import 'dart:async';

import 'package:flutter/widgets.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'package:intl/intl.dart';
import 'package:workmanager/workmanager.dart';

import '../local/hive_boxes.dart';
import '../local/models/app_settings.dart';
import 'myquran_sholat_service.dart';
import 'notification_orchestrator_service.dart';
import 'notification_service.dart';

class BackgroundSyncService {
  BackgroundSyncService._();
  static final BackgroundSyncService instance = BackgroundSyncService._();

  static const String periodicTaskName = 'jamshalat_periodic_sync';
  static const String periodicUniqueName = 'jamshalat_periodic_sync_unique';

  Future<void> init() async {
    await Workmanager().initialize(_workmanagerCallbackDispatcher);
  }

  Future<void> registerPeriodicSync() async {
    await Workmanager().registerPeriodicTask(
      periodicUniqueName,
      periodicTaskName,
      existingWorkPolicy: ExistingPeriodicWorkPolicy.update,
      frequency: const Duration(hours: 6),
      initialDelay: const Duration(minutes: 15),
      constraints: Constraints(
        networkType: NetworkType.connected,
      ),
      backoffPolicy: BackoffPolicy.exponential,
      backoffPolicyDelay: const Duration(minutes: 10),
    );
  }

  static Future<void> runSyncPass() async {
    WidgetsFlutterBinding.ensureInitialized();
    await initHive();

    final settingsBox = Hive.box<AppSettings>(HiveBoxes.settings);
    final settings = settingsBox.get('default') ?? AppSettings();
    final cityId = _resolveCityId(settings);

    final schedulesByDate = await _buildWindowSchedules(cityId);
    if (schedulesByDate.isNotEmpty) {
      await NotificationService.instance.syncPrayerNotifications(
        cityId: cityId,
        adhanEnabled: settings.adhanEnabled,
        iqamahOffset: settings.iqamahOffset,
        schedulesByDate: schedulesByDate,
        reportReminderEnabled: settings.shalatReportReminderEnabled,
        reportReminderDelayMinutes: settings.shalatReportReminderDelayMinutes,
        reportReminderRepeatCount: settings.shalatReportReminderRepeatCount,
        reportReminderRepeatIntervalMinutes:
            settings.shalatReportReminderRepeatIntervalMinutes,
      );
    }

    await NotificationService.instance.syncHabitNotifications(
      settings: settings,
    );
    await NotificationOrchestratorService.instance.runPassivePass(
      settings: settings,
    );
  }

  static Future<Map<String, Map<String, String>>> _buildWindowSchedules(
      String cityId) async {
    final now = DateTime.now();
    final startDate = DateTime(now.year, now.month, now.day);
    final endDate = startDate.add(const Duration(days: 35));

    final monthKeys = <String>{
      DateFormat('yyyy-MM').format(startDate),
      DateFormat('yyyy-MM').format(endDate),
    };

    final schedulesByDate = <String, Map<String, String>>{};
    for (final monthKey in monthKeys) {
      final monthly = await MyQuranSholatService.instance
          .getMonthlySchedule(cityId, monthKey);
      for (final entry in monthly.entries) {
        final date = DateTime.tryParse(entry.key);
        if (date == null) continue;
        final normalized = DateTime(date.year, date.month, date.day);
        if (normalized.isBefore(startDate) || normalized.isAfter(endDate)) {
          continue;
        }
        schedulesByDate[entry.key] = entry.value;
      }
    }
    return schedulesByDate;
  }

  static String _resolveCityId(AppSettings settings) {
    final stored = settings.lastCityName ?? '';
    if (stored.contains('|')) {
      return stored.split('|').last;
    }
    return '58a2fc6ed39fd083f55d4182bf88826d';
  }
}

@pragma('vm:entry-point')
void _workmanagerCallbackDispatcher() {
  Workmanager().executeTask((task, inputData) async {
    if (task == BackgroundSyncService.periodicTaskName) {
      await BackgroundSyncService.runSyncPass();
      return true;
    }
    return true;
  });
}