import UserNotifications

/// Notification Service Extension — runs as a separate process even when the main app
/// is terminated. Intercepts push notifications with `mutable-content: 1` and:
/// 1. Adds `.default` sound for vibration (server payload has no sound)
/// 2. Increments the app icon badge from shared App Group storage
final class NotificationService: UNNotificationServiceExtension {

    private static let appGroupID = "group.com.rosetta.dev"
    private static let badgeKey = "app_badge_count"

    private var contentHandler: ((UNNotificationContent) -> Void)?
    private var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(
        _ request: UNNotificationRequest,
        withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void
    ) {
        self.contentHandler = contentHandler
        bestAttemptContent = request.content.mutableCopy() as? UNMutableNotificationContent

        guard let content = bestAttemptContent else {
            contentHandler(request.content)
            return
        }

        // 1. Add sound for vibration — server APNs payload has no sound field.
        content.sound = .default

        // 2. Increment badge count from shared App Group storage.
        if let shared = UserDefaults(suiteName: Self.appGroupID) {
            let current = shared.integer(forKey: Self.badgeKey)
            let newBadge = current + 1
            shared.set(newBadge, forKey: Self.badgeKey)
            content.badge = NSNumber(value: newBadge)
        }

        // 3. Ensure notification category for CarPlay parity.
        if content.categoryIdentifier.isEmpty {
            content.categoryIdentifier = "message"
        }

        contentHandler(content)
    }

    /// Called if the extension takes too long (30s limit).
    /// Deliver the best attempt content with at least the sound set.
    override func serviceExtensionTimeWillExpire() {
        if let handler = contentHandler, let content = bestAttemptContent {
            content.sound = .default
            handler(content)
        }
    }
}