fix bar crashing on monitor add/remove

include/app.hpp

@@ -1,31 +1,36 @@
 #pragma once
 
-#include <vector>
+#include <memory>
 
 #include "bar/bar.hpp"
 #include "connection/dbus/notification.hpp"
 #include "connection/dbus/tray.hpp"
 #include "services/hyprland.hpp"
-#include "widgets/wallpaperWindow.hpp"
+#include "services/notificationController.hpp"
 
+#include "gdkmm/monitor.h"
 #include "glibmm/refptr.h"
 #include "gtkmm/application.h"
 
-class MprisController;
-
 class App {
   public:
+    struct BarMonitorPair {
+        std::shared_ptr<Bar> bar;
+        std::shared_ptr<Gdk::Monitor> window;
+    };
+
     App();
 
     int run();
 
   private:
     Glib::RefPtr<Gtk::Application> app;
-    std::vector<std::shared_ptr<Bar>> bars;
-    std::vector<std::shared_ptr<WallpaperWindow>> wallpaperWindows;
-    std::shared_ptr<NotificationService> notificationService = nullptr;
-    std::shared_ptr<MprisController> mprisController         = nullptr;
-    HyprlandService *hyprlandService                         = nullptr;
+    std::map<std::string, BarMonitorPair> bars;
+
+    std::shared_ptr<NotificationService> notificationService       = NotificationService::getInstance();
+    std::shared_ptr<NotificationController> notificationController = NotificationController::getInstance();
+    std::shared_ptr<MprisController> mprisController               = MprisController::getInstance();
+    std::shared_ptr<HyprlandService> hyprlandService               = HyprlandService::getInstance();
 
     TrayService *trayService = TrayService::getInstance();
     void setupServices();