feat: Add polling position change notifier

webapp/frontend/lib/main.dart

@@ -3,6 +3,8 @@ import 'package:get_10101/auth/auth_service.dart';
 import 'package:get_10101/common/version_service.dart';
 import 'package:get_10101/logger/logger.dart';
 import 'package:get_10101/routes.dart';
+import 'package:get_10101/trade/position_change_notifier.dart';
+import 'package:get_10101/trade/position_service.dart';
 import 'package:get_10101/trade/quote_change_notifier.dart';
 import 'package:get_10101/trade/quote_service.dart';
 import 'package:get_10101/settings/settings_service.dart';
@@ -22,6 +24,7 @@ void main() {
     Provider(create: (context) => const VersionService()),
     ChangeNotifierProvider(create: (context) => WalletChangeNotifier(const WalletService())),
     ChangeNotifierProvider(create: (context) => QuoteChangeNotifier(const QuoteService())),
+    ChangeNotifierProvider(create: (context) => PositionChangeNotifier(const PositionService())),
     Provider(create: (context) => const SettingsService()),
     Provider(create: (context) => AuthService())
   ];

webapp/frontend/lib/trade/order_and_position_table.dart

@@ -1,8 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:get_10101/common/color.dart';
-import 'package:get_10101/logger/logger.dart';
-import 'package:get_10101/trade/open_position_service.dart';
+import 'package:get_10101/trade/position_change_notifier.dart';
+import 'package:get_10101/trade/position_service.dart';
 import 'package:intl/intl.dart';
+import 'package:provider/provider.dart';
 
 class OrderAndPositionTable extends StatefulWidget {
   const OrderAndPositionTable({super.key});
@@ -53,21 +54,18 @@ class OpenPositionTable extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return FutureBuilder<List<Position>>(
-      future: OpenPositionsService.fetchOpenPositions(),
-      builder: (context, snapshot) {
-        if (snapshot.connectionState == ConnectionState.waiting) {
-          return const Center(child: CircularProgressIndicator());
-        } else if (snapshot.hasError) {
-          logger.i("received ${snapshot.error}");
-          return const Center(child: Text('Error loading data'));
-        } else if (!snapshot.hasData || snapshot.data!.isEmpty) {
-          return const Center(child: Text('No data available'));
-        } else {
-          return buildTable(snapshot.data!);
-        }
-      },
-    );
+    final positionChangeNotifier = context.watch<PositionChangeNotifier>();
+    final positions = positionChangeNotifier.getPositions();
+
+    if (positions == null) {
+      return const Center(child: CircularProgressIndicator());
+    }
+
+    if (positions.isEmpty) {
+      return const Center(child: Text('No data available'));
+    } else {
+      return buildTable(positions);
+    }
   }
 
   Widget buildTable(List<Position> positions) {

webapp/frontend/lib/trade/position_change_notifier.dart

@@ -0,0 +1,38 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:get_10101/logger/logger.dart';
+import 'package:get_10101/trade/position_service.dart';
+
+class PositionChangeNotifier extends ChangeNotifier {
+  final PositionService service;
+  late Timer timer;
+
+  List<Position>? _positions;
+
+  PositionChangeNotifier(this.service) {
+    _refresh();
+    Timer.periodic(const Duration(seconds: 2), (timer) async {
+      _refresh();
+    });
+  }
+
+  void _refresh() async {
+    try {
+      final positions = await service.fetchOpenPositions();
+      _positions = positions;
+
+      super.notifyListeners();
+    } catch (error) {
+      logger.e(error);
+    }
+  }
+
+  List<Position>? getPositions() => _positions;
+
+  @override
+  void dispose() {
+    super.dispose();
+    timer.cancel();
+  }
+}

webapp/frontend/lib/trade/open_position_service.dart → webapp/frontend/lib/trade/position_service.dart

@@ -3,10 +3,10 @@ import 'package:flutter/cupertino.dart';
 import 'package:get_10101/common/http_client.dart';
 import 'package:get_10101/common/model.dart';
 
-class OpenPositionsService {
-  const OpenPositionsService();
+class PositionService {
+  const PositionService();
 
-  static Future<List<Position>> fetchOpenPositions() async {
+  Future<List<Position>> fetchOpenPositions() async {
     final response = await HttpClientManager.instance.get(Uri(path: '/api/positions'));
 
     if (response.statusCode == 200) {