Add base skeleton

moneymgr_mobile/lib/services/storage/secure_storage.dart

@@ -0,0 +1,42 @@
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'secure_storage.g.dart';
+
+@riverpod
+Future<SecureStorage> secureStorage(Ref ref) =>
+    SecureStorage.getInstance(keys: {'token'});
+
+class SecureStorage {
+  SecureStorage._(this._flutterSecureStorage, this._cache);
+
+  late final FlutterSecureStorage _flutterSecureStorage;
+
+  late final Map<String, String> _cache;
+
+  static Future<SecureStorage> getInstance({required Set<String> keys}) async {
+    const flutterSecureStorage = FlutterSecureStorage();
+    final cache = <String, String>{};
+    await keys
+        .map((key) => flutterSecureStorage.read(key: key).then((value) {
+      if (value != null) {
+        cache[key] = value;
+      }
+    }))
+        .wait;
+    return SecureStorage._(flutterSecureStorage, cache);
+  }
+
+  String? get(String key) => _cache[key];
+
+  Future<void> set(String key, String value) {
+    _cache[key] = value;
+    return _flutterSecureStorage.write(key: key, value: value);
+  }
+
+  Future<void> remove(String key) {
+    _cache.remove(key);
+    return _flutterSecureStorage.delete(key: key);
+  }
+}