import ExpoModulesCore
import WatchConnectivity

private class SessionDelegate: NSObject, WCSessionDelegate {
    var onActivationComplete: ((WCSessionActivationState) -> Void)?
    var onMessageReceived: (([String: Any]) -> Void)?
    var onUserInfoReceived: (([String: Any]) -> Void)?

    func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: Error?) {
        if let error = error {
            print("[WatchConnectivity] Activation failed: \(error)")
        } else {
            print("[WatchConnectivity] Activation complete: state=\(activationState.rawValue)")
        }
        onActivationComplete?(activationState)
    }

    func session(_ session: WCSession, didReceiveMessage message: [String: Any], replyHandler: @escaping ([String: Any]) -> Void) {
        print("[WatchConnectivity] Received message with reply: \(message["type"] ?? "unknown")")
        replyHandler(["status": "received"])
        onMessageReceived?(message)
    }

    func session(_ session: WCSession, didReceiveUserInfo userInfo: [String: Any] = [:]) {
        print("[WatchConnectivity] Received userInfo: \(userInfo["type"] ?? "unknown")")
        onUserInfoReceived?(userInfo)
    }

    func sessionDidBecomeInactive(_ session: WCSession) {}

    func sessionDidDeactivate(_ session: WCSession) {
        session.activate()
    }
}

public class WatchConnectivityModule: Module {
    private var session: WCSession?
    private let delegate = SessionDelegate()
    private var isActivated = false
    private var pendingPromises: [(() -> Void)] = []
    private var pendingEvents: [[String: Any]] = []

    // WCSession only supports NSString, NSNumber, NSData, NSArray, NSDictionary
    private func cleanForWCSession(_ obj: Any) -> Any {
        if let dict = obj as? [String: Any] {
            var cleaned: [String: Any] = [:]
            for (key, value) in dict {
                if value is NSNull { continue }
                cleaned[key] = cleanForWCSession(value)
            }
            return cleaned
        } else if let arr = obj as? [Any] {
            return arr.filter { !($0 is NSNull) }.map { cleanForWCSession($0) }
        }
        return obj
    }

    public func definition() -> ModuleDefinition {
        Name("WatchConnectivity")

        OnCreate {
            guard WCSession.isSupported() else { return }
            let session = WCSession.default
            session.delegate = self.delegate
            self.delegate.onActivationComplete = { [weak self] state in
                DispatchQueue.main.async {
                    self?.isActivated = (state == .activated)
                    print("[WatchConnectivity] isActivated = \(self?.isActivated ?? false)")
                    let pending = self?.pendingPromises ?? []
                    self?.pendingPromises = []
                    pending.forEach { $0() }
                }
            }
            self.delegate.onMessageReceived = { [weak self] message in
                self?.handleIncomingMessage(message)
            }
            self.delegate.onUserInfoReceived = { [weak self] userInfo in
                self?.handleIncomingMessage(userInfo)
            }
            session.activate()
            self.session = session
        }

        AsyncFunction("isSupported") { () -> Bool in
            return WCSession.isSupported()
        }

        AsyncFunction("isPaired") { () -> Bool in
            guard let session = self.session else { return false }
            return session.isPaired
        }

        AsyncFunction("isWatchAppInstalled") { () -> Bool in
            guard let session = self.session else { return false }
            return session.isWatchAppInstalled
        }

        AsyncFunction("isReachable") { () -> Bool in
            guard let session = self.session else { return false }
            return session.isReachable
        }

        AsyncFunction("sendWorkoutPlan") { (plan: [String: Any], promise: Promise) in
            guard let session = self.session else {
                print("[WatchConnectivity] sendWorkoutPlan: NO_SESSION")
                promise.reject("NO_SESSION", "WCSession not available")
                return
            }

            func doSend() {
                var message = plan
                message["type"] = "workoutPlan"

                print("[WatchConnectivity] sendWorkoutPlan: isReachable=\(session.isReachable), activationState=\(session.activationState.rawValue)")

                guard let cleaned = self.cleanForWCSession(message) as? [String: Any] else {
                    promise.resolve(["status": "sent"])
                    return
                }

                session.sendMessage(cleaned, replyHandler: nil, errorHandler: { error in
                    print("[WatchConnectivity] sendMessage failed: \(error), falling back to transferUserInfo")
                    session.transferUserInfo(cleaned)
                })
                promise.resolve(["status": "sent"])
            }

            if session.activationState == .activated {
                doSend()
            } else {
                print("[WatchConnectivity] Session not activated yet (state=\(session.activationState.rawValue)), queuing...")
                self.pendingPromises.append(doSend)
            }
        }

        AsyncFunction("sendWorkoutCompletion") { (data: [String: Any], promise: Promise) in
            guard let session = self.session else {
                promise.reject("NO_SESSION", "WCSession not available")
                return
            }

            func doSend() {
                var message = data
                message["type"] = "workoutCompleted"

                guard let cleaned = self.cleanForWCSession(message) as? [String: Any] else {
                    promise.resolve(["status": "sent"])
                    return
                }

                if session.isReachable {
                    session.sendMessage(cleaned, replyHandler: nil, errorHandler: { error in
                        print("[WatchConnectivity] sendMessage failed: \(error), falling back to transferUserInfo")
                        session.transferUserInfo(cleaned)
                    })
                } else {
                    session.transferUserInfo(cleaned)
                }
                promise.resolve(["status": "sent"])
            }

            if self.isActivated {
                doSend()
            } else {
                self.pendingPromises.append(doSend)
            }
        }

        AsyncFunction("getApplicationContext") { () -> [String: Any]? in
            return self.session?.receivedApplicationContext as? [String: Any]
        }

        AsyncFunction("updateApplicationContext") { (context: [String: Any]) in
            try? self.session?.updateApplicationContext(context)
        }

        AsyncFunction("pollEvents") { () -> [[String: Any]] in
            let events = self.pendingEvents
            self.pendingEvents = []
            return events
        }
    }

    private func handleIncomingMessage(_ message: [String: Any]) {
        guard let type = message["type"] as? String else { return }
        print("[WatchConnectivity] handleIncomingMessage type=\(type)")

        DispatchQueue.main.async {
            self.pendingEvents.append(message)
        }
    }
}