//
//  LocationManager.swift
//  Pods
//
//  Created by Groot on 2025/5/15.
//

import Foundation
import CoreLocation
import Flutter

class LocationManager: NSObject {

    static let shared = LocationManager()

    private var locationUpdateEventChannel: FlutterEventChannel?
    private var locationEventSink: FlutterEventSink?

    private let locationManager = CLLocationManager()

    var onLocationUpdate: ((CLLocation) -> Void)?

    private override init() {
        super.init()
        locationManager.delegate = self
        setup()
    }

    func start(withMessenger messenger: FlutterBinaryMessenger) -> Bool {
        // permission detect
        switch CLLocationManager.authorizationStatus() {
        case .authorizedWhenInUse, .authorizedAlways:
            locationManager.startUpdatingLocation()
            setupMessenger(messenger: messenger)
            return true
        case .notDetermined:
            locationManager.requestWhenInUseAuthorization()
            return false
        default:
            print("LocationManager: authorizationStatus: \(CLLocationManager.authorizationStatus())")
            return false
        }
    }

    func stop() {
        locationManager.stopUpdatingLocation()
    }

    func setupMessenger(messenger: FlutterBinaryMessenger) {
        guard locationUpdateEventChannel == nil && locationEventSink == nil else { return }
        locationUpdateEventChannel = FlutterEventChannel(name: MapKitConstans.locationUpdateEventChannelName, binaryMessenger: messenger)
        locationUpdateEventChannel?.setStreamHandler(self)
    }

    func setup() {
//        locationManager.allowsBackgroundLocationUpdates = true
        locationManager.pausesLocationUpdatesAutomatically = false
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.distanceFilter = 5.0
        locationManager.activityType = .fitness
        locationManager.showsBackgroundLocationIndicator = false
    }
}

extension LocationManager: CLLocationManagerDelegate {
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        guard let location = locations.last else { return }
        onLocationUpdate?(location)
        if let eventSink = locationEventSink {
            // 转换GPS坐标系到中国坐标系
            let transformedCoordinate = location.coordinate.wgc84ToGCJ02
            let atLocation = ATMapLocation.fromLocation(location: location)
            atLocation.longitude = transformedCoordinate.longitude
            atLocation.latitude = transformedCoordinate.latitude
            
            let jsonMessage = atLocation.toJson()
            print(jsonMessage)
            eventSink(jsonMessage)
        }
    }

    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        print("LocationManager: didFailWithError: \(error)")
    }
}

extension LocationManager: FlutterStreamHandler {
    func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {
        locationEventSink = events
        return nil
    }

    func onCancel(withArguments arguments: Any?) -> FlutterError? {
        locationEventSink = nil
        return nil
    }
}