import Foundation
import Observation
import WatchConnectivity

@MainActor
@Observable
final class WatchConnectivityService: NSObject, WCSessionDelegate {
    static let shared = WatchConnectivityService()

    private(set) var profile: UserProfile?
    private(set) var statusMessage: String = ""

    private override init() {
        super.init()
        activateIfSupported()
        loadCurrentContext()
    }

    private func activateIfSupported() {
        guard WCSession.isSupported() else {
            statusMessage = "WatchConnectivity not supported"
            return
        }
        let session = WCSession.default
        session.delegate = self
        session.activate()
    }

    private func loadCurrentContext() {
        guard WCSession.isSupported() else { return }
        updateProfile(from: WCSession.default.applicationContext)
    }

    private func updateProfile(from context: [String: Any]) {
        guard let data = context[UserProfile.storageKeyName] as? Data else {
            statusMessage = "No profile received"
            return
        }

        do {
            profile = try JSONDecoder().decode(UserProfile.self, from: data)
            statusMessage = "Profile synced"
        } catch {
            statusMessage = "Failed to decode profile"
        }
    }

    func session(
        _ session: WCSession,
        activationDidCompleteWith activationState: WCSessionActivationState,
        error: Error?
    ) {
        loadCurrentContext()
    }

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