add structure

lib/model/shared_pref.dart

@@ -0,0 +1,76 @@
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:fcs/vo/report.dart';
+import 'dart:convert';
+
+import 'package:fcs/vo/user.dart';
+
+class SharedPref {
+  static final SharedPref instance = SharedPref._();
+  SharedPref._();
+
+  static Future<String> getLang() async {
+    SharedPreferences prefs = await SharedPreferences.getInstance();
+    return prefs.getString('language');
+  }
+
+  static Future<void> saveLang(String lang) async {
+    SharedPreferences prefs = await SharedPreferences.getInstance();
+    prefs.setString('language', lang);
+  }
+
+  static Future<void> saveUser(User user) async {
+    await _save("user", user.toJson());
+  }
+
+  static Future<void> saveReport(ReportFieldPositionSelection report) async {
+    await _save('report-${report.id}', report.toJson());
+  }
+
+  static Future<ReportFieldPositionSelection> getReport(String id) async {
+    try {
+      return ReportFieldPositionSelection.fromJson(await _read("report-$id"));
+    } catch (e) {
+      return null;
+    }
+  }
+
+  static Future<User> getUser() async {
+    try {
+      return User.fromJson(await _read("user"));
+    } catch (e) {
+      return null;
+    }
+  }
+
+  static Future<User> removeUser() async {
+    return await _remove("user");
+  }
+
+  static Future<void> saveSkippedRecoverEmail(bool skipped) async {
+    await _save("skipped_recovery_email", skipped);
+  }
+
+  static Future<bool> getSkippedRecoverEmail() async {
+    try {
+      bool _skipped = await _read("skipped_recovery_email");
+      return _skipped;
+    } catch (e) {
+      return null;
+    }
+  }
+
+  static _read(String key) async {
+    final prefs = await SharedPreferences.getInstance();
+    return json.decode(prefs.getString(key));
+  }
+
+  static _save(String key, value) async {
+    final prefs = await SharedPreferences.getInstance();
+    prefs.setString(key, json.encode(value));
+  }
+
+  static _remove(String key) async {
+    final prefs = await SharedPreferences.getInstance();
+    prefs.remove(key);
+  }
+}