Add powerlevel checks

lib/controllers/power_level_controller.dart

@@ -0,0 +1,48 @@
+import "package:collection/collection.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/client_state_controller.dart";
+import "package:nexus/controllers/selected_room_controller.dart";
+import "package:nexus/models/configs/power_level_config.dart";
+import "package:nexus/models/requests/membership_action.dart";
+
+class PowerLevelController extends Notifier<bool> {
+  final PowerLevelConfig config;
+  PowerLevelController(this.config);
+
+  @override
+  bool build() {
+    final room = ref.watch(SelectedRoomController.provider);
+    final event = room?.events.firstWhereOrNull(
+      (event) => event.rowId == room.state["m.room.power_levels"]?[""],
+    );
+    final user = ref.watch(ClientStateController.provider)?.userId;
+    if (event == null || user == null) return false;
+
+    final users = (event.content["users"] as Map<String, dynamic>? ?? {});
+    final events = (event.content["events"] as Map<String, dynamic>? ?? {});
+
+    final userLevel = users.containsKey(user)
+        ? (users[user] as int)
+        : (event.content["users_default"] as int? ?? 0);
+
+    final requiredLevel = switch (config.action) {
+      MembershipAction.ban ||
+      MembershipAction.unban => (event.content["ban"] as int? ?? 50),
+      MembershipAction.kick => (event.content["kick"] as int? ?? 50),
+      MembershipAction.invite => (event.content["invite"] as int? ?? 0),
+      null =>
+        events.containsKey(config.eventType)
+            ? (events[config.eventType] as int)
+            : (config.isStateEvent
+                  ? (event.content["state_default"] as int? ?? 50)
+                  : (event.content["events_default"] as int? ?? 0)),
+    };
+
+    return userLevel >= requiredLevel;
+  }
+
+  static final provider = NotifierProvider.autoDispose
+      .family<PowerLevelController, bool, PowerLevelConfig>(
+        PowerLevelController.new,
+      );
+}