import 'package:flutter/material.dart';
import 'package:logging/logging.dart';
import 'package:relatica/services/network_status_service.dart';
import 'package:result_monad/result_monad.dart';
import 'package:uuid/uuid.dart';

import '../friendica_client/friendica_client.dart';
import '../friendica_client/paged_response.dart';
import '../friendica_client/pages_manager.dart';
import '../friendica_client/paging_data.dart';
import '../globals.dart';
import '../models/exec_error.dart';
import '../models/user_notification.dart';
import 'auth_service.dart';
import 'direct_message_service.dart';

class NotificationsManager extends ChangeNotifier {
  static final _logger = Logger('NotificationManager');
  final _notifications = <String, UserNotification>{};
  final _pm = PagesManager<List<UserNotification>, String>(
    idMapper: (nn) => nn.map((n) => n.id).toList(),
    onRequest: _clientGetNotificationsRequest,
  );

  List<UserNotification> get notifications {
    final result = List<UserNotification>.from(_notifications.values);
    result.sort((n1, n2) {
      if (n1.dismissed == n2.dismissed) {
        return n2.timestamp.compareTo(n1.timestamp);
      }

      if (n1.dismissed && !n2.dismissed) {
        return 1;
      }

      return -1;
    });

    return result;
  }

  void clear() {
    _notifications.clear();
  }

  FutureResult<List<UserNotification>, ExecError> updateNotifications() async {
    const initialPull = 25;
    final nn = <UserNotification>[];
    if (_pm.pages.isEmpty) {
      final result = await _pm.initialize(initialPull);
      result.andThenSuccess((response) => nn.addAll(response.data));
    } else {
      for (var i = 0; i < _pm.pages.length; i++) {
        if (i > 0 && i == _pm.pages.length - 1) {
          continue;
        }
        final page = _pm.pages[i];
        PagingData? pd;
        if (i == 0) {
          if (page.next == null) {
            _logger.severe(
                "Expected first page to have a next page so can query on this page of data but doesn't exist.");
            continue;
          }
          final response = await _clientGetNotificationsRequest(page.next!);
          response.match(
              onSuccess: (response) => pd = response.previous,
              onError: (error) =>
                  _logger.severe('Error getting previous page: $error'));
          if (pd == null && page.previous == null) {
            _logger.severe(
                'Next page returned no results and no previous page so need to re-initalize');
          } else {
            final response =
                await _clientGetNotificationsRequest(page.previous!);
            response.match(
                onSuccess: (response) => pd = response.next,
                onError: (error) =>
                    _logger.severe('Error getting previous page: $error'));
          }

          if (pd == null) {
            _logger.severe(
                'Previous and next page both returned nulls so need to reinitialize');
            _pm.clear();
            final result = await _pm.initialize(initialPull);
            result.andThenSuccess((response) => nn.addAll(response.data));
          }
        }

        if (page.next == null) {
          if (i != _pm.pages.length - 2) {
            _logger
                .severe('No forward paging data in middle page but expected');
          }
          continue;
        }

        final response = await _clientGetNotificationsRequest(page.next!);
        response.match(
            onSuccess: (response) => nn.addAll(response.data),
            onError: (error) =>
                _logger.severe('Error getting previous page: $error'));
      }
    }

    for (final n in nn) {
      _notifications[n.id] = n;
    }

    _notifications.removeWhere(
      (key, value) => value.type == NotificationType.direct_message,
    );
    getIt<NetworkStatusService>().startNotificationUpdate();
    await getIt<DirectMessageService>().updateThreads();
    getIt<NetworkStatusService>().finishNotificationUpdate();
    for (final n in buildUnreadMessageNotifications()) {
      _notifications[n.id] = n;
    }

    notifyListeners();
    return Result.ok(notifications);
  }

  FutureResult<List<UserNotification>, ExecError>
      loadNewerNotifications() async {
    final result = await _pm.previousFromBeginning();
    result.match(onSuccess: (response) {
      for (final n in response.data) {
        _notifications[n.id] = n;
      }
      notifyListeners();
    }, onError: (error) {
      _logger.info('Error getting more updates: $error');
    });

    return result.mapValue((response) => response.data);
  }

  FutureResult<List<UserNotification>, ExecError>
      loadOlderNotifications() async {
    final result = await _pm.nextFromEnd();
    result.match(onSuccess: (response) {
      for (final n in response.data) {
        _notifications[n.id] = n;
      }
      notifyListeners();
    }, onError: (error) {
      _logger.info('Error getting more updates: $error');
    });

    return result.mapValue((response) => response.data);
  }

  FutureResult<bool, ExecError> markSeen(UserNotification notification) async {
    final result =
        await NotificationsClient(getIt<AccountsService>().currentProfile)
            .clearNotification(notification);
    if (result.isSuccess) {
      notifyListeners();
    }

    updateNotifications();
    return result;
  }

  FutureResult<List<UserNotification>, ExecError> markAllAsRead() async {
    final result =
        await NotificationsClient(getIt<AccountsService>().currentProfile)
            .clearNotifications();
    if (result.isFailure) {
      return result.errorCast();
    }

    _pm.clear();
    _notifications.clear();
    return updateNotifications();
  }

  List<UserNotification> buildUnreadMessageNotifications() {
    final myId = getIt<AccountsService>().currentProfile.userId;
    final result =
        getIt<DirectMessageService>().getThreads(unreadyOnly: true).map((t) {
      final fromAccount = t.participants.firstWhere((p) => p.id != myId);
      final latestMessage =
          t.messages.reduce((s, m) => s.createdAt > m.createdAt ? s : m);
      return UserNotification(
          id: const Uuid().v4(),
          type: NotificationType.direct_message,
          fromId: fromAccount.id,
          fromName: fromAccount.name,
          fromUrl: fromAccount.profileUrl,
          timestamp: latestMessage.createdAt,
          iid: t.parentUri,
          dismissed: false,
          content: '${fromAccount.name} sent you a direct message',
          link: '');
    }).toList();

    return result;
  }

  static FutureResult<PagedResponse<List<UserNotification>>, ExecError>
      _clientGetNotificationsRequest(PagingData page) async {
    final result =
        await NotificationsClient(getIt<AccountsService>().currentProfile)
            .getNotifications(page);
    return result;
  }
}