Start writing the web app

Signed-off-by: Nikolai Rodionov <allanger@posteo.com>

lib/core/tokens/data/token_storage_repository.dart

@@ -0,0 +1,42 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+const accessTokenKey = "access_token";
+const refreshTokenKey = "refresh_token";
+
+final tokenStorageRepositoryProvider = Provider<TokenStorageRepository>((ref) {
+  return TokenStorageRepository();
+});
+
+// Secure storage backend for storing tokens in the browser
+class TokenStorageRepository {
+  static const _storage = FlutterSecureStorage();
+  TokenStorageRepository();
+
+  // Store the refresh token in the storage
+  Future<void> storeRefreshToken(String token) async {
+    await _storage.write(key: refreshTokenKey, value: token);
+  }
+
+  // Store the access token in the storage
+  Future<void> storeAccessToken(String token) async {
+    await _storage.write(key: accessTokenKey, value: token);
+  }
+
+  // Get the acccess token from the storage
+  Future<String?> getAccessToken() async {
+    final token = await _storage.read(key: accessTokenKey);
+    return token;
+  }
+
+  // Get the refresh token from the storage
+  Future<String?> getRefreshToken() async {
+    final token = await _storage.read(key: refreshTokenKey);
+    return token;
+  }
+
+  Future<void> clearStorage() async {
+    await _storage.delete(key: refreshTokenKey);
+    await _storage.delete(key: accessTokenKey);
+  }
+}