feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

mobile/lib/shared/community/community_provider.dart

@@ -0,0 +1,127 @@
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+
+import '../auth/auth_provider.dart';
+import 'community.dart';
+import 'community_storage.dart';
+
+final communityStorageProvider = Provider<CommunityStorage>((ref) {
+  return CommunityStorage();
+});
+
+class CommunityListNotifier extends AsyncNotifier<List<Community>> {
+  @override
+  Future<List<Community>> build() async {
+    final storage = ref.read(communityStorageProvider);
+    return storage.loadAll();
+  }
+
+  /// Add a community. If one with the same relay URL already exists, update
+  /// its credentials instead. Returns the effective community ID.
+  Future<String> addCommunity(Community community) async {
+    final storage = ref.read(communityStorageProvider);
+    final current = state.value ?? [];
+
+    // If a community with the same relay URL exists, update its credentials
+    // instead of creating a duplicate entry.
+    final existingIndex = current.indexWhere(
+      (w) => w.relayUrl == community.relayUrl,
+    );
+    if (existingIndex >= 0) {
+      final existing = current[existingIndex];
+      final updated = existing.copyWith(
+        pubkey: community.pubkey,
+        nsec: community.nsec,
+      );
+      await storage.save(updated);
+      final updatedList = [...current];
+      updatedList[existingIndex] = updated;
+      state = AsyncData(updatedList);
+      return existing.id;
+    }
+
+    await storage.save(community);
+    state = AsyncData([...current, community]);
+    return community.id;
+  }
+
+  Future<void> removeCommunity(String id) async {
+    final storage = ref.read(communityStorageProvider);
+    await storage.remove(id);
+
+    final current = state.value ?? [];
+    state = AsyncData(current.where((w) => w.id != id).toList());
+
+    // If we removed the active community, switch to another or sign out.
+    final activeId = await storage.loadActiveId();
+    if (activeId == id) {
+      final remaining = state.value ?? [];
+      if (remaining.isNotEmpty) {
+        await switchCommunity(remaining.first.id);
+      } else {
+        await storage.clearActiveId();
+        // Invalidate auth so it re-evaluates against the now-empty storage
+        // and transitions to unauthenticated.
+        ref.invalidate(authProvider);
+      }
+    }
+  }
+
+  Future<void> switchCommunity(String id) async {
+    final storage = ref.read(communityStorageProvider);
+    await storage.saveActiveId(id);
+    // Reassign list state to trigger activeCommunityProvider (which watches
+    // communityListProvider.future) to rebuild and pick up the new active ID.
+    // We can't use ref.invalidate(activeCommunityProvider) here because that
+    // creates a circular dependency — activeCommunityProvider watches us.
+    state = AsyncData([...state.value ?? []]);
+    // Invalidate auth so AuthState.community reflects the new active community.
+    ref.invalidate(authProvider);
+  }
+
+  Future<void> renameCommunity(String id, String name) async {
+    final storage = ref.read(communityStorageProvider);
+    final current = state.value ?? [];
+    final index = current.indexWhere((w) => w.id == id);
+    if (index < 0) return;
+
+    final updated = current[index].copyWith(name: name);
+    await storage.save(updated);
+
+    final updatedList = [...current];
+    updatedList[index] = updated;
+    state = AsyncData(updatedList);
+  }
+}
+
+final communityListProvider =
+    AsyncNotifierProvider<CommunityListNotifier, List<Community>>(
+      CommunityListNotifier.new,
+    );
+
+/// The currently active community, derived from the stored active ID and
+/// the community list.
+final activeCommunityProvider = FutureProvider<Community?>((ref) async {
+  final communities = await ref.watch(communityListProvider.future);
+  final storage = ref.read(communityStorageProvider);
+  final activeId = await storage.loadActiveId();
+
+  if (communities.isEmpty) return null;
+
+  if (activeId == null) {
+    // No active ID stored but communities exist — fall back to first.
+    await storage.saveActiveId(communities.first.id);
+    return communities.first;
+  }
+
+  try {
+    return communities.firstWhere((w) => w.id == activeId);
+  } on StateError {
+    // Active ID points to a community that no longer exists.
+    // Fall back to first community.
+    if (communities.isNotEmpty) {
+      await storage.saveActiveId(communities.first.id);
+      return communities.first;
+    }
+    return null;
+  }
+});