import 'dart:convert';

import 'package:flutter/widgets.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:rental_income_tracker/services/time_service.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:timezone/timezone.dart' as tz;

const String yesActionId = 'rent_yes';
const String noActionId = 'rent_no';
const String _pendingActionKey = 'pending_notification_actions';

@pragma('vm:entry-point')
void notificationTapBackground(
  NotificationResponse notificationResponse,
) async {
  WidgetsFlutterBinding.ensureInitialized();
  final prefs = await SharedPreferences.getInstance();
  final list = prefs.getStringList(_pendingActionKey) ?? <String>[];
  list.add(
    jsonEncode(<String, String?>{
      'actionId': notificationResponse.actionId,
      'payload': notificationResponse.payload,
    }),
  );
  await prefs.setStringList(_pendingActionKey, list);
}

class NotificationActionEvent {
  NotificationActionEvent({
    required this.year,
    required this.month,
    required this.isYes,
    required this.isRetry,
  });

  final int year;
  final int month;
  final bool isYes;
  final bool isRetry;
}

typedef NotificationActionHandler =
    Future<void> Function(NotificationActionEvent event);

class NotificationService {
  NotificationService(this._onAction);

  final NotificationActionHandler _onAction;
  final FlutterLocalNotificationsPlugin _plugin =
      FlutterLocalNotificationsPlugin();

  Future<void> initialize() async {
    final darwinCategory = DarwinNotificationCategory(
      'rent_actions',
      actions: <DarwinNotificationAction>[
        DarwinNotificationAction.plain(yesActionId, 'Yes'),
        DarwinNotificationAction.plain(noActionId, 'No'),
      ],
    );

    final initSettings = InitializationSettings(
      android: AndroidInitializationSettings('@mipmap/ic_launcher'),
      iOS: DarwinInitializationSettings(
        requestAlertPermission: true,
        requestBadgePermission: true,
        requestSoundPermission: true,
        notificationCategories: <DarwinNotificationCategory>[darwinCategory],
      ),
    );

    await _plugin.initialize(
      initSettings,
      onDidReceiveNotificationResponse: _handleNotificationResponse,
      onDidReceiveBackgroundNotificationResponse: notificationTapBackground,
    );

    await _plugin
        .resolvePlatformSpecificImplementation<
          AndroidFlutterLocalNotificationsPlugin
        >()
        ?.requestNotificationsPermission();

    await _plugin
        .resolvePlatformSpecificImplementation<
          IOSFlutterLocalNotificationsPlugin
        >()
        ?.requestPermissions(alert: true, badge: true, sound: true);
  }

  Future<void> processPendingActions() async {
    final prefs = await SharedPreferences.getInstance();
    final list = prefs.getStringList(_pendingActionKey) ?? <String>[];
    if (list.isEmpty) {
      return;
    }

    await prefs.remove(_pendingActionKey);

    for (final item in list) {
      final decoded = jsonDecode(item) as Map<String, dynamic>;
      final actionId = decoded['actionId'] as String?;
      final payload = decoded['payload'] as String?;
      await _dispatchAction(actionId: actionId, payload: payload);
    }
  }

  Future<void> scheduleForMonth({
    required int year,
    required int month,
    required int quietHourStart,
    required int fallbackHour,
  }) async {
    final firstId = _firstNotificationId(year, month);
    final retryId = _retryNotificationId(year, month);

    await _plugin.cancel(firstId);
    await _plugin.cancel(retryId);

    final estFirst = TimeService.estFirstReminderAt(year, month);
    final localFirst = tz.TZDateTime.from(estFirst, tz.local);
    final firstDate = TimeService.nextEligibleLocal(
      candidate: TimeService.applyQuietHours(
        localTime: localFirst,
        quietHourStart: quietHourStart,
        fallbackHour: fallbackHour,
      ),
      quietHourStart: quietHourStart,
      fallbackHour: fallbackHour,
    );

    final retryDate = TimeService.nextEligibleLocal(
      candidate: DateTime(
        firstDate.year,
        firstDate.month,
        firstDate.day + 1,
        firstDate.hour,
        firstDate.minute,
      ),
      quietHourStart: quietHourStart,
      fallbackHour: fallbackHour,
    );

    await _schedule(
      id: firstId,
      title: 'Rent check ($month/$year)',
      body: 'Was rent paid this month?',
      date: firstDate,
      payload: jsonEncode(<String, dynamic>{
        'year': year,
        'month': month,
        'isRetry': false,
      }),
    );

    await _schedule(
      id: retryId,
      title: 'Rent check retry ($month/$year)',
      body: 'Please confirm rent payment status.',
      date: retryDate,
      payload: jsonEncode(<String, dynamic>{
        'year': year,
        'month': month,
        'isRetry': true,
      }),
    );
  }

  Future<void> cancelForMonth(int year, int month) async {
    await _plugin.cancel(_firstNotificationId(year, month));
    await _plugin.cancel(_retryNotificationId(year, month));
  }

  Future<void> cancelAll() => _plugin.cancelAll();

  Future<void> _schedule({
    required int id,
    required String title,
    required String body,
    required DateTime date,
    required String payload,
  }) async {
    final tzDate = tz.TZDateTime.from(date, tz.local);
    await _plugin.zonedSchedule(
      id,
      title,
      body,
      tzDate,
      const NotificationDetails(
        android: AndroidNotificationDetails(
          'rent_channel',
          'Rent reminders',
          channelDescription: 'Monthly rent confirmation reminders',
          importance: Importance.high,
          priority: Priority.high,
          actions: <AndroidNotificationAction>[
            AndroidNotificationAction(yesActionId, 'Yes'),
            AndroidNotificationAction(noActionId, 'No'),
          ],
        ),
        iOS: DarwinNotificationDetails(categoryIdentifier: 'rent_actions'),
      ),
      payload: payload,
      androidScheduleMode: AndroidScheduleMode.exactAllowWhileIdle,
    );
  }

  Future<void> _handleNotificationResponse(NotificationResponse response) {
    return _dispatchAction(
      actionId: response.actionId,
      payload: response.payload,
    );
  }

  Future<void> _dispatchAction({
    required String? actionId,
    required String? payload,
  }) async {
    if (actionId != yesActionId && actionId != noActionId) {
      return;
    }
    if (payload == null) {
      return;
    }

    final decoded = jsonDecode(payload) as Map<String, dynamic>;
    final year = decoded['year'] as int;
    final month = decoded['month'] as int;
    final isRetry = decoded['isRetry'] as bool? ?? false;

    await _onAction(
      NotificationActionEvent(
        year: year,
        month: month,
        isYes: actionId == yesActionId,
        isRetry: isRetry,
      ),
    );
  }

  int _firstNotificationId(int year, int month) {
    return year * 100 + month;
  }

  int _retryNotificationId(int year, int month) {
    return 100000 + year * 100 + month;
  }
}