Add dark theme

lib/helpers/preferences_helper.dart

@@ -9,9 +9,12 @@ import 'package:shared_preferences/shared_preferences.dart';
 ///
 /// @author Pierre HUBERT
 
-enum PreferencesKeyList { LOGIN_TOKENS }
+enum PreferencesKeyList { LOGIN_TOKENS, ENABLE_DARK_THEME }
 
-const _PreferenceKeysName = {PreferencesKeyList.LOGIN_TOKENS: "login_tokens"};
+const _PreferenceKeysName = {
+  PreferencesKeyList.LOGIN_TOKENS: "login_tokens",
+  PreferencesKeyList.ENABLE_DARK_THEME: "dark_theme",
+};
 
 class PreferencesHelper {
   static PreferencesHelper _instance;
@@ -51,11 +54,20 @@ class PreferencesHelper {
     }
   }
 
-  Future<void> setString(PreferencesKeyList key, String value) async {
+  Future<bool> setString(PreferencesKeyList key, String value) async {
-    await _sharedPreferences.setString(_PreferenceKeysName[key], value);
+    return await _sharedPreferences.setString(_PreferenceKeysName[key], value);
   }
 
   String getString(PreferencesKeyList key) {
     return _sharedPreferences.getString(_PreferenceKeysName[key]);
   }
+
+  Future<bool> setBool(PreferencesKeyList key, bool value) async {
+    return await _sharedPreferences.setBool(_PreferenceKeysName[key], value);
+  }
+
+  bool getBool(PreferencesKeyList key, {bool alternative = false}) {
+    final v = _sharedPreferences.getBool(_PreferenceKeysName[key]);
+    return v == null ? alternative : v;
+  }
 }

lib/main.dart

@@ -1,5 +1,6 @@
 import 'package:comunic/helpers/account_helper.dart';
 import 'package:comunic/helpers/database/database_helper.dart';
+import 'package:comunic/helpers/preferences_helper.dart';
 import 'package:comunic/ui/routes/home_route.dart';
 import 'package:comunic/ui/routes/login_route.dart';
 import 'package:comunic/utils/ui_utils.dart';
@@ -9,19 +10,29 @@ import 'package:flutter/material.dart';
 ///
 /// @author Pierre HUBERT
 
-void subMain() {
+void subMain() async {
   // Connect to database
-  DatabaseHelper.open();
+  await DatabaseHelper.open();
 
-  runApp(ComunicApplication());
+  runApp(ComunicApplication(
+    darkMode: (await PreferencesHelper.getInstance())
+        .getBool(PreferencesKeyList.ENABLE_DARK_THEME),
+  ));
 }
 
 class ComunicApplication extends StatelessWidget {
+  final bool darkMode;
+
+  const ComunicApplication({Key key, @required this.darkMode})
+      : assert(darkMode != null),
+        super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       debugShowCheckedModeBanner: false,
       home: ComunicApplicationHome(),
+      theme: darkMode ? ThemeData.dark() : null,
     );
   }
 }

lib/ui/routes/app_settings_route.dart

@@ -1,3 +1,4 @@
+import 'package:comunic/helpers/preferences_helper.dart';
 import 'package:comunic/utils/intl_utils.dart';
 import 'package:flutter/material.dart';
 
@@ -23,9 +24,81 @@ class _AppSettingsBody extends StatefulWidget {
 }
 
 class __AppSettingsBodyState extends State<_AppSettingsBody> {
+  PreferencesHelper _preferencesHelper;
+
+  @override
+  void initState() {
+    super.initState();
+    _load();
+  }
+
+  void _load() async {
+    final prefs = await PreferencesHelper.getInstance();
+    setState(() {
+      _preferencesHelper = prefs;
+    });
+  }
+
+  void _needRefresh() {
+    setState(() {});
+  }
+
   @override
   Widget build(BuildContext context) {
-    return ListView(children: <Widget>[],);
+    if (_preferencesHelper == null)
+      return Center(child: CircularProgressIndicator());
+
+    return Padding(
+      padding: const EdgeInsets.all(8.0),
+      child: ListView(
+        children: <Widget>[
+          // Dark theme
+          _CheckBoxPreference(
+            preferenceKey: PreferencesKeyList.ENABLE_DARK_THEME,
+            preferencesHelper: _preferencesHelper,
+            onUpdate: _needRefresh,
+            title: tr("Enable dark theme"),
+            description:
+                tr("You will need to restart the application to apply changes"),
+          ),
+        ],
+      ),
+    );
   }
 }
 
+class _CheckBoxPreference extends StatelessWidget {
+  final PreferencesKeyList preferenceKey;
+  final PreferencesHelper preferencesHelper;
+  final VoidCallback onUpdate;
+  final String title;
+  final String description;
+
+  const _CheckBoxPreference({
+    Key key,
+    @required this.preferenceKey,
+    @required this.preferencesHelper,
+    @required this.onUpdate,
+    @required this.title,
+    @required this.description,
+  })  : assert(preferencesHelper != null),
+        assert(preferencesHelper != null),
+        assert(onUpdate != null),
+        assert(title != null),
+        assert(description != null),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return SwitchListTile(
+      value: preferencesHelper.getBool(preferenceKey),
+      onChanged: (b) async {
+        await preferencesHelper.setBool(preferenceKey, b);
+        onUpdate();
+        return true;
+      },
+      title: Text(title),
+      subtitle: Text(description),
+    );
+  }
+}