Feed stream with changenotifier

lib/main.dart

@@ -1,11 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:maggs_victory_voyage/services/feed_provider.dart';
+import 'package:provider/provider.dart';
 import 'package:maggs_victory_voyage/services/db_helper.dart';
 import 'pages/splash_page.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   await DbHelper.init();
-  runApp(const Application());
+  runApp(
+    MultiProvider(
+      providers: [
+        ChangeNotifierProvider(
+          create: (_) => Feed(),
+        )
+      ],
+      child: const Application(),
+    ),
+  );
 }
 
 class Application extends StatelessWidget {

lib/models/feed_item.dart

@@ -0,0 +1,16 @@
+class FeedItem {
+  final String text;
+  final DateTime timestamp;
+
+  FeedItem.fromMap(Map<String, dynamic> map)
+      : text = map['text'],
+        timestamp = DateTime.parse(map['timestamp']);
+
+  @override
+  bool operator ==(Object other) {
+    if (other is FeedItem) {
+      return other.timestamp == timestamp;
+    }
+    return false;
+  }
+}

lib/pages/splash_page.dart

@@ -1,6 +1,8 @@
 import 'package:flutter/material.dart';
 import 'package:maggs_victory_voyage/services/db_helper.dart';
+import 'package:provider/provider.dart';
 
+import '../services/feed_provider.dart';
 import 'login_page.dart';
 
 class SplashPage extends StatefulWidget {
@@ -41,6 +43,8 @@ class _SplashPageState extends State<SplashPage> {
     if (DbHelper.currentUser == null) {
       return const LoginPage();
     }
+
+    Provider.of<Feed>(context, listen: false).feed;
     return Scaffold(
       body: const Column(
         children: [

lib/services/db_helper.dart

@@ -2,6 +2,8 @@ import 'package:flutter/foundation.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:supabase_flutter/supabase_flutter.dart';
 
+import '../models/feed_item.dart';
+
 class DbHelper {
   static Future<SharedPreferences> get _prefs async =>
       SharedPreferences.getInstance();
@@ -58,9 +60,21 @@ class DbHelper {
     return false;
   }
 
+  static Future<List<FeedItem>> fetchFeed() async {
+    List<FeedItem> items = [];
+    final res = await _supabase.from('feed').select();
+    for (final map in res) {
+      items.add(FeedItem.fromMap(map));
+    }
+    return items;
+  }
+
   static void logout() async {
     final prefs = await _prefs;
     bool success = await prefs.remove('username');
     _supabase.auth.signOut();
   }
+
+  static Stream<List<Map<String, dynamic>>> get feedStream =>
+      _supabase.from('feed').stream(primaryKey: ['timestamp']);
 }

lib/services/feed_provider.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/material.dart';
+import 'package:maggs_victory_voyage/services/db_helper.dart';
+
+import '../models/feed_item.dart';
+
+class Feed extends ChangeNotifier {
+  final List<FeedItem> _feed = [];
+  Stream? feedStream;
+
+  List<FeedItem> get feed {
+    if (feedStream == null) {
+      DbHelper.fetchFeed().then((value) {
+        _feed.clear();
+        _feed.addAll(value);
+      });
+      feedStream = DbHelper.feedStream;
+      feedStream!.listen(
+        (event) => _updateFeed(event),
+      );
+    }
+    return _feed;
+  }
+
+  void _updateFeed(List<Map<String, dynamic>> data) {
+    final List<FeedItem> newFeed =
+        data.map((e) => FeedItem.fromMap(e)).toList();
+
+    final newItems =
+        newFeed.where((element) => !_feed.contains(element)).toList();
+
+    if (newItems.isNotEmpty) {
+      _feed.addAll(newItems);
+      notifyListeners();
+    }
+  }
+}