import Foundation
import WatchConnectivity

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

    private let store: WatchProfileStore
    private var handlers: [String: WatchDataHandling] = [:]

    private override init() {
        self.store = .shared
        super.init()
        registerDefaultHandlers()
        activateIfSupported()
        loadCurrentContext()
    }

    private func registerDefaultHandlers() {
        let profileHandler = UserProfileWatchHandler(store: store)
        registerHandler(profileHandler)
    }

    func registerHandler(_ handler: WatchDataHandling) {
        handlers[handler.key] = handler
    }

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

    private func loadCurrentContext() {
        guard WCSession.isSupported() else { return }
        handleContext(WCSession.default.applicationContext)
    }

    private func handleContext(_ context: [String: Any]) {
        for (key, handler) in handlers {
            guard let data = context[key] as? Data else { continue }
            handler.handle(data: data)
        }
    }

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

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