Get system theme for Flatpak build

Fixes flathub/codes.merritt.FeelingFinder#3

lib/main.dart

@@ -28,6 +28,7 @@ void main() async {
 
   // Initialize the settings service.
   final settingsService = SettingsService(storageService);
+  final _settingsCubit = await SettingsCubit.init(settingsService);
 
   // Run the app and pass in the state controllers.
   runApp(
@@ -40,10 +41,7 @@ void main() async {
           ),
           lazy: false,
         ),
-        BlocProvider(
-          create: (context) => SettingsCubit(settingsService),
-          lazy: false,
-        ),
+        BlocProvider.value(value: _settingsCubit),
       ],
       child: const App(),
     ),

lib/src/settings/cubit/settings_cubit.dart

@@ -17,17 +17,23 @@ late SettingsCubit settingsCubit;
 class SettingsCubit extends Cubit<SettingsState> {
   final SettingsService _settingsService;
 
-  SettingsCubit(
-    this._settingsService,
-  ) : super(
+  SettingsCubit._(this._settingsService, {required ThemeMode themeMode})
+      : super(
           SettingsState(
             exitOnCopy: _settingsService.exitOnCopy(),
-            themeMode: _settingsService.themeMode(),
+            themeMode: themeMode,
           ),
         ) {
     settingsCubit = this;
   }
 
+  static Future<SettingsCubit> init(SettingsService settingsService) async {
+    return SettingsCubit._(
+      settingsService,
+      themeMode: await settingsService.themeMode(),
+    );
+  }
+
   /// Update and persist whether the app should exit after copy.
   Future<void> updateExitOnCopy(bool value) async {
     emit(state.copyWith(exitOnCopy: value));

lib/src/settings/settings_service.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 
 import 'package:flutter/material.dart';
+import 'package:flutter_flatpak/flutter_flatpak.dart';
 
 import '../emoji/emoji.dart';
 import '../storage/storage_service.dart';
@@ -66,16 +67,28 @@ class SettingsService {
   }
 
   /// Loads the user's preferred ThemeMode from storage.
-  ThemeMode themeMode() {
+  Future<ThemeMode> themeMode() async {
     final theme = _storageService.getValue('ThemeMode');
     switch (theme) {
       case 'ThemeMode.dark':
         return ThemeMode.dark;
       case 'ThemeMode.light':
         return ThemeMode.light;
       default:
-        // If the user has not made a choice we follow system theme.
-        return ThemeMode.system;
+        final Flatpak? flatpak = await Flatpak.init();
+
+        ThemeMode themeMode;
+        if (flatpak != null) {
+          /// If the app is running in Flatpak we check the system theme
+          /// through the `flutter_flatpak` package.
+          themeMode = flatpak.themeMode;
+        } else {
+          /// If the user has not specified a specific theme for
+          /// the app we follow the system theme.
+          themeMode = ThemeMode.system;
+        }
+
+        return themeMode;
     }
   }
 

pubspec.lock

@@ -151,6 +151,15 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_flatpak:
+    dependency: "direct main"
+    description:
+      path: "."
+      ref: HEAD
+      resolved-ref: "67f21802d33ac1f6137acf3ac64c7452526dea33"
+      url: "https://github.com/Merrit/flutter_flatpak.git"
+    source: git
+    version: "0.0.1"
   flutter_launcher_icons:
     dependency: "direct dev"
     description:
@@ -620,5 +629,5 @@ packages:
     source: hosted
     version: "3.1.0"
 sdks:
-  dart: ">=2.17.0-0 <3.0.0"
+  dart: ">=2.17.0 <3.0.0"
   flutter: ">=2.5.0"

pubspec.yaml

@@ -14,6 +14,9 @@ dependencies:
   flutter:
     sdk: flutter
   flutter_bloc: ^7.3.3
+  flutter_flatpak:
+    git:
+      url: https://github.com/Merrit/flutter_flatpak.git
   flutter_localizations:
     sdk: flutter
   hive: ^2.0.4