Refactor abstract class to separate file

mobile/lib/shared/services/json_cache.dart

@@ -0,0 +1,49 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:path_provider/path_provider.dart';
+
+abstract class JsonCache<T> {
+  final String cacheFileName;
+
+  JsonCache(this.cacheFileName);
+
+  Future<File> _getCacheFile() async {
+    final basePath = await getTemporaryDirectory();
+    final basePathName = basePath.path;
+
+    final file = File("$basePathName/$cacheFileName.bin");
+
+    return file;
+  }
+
+  Future<bool> isValid() async {
+    final file = await _getCacheFile();
+    return await file.exists();
+  }
+
+  Future<void> invalidate() async {
+    final file = await _getCacheFile();
+    await file.delete();
+  }
+
+  Future<void> putRawData(dynamic data) async {
+    final jsonString = json.encode(data);
+    final file = await _getCacheFile();
+
+    if (!await file.exists()) {
+      await file.create();
+    }
+
+    await file.writeAsString(jsonString);
+  }
+
+  dynamic readRawData() async {
+    final file = await _getCacheFile();
+    final data = await file.readAsString();
+    return json.decode(data);
+  }
+
+  void put(T data);
+  Future<T> get();
+}