TKK_E32232282/Source Code Mobile/notification_provider.dart

65 lines
1.8 KiB
Dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:firebase_database/firebase_database.dart';
import '../models/notification_model.dart';
import '../services/firebase_service.dart';
import '../services/notification_service.dart';
class NotificationProvider extends ChangeNotifier {
List<NotificationModel> _notifications = [];
List<NotificationModel> get notifications => _notifications;
/// Track how many notifications existed on the previous update so we can
/// detect newly added entries and fire an OS push for them.
int _previousCount = 0;
StreamSubscription<DatabaseEvent>? subscription;
void startListening() {
subscription?.cancel();
subscription = FirebaseService.notificationRef.onValue.listen((event) {
final prev = _previousCount;
_notifications = [];
if (event.snapshot.value == null) {
_previousCount = 0;
notifyListeners();
return;
}
final data = Map<dynamic, dynamic>.from(event.snapshot.value as Map);
data.forEach((key, value) {
_notifications.add(
NotificationModel.fromMap(Map<dynamic, dynamic>.from(value)),
);
});
_notifications = _notifications.reversed.toList();
_previousCount = _notifications.length;
// If new entries appeared, fire an OS notification for the latest one
if (_notifications.isNotEmpty && _notifications.length > prev) {
final latest = _notifications.first;
NotificationService.showNotification(
title: latest.title,
body: latest.message,
id: DateTime.now().millisecondsSinceEpoch ~/ 1000,
);
}
notifyListeners();
});
}
@override
void dispose() {
subscription?.cancel();
super.dispose();
}
}