// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.

import Foundation
import GRDB
import PromiseKit
import SessionMessagingKit
import SessionUtilitiesKit
import SessionUIKit
import UserNotifications
import UIKit
import SignalUtilitiesKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate, AppModeManagerDelegate {
    var window: UIWindow?
    var backgroundSnapshotBlockerWindow: UIWindow?
    var appStartupWindow: UIWindow?
    var hasInitialRootViewController: Bool = false
    
    /// This needs to be a lazy variable to ensure it doesn't get initialized before it actually needs to be used
    lazy var poller: Poller = {
        return Poller()
    }()
    
    // MARK: - Lifecycle

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // These should be the first things we do (the startup process can fail without them)
        SetCurrentAppContext(MainAppContext())
        verifyDBKeysAvailableBeforeBackgroundLaunch()

        AppModeManager.configure(delegate: self)
        Cryptography.seedRandom()
        AppVersion.sharedInstance()

        // Prevent the device from sleeping during database view async registration
        // (e.g. long database upgrades).
        //
        // This block will be cleared in storageIsReady.
        DeviceSleepManager.sharedInstance.addBlock(blockObject: self)
        
        let mainWindow: UIWindow = UIWindow(frame: UIScreen.main.bounds)
        let loadingViewController: LoadingViewController = LoadingViewController()
        
        AppSetup.setupEnvironment(
            appSpecificBlock: {
                // Create AppEnvironment
                AppEnvironment.shared.setup()
                
                // Note: Intentionally dispatching sync as we want to wait for these to complete before
                // continuing
                DispatchQueue.main.sync {
                    OWSScreenLockUI.sharedManager().setup(withRootWindow: mainWindow)
                    OWSWindowManager.shared().setup(
                        withRootWindow: mainWindow,
                        screenBlockingWindow: OWSScreenLockUI.sharedManager().screenBlockingWindow
                    )
                    OWSScreenLockUI.sharedManager().startObserving()
                }
            },
            migrationProgressChanged: { progress, minEstimatedTotalTime in
                loadingViewController.updateProgress(
                    progress: progress,
                    minEstimatedTotalTime: minEstimatedTotalTime
                )
            },
            migrationsCompletion: { [weak self] successful, needsConfigSync in
                guard let strongSelf = self else { return }
                guard successful else {
                    return
                }
                
                Configuration.performMainSetup()
                JobRunner.add(executor: SyncPushTokensJob.self, for: .syncPushTokens)
                
                // Trigger any launch-specific jobs and start the JobRunner
                JobRunner.appDidFinishLaunching()
                
                // Note that this does much more than set a flag;
                // it will also run all deferred blocks (including the JobRunner
                // 'appDidBecomeActive' method)
                AppReadiness.setAppIsReady()
                
                DeviceSleepManager.sharedInstance.removeBlock(blockObject: strongSelf)
                AppVersion.sharedInstance().mainAppLaunchDidComplete()
                Environment.shared.audioSession.setup()
                Environment.shared.reachabilityManager.setup()
                
                GRDBStorage.shared.writeAsync { db in
                    // Disable the SAE until the main app has successfully completed launch process
                    // at least once in the post-SAE world.
                    db[.isReadyForAppExtensions] = true
                    
                    if Identity.userExists(db) {
                        let appVersion: AppVersion = AppVersion.sharedInstance()
                        
                        // If the device needs to sync config or the user updated to a new version
                        if
                            needsConfigSync || (
                                (appVersion.lastAppVersion?.count ?? 0) > 0 &&
                                appVersion.lastAppVersion != appVersion.currentAppVersion
                            )
                        {
                            try MessageSender.syncConfiguration(db, forceSyncNow: true).retainUntilComplete()
                        }
                    }
                }
                
                // Setup the UI
                self?.ensureRootViewController()
            }
        )
        
        SNAppearance.switchToSessionAppearance()
        
        // No point continuing if we are running tests
        guard !CurrentAppContext().isRunningTests else { return true }

        self.window = mainWindow
        CurrentAppContext().mainWindow = mainWindow
        
        // Show LoadingViewController until the async database view registrations are complete.
        mainWindow.rootViewController = loadingViewController
        mainWindow.makeKeyAndVisible()

        adapt(appMode: AppModeManager.getAppModeOrSystemDefault())

        // This must happen in appDidFinishLaunching or earlier to ensure we don't
        // miss notifications.
        // Setting the delegate also seems to prevent us from getting the legacy notification
        // notification callbacks upon launch e.g. 'didReceiveLocalNotification'
        UNUserNotificationCenter.current().delegate = self
        
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(registrationStateDidChange),
            name: .registrationStateDidChange,
            object: nil
        )
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(handleDataNukeRequested),   // TODO: This differently???
            name: .dataNukeRequested,
            object: nil
        )
        
        Logger.info("application: didFinishLaunchingWithOptions completed.")

        return true
    }
    
    func applicationDidEnterBackground(_ application: UIApplication) {
        DDLog.flushLog()
        
        stopPollers()
    }
    
    func applicationDidReceiveMemoryWarning(_ application: UIApplication) {
        Logger.info("applicationDidReceiveMemoryWarning")
    }
    
    func applicationWillTerminate(_ application: UIApplication) {
        DDLog.flushLog()
        
        stopPollers()
    }
    
    func applicationDidBecomeActive(_ application: UIApplication) {
        guard !CurrentAppContext().isRunningTests else { return }
        
        UserDefaults.sharedLokiProject?[.isMainAppActive] = true
        
        ensureRootViewController()
        adapt(appMode: AppModeManager.getAppModeOrSystemDefault())

        AppReadiness.runNowOrWhenAppDidBecomeReady { [weak self] in
            self?.handleActivation()
        }

        // Clear all notifications whenever we become active.
        // When opening the app from a notification,
        // AppDelegate.didReceiveLocalNotification will always
        // be called _before_ we become active.
        clearAllNotificationsAndRestoreBadgeCount()

        // On every activation, clear old temp directories.
        ClearOldTemporaryDirectories();
    }
    
    func applicationWillResignActive(_ application: UIApplication) {
        clearAllNotificationsAndRestoreBadgeCount()
        
        UserDefaults.sharedLokiProject?[.isMainAppActive] = false

        DDLog.flushLog()
    }
    
    // MARK: - Orientation

    func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
        return .portrait
    }
    
    // MARK: - Background Fetching
    
    func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        AppReadiness.runNowOrWhenAppDidBecomeReady {
            BackgroundPoller.poll(completionHandler: completionHandler)
        }
    }
    
    // MARK: - App Readiness
    
    /// The user must unlock the device once after reboot before the database encryption key can be accessed.
    private func verifyDBKeysAvailableBeforeBackgroundLaunch() {
        guard UIApplication.shared.applicationState == .background else { return }
        
        // Ensure both databases are accessible (as long as we are supporting the YDB migration
        // we should keep this check)
        let databasePasswordAccessible: Bool = (
            GRDBStorage.isDatabasePasswordAccessible &&                      // GRDB password access
            OWSStorage.isDatabasePasswordAccessible()                        // YapDatabase password access
        )
        
        guard !databasePasswordAccessible else { return }    // All good
        
        Logger.info("Exiting because we are in the background and the database password is not accessible.")
        
        let notificationContent: UNMutableNotificationContent = UNMutableNotificationContent()
        notificationContent.body = String(
            format: NSLocalizedString("NOTIFICATION_BODY_PHONE_LOCKED_FORMAT", comment: ""),
            UIDevice.current.localizedModel
        )
        let notificationRequest: UNNotificationRequest = UNNotificationRequest(
            identifier: UUID().uuidString,
            content: notificationContent,
            trigger: nil
        )

        // Make sure we clear any existing notifications so that they don't start stacking up
        // if the user receives multiple pushes.
        UNUserNotificationCenter.current().removeAllPendingNotificationRequests()
        UIApplication.shared.applicationIconBadgeNumber = 0
        
        UNUserNotificationCenter.current().add(notificationRequest, withCompletionHandler: nil)
        UIApplication.shared.applicationIconBadgeNumber = 1
        
        DDLog.flushLog()
        exit(0)
    }
    
    private func enableBackgroundRefreshIfNecessary() {
        AppReadiness.runNowOrWhenAppDidBecomeReady {
            UIApplication.shared.setMinimumBackgroundFetchInterval(UIApplication.backgroundFetchIntervalMinimum)
        }
    }

    private func handleActivation() {
        guard Identity.userExists() else { return }
        
        enableBackgroundRefreshIfNecessary()
        JobRunner.appDidBecomeActive()
        
        startPollersIfNeeded()
        
        if CurrentAppContext().isMainApp {
            syncConfigurationIfNeeded()
        }
    }
    
    private func ensureRootViewController() {
        guard AppReadiness.isAppReady() && GRDBStorage.shared.isValid && !hasInitialRootViewController else {
            return
        }
        
        let navController: UINavigationController = OWSNavigationController(
            rootViewController: (Identity.userExists() ?
                HomeVC() :
                LandingVC()
            )
        )
        navController.isNavigationBarHidden = !(navController.viewControllers.first is HomeVC)
        self.window?.rootViewController = navController
        UIViewController.attemptRotationToDeviceOrientation()
    }
    
    // MARK: - Notifications
    
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        PushRegistrationManager.shared.didReceiveVanillaPushToken(deviceToken)
        Logger.info("Registering for push notifications with token: \(deviceToken).")
    }
    
    func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
        Logger.error("Failed to register push token with error: \(error).")
        
        #if DEBUG
        Logger.warn("We're in debug mode. Faking success for remote registration with a fake push identifier.")
        PushRegistrationManager.shared.didReceiveVanillaPushToken(Data(count: 32))
        #else
        PushRegistrationManager.shared.didFailToReceiveVanillaPushToken(error: error)
        #endif
    }
    
    private func clearAllNotificationsAndRestoreBadgeCount() {
        AppReadiness.runNowOrWhenAppDidBecomeReady {
            AppEnvironment.shared.notificationPresenter.clearAllNotifications()
            
            guard CurrentAppContext().isMainApp else { return }
            
            CurrentAppContext().setMainAppBadgeNumber(
                GRDBStorage.shared
                    .read { db in
                        let userPublicKey: String = getUserHexEncodedPublicKey(db)
                        let thread: TypedTableAlias<SessionThread> = TypedTableAlias()
                        
                        return try Interaction
                            .filter(Interaction.Columns.wasRead == false)
                            .filter(
                                // Only count mentions if 'onlyNotifyForMentions' is set
                                thread[.onlyNotifyForMentions] == false ||
                                Interaction.Columns.hasMention == true
                            )
                            .joining(
                                required: Interaction.thread
                                    .aliased(thread)
                                    .joining(optional: SessionThread.contact)
                                    .filter(
                                        // Ignore muted threads
                                        SessionThread.Columns.mutedUntilTimestamp == nil ||
                                        SessionThread.Columns.mutedUntilTimestamp < Date().timeIntervalSince1970
                                    )
                                    .filter(
                                        // Ignore message request threads
                                        SessionThread.Columns.variant != SessionThread.Variant.contact ||
                                        !SessionThread.isMessageRequest(userPublicKey: userPublicKey)
                                    )
                            )
                            .fetchCount(db)
                    }
                    .defaulting(to: 0)
            )
        }
    }
    
    func application(_ application: UIApplication, performActionFor shortcutItem: UIApplicationShortcutItem, completionHandler: @escaping (Bool) -> Void) {
        AppReadiness.runNowOrWhenAppDidBecomeReady {
            guard Identity.userExists() else { return }
            
            SessionApp.homeViewController.wrappedValue?.createNewDM()
            completionHandler(true)
        }
    }

    /// The method will be called on the delegate only if the application is in the foreground. If the method is not implemented or the
    /// handler is not called in a timely manner then the notification will not be presented. The application can choose to have the
    /// notification presented as a sound, badge, alert and/or in the notification list.
    ///
    /// This decision should be based on whether the information in the notification is otherwise visible to the user.
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        if notification.request.content.userInfo["remote"] != nil {
            Logger.info("[Loki] Ignoring remote notifications while the app is in the foreground.")
            return
        }
        
        AppReadiness.runNowOrWhenAppDidBecomeReady {
            // We need to respect the in-app notification sound preference. This method, which is called
            // for modern UNUserNotification users, could be a place to do that, but since we'd still
            // need to handle this behavior for legacy UINotification users anyway, we "allow" all
            // notification options here, and rely on the shared logic in NotificationPresenter to
            // honor notification sound preferences for both modern and legacy users.
            completionHandler([.alert, .badge, .sound])
        }
    }

    /// The method will be called on the delegate when the user responded to the notification by opening the application, dismissing
    /// the notification or choosing a UNNotificationAction. The delegate must be set before the application returns from
    /// application:didFinishLaunchingWithOptions:.
    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
        AppReadiness.runNowOrWhenAppDidBecomeReady {
            AppEnvironment.shared.userNotificationActionHandler.handleNotificationResponse(response, completionHandler: completionHandler)
        }
    }

    /// The method will be called on the delegate when the application is launched in response to the user's request to view in-app
    /// notification settings. Add UNAuthorizationOptionProvidesAppNotificationSettings as an option in
    /// requestAuthorizationWithOptions:completionHandler: to add a button to inline notification settings view and the notification
    /// settings view in Settings. The notification will be nil when opened from Settings.
    func userNotificationCenter(_ center: UNUserNotificationCenter, openSettingsFor notification: UNNotification?) {
    }
    
    // MARK: - Notification Handling
    
    @objc private func registrationStateDidChange() {
        enableBackgroundRefreshIfNecessary()

        guard Identity.userExists() else { return }
        
        startPollersIfNeeded()
    }
    
    @objc public func handleDataNukeRequested() {
        let isUsingFullAPNs: Bool = UserDefaults.standard[.isUsingFullAPNs]
        let maybeDeviceToken: String? = UserDefaults.standard[.deviceToken]
        // TODO: Clean up how this works
        if isUsingFullAPNs, let deviceToken: String = maybeDeviceToken {
            let data: Data = Data(hex: deviceToken)
            PushNotificationAPI.unregister(data).retainUntilComplete()
        }
        
        GRDBStorage.shared.write { db in
            _ = try SessionThread.deleteAll(db)
            _ = try Identity.deleteAll(db)
        }
        
        SnodeAPI.clearSnodePool()
        stopPollers()
        
        let wasUnlinked: Bool = UserDefaults.standard[.wasUnlinked]
        SessionApp.resetAppData {
            // Resetting the data clears the old user defaults. We need to restore the unlink default.
            UserDefaults.standard[.wasUnlinked] = wasUnlinked
        }
    }
    
    // MARK: - Polling
    
    public func startPollersIfNeeded() {
        guard Identity.userExists() else { return }
        
        poller.startIfNeeded()
        ClosedGroupPoller.shared.start()
        OpenGroupManagerV2.shared.startPolling()
    }
    
    public func stopPollers() {
        poller.stop()
        ClosedGroupPoller.shared.stop()
        OpenGroupManagerV2.shared.stopPolling()
    }
    
    // MARK: - App Mode

    private func adapt(appMode: AppMode) {
        guard let window: UIWindow = UIApplication.shared.keyWindow else { return }
        
        switch (appMode) {
            case .light:
                window.overrideUserInterfaceStyle = .light
                window.backgroundColor = .white
            
            case .dark:
                window.overrideUserInterfaceStyle = .dark
                window.backgroundColor = .black
        }
        
        if LKAppModeUtilities.isSystemDefault {
            window.overrideUserInterfaceStyle = .unspecified
        }
        
        NotificationCenter.default.post(name: .appModeChanged, object: nil)
    }
    
    func setCurrentAppMode(to appMode: AppMode) {
        UserDefaults.standard[.appMode] = appMode.rawValue
        adapt(appMode: appMode)
    }
    
    func setAppModeToSystemDefault() {
        UserDefaults.standard.removeObject(forKey: SNUserDefaults.Int.appMode.rawValue)
        adapt(appMode: AppModeManager.getAppModeOrSystemDefault())
    }
    
    // MARK: - App Link

    func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
        guard let components: URLComponents = URLComponents(url: url, resolvingAgainstBaseURL: true) else {
            return false
        }
        
        // URL Scheme is sessionmessenger://DM?sessionID=1234
        // We can later add more parameters like message etc.
        if components.host == "DM" {
            let matches: [URLQueryItem] = (components.queryItems ?? [])
                .filter { item in item.name == "sessionID" }
            
            if let sessionId: String = matches.first?.value {
                createNewDMFromDeepLink(sessionId: sessionId)
                return true
            }
        }
        
        return false
    }

    private func createNewDMFromDeepLink(sessionId: String) {
        guard let homeViewController: HomeVC = (window?.rootViewController as? OWSNavigationController)?.visibleViewController as? HomeVC else {
            return
        }
        
        homeViewController.createNewDMFromDeepLink(sessionID: sessionId)
    }
    
    // MARK: - Config Sync
    
    func syncConfigurationIfNeeded() {
        let lastSync: Date = (UserDefaults.standard[.lastConfigurationSync] ?? .distantPast)
        
        guard Date().timeIntervalSince(lastSync) > (7 * 24 * 60 * 60) else { return } // Sync every 2 days
        
        GRDBStorage.shared.write { db in
            try MessageSender.syncConfiguration(db, forceSyncNow: false)
                .done {
                    // Only update the 'lastConfigurationSync' timestamp if we have done the
                    // first sync (Don't want a new device config sync to override config
                    // syncs from other devices)
                    if UserDefaults.standard[.hasSyncedInitialConfiguration] {
                        UserDefaults.standard[.lastConfigurationSync] = Date()
                    }
                }
                .retainUntilComplete()
        }
    }
}