartAppInstanceId"];',
          'contextId': contextId,
        });
        var evaluatedAppId = result.result['result']['value'];
        if (evaluatedAppId == appInstanceId) {
          appTab = tab;
          executionContext = RemoteDebuggerExecutionContext(
              contextId, WebkitDebugger(WipDebugger(tabConnection)));
          break;
        }
      }
      if (appTab != null) break;
      unawaited(tabConnection.close());
    }
    if (appTab == null) {
      throw AppConnectionException(
          'Could not connect to application with appInstanceId: '
          '$appInstanceId');
    }

    var webkitDebugger = WebkitDebugger(WipDebugger(tabConnection));

    return DebugService.start(
      // We assume the user will connect to the debug service on the same
      // machine. This allows consumers of DWDS to provide a `hostname` for
      // debugging through the Dart Debug Extension without impacting the local
      // debug workflow.
      'localhost',
      webkitDebugger,
      executionContext,
      appTab.url,
      _assetReader,
      _loadStrategy,
      appConnection,
      _urlEncoder,
      onResponse: (response) {
        if (response['error'] == null) return;
        _logger.finest('VmService proxy responded with an error:\n$response');
        if (_enableLogging) {
          _log('vm', '<== ${response.toString().replaceAll('\n', ' ')}');
        }
      },
      onRequest: (request) {
        if (_enableLogging) {
          _log('vm', '==> ${request.toString().replaceAll('\n', ' ')}');
        }
      },
      // This will provide a websocket based service.
      useSse: false,
      expressionCompiler: _expressionCompiler,
      spawnDds: _spawnDds,
    );
  }