clickable user mentions

lib/controllers/user_controller.dart

@@ -0,0 +1,40 @@
+import "dart:async";
+import "package:collection/collection.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/members_controller.dart";
+import "package:nexus/controllers/profile_controller.dart";
+import "package:nexus/helpers/extensions/get_localpart.dart";
+import "package:nexus/models/membership.dart";
+import "package:nexus/models/membership_status.dart";
+
+class UserController extends AsyncNotifier<Membership?> {
+  final String userId;
+  UserController(this.userId);
+
+  @override
+  Future<Membership?> build() async {
+    final member = await ref.watch(
+      MembersController.provider.selectAsync(
+        (value) =>
+            value.firstWhereOrNull((membership) => membership.userId == userId),
+      ),
+    );
+
+    if (member != null) return member;
+
+    final profile = await ref.watch(ProfileController.provider(userId).future);
+    return Membership(
+      status: MembershipStatus.leave,
+      avatarUrl: profile.avatarUrl == null
+          ? null
+          : Uri.tryParse(profile.avatarUrl!),
+      displayName: profile.displayName ?? userId.localpart,
+      userId: userId,
+    );
+  }
+
+  static final provider =
+      AsyncNotifierProvider.family<UserController, Membership?, String>(
+        UserController.new,
+      );
+}