import 'dart:io';
import 'dart:math';

import 'package:flutter_background_geolocation/flutter_background_geolocation.dart' as bg;
import 'package:shared_preferences/shared_preferences.dart';
import 'package:shared_preferences_android/shared_preferences_android.dart';

class Preferences {
  static Future<void>? _initFuture;
  static late SharedPreferencesWithCache instance;

  static const String id = 'id';
  static const String url = 'url';
  static const String accuracy = 'accuracy';
  static const String distance = 'distance';
  static const String interval = 'interval';
  static const String angle = 'angle';
  static const String heartbeat = 'heartbeat';
  static const String fastestInterval = 'fastest_interval';
  static const String buffer = 'buffer';
  static const String wakelock = 'wakelock';
  static const String stopDetection = 'stop_detection';
  static const String password = 'password';

  static const String lastTimestamp = 'lastTimestamp';
  static const String lastLatitude = 'lastLatitude';
  static const String lastLongitude = 'lastLongitude';
  static const String lastHeading = 'lastHeading';

  static Future<void> init() async {
    _initFuture ??= _createInstance();
    await _initFuture;
  }

  static Future<void> _createInstance() async {
    instance = await SharedPreferencesWithCache.create(
      sharedPreferencesOptions: Platform.isAndroid
        ? SharedPreferencesAsyncAndroidOptions(backend: SharedPreferencesAndroidBackendLibrary.SharedPreferences)
        : SharedPreferencesOptions(),
      cacheOptions: SharedPreferencesWithCacheOptions(
        allowList: {
          id, url, accuracy, distance, interval, angle, heartbeat,
          fastestInterval, buffer,  wakelock, stopDetection, password,
          lastTimestamp, lastLatitude, lastLongitude, lastHeading,
        },
      ),
    );
    if (instance.getString(id) == null) {
      await instance.setString(id, (Random().nextInt(90000000) + 10000000).toString());
      await instance.setString(url, 'http://demo.traccar.org:5055');
      await instance.setString(accuracy, 'medium');
      await instance.setInt(interval, 300);
      await instance.setInt(distance, 75);
      await instance.setBool(buffer, true);
      await instance.setBool(stopDetection, true);
      await instance.setInt(fastestInterval, 30);
    }
  }

  static bg.Config geolocationConfig() {
    final isHighestAccuracy = instance.getString(accuracy) == 'highest';
    final locationUpdateInterval = (instance.getInt(interval) ?? 0) * 1000;
    final fastestLocationUpdateInterval = (instance.getInt(fastestInterval) ?? 30) * 1000;
    final heartbeatInterval = instance.getInt(heartbeat) ?? 0;
    return bg.Config(
      isMoving: true,
      geolocation: bg.GeoConfig(
        desiredAccuracy: switch (instance.getString(accuracy)) {
          'highest' => Platform.isIOS ? bg.DesiredAccuracy.navigation : bg.DesiredAccuracy.high,
          'high' => bg.DesiredAccuracy.high,
          'low' => bg.DesiredAccuracy.low,
          _ => bg.DesiredAccuracy.medium,
        },
        distanceFilter: isHighestAccuracy ? 0 : instance.getInt(distance)?.toDouble(),
        locationUpdateInterval: Platform.isAndroid
            ? (isHighestAccuracy ? 0 : (locationUpdateInterval > 0 ? locationUpdateInterval : null))
            : null,
        fastestLocationUpdateInterval: Platform.isAndroid ? (isHighestAccuracy ? 0 : fastestLocationUpdateInterval) : null,
        disableElasticity: true,
        pausesLocationUpdatesAutomatically: Platform.isIOS ? !(isHighestAccuracy || instance.getBool(stopDetection) == false) : null,
        showsBackgroundLocationIndicator: Platform.isIOS ? false : null,
      ),
      app: bg.AppConfig(
        enableHeadless: Platform.isAndroid ? true : null,
        stopOnTerminate: false,
        startOnBoot: Platform.isAndroid ? true : null,
        heartbeatInterval: heartbeatInterval > 0 ? heartbeatInterval.toDouble() : null,
        preventSuspend: Platform.isIOS ? (heartbeatInterval > 0) : null,
        backgroundPermissionRationale: Platform.isAndroid
            ? bg.PermissionRationale(
                title: 'Allow {applicationName} to access this device\'s location in the background',
                message: 'For reliable tracking, please enable {backgroundPermissionOptionLabel} location access.',
                positiveAction: 'Change to {backgroundPermissionOptionLabel}',
                negativeAction: 'Cancel')
            : null,
        notification: Platform.isAndroid
            ? bg.Notification(
                smallIcon: 'drawable/ic_stat_notify',
                priority: bg.NotificationPriority.low,
              )
            : null,
      ),
      http: bg.HttpConfig(
        autoSync: false,
        url: _formatUrl(instance.getString(url)),
        params: {
          'device_id': instance.getString(id),
        },
      ),
      logger: const bg.LoggerConfig(
        logLevel: bg.LogLevel.verbose,
        logMaxDays: 1,
      ),
      activity: bg.ActivityConfig(
        disableStopDetection: instance.getBool(stopDetection) == false,
      ),
      persistence: bg.PersistenceConfig(
        maxRecordsToPersist: instance.getBool(buffer) != false ? -1 : 1,
        locationTemplate: _locationTemplate(),
      ),
    );
  }

  static String? _formatUrl(String? url) {
    if (url == null) return null;
    final uri = Uri.parse(url);
    if ((uri.path.isEmpty || uri.path == '') && !url.endsWith('/')) return '$url/';
    return url;
  }

  static String _locationTemplate() {
    return '''{
      "timestamp": "<%= timestamp %>",
      "coords": {
        "latitude": <%= latitude %>,
        "longitude": <%= longitude %>,
        "accuracy": <%= accuracy %>,
        "speed": <%= speed %>,
        "heading": <%= heading %>,
        "altitude": <%= altitude %>
      },
      "is_moving": <%= is_moving %>,
      "odometer": <%= odometer %>,
      "event": "<%= event %>",
      "battery": {
        "level": <%= battery.level %>,
        "is_charging": <%= battery.is_charging %>
      },
      "activity": {
        "type": "<%= activity.type %>"
      },
      "extras": {},
      "_": "&id=${instance.getString(id)}&lat=<%= latitude %>&lon=<%= longitude %>&timestamp=<%= timestamp %>&"
    }'''.split('\n').map((line) => line.trimLeft()).join();
  }
}