import SwiftUI
import SwiftData
import UIKit
import FirebaseCore
import FirebaseCrashlytics
#if canImport(GoogleMobileAds)
import GoogleMobileAds
#endif

/// Registers for remote notifications so CloudKit (the NSPersistentCloudKitContainer
/// behind SwiftData) receives its silent-push subscriptions and imports changes
/// in near-real-time across devices. Silent pushes are coalesced by the system,
/// so battery cost is negligible — no polling.
final class AppDelegate: NSObject, UIApplicationDelegate {
    func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool {
        application.registerForRemoteNotifications()
        return true
    }

    func application(_ application: UIApplication,
                     didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                     fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        // CloudKit silent push: SwiftData's mirror imports on its own once woken;
        // report new data so the system keeps delivering sync pushes.
        completionHandler(.newData)
    }
}

/// Whether the store is syncing through CloudKit this launch. When true, the
/// legacy iCloud KV snapshot sync must stay inert (both would fight).
enum CloudSyncRuntime {
    // Written exactly once during app start (before any concurrency), then
    // read-only for the rest of the launch.
    nonisolated(unsafe) static var isCloudKitActive = false
}

@main
struct MealMoodApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) private var appDelegate

    private let modelContainer: ModelContainer = {
        let schema = Schema([
            AppSettings.self,
            Tag.self,
            Dish.self,
            WeekPlan.self,
            MealSlot.self,
            ShoppingItem.self
        ])

        // 2.0: CloudKit private-database sync (multi-device, same Apple ID).
        // Falls back to the local-only store when CloudKit isn't available
        // (signed-out iCloud, missing entitlement in dev builds, etc.).
        let cloudConfiguration = ModelConfiguration(cloudKitDatabase: .automatic)
        do {
            let container = try ModelContainer(for: schema, configurations: [cloudConfiguration])
            CloudSyncRuntime.isCloudKitActive = true
            return container
        } catch {
            CrashlyticsService.record(error, context: "cloudkit_container")
            print("CloudKit container unavailable, using local store: \(error)")
        }

        let configuration = ModelConfiguration(cloudKitDatabase: .none)
        do {
            return try ModelContainer(for: schema, configurations: [configuration])
        } catch {
            // Migration failed — reset the store to avoid a crash loop
            let storeURL = configuration.url
            for ext in ["", "-shm", "-wal"] {
                try? FileManager.default.removeItem(at: URL(fileURLWithPath: storeURL.path + ext))
            }
            do {
                return try ModelContainer(for: schema, configurations: [configuration])
            } catch {
                fatalError("Cannot create ModelContainer after reset: \(error)")
            }
        }
    }()

    init() {
        FirebaseApp.configure()
#if canImport(GoogleMobileAds)
        GADMobileAds.sharedInstance().start(completionHandler: nil)
#endif
    }

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(modelContainer)
    }
}