//
// WatchConnectivityManager.swift
// Workouts
//
// Copyright 2025 Rouslan Zenetl. All Rights Reserved.
//

import Foundation
import WatchConnectivity
import CoreData

class WatchConnectivityManager: NSObject, ObservableObject {
    static let shared = WatchConnectivityManager()

    private var session: WCSession?
    private var viewContext: NSManagedObjectContext?

    override init() {
        super.init()

        if WCSession.isSupported() {
            session = WCSession.default
            session?.delegate = self
            session?.activate()
        }
    }

    func setViewContext(_ context: NSManagedObjectContext) {
        self.viewContext = context
    }

    // MARK: - Send Data to Watch

    func syncAllData() {
        guard let session = session else {
            print("[WC-iOS] No WCSession")
            return
        }

        print("[WC-iOS] Session state: \(session.activationState.rawValue), reachable: \(session.isReachable), paired: \(session.isPaired), installed: \(session.isWatchAppInstalled)")

        guard session.activationState == .activated else {
            print("[WC-iOS] Session not activated")
            return
        }

        guard let context = viewContext else {
            print("[WC-iOS] No view context")
            return
        }

        context.perform {
            do {
                let workoutsData = try self.encodeAllWorkouts(context: context)
                let splitsData = try self.encodeAllSplits(context: context)

                let payload: [String: Any] = [
                    "workouts": workoutsData,
                    "splits": splitsData,
                    "timestamp": Date().timeIntervalSince1970
                ]

                // Use updateApplicationContext for persistent state
                try session.updateApplicationContext(payload)
                print("[WC-iOS] Synced \(workoutsData.count) workouts, \(splitsData.count) splits to Watch")

            } catch {
                print("Failed to sync data: \(error)")
            }
        }
    }

    func sendWorkoutUpdate(_ workout: Workout) {
        guard let session = session, session.activationState == .activated else { return }

        do {
            let workoutData = try encodeWorkout(workout)
            let message: [String: Any] = [
                "type": "workoutUpdate",
                "workout": workoutData
            ]

            if session.isReachable {
                session.sendMessage(message, replyHandler: nil) { error in
                    print("Failed to send workout update: \(error)")
                }
            } else {
                // Queue for later via application context
                syncAllData()
            }
        } catch {
            print("Failed to encode workout: \(error)")
        }
    }

    // MARK: - Encoding

    private func encodeAllWorkouts(context: NSManagedObjectContext) throws -> [[String: Any]] {
        let request = Workout.fetchRequest()
        request.sortDescriptors = [NSSortDescriptor(keyPath: \Workout.start, ascending: false)]
        let workouts = try context.fetch(request)
        return try workouts.map { try encodeWorkout($0) }
    }

    private func encodeAllSplits(context: NSManagedObjectContext) throws -> [[String: Any]] {
        let request = Split.fetchRequest()
        request.sortDescriptors = [NSSortDescriptor(keyPath: \Split.order, ascending: true)]
        let splits = try context.fetch(request)
        return try splits.map { try encodeSplit($0) }
    }

    private func encodeWorkout(_ workout: Workout) throws -> [String: Any] {
        var data: [String: Any] = [
            "id": workout.objectID.uriRepresentation().absoluteString,
            "start": workout.start.timeIntervalSince1970,
            "status": workout.status.rawValue
        ]

        if let end = workout.end {
            data["end"] = end.timeIntervalSince1970
        }

        if let split = workout.split {
            data["splitId"] = split.objectID.uriRepresentation().absoluteString
            data["splitName"] = split.name
        }

        data["logs"] = workout.logsArray.map { encodeWorkoutLog($0) }

        return data
    }

    private func encodeWorkoutLog(_ log: WorkoutLog) -> [String: Any] {
        var data: [String: Any] = [
            "id": log.objectID.uriRepresentation().absoluteString,
            "exerciseName": log.exerciseName,
            "date": log.date.timeIntervalSince1970,
            "order": log.order,
            "sets": log.sets,
            "reps": log.reps,
            "weight": log.weight,
            "status": log.status.rawValue,
            "currentStateIndex": log.currentStateIndex,
            "completed": log.completed,
            "loadType": log.loadType
        ]

        if let duration = log.duration {
            data["duration"] = duration.timeIntervalSince1970
        }

        if let notes = log.notes {
            data["notes"] = notes
        }

        return data
    }

    private func encodeSplit(_ split: Split) throws -> [String: Any] {
        var data: [String: Any] = [
            "id": split.objectID.uriRepresentation().absoluteString,
            "name": split.name,
            "color": split.color,
            "systemImage": split.systemImage,
            "order": split.order
        ]

        data["exercises"] = split.exercisesArray.map { encodeExercise($0) }

        return data
    }

    private func encodeExercise(_ exercise: Exercise) -> [String: Any] {
        var data: [String: Any] = [
            "id": exercise.objectID.uriRepresentation().absoluteString,
            "name": exercise.name,
            "order": exercise.order,
            "sets": exercise.sets,
            "reps": exercise.reps,
            "weight": exercise.weight,
            "loadType": exercise.loadType
        ]

        if let duration = exercise.duration {
            data["duration"] = duration.timeIntervalSince1970
        }

        return data
    }
}

// MARK: - WCSessionDelegate

extension WatchConnectivityManager: WCSessionDelegate {
    func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: Error?) {
        if let error = error {
            print("[WC-iOS] Activation failed: \(error)")
        } else {
            print("[WC-iOS] Activated with state: \(activationState.rawValue), paired: \(session.isPaired), installed: \(session.isWatchAppInstalled)")
            // Sync data when session activates
            DispatchQueue.main.async {
                self.syncAllData()
            }
        }
    }

    func sessionDidBecomeInactive(_ session: WCSession) {
        print("[WC-iOS] Session became inactive")
    }

    func sessionDidDeactivate(_ session: WCSession) {
        print("[WC-iOS] Session deactivated")
        // Reactivate for switching watches
        session.activate()
    }

    func sessionReachabilityDidChange(_ session: WCSession) {
        print("[WC-iOS] Reachability changed: \(session.isReachable)")
        if session.isReachable {
            syncAllData()
        }
    }

    // Receive messages from Watch (for bidirectional sync)
    func session(_ session: WCSession, didReceiveMessage message: [String: Any]) {
        print("[WC-iOS] Received message with keys: \(message.keys)")
        if let type = message["type"] as? String {
            switch type {
            case "requestSync":
                syncAllData()
            case "syncFromWatch":
                processWatchSync(message)
            default:
                break
            }
        }
    }

    // Receive user info transfers from Watch (background delivery)
    func session(_ session: WCSession, didReceiveUserInfo userInfo: [String: Any]) {
        print("[WC-iOS] Received userInfo with keys: \(userInfo.keys)")
        if let type = userInfo["type"] as? String, type == "syncFromWatch" {
            processWatchSync(userInfo)
        }
    }

    // MARK: - Process Watch Sync

    private func processWatchSync(_ data: [String: Any]) {
        guard let viewContext = viewContext else {
            print("[WC-iOS] No view context for Watch sync")
            return
        }

        guard let workoutsData = data["workouts"] as? [[String: Any]] else {
            print("[WC-iOS] No workouts in Watch sync data")
            return
        }

        print("[WC-iOS] Processing \(workoutsData.count) workouts from Watch")

        DispatchQueue.main.async {
            viewContext.perform {
                for workoutData in workoutsData {
                    self.updateWorkoutFromWatch(workoutData, context: viewContext)
                }

                do {
                    try viewContext.save()
                    print("[WC-iOS] Successfully saved Watch sync data")

                    // Refresh all objects to ensure SwiftUI observes changes
                    viewContext.refreshAllObjects()
                } catch {
                    print("[WC-iOS] Failed to save Watch sync: \(error)")
                }
            }
        }
    }

    private func updateWorkoutFromWatch(_ data: [String: Any], context: NSManagedObjectContext) {
        guard let startInterval = data["start"] as? TimeInterval else { return }

        // Find workout by start date
        let request = Workout.fetchRequest()
        let startDate = Date(timeIntervalSince1970: startInterval)
        request.predicate = NSPredicate(
            format: "start >= %@ AND start <= %@",
            Date(timeIntervalSince1970: startInterval - 1) as NSDate,
            Date(timeIntervalSince1970: startInterval + 1) as NSDate
        )
        request.fetchLimit = 1

        guard let workout = try? context.fetch(request).first else {
            print("[WC-iOS] Workout not found for start date: \(startDate)")
            return
        }

        // Update workout status
        if let statusRaw = data["status"] as? String,
           let status = WorkoutStatus(rawValue: statusRaw) {
            workout.status = status
        }

        if let endInterval = data["end"] as? TimeInterval {
            workout.end = Date(timeIntervalSince1970: endInterval)
        }

        // Update logs
        if let logsData = data["logs"] as? [[String: Any]] {
            for logData in logsData {
                updateWorkoutLogFromWatch(logData, workout: workout, context: context)
            }
        }
    }

    private func updateWorkoutLogFromWatch(_ data: [String: Any], workout: Workout, context: NSManagedObjectContext) {
        guard let exerciseName = data["exerciseName"] as? String else { return }

        // Find log by exercise name in this workout
        guard let log = workout.logsArray.first(where: { $0.exerciseName == exerciseName }) else {
            print("[WC-iOS] Log not found for exercise: \(exerciseName)")
            return
        }

        // Update status and progress
        if let statusRaw = data["status"] as? String,
           let status = WorkoutStatus(rawValue: statusRaw) {
            log.status = status
        }

        if let currentStateIndex = data["currentStateIndex"] as? Int {
            log.currentStateIndex = Int32(currentStateIndex)
        }

        if let completed = data["completed"] as? Bool {
            log.completed = completed
        }

        // Update other fields that might have changed
        if let notes = data["notes"] as? String {
            log.notes = notes
        }
    }
}