ladill-mini/apps/ios/LadillMini/Push/PushTokenRegistrar.swift

import FirebaseMessaging
import UIKit
import UserNotifications

/// Registers the FCM device token with the Ladill Mini API when the user is signed in.
@MainActor
enum PushTokenRegistrar {

    static func requestPermissionAndRegisterForRemoteNotifications() async {
        let center = UNUserNotificationCenter.current()
        let granted = (try? await center.requestAuthorization(options: [.alert, .badge, .sound])) ?? false
        guard granted else { return }
        UIApplication.shared.registerForRemoteNotifications()
    }

    static func registerIfLoggedIn() async {
        guard SessionStore.shared.isLoggedIn else { return }
        await requestPermissionAndRegisterForRemoteNotifications()
        await uploadCurrentTokenIfAvailable()
    }

    static func onTokenRefresh(_ token: String) async {
        guard SessionStore.shared.isLoggedIn else { return }
        await upload(token: token)
    }

    static func unregister() async {
        guard let token = await fetchFCMToken() else { return }
        try? await APIClient.shared.unregisterPushToken(token: token)
    }

    private static func uploadCurrentTokenIfAvailable() async {
        guard let token = await fetchFCMToken() else { return }
        await upload(token: token)
    }

    private static func upload(token: String) async {
        do {
            try await APIClient.shared.registerPushToken(PushTokenRequest(token: token))
        } catch {
            #if DEBUG
            print("PushTokenRegistrar: upload failed — \(error.localizedDescription)")
            #endif
        }
    }

    private static func fetchFCMToken() async -> String? {
        await withCheckedContinuation { continuation in
            Messaging.messaging().token { token, error in
                if let error {
                    #if DEBUG
                    print("PushTokenRegistrar: FCM token fetch failed — \(error.localizedDescription)")
                    #endif
                    continuation.resume(returning: nil)
                    return
                }
                continuation.resume(returning: token)
            }
        }
    }
}