reset direct dns when region change

lib/core/utils/preferences_utils.dart

@@ -106,12 +106,36 @@ class PreferencesNotifier<T, P> extends StateNotifier<T> {
   static StateNotifierProvider<PreferencesNotifier<T, P>, T> create<T, P>(
     String key,
     T defaultValue, {
+    T Function(Ref ref)? defaultValueFunction,
     T Function(P value)? mapFrom,
     P Function(T value)? mapTo,
     bool Function(T value)? validator,
     T? overrideValue,
   }) =>
       StateNotifierProvider(
+        (ref) => PreferencesNotifier._(
+          ref: ref,
+          entry: PreferencesEntry<T, P>(
+            preferences: ref.read(sharedPreferencesProvider).requireValue,
+            key: key,
+            defaultValue: defaultValueFunction?.call(ref) ?? defaultValue,
+            mapFrom: mapFrom,
+            mapTo: mapTo,
+            validator: validator,
+          ),
+          overrideValue: overrideValue,
+        ),
+      );
+
+  static AutoDisposeStateNotifierProvider<PreferencesNotifier<T, P>, T> createAutoDispose<T, P>(
+    String key,
+    T defaultValue, {
+    T Function(P value)? mapFrom,
+    P Function(T value)? mapTo,
+    bool Function(T value)? validator,
+    T? overrideValue,
+  }) =>
+      StateNotifierProvider.autoDispose(
         (ref) => PreferencesNotifier._(
           ref: ref,
           entry: PreferencesEntry<T, P>(
@@ -126,30 +150,6 @@ class PreferencesNotifier<T, P> extends StateNotifier<T> {
         ),
       );
 
-  static AutoDisposeStateNotifierProvider<PreferencesNotifier<T, P>, T>
-      createAutoDispose<T, P>(
-    String key,
-    T defaultValue, {
-    T Function(P value)? mapFrom,
-    P Function(T value)? mapTo,
-    bool Function(T value)? validator,
-    T? overrideValue,
-  }) =>
-          StateNotifierProvider.autoDispose(
-            (ref) => PreferencesNotifier._(
-              ref: ref,
-              entry: PreferencesEntry<T, P>(
-                preferences: ref.read(sharedPreferencesProvider).requireValue,
-                key: key,
-                defaultValue: defaultValue,
-                mapFrom: mapFrom,
-                mapTo: mapTo,
-                validator: validator,
-              ),
-              overrideValue: overrideValue,
-            ),
-          );
-
   P raw() {
     final value = overrideValue ?? state;
     if (entry.mapTo != null) return entry.mapTo!(value);

lib/features/common/general_pref_tiles.dart

@@ -84,8 +84,11 @@ class RegionPrefTile extends HookConsumerWidget {
         );
         if (selectedRegion != null) {
           // await ref.read(Preferences.region.notifier).update(selectedRegion);
+
           await ref.watch(ConfigOptions.region.notifier).update(selectedRegion);
 
+          await ref.watch(ConfigOptions.directDnsAddress.notifier).reset();
+
           // await ref.read(configOptionNotifierProvider.notifier).build();
           // await ref.watch(ConfigOptions.resolveDestination.notifier).update(!ref.watch(ConfigOptions.resolveDestination.notifier).raw());
           //for reload config

lib/features/config_option/data/config_option_repository.dart

@@ -71,6 +71,7 @@ abstract class ConfigOptions {
   static final directDnsAddress = PreferencesNotifier.create<String, String>(
     "direct-dns-address",
     "1.1.1.1",
+    defaultValueFunction: (ref) => ref.read(region) == Region.cn ? "223.5.5.5" : "1.1.1.1",
     validator: (value) => value.isNotBlank,
   );
 

lib/features/config_option/overview/config_options_page.dart

@@ -146,6 +146,7 @@ class ConfigOptionsPage extends HookConsumerWidget {
                     choices: Region.values,
                     title: t.settings.general.region,
                     presentChoice: (value) => value.present(t),
+                    onChanged: (val) => ref.watch(ConfigOptions.directDnsAddress.notifier).reset(),
                   ),
                   SwitchListTile(
                     title: Text(experimental(t.config.blockAds)),

lib/features/config_option/widget/preference_tile.dart

@@ -61,6 +61,7 @@ class ChoicePreferenceWidget<T> extends StatelessWidget {
     required this.title,
     required this.presentChoice,
     this.validateInput,
+    this.onChanged,
   });
 
   final T selected;
@@ -70,7 +71,7 @@ class ChoicePreferenceWidget<T> extends StatelessWidget {
   final String title;
   final String Function(T value) presentChoice;
   final bool Function(String value)? validateInput;
-
+  final ValueChanged<T>? onChanged;
   @override
   Widget build(BuildContext context) {
     return ListTile(
@@ -88,7 +89,9 @@ class ChoicePreferenceWidget<T> extends StatelessWidget {
         if (selection == null) {
           return;
         }
-        await preferences.update(selection);
+        final out = await preferences.update(selection);
+        onChanged?.call(selection);
+        return out;
       },
     );
   }

lib/features/intro/widget/intro_page.dart

@@ -124,6 +124,7 @@ class IntroPage extends HookConsumerWidget with PresLogger {
         'Timezone Region: ${regionLocale.region} Locale: ${regionLocale.locale}',
       );
       await ref.read(ConfigOptions.region.notifier).update(regionLocale.region);
+      await ref.watch(ConfigOptions.directDnsAddress.notifier).reset();
       await ref.read(localePreferencesProvider.notifier).changeLocale(regionLocale.locale);
       return;
     } catch (e) {