added cargo files

PinePods-0.8.2/mobile/lib/repository/sembast/sembast_database_service.dart

@@ -0,0 +1,52 @@
+// Copyright 2020 Ben Hills and the project contributors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:path/path.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:sembast/sembast.dart';
+import 'package:sembast/sembast_io.dart';
+
+typedef DatabaseUpgrade = Future<void> Function(Database, int, int);
+
+/// Provides a database instance to other services and handles the opening
+/// of the Sembast DB.
+class DatabaseService {
+  Completer<Database>? _databaseCompleter;
+  String databaseName;
+  int? version = 1;
+  DatabaseUpgrade? upgraderCallback;
+
+  DatabaseService(
+    this.databaseName, {
+    this.version,
+    this.upgraderCallback,
+  });
+
+  Future<Database> get database async {
+    if (_databaseCompleter == null) {
+      _databaseCompleter = Completer();
+      await _openDatabase();
+    }
+
+    return _databaseCompleter!.future;
+  }
+
+  Future _openDatabase() async {
+    final appDocumentDir = await getApplicationDocumentsDirectory();
+    final dbPath = join(appDocumentDir.path, databaseName);
+    final database = await databaseFactoryIo.openDatabase(
+      dbPath,
+      version: version,
+      onVersionChanged: (db, oldVersion, newVersion) async {
+        if (upgraderCallback != null) {
+          await upgraderCallback!(db, oldVersion, newVersion);
+        }
+      },
+    );
+
+    _databaseCompleter!.complete(database);
+  }
+}