Finished custom sorting of deliveries

lib/feature/delivery/overview/service/reorder_service.dart

@@ -0,0 +1,53 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:hl_lieferservice/model/tour.dart';
+import 'package:path_provider/path_provider.dart';
+
+import '../model/sorting_information.dart';
+
+class ReorderService {
+  get _path async {
+    final dir = await getApplicationDocumentsDirectory();
+    final date = DateTime.now();
+    final filename =
+        "custom_sort_${date.year}_${date.month}_${date.day}.json";
+    final path = "${dir.path}/$filename";
+
+    return path;
+  }
+
+  Future<File> get _file async {
+    final path = await _path;
+    final file = File(path);
+
+    return file;
+  }
+
+  Future<void> saveSortingInformation(SortingInformationContainer container) async {
+    (await _file).writeAsString(jsonEncode(container.toJson()));
+  }
+
+  Future<void> initializeTour(Tour tour) async {
+    (await _file).create();
+    SortingInformationContainer container = SortingInformationContainer(sorting: []);
+    
+    for (final (index, delivery) in tour.deliveries.indexed) {
+      container.sorting.add(
+        SortingInformation(deliveryId: delivery.id, position: index),
+      );
+    }
+
+    (await _file).writeAsString(jsonEncode(container.toJson()));
+  }
+
+  bool orderInformationExist() {
+    return false;
+  }
+
+  Future<SortingInformationContainer> loadSortingInformation() async {
+    return SortingInformationContainer.fromJson(
+        jsonDecode(await (await _file).readAsString()),
+    );
+  }
+}