Future main()

in dwds/web/client.dart [41:177]
115 lines of code
25 McCabe index (conditional complexity)

Future<void> main() {
  return runZonedGuarded(() async {
    // Set the unique id for this instance of the app.
    // Test apps may already have this set.
    dartAppInstanceId ??= const Uuid().v1();

    var fixedPath = _fixProtocol(dwdsDevHandlerPath);
    var fixedUri = Uri.parse(fixedPath);
    var client = fixedUri.isScheme('ws') || fixedUri.isScheme('wss')
        ? WebSocketClient(WebSocketChannel.connect(fixedUri))
        : SseSocketClient(SseClient(fixedPath));

    Restarter restarter;
    if (dartModuleStrategy == 'require-js') {
      restarter = await RequireRestarter.create();
    } else if (dartModuleStrategy == 'legacy') {
      restarter = LegacyRestarter();
    } else {
      throw StateError('Unknown module strategy: $dartModuleStrategy');
    }

    var manager = ReloadingManager(client, restarter);

    hotRestartJs = allowInterop((String runId) {
      return toPromise(manager.hotRestart(runId: runId));
    });

    var debugEventController =
        BatchedStreamController<DebugEvent>(delay: _batchDelayMilliseconds);
    debugEventController.stream.listen((events) {
      client.sink.add(jsonEncode(serializers.serialize(BatchedDebugEvents(
          (b) => b.events = ListBuilder<DebugEvent>(events)))));
    });

    emitDebugEvent = allowInterop((String kind, String eventData) {
      if (dartEmitDebugEvents) {
        debugEventController.sink.add(DebugEvent((b) => b
          ..timestamp = (DateTime.now().millisecondsSinceEpoch)
          ..kind = kind
          ..eventData = eventData));
      }
    });

    emitRegisterEvent = allowInterop((String eventData) {
      client.sink.add(jsonEncode(serializers.serialize(RegisterEvent((b) => b
        ..timestamp = (DateTime.now().millisecondsSinceEpoch)
        ..eventData = eventData))));
    });

    launchDevToolsJs = allowInterop(() {
      if (!_isChromium) {
        window.alert(
            'Dart DevTools is only supported on Chromium based browsers.');
        return;
      }
      client.sink.add(jsonEncode(serializers.serialize(DevToolsRequest((b) => b
        ..appId = dartAppId
        ..instanceId = dartAppInstanceId))));
    });

    client.stream.listen((serialized) async {
      var event = serializers.deserialize(jsonDecode(serialized));
      if (event is BuildResult) {
        if (reloadConfiguration == 'ReloadConfiguration.liveReload') {
          manager.reloadPage();
        } else if (reloadConfiguration == 'ReloadConfiguration.hotRestart') {
          await manager.hotRestart();
        } else if (reloadConfiguration == 'ReloadConfiguration.hotReload') {
          print('Hot reload is currently unsupported. Ignoring change.');
        }
      } else if (event is DevToolsResponse) {
        if (!event.success) {
          var alert = 'DevTools failed to open with:\n${event.error}';
          if (event.promptExtension && window.confirm(alert)) {
            // ignore: unsafe_html
            window.open('https://goo.gle/dart-debug-extension', '_blank');
          } else {
            window.alert(alert);
          }
        }
      } else if (event is RunRequest) {
        runMain();
      } else if (event is ErrorResponse) {
        window.console.error('Error from backend:\n\nError: ${event.error}\n\n'
            'Stack Trace:\n${event.stackTrace}');
      }
    }, onError: (error) {
      // An error is propagated on a full page reload as Chrome presumably
      // forces the SSE connection to close in a bad state. This does not cause
      // any adverse effects so simply swallow this error as to not print the
      // misleading unhandled error message.
    });

    if (dwdsEnableDevtoolsLaunch) {
      window.onKeyDown.listen((Event e) {
        if (e is KeyboardEvent &&
            const [
              'd',
              'D',
              '∂', // alt-d output on Mac
              'Î', // shift-alt-D output on Mac
            ].contains(e.key) &&
            e.altKey &&
            !e.ctrlKey &&
            !e.metaKey) {
          e.preventDefault();
          launchDevToolsJs();
        }
      });
    }

    if (_isChromium) {
      client.sink.add(jsonEncode(serializers.serialize(ConnectRequest((b) => b
        ..appId = dartAppId
        ..instanceId = dartAppInstanceId
        ..entrypointPath = dartEntrypointPath))));
    } else {
      // If not Chromium we just invoke main, devtools aren't supported.
      runMain();
    }
    dispatchEvent(CustomEvent('dart-app-ready'));
  }, (error, stackTrace) {
    print('''
Unhandled error detected in the injected client.js script.

You can disable this script in webdev by passing --no-injected-client if it
is preventing your app from loading, but note that this will also prevent
all debugging and hot reload/restart functionality from working.

The original error is below, please file an issue at
https://github.com/dart-lang/webdev/issues/new and attach this output:

$error
$stackTrace
''');
  });
}