import AppKit
import UserNotifications

final class MailNotificationDelegate: NSObject, UNUserNotificationCenterDelegate {
    static let shared = MailNotificationDelegate()

    func userNotificationCenter(
        _ center: UNUserNotificationCenter,
        willPresent notification: UNNotification,
        withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void
    ) {
        completionHandler([.banner, .list, .sound])
    }
}

struct NewMailNotification: Sendable {
    let sender: String
    let subject: String
}

@MainActor
enum MailNotifications {
    static let enabledKey = "newMailNotifications"

    static func configure() {
        UNUserNotificationCenter.current().delegate = MailNotificationDelegate.shared
    }

    static func requestAuthorization() async -> Bool {
        let center = UNUserNotificationCenter.current()
        let settings = await center.notificationSettings()
        switch settings.authorizationStatus {
        case .authorized, .provisional:
            return true
        case .notDetermined:
            return (try? await center.requestAuthorization(options: [.alert, .sound])) == true
        default:
            return false
        }
    }

    static func postNewMail(_ messages: [NewMailNotification], badgeCount: Int) async {
        guard !messages.isEmpty, UserDefaults.standard.bool(forKey: enabledKey) else { return }
        guard await requestAuthorization() else { return }

        for message in messages {
            let content = UNMutableNotificationContent()
            content.title = String(localized: "Neue Mail")
            content.subtitle = message.sender.isEmpty
                ? String(localized: "Unbekannter Absender")
                : message.sender
            content.body = message.subject.isEmpty
                ? String(localized: "(Ohne Betreff)")
                : message.subject
            content.sound = .default
            content.badge = NSNumber(value: badgeCount)

            let request = UNNotificationRequest(
                identifier: UUID().uuidString,
                content: content,
                trigger: nil
            )
            try? await UNUserNotificationCenter.current().add(request)
        }
    }

    static func updateBadge(_ count: Int) {
        NSApp.dockTile.badgeLabel = count > 0 ? String(count) : nil
    }
}