lazy load memberships

lib/controllers/author_controller.dart

@@ -0,0 +1,44 @@
+import "dart:async";
+import "package:collection/collection.dart";
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/members_controller.dart";
+import "package:nexus/models/configs/author_config.dart";
+import "package:nexus/models/membership.dart";
+
+class AuthorController extends AsyncNotifier<Membership> {
+  final AuthorConfig config;
+  AuthorController(this.config);
+
+  @override
+  Future<Membership> build() async {
+    var member = ref.watch(
+      MembersController.provider(config.room).select(
+        (value) => value.firstWhereOrNull(
+          (membership) => membership.userId == config.message.authorId,
+        ),
+      ),
+    );
+
+    final pmp = config.message.metadata?["pmp"] == null
+        ? null
+        : Membership.fromContent(
+            IMap(config.message.metadata?["pmp"]),
+            config.message.authorId,
+          );
+
+    return Membership(
+      avatarUrl: pmp?.avatarUrl ?? member?.avatarUrl,
+      displayName:
+          pmp?.displayName ??
+          member?.displayName ??
+          config.message.authorId.substring(1).split(":").first,
+      userId: config.message.authorId,
+    );
+  }
+
+  static final provider = AsyncNotifierProvider.family
+      .autoDispose<AuthorController, Membership, AuthorConfig>(
+        AuthorController.new,
+      );
+}