import Foundation
import Network
import NetworkExtension
import Combine

@MainActor
final class LANMonitor: ObservableObject {
    static let shared = LANMonitor()

    @Published private(set) var isOnNetwork: Bool = false
    @Published private(set) var currentSSID: String? = nil

    private let monitor = NWPathMonitor()
    private let queue = DispatchQueue(label: "com.albert.nasbackup.lan", qos: .utility)

    var onTrustedNetworkJoined: ((String) -> Void)?

    private init() {}

    func start() {
        monitor.pathUpdateHandler = { [weak self] path in
            guard let self else { return }
            Task { @MainActor in
                let satisfied = path.status == .satisfied
                self.isOnNetwork = satisfied

                if satisfied {
                    await self.checkSSID()
                } else {
                    self.currentSSID = nil
                }
            }
        }
        monitor.start(queue: queue)
    }

    func stop() {
        monitor.cancel()
    }

    private func checkSSID() async {
        let ssid = await fetchCurrentSSID()
        self.currentSSID = ssid
    }

    func fetchCurrentSSID() async -> String? {
        await withCheckedContinuation { continuation in
            NEHotspotNetwork.fetchCurrent { network in
                continuation.resume(returning: network?.ssid)
            }
        }
    }

    func checkAndTriggerIfTrusted(trustedSSIDs: [String]) async {
        let ssid = await fetchCurrentSSID()
        guard let ssid, trustedSSIDs.contains(ssid) else { return }
        onTrustedNetworkJoined?(ssid)
    }
}