import SwiftUI
import WatchConnectivity

private final class WatchSnapshotTransport: NSObject, ObservableObject, WCSessionDelegate {
    private static let snapshotKey = "de.rfc1437.ironstorage.watch.snapshot"
    private static let deliveredReceiptKey = "de.rfc1437.ironstorage.watch.delivered"

    override init() {
        super.init()
        guard WCSession.isSupported() else { return }
        let session = WCSession.default
        session.delegate = self
        session.activate()
    }

    private func receive(_ applicationContext: [String: Any], session: WCSession) {
        guard
            applicationContext[Self.snapshotKey] is Data,
            let receipt = applicationContext[Self.deliveredReceiptKey] as? Data
        else { return }
        let acknowledgement = [Self.deliveredReceiptKey: receipt]
        if session.isReachable {
            session.sendMessage(acknowledgement, replyHandler: nil) { _ in
                session.transferUserInfo(acknowledgement)
            }
        } else {
            session.transferUserInfo(acknowledgement)
        }
    }

    func session(
        _ session: WCSession,
        activationDidCompleteWith activationState: WCSessionActivationState,
        error: Error?
    ) {
        guard activationState == .activated, error == nil else { return }
        receive(session.receivedApplicationContext, session: session)
    }

    func session(
        _ session: WCSession,
        didReceiveApplicationContext applicationContext: [String: Any]
    ) {
        receive(applicationContext, session: session)
    }
}

@main
struct IronStorageWatchApp: App {
    @StateObject private var transport = WatchSnapshotTransport()

    var body: some Scene {
        WindowGroup {
            ContentUnavailableView("No TOTP Codes", systemImage: "timer")
        }
    }
}