treewide cleanups

lib/controllers/room_chat.dart

@@ -243,17 +243,14 @@ class RoomChatController(final ChatParams info)
       ref.invalidate(provider);
     }
 
-    var taggedMessage = text;
-
-    for (final tag in tags) {
-      final escaped = RegExp.escape(tag.id);
-      final pattern = RegExp(r"@+(" + escaped + r")(#[^#]*#)?");
-
-      taggedMessage = taggedMessage.replaceAllMapped(
-        pattern,
+    // Replaces each formatted tag, like "@id#name#", with its ID
+    final taggedMessage = tags.fold(
+      text,
+      (message, tag) => message.replaceAllMapped(
+        RegExp(r"@+(" + RegExp.escape(tag.id) + r")(#[^#]*#)?"),
         (match) => match.group(1)!,
-      );
-    }
+      ),
+    );
 
     final client = ref.read(ClientController.provider.notifier);
     final event = await client.sendMessage(

lib/controllers/spaces.dart

@@ -25,55 +25,50 @@ class SpacesController extends AsyncNotifier<IList<Space>> {
           MapEntry(spaceId, edges.map((edge) => edge.childId).toList()),
     );
 
-    Set<String> collectDescendants(String startId) {
-      final visited = <String>{};
-      final stack = [startId];
-
-      while (stack.isNotEmpty) {
-        final current = stack.removeLast();
-        final children = childrenById[current] ?? const [];
-
-        for (final child in children) {
-          if (visited.add(child)) {
-            stack.add(child);
-          }
-        }
-      }
-
-      return visited;
-    }
+    /// Everything under [spaceId], however deep, skipping any already
+    /// [visited] so cycles end.
+    ISet<String> collectDescendants(
+      String spaceId, [
+      ISet<String> visited = const .empty(),
+    ]) => (childrenById[spaceId] ?? const []).fold(
+      visited,
+      (visited, childId) => visited.contains(childId)
+          ? visited
+          : collectDescendants(childId, visited.add(childId)),
+    );
 
     Space buildSpace(String spaceId) {
       final space = rooms[spaceId];
       final directChildrenIds = childrenById[spaceId] ?? const [];
 
-      final directRooms = <Room>[];
-      final subSpaces = <Subspace>[];
-
-      for (final childId in directChildrenIds) {
-        final room = rooms[childId];
-        if (room == null) continue;
-
-        if (childrenById.containsKey(childId)) {
-          final descendants = collectDescendants(childId);
-
-          subSpaces.add(
-            .new(
-              room: room,
-              children: .new(descendants.map((id) => rooms[id]).nonNulls),
-            ),
-          );
-        } else {
-          directRooms.add(room);
-        }
-      }
-
       return .new(
         id: spaceId,
         room: space,
         title: space?.metadata?.name ?? "Unnamed Space",
-        children: .new(directRooms),
-        subSpaces: .new(subSpaces),
+        children: .new(
+          directChildrenIds
+              .where((childId) => !childrenById.containsKey(childId))
+              .map((childId) => rooms[childId])
+              .nonNulls,
+        ),
+        subSpaces: .new(
+          directChildrenIds
+              .where(childrenById.containsKey)
+              .map(
+                (childId) => switch (rooms[childId]) {
+                  final room? => Subspace(
+                    room: room,
+                    children: .new(
+                      collectDescendants(childId)
+                          .map((id) => rooms[id])
+                          .nonNulls,
+                    ),
+                  ),
+                  null => null,
+                },
+              )
+              .nonNulls,
+        ),
       );
     }
 

lib/controllers/via.dart

@@ -1,53 +1,48 @@
-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/client_state.dart";
 import "package:nexus/models/content/content.dart";
 import "package:nexus/models/content/membership.dart";
 import "package:nexus/models/content/power_levels.dart";
+import "package:nexus/models/event.dart";
 import "package:nexus/models/room.dart";
 
 class ViaController(final Room room) extends Notifier<String> {
   @override
   String build() {
-    final servers = <String>{};
+    final powerLevelUsers =
+        switch (room.state[EventType.powerLevels.type]?[""]) {
+          final rowId? => switch (room.events[rowId]?.content) {
+            PowerLevelsContent(:final users) => users.keys.toIList(),
+            _ => null,
+          },
+          null => null,
+        } ??
+        .new([]);
 
-    void addUserId(String? userId) {
-      final server = userId?.split(":").lastOrNull;
-      if (server != null) {
-        servers.add(server);
-      }
-    }
+    final joinedMembers =
+        (room.state[EventType.membership.type]?.values ?? const [])
+            .map(
+              (rowId) => switch (room.events[rowId]) {
+                Event(
+                  stateKey: final userId?,
+                  content: MembershipContent(status: .join),
+                ) =>
+                  userId,
+                _ => null,
+              },
+            )
+            .nonNulls
+            .toIList();
 
-    addUserId(ref.watch(ClientStateController.provider)?.userId);
-
-    final powerLevelsEventId = room.state[EventType.powerLevels.type]?[""];
-    final powerLevels = powerLevelsEventId == null
-        ? null
-        : room.events[powerLevelsEventId];
-
-    if (powerLevels?.content case PowerLevelsContent(:final users)) {
-      for (final userId in users.keys) {
-        addUserId(userId);
-        if (servers.length >= 5) break;
-      }
-    }
-
-    final members = room.state[EventType.membership.type]?.values.toIList();
-    for (var i = 0; servers.length < 5; i++) {
-      final membershipEventId = members?.getOrNull(i);
-      final member = membershipEventId == null
-          ? null
-          : room.events[membershipEventId];
-
-      if (member?.content case MembershipContent(:final status)) {
-        if (status == .join) {
-          addUserId(member?.stateKey);
-        }
-      }
-
-      if (members?.getOrNull(i) == null) break;
-    }
+    final servers = [?ref.watch(ClientStateController.provider)?.userId]
+        .toIList()
+        .addAll(powerLevelUsers)
+        .addAll(joinedMembers)
+        .map((userId) => userId.substring(userId.indexOf(":") + 1))
+        .whereNoDuplicates()
+        .take(5)
+        .toISet();
 
     return servers.isEmpty
         ? ""