import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:timezone/timezone.dart' as tz;
import 'package:timezone/data/latest.dart' as tz;
import 'package:flutter_timezone/flutter_timezone.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../services/google_calendar_service.dart';

class NotificationService {
  static final NotificationService _instance = NotificationService._internal();
  factory NotificationService() => _instance;
  NotificationService._internal();

  final FlutterLocalNotificationsPlugin _plugin = FlutterLocalNotificationsPlugin();
  bool _initialized = false;

  static const _channel = AndroidNotificationChannel(
    'shooting_app_events',
    'Event Reminders',
    description: 'Notifications for upcoming shooting events',
    importance: Importance.max,
    playSound: true,
    enableVibration: true,
  );

  NotificationDetails get _notifDetails => const NotificationDetails(
    android: AndroidNotificationDetails(
      'shooting_app_events',
      'Event Reminders',
      channelDescription: 'Notifications for upcoming shooting events',
      importance: Importance.max,
      priority: Priority.high,
      icon: '@drawable/ic_stat_icon_white',
    ),
    iOS: DarwinNotificationDetails(
      presentAlert: true,
      presentBadge: true,
      presentSound: true,
    ),
  );

  Future<void> initialize() async {
    if (_initialized) return;
    _initialized = true; // set early to prevent re-entry

    try {
      tz.initializeTimeZones();
      final String timezoneName = await FlutterTimezone.getLocalTimezone();
      tz.setLocalLocation(tz.getLocation(timezoneName));
    } catch (_) {}

    try {
      const androidSettings = AndroidInitializationSettings('@mipmap/ic_launcher');
      const iosSettings = DarwinInitializationSettings(
        requestAlertPermission: true,
        requestBadgePermission: true,
        requestSoundPermission: true,
      );
      const initSettings = InitializationSettings(android: androidSettings, iOS: iosSettings);
      await _plugin.initialize(initSettings);

      final androidPlugin = _plugin.resolvePlatformSpecificImplementation<
          AndroidFlutterLocalNotificationsPlugin>();
      await androidPlugin?.createNotificationChannel(_channel);
      await requestPermissions();
    } catch (_) {}
  }

  Future<bool> requestPermissions() async {
    final android = _plugin.resolvePlatformSpecificImplementation<
        AndroidFlutterLocalNotificationsPlugin>();
    final ios = _plugin.resolvePlatformSpecificImplementation<
        IOSFlutterLocalNotificationsPlugin>();

    bool granted = false;
    if (android != null) {
      granted = await android.requestNotificationsPermission() ?? false;
    }
    if (ios != null) {
      granted = await ios.requestPermissions(alert: true, badge: true, sound: true) ?? false;
    }
    return granted;
  }

  Future<void> cancelAll() async {
    await _plugin.cancelAll();
  }

  Future<void> scheduleEventNotifications(List<CalendarEvent> events) async {
    try {
      await initialize();

      final prefs = await SharedPreferences.getInstance();
      final hours = prefs.getInt('notificationHours_single') ?? 1;
      final notifyDezuranje = prefs.getBool('notifyDezuranje') ?? true;
      final notifySestanek = prefs.getBool('notifySestanek') ?? true;
      final notifyTekma = prefs.getBool('notifyTekma') ?? true;
      final isSlovenian = (prefs.getString('language') ?? 'English') == 'Slovenian';
      final now = DateTime.now();

      await _plugin.cancelAll();

      int notifId = 0;
      for (final event in events) {
        if (event.startTime == null) continue;

        final summary = (event.summary ?? '').toLowerCase();
        final isCompetition = summary.contains('liga') || summary.contains('tekmovanje');
        final isSestanek = summary.contains('sestanek');
        final isDezuranje = !isCompetition && !isSestanek;

        if (isCompetition && !notifyTekma) continue;
        if (isSestanek && !notifySestanek) continue;
        if (isDezuranje && !notifyDezuranje) continue;

        final notifyAt = event.startTime!.subtract(Duration(hours: hours));
        if (notifyAt.isAfter(now)) {
          await _scheduleNotification(
            id: notifId++,
            title: event.summary ?? 'Event',
            body: isSlovenian
              ? (hours == 1 ? 'Začne se čez 1 uro' : 'Začne se čez $hours ur')
              : (hours == 1 ? 'Starts in 1 hour' : 'Starts in $hours hours'),
            scheduledDate: notifyAt,
          );
        }
      }
    } catch (_) {}
  }

  Future<void> scheduleTestNotification() async {
    try {
      await initialize();
      final prefs = await SharedPreferences.getInstance();
      final isSlovenian = (prefs.getString('language') ?? 'English') == 'Slovenian';
      await _plugin.show(
        9999,
        isSlovenian ? 'Testno obvestilo' : 'Test Notification',
        isSlovenian ? 'Obvestila delujejo!' : 'Notifications are working!',
        _notifDetails,
      );
      final in10s = DateTime.now().add(const Duration(seconds: 10));
      await _scheduleNotification(
        id: 9998,
        title: isSlovenian ? 'Načrtovano testno obvestilo' : 'Scheduled Test',
        body: isSlovenian ? 'Načrtovana obvestila delujejo!' : 'Scheduled notifications are working!',
        scheduledDate: in10s,
      );
    } catch (_) {}
  }

  Future<void> _scheduleNotification({
    required int id,
    required String title,
    required String body,
    required DateTime scheduledDate,
  }) async {
    final tzDate = tz.TZDateTime.from(scheduledDate, tz.local);
    await _plugin.zonedSchedule(
      id,
      title,
      body,
      tzDate,
      _notifDetails,
      androidScheduleMode: AndroidScheduleMode.inexactAllowWhileIdle,
      uiLocalNotificationDateInterpretation:
          UILocalNotificationDateInterpretation.absoluteTime,
    );
  }
}