#if os(iOS)
  import Models
  import Services
  import SwiftUI
  import Utils
  import Views

  @MainActor final class PushNotificationSettingsViewModel: ObservableObject {
    @Published var isLoading = false
    @Published var emails = [NewsletterEmail]()
    @Published var desiredNotificationsEnabled = false
    @AppStorage(UserDefaultKey.notificationsEnabled.rawValue) var notificationsEnabled = false

    func checkPushNotificationsStatus() {
      UNUserNotificationCenter.current().getNotificationSettings { settings in
        DispatchQueue.main.async {
          self.desiredNotificationsEnabled = settings.alertSetting == UNNotificationSetting.enabled
        }
      }
    }

    func tryUpdateToDesired(dataService: DataService) {
      UserDefaults.standard.set(desiredNotificationsEnabled, forKey: UserDefaultKey.notificationsEnabled.rawValue)

      if desiredNotificationsEnabled {
        UNUserNotificationCenter.current().requestAuthorization(options: [.alert]) { granted, _ in
          DispatchQueue.main.async {
            self.desiredNotificationsEnabled = granted
            Task {
              if let savedToken = UserDefaults.standard.string(forKey: UserDefaultKey.firebasePushToken.rawValue) {
                _ = try? await dataService.syncDeviceToken(
                  deviceTokenOperation: DeviceTokenOperation.addToken(token: savedToken))
              }
              NotificationCenter.default.post(name: Notification.Name("ReconfigurePushNotifications"), object: nil)
            }
          }
        }
      } else {
        if let tokenID = UserDefaults.standard.string(forKey: UserDefaultKey.deviceTokenID.rawValue) {
          Task {
            try? await Services().dataService.syncDeviceToken(deviceTokenOperation: .deleteToken(tokenID: tokenID))
          }
        }
      }
    }
  }

  struct PushNotificationSettingsView: View {
    @EnvironmentObject var dataService: DataService
    @StateObject var viewModel = PushNotificationSettingsViewModel()
    @State var desiredNotificationsEnabled: Bool = false

    var body: some View {
      Group {
        #if os(iOS)
          Form {
            innerBody
          }
        #elseif os(macOS)
          List {
            innerBody
          }
          .listStyle(InsetListStyle())
        #endif
      }
      .task { viewModel.checkPushNotificationsStatus() }
    }

    private var notificationsText: some View {
      let markdown = "\(LocalText.notificationsExplainer)\n\n\(LocalText.notificationsTriggerExplainer)"
      if let notificationsText = try? AttributedString(
        markdown: markdown,
        options: .init(interpretedSyntax: .inlineOnlyPreservingWhitespace)
      ) {
        return Text(notificationsText)
          .accentColor(.blue)
      }
      return Text(markdown)
        .accentColor(.blue)
    }

    private var innerBody: some View {
      Group {
        Section {
          Toggle(isOn: $viewModel.desiredNotificationsEnabled, label: { Text(LocalText.notificationsEnabled) })
        }.onChange(of: viewModel.desiredNotificationsEnabled) { _ in
          viewModel.tryUpdateToDesired(dataService: dataService)
        }

        Section {
          notificationsText
        }

        Section {
          NavigationLink("Devices") {
            PushNotificationDevicesView()
          }
        }
      }
      .navigationTitle(LocalText.pushNotificationsGeneric)
    }
  }
#endif