binding: Prefetch deviceInfo during initialization

This is a preparatory commit for the work of embedding the
device info in user-agent header.

Author: rajveermalviya

lib/main.dart

@@ -13,8 +13,8 @@ void main() {
     return true;
   }());
   LicenseRegistry.addLicense(additionalLicenses);
-  LiveZulipBinding.ensureInitialized();
   WidgetsFlutterBinding.ensureInitialized();
+  LiveZulipBinding.ensureInitialized();
   NotificationService.instance.start();
   runApp(const ZulipApp());
 }

lib/model/binding.dart

@@ -6,6 +6,7 @@ import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
 
 import '../host/android_notifications.dart';
+import '../log.dart';
 import '../widgets/store.dart';
 import 'store.dart';
 
@@ -66,6 +67,20 @@ abstract class ZulipBinding {
     _instance = this;
   }
 
+  /// Provides device and operating system information,
+  /// via package:device_info_plus.
+  ///
+  /// The returned Future resolves to null if an error is
+  /// encountered while fetching the data.
+  Future<BaseDeviceInfo?> get deviceInfo;
+
+  /// Provides device and operating system information,
+  /// via package:device_info_plus.
+  ///
+  /// May return null if prefetching hasn't completed yet,
+  /// or an error occured while fetching the data.
+  BaseDeviceInfo? get maybeDeviceInfo;
+
   /// Prepare the app's [GlobalStore], loading the necessary data.
   ///
   /// Generally the app should call this function only once.
@@ -98,12 +113,6 @@ abstract class ZulipBinding {
   /// This wraps [url_launcher.closeInAppWebView].
   Future<void> closeInAppWebView();
 
-  /// Provides device and operating system information,
-  /// via package:device_info_plus.
-  ///
-  /// This wraps [device_info_plus.DeviceInfoPlugin.deviceInfo].
-  Future<BaseDeviceInfo> deviceInfo();
-
   /// Initialize Firebase, to use for notifications.
   ///
   /// This wraps [firebase_core.Firebase.initializeApp].
@@ -164,11 +173,35 @@ class LiveZulipBinding extends ZulipBinding {
   /// Initialize the binding if necessary, and ensure it is a [LiveZulipBinding].
   static LiveZulipBinding ensureInitialized() {
     if (ZulipBinding._instance == null) {
-      LiveZulipBinding();
+      final binding = LiveZulipBinding();
+      binding._deviceInfo = binding._prefetchDeviceInfo();
     }
     return ZulipBinding.instance as LiveZulipBinding;
   }
 
+  @override
+  Future<BaseDeviceInfo?> get deviceInfo => _deviceInfo;
+  late Future<BaseDeviceInfo?> _deviceInfo;
+
+  @override
+  BaseDeviceInfo? get maybeDeviceInfo => _maybeDeviceInfo;
+  BaseDeviceInfo? _maybeDeviceInfo;
+
+  Future<BaseDeviceInfo?> _prefetchDeviceInfo() async {
+    try {
+      final info = await device_info_plus.DeviceInfoPlugin().deviceInfo;
+      _maybeDeviceInfo = switch (info) {
+        device_info_plus.AndroidDeviceInfo(:var version)   => AndroidDeviceInfo(sdkInt: version.sdkInt),
+        device_info_plus.IosDeviceInfo(:var systemVersion) => IosDeviceInfo(systemVersion: systemVersion),
+        _                                                  => throw UnimplementedError(),
+      };
+    } catch (e) {
+      assert(debugLog('Failed to prefetch device info: $e'));
+      // TODO(log)
+    }
+    return _maybeDeviceInfo;
+  }
+
   @override
   Future<GlobalStore> loadGlobalStore() {
     return LiveGlobalStore.load();
@@ -195,16 +228,6 @@ class LiveZulipBinding extends ZulipBinding {
     return url_launcher.closeInAppWebView();
   }
 
-  @override
-  Future<BaseDeviceInfo> deviceInfo() async {
-    final deviceInfo = await device_info_plus.DeviceInfoPlugin().deviceInfo;
-    return switch (deviceInfo) {
-      device_info_plus.AndroidDeviceInfo(:var version)   => AndroidDeviceInfo(sdkInt: version.sdkInt),
-      device_info_plus.IosDeviceInfo(:var systemVersion) => IosDeviceInfo(systemVersion: systemVersion),
-      _                                                  => throw UnimplementedError(),
-    };
-  }
-
   @override
   Future<void> firebaseInitializeApp({
       required firebase_core.FirebaseOptions options}) {

lib/widgets/clipboard.dart

@@ -18,7 +18,7 @@ void copyWithPopup({
   required Widget successContent,
 }) async {
   await Clipboard.setData(data);
-  final deviceInfo = await ZulipBinding.instance.deviceInfo();
+  final deviceInfo = await ZulipBinding.instance.deviceInfo;
 
   if (!context.mounted) return;
 

test/model/binding.dart

@@ -204,21 +204,20 @@ class TestZulipBinding extends ZulipBinding {
     _closeInAppWebViewCallCount++;
   }
 
-  /// The value that `ZulipBinding.instance.deviceInfo()` should return.
-  ///
-  /// See also [takeDeviceInfoCalls].
+  @override
+  Future<BaseDeviceInfo?> get deviceInfo async => deviceInfoResult;
+
+  @override
+  BaseDeviceInfo? get maybeDeviceInfo => deviceInfoResult;
+
+  /// The value that `ZulipBinding.instance.deviceInfo` should return.
   BaseDeviceInfo deviceInfoResult = _defaultDeviceInfoResult;
   static final _defaultDeviceInfoResult = AndroidDeviceInfo(sdkInt: 33);
 
   void _resetDeviceInfo() {
     deviceInfoResult = _defaultDeviceInfoResult;
   }
 
-  @override
-  Future<BaseDeviceInfo> deviceInfo() {
-    return Future(() => deviceInfoResult);
-  }
-
   void _resetFirebase() {
     _firebaseInitialized = false;
     _firebaseMessaging = null;