Architecture Overview

@main
struct ChapterApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    @StateObject var snapchatManager = SnapchatManager.shared
    let container = AppContainer.shared
    
    var body: some Scene {
        WindowGroup {
            MasterTabView(authManager: AuthManager.shared)
                .environmentObject(container)
                .environmentObject(snapchatManager)
                .fontDesign(.rounded)
        }
    }
}

@MainActor
class AppContainer: ObservableObject {
    static let shared = AppContainer()
    
    // Filter ViewModels
    @Published var searchCourseFilter: CourseV2FilterViewModel
    @Published var searchUniFilter: UniversityV2FilterManager
    
    // Core Managers (NOT @Published to avoid cascade)
    var authManager: AuthManager
    var locationManager: DeviceLocationManager
    var deepLinkManager = DeepLinkManager.shared
    
    // Data Services
    var searchCourseDataService: CourseDataServiceV2
    var shortlistManager: ShortlistV2Manager
    var whatsOnManager: WhatsOnManager
}

private func setupAuthObservation() {
    // Throttle and dedupe auth changes
    authManager.$currentUser
        .dropFirst()
        .debounce(for: .milliseconds(250), scheduler: DispatchQueue.main)
        .removeDuplicates { old, new in
            // Only trigger update if auth state or enrollment status changed
            let oldAuth = old != nil
            let newAuth = new != nil
            return oldAuth == newAuth && oldStatus == newStatus
        }
        .sink { [weak self] user in
            self?.isAuthenticated = user != nil
        }
        .store(in: &cancellables)
}

func handleScenePhaseChange(from oldPhase: ScenePhase, to newPhase: ScenePhase) {
    switch newPhase {
    case .background:
        print("📱 App entered background - cleaning up resources")
        DeviceLocationManager.shared.stopLocationServices()
        
    case .active:
        print("📱 App became active")
        // Resources restored by individual managers
        
    default:
        break
    }
}

await withTaskGroup(of: Void.self) { group in
    // Load university courses
    if authManager.cachedUniID != 9999 {
        group.addTask { @MainActor in
            _ = try? await self.authManager.getCoursesForUni(
                uniID: self.authManager.cachedUniID
            )
        }
    }
    
    // Load cached course
    if let uuid = UUID(uuidString: authManager.cachedCourseID) {
        group.addTask { @MainActor in
            self.authManager.course = try? await SupabaseMethods
                .getMultipleCoursesV2(ids: [uuid]).first
        }
    }
}