add mobile switch language

flutter/lib/main.dart

@@ -39,7 +39,7 @@ class App extends StatelessWidget {
             primarySwatch: Colors.blue,
             visualDensity: VisualDensity.adaptivePlatformDensity,
           ),
-          home: !isAndroid ? WebHomePage() : HomePage(),
+          home: !isAndroid ? WebHomePage() : HomePage(key: homeKey),
           navigatorObservers: [
             FirebaseAnalyticsObserver(analytics: analytics),
             FlutterSmartDialog.observer

flutter/lib/pages/chat_page.dart

@@ -6,8 +6,6 @@ import 'package:provider/provider.dart';
 import '../models/model.dart';
 import 'home_page.dart';
 
-ChatPage chatPage = ChatPage();
-
 class ChatPage extends StatelessWidget implements PageShape {
   @override
   final title = translate("Chat");

flutter/lib/pages/home_page.dart

@@ -12,6 +12,8 @@ abstract class PageShape extends Widget {
   final List<Widget> appBarActions = [];
 }
 
+final homeKey = GlobalKey<_HomePageState>();
+
 class HomePage extends StatefulWidget {
   HomePage({Key? key}) : super(key: key);
 
@@ -23,12 +25,23 @@ class _HomePageState extends State<HomePage> {
   var _selectedIndex = 0;
   final List<PageShape> _pages = [];
 
+  void refreshPages() {
+    setState(() {
+      initPages();
+    });
+  }
+
   @override
   void initState() {
     super.initState();
+    initPages();
+  }
+
+  void initPages() {
+    _pages.clear();
     _pages.add(ConnectionPage());
     if (isAndroid) {
-      _pages.addAll([chatPage, ServerPage()]);
+      _pages.addAll([ChatPage(), ServerPage()]);
     }
     _pages.add(SettingsPage());
   }

flutter/lib/pages/settings_page.dart

@@ -146,6 +146,12 @@ class _SettingsState extends State<SettingsPage> with WidgetsBindingObserver {
               leading: Icon(Icons.cloud),
               onPressed: (context) {
                 showServerSettings();
+              }),
+          SettingsTile.navigation(
+              title: Text(translate('Language')),
+              leading: Icon(Icons.translate),
+              onPressed: (context) {
+                showLanguageSettings();
               })
         ]),
         SettingsSection(
@@ -185,6 +191,42 @@ void showServerSettings() {
   showServerSettingsWithValue(id, relay, key, api);
 }
 
+void showLanguageSettings() {
+  try {
+    final langs = json.decode(FFI.getByName('langs')) as List<dynamic>;
+    var lang = FFI.getByName('local_option', 'lang');
+    DialogManager.show((setState, close) {
+      final setLang = (v) {
+        if (lang != v) {
+          setState(() {
+            lang = v;
+          });
+          final msg = Map()
+            ..['name'] = 'lang'
+            ..['value'] = v;
+          FFI.setByName('local_option', json.encode(msg));
+          homeKey.currentState?.refreshPages();
+          Future.delayed(Duration(milliseconds: 200), close);
+        }
+      };
+      return CustomAlertDialog(
+          title: SizedBox.shrink(),
+          content: Column(
+            children: [
+                  getRadio('Default', '', lang, setLang),
+                  Divider(color: MyTheme.border),
+                ] +
+                langs.map((e) {
+                  final key = e[0] as String;
+                  final name = e[1] as String;
+                  return getRadio(name, key, lang, setLang);
+                }).toList(),
+          ),
+          actions: []);
+    }, backDismiss: true, clickMaskDismiss: true);
+  } catch (_e) {}
+}
+
 void showAbout() {
   DialogManager.show((setState, close) {
     return CustomAlertDialog(

flutter/lib/widgets/overlay.dart

@@ -27,7 +27,7 @@ class DraggableChatWindow extends StatelessWidget {
         height: height,
         builder: (_, onPanUpdate) {
           return isIOS
-              ? chatPage
+              ? ChatPage()
               : Scaffold(
                   resizeToAvoidBottomInset: false,
                   appBar: CustomAppBar(
@@ -68,7 +68,7 @@ class DraggableChatWindow extends StatelessWidget {
                       ),
                     ),
                   ),
-                  body: chatPage,
+                  body: ChatPage(),
                 );
         });
   }

src/mobile_ffi.rs

@@ -113,6 +113,14 @@ unsafe extern "C" fn get_by_name(name: *const c_char, arg: *const c_char) -> *co
                     res = Session::get_option(arg);
                 }
             }
+            "local_option" => {
+                if let Ok(arg) = arg.to_str() {
+                    res = LocalConfig::get_option(arg);
+                }
+            }
+            "langs" => {
+                res = crate::lang::LANGS.to_string();
+            }
             // File Action
             "get_home_dir" => {
                 res = fs::get_home_as_string();
@@ -311,6 +319,15 @@ unsafe extern "C" fn set_by_name(name: *const c_char, value: *const c_char) {
                         }
                     }
                 }
+                "local_option" => {
+                    if let Ok(m) = serde_json::from_str::<HashMap<String, String>>(value) {
+                        if let Some(name) = m.get("name") {
+                            if let Some(value) = m.get("value") {
+                                LocalConfig::set_option(name.to_owned(), value.to_owned());
+                            }
+                        }
+                    }
+                }
                 "input_os_password" => {
                     Session::input_os_password(value.to_owned(), true);
                 }