import 'dart:convert';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:timezone/timezone.dart' as tz;

class NotificationManger {
  // private constructor to avoid create object
  NotificationManger._();

  static late FlutterLocalNotificationsPlugin localNotificationsPlugin;

  /// initialisation setting for all platform
  /// onNotificationPressed action when notification pressed to open tap
  /// onIOSNotificationPressed action when notification pressed
  /// to open tap in iOS versions older than 10
  static Future<void> initialisation(Function(NotificationResponse) onNotificationPressed, DidReceiveLocalNotificationCallback onIOSNotificationPressed) async {
    final FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
    // initialise the plugin. app_icon needs to be a added as a drawable resource to the Android head project
    const AndroidInitializationSettings initializationSettingsAndroid = AndroidInitializationSettings('@drawable/ic_stat_name');

    final DarwinInitializationSettings initializationSettingsDarwin = DarwinInitializationSettings(onDidReceiveLocalNotification: onIOSNotificationPressed);

    final InitializationSettings initializationSettings = InitializationSettings(android: initializationSettingsAndroid, iOS: initializationSettingsDarwin, macOS: initializationSettingsDarwin);
    localNotificationsPlugin = flutterLocalNotificationsPlugin;

    if (Platform.isIOS) {
      await localNotificationsPlugin.resolvePlatformSpecificImplementation<IOSFlutterLocalNotificationsPlugin>()?.requestPermissions(alert: true, badge: true, sound: true);
    } else if (Platform.isAndroid) {
      final AndroidFlutterLocalNotificationsPlugin? androidImplementation = localNotificationsPlugin.resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>();
      final bool granted = await androidImplementation?.requestNotificationsPermission() ?? false;
      if (!granted) {
        if (kDebugMode) {
          print("-------------------- Permission Granted ------------------------");
          print(granted);
        }
        await Permission.notification.request();
      }
    }

    await localNotificationsPlugin.initialize(initializationSettings, onDidReceiveNotificationResponse: onNotificationPressed);
  } // push new notification

  static AndroidNotificationDetails androidNotificationDetails(String? groupId, String? channelId) => AndroidNotificationDetails(
        channelId ?? 'com.hmg.atoms',
        'ATOMS',
        channelDescription: 'Push notification service for ATOMS',
        importance: Importance.max,
        priority: Priority.max,
        icon: "@drawable/ic_stat_name",
        playSound: true,
        channelShowBadge: true,
        visibility: NotificationVisibility.public,
        enableVibration: true,
        groupKey: groupId ?? 'com.hmg.atoms',
        setAsGroupSummary: false,
      );

  static DarwinNotificationDetails iosNotificationDetails(String? threadId) => DarwinNotificationDetails(categoryIdentifier: "atoms", threadIdentifier: threadId);

  static Future<void> showNotification({required BuildContext context, required String title, required String subtext, required int hashcode, String? payload}) async {
    var dataPayload = json.decode(payload ?? "{}");
    String? groupId = dataPayload["group_id"];
    NotificationDetails platformChannel = NotificationDetails(android: androidNotificationDetails(groupId, groupId), iOS: iosNotificationDetails(groupId), macOS: iosNotificationDetails(groupId));

    await localNotificationsPlugin.show(hashcode, title, subtext, platformChannel, payload: payload);

    // If there's a group_id, also show/update the summary notification
    if (groupId != null && Platform.isAndroid) {
      await _showGroupSummary(groupId);
    }
  }

  static final Map<String, int> _groupCounts = {};

  static Future<void> _showGroupSummary(String groupId) async {
    // Query actual active notifications from the system
    final androidPlugin = localNotificationsPlugin.resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>();

    final List<ActiveNotification>? activeNotifications = await androidPlugin?.getActiveNotifications();

    // Count notifications that actually exist in this group (exclude summary itself)
    int count = 0;
    if (activeNotifications != null) {
      count = activeNotifications.where((notification) {
        return notification.groupKey == groupId && notification.id != groupId.hashCode; // Exclude summary notification
      }).length;
    }

    // Fallback to in-memory count if query fails (for older Android versions)
    if (count == 0) {
      _groupCounts[groupId] = (_groupCounts[groupId] ?? 0) + 1;
      count = _groupCounts[groupId]!;
    }

    // Only show summary if we have 2+ notifications
    if (count < 2) return;

    final AndroidNotificationDetails summaryDetails = AndroidNotificationDetails(
      'com.hmg.atoms',
      'ATOMS',
      channelDescription: 'Push notification service for ATOMS',
      importance: Importance.max,
      priority: Priority.max,
      icon: "@drawable/ic_stat_name",
      groupKey: groupId,
      setAsGroupSummary: true,
      onlyAlertOnce: true,
      autoCancel: true,
      styleInformation: InboxStyleInformation(
        [],
        contentTitle: 'ATOMS',
        summaryText: 'You have $count new notifications',
      ),
    );

    // Use group_id's hashCode as the summary notification ID to ensure uniqueness
    final int summaryId = groupId.hashCode;

    await localNotificationsPlugin.show(
      summaryId,
      'ATOMS',
      '$count new notifications',
      NotificationDetails(android: summaryDetails),
    );
  }

  static Future scheduleNotification({int? id, String? title, String? body, String? payLoad, required DateTime scheduledNotificationDateTime}) async {
    return localNotificationsPlugin.zonedSchedule(
        id ?? 0,
        title,
        body,
        // tz.TZDateTime.now(tz.local).add(const Duration(seconds: 5)),
        tz.TZDateTime.from(
          scheduledNotificationDateTime,
          tz.local,
        ),
        NotificationDetails(android: androidNotificationDetails(null, null), iOS: iosNotificationDetails(null), macOS: iosNotificationDetails(null)),
        androidScheduleMode: AndroidScheduleMode.exactAllowWhileIdle,
        uiLocalNotificationDateInterpretation: UILocalNotificationDateInterpretation.absoluteTime);
  }

  static Future<void> cancelNotificationById(int notificationId) async {
    await localNotificationsPlugin.cancel(notificationId);
  }

  /// Show group summary notification (for background isolate)
  static Future<void> _showGroupSummaryBackground(String groupId, FlutterLocalNotificationsPlugin plugin) async {
    final AndroidNotificationDetails summaryDetails = AndroidNotificationDetails(
      'com.hmg.atoms',
      'ATOMS',
      channelDescription: 'Push notification service for ATOMS',
      importance: Importance.max,
      priority: Priority.max,
      icon: "@drawable/ic_stat_name",
      groupKey: groupId,
      setAsGroupSummary: true,
      autoCancel: true,
      onlyAlertOnce: true,
      styleInformation: InboxStyleInformation(
        [],
        contentTitle: 'ATOMS',
        summaryText: 'New notifications',
      ),
    );

    final int summaryId = groupId.hashCode;

    await plugin.show(
      summaryId,
      'ATOMS',
      'New notifications',
      NotificationDetails(android: summaryDetails),
    );
  }
}