import Foundation
import WatchConnectivity
import os

private let connLog = Logger(subsystem: "ch.hypnotruck.coach.watchkitapp", category: "connectivity")

/// Envoie les samples de séance vers l'iPhone.
/// - `sendMessage` quand l'iPhone est joignable (temps réel)
/// - sinon buffer + `transferUserInfo` (livraison différée garantie)
final class ConnectivityManager: NSObject, ObservableObject {
    static let shared = ConnectivityManager()

    @Published private(set) var isReachable = false

    private let queue = DispatchQueue(label: "ch.hypnotruck.coach.connectivity")
    private var buffer: [[String: Any]] = []

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

    func sendSample(_ payload: [String: Any]) {
        queue.async {
            let session = WCSession.default
            let hr = (payload["heartRate"] as? Double) ?? -1
            connLog.info("sendSample activated=\(session.activationState == .activated, privacy: .public) reachable=\(session.isReachable, privacy: .public) hr=\(hr, privacy: .public)")
            guard session.activationState == .activated else {
                self.buffer.append(payload)
                return
            }
            if session.isReachable {
                session.sendMessage(payload, replyHandler: nil) { [weak self] _ in
                    // échec d'envoi temps réel -> bascule en livraison différée
                    self?.queue.async {
                        self?.buffer.append(payload)
                        self?.flushLocked()
                    }
                }
            } else {
                self.buffer.append(payload)
                self.flushLocked()
            }
        }
    }

    /// À appeler sur `queue` uniquement.
    private func flushLocked() {
        guard !buffer.isEmpty else { return }
        let session = WCSession.default
        guard session.activationState == .activated else { return }
        session.transferUserInfo(["samples": buffer])
        buffer.removeAll()
    }

    private func updateReachable(_ value: Bool) {
        DispatchQueue.main.async { [weak self] in self?.isReachable = value }
    }
}

extension ConnectivityManager: WCSessionDelegate {
    func session(_ session: WCSession,
                 activationDidCompleteWith activationState: WCSessionActivationState,
                 error: Error?) {
        updateReachable(session.isReachable)
        if activationState == .activated {
            queue.async { [weak self] in self?.flushLocked() }
        }
    }

    func sessionReachabilityDidChange(_ session: WCSession) {
        let reachable = session.isReachable
        updateReachable(reachable)
        if reachable {
            queue.async { [weak self] in self?.flushLocked() }
        }
    }
}