import 'package:shared_preferences/shared_preferences.dart'; import '../models/user_model.dart'; abstract class BillingService { Future purchasePro(); Future restorePurchases(); Future getCurrentPlan(); } class MockBillingService implements BillingService { static const _key = 'user_plan'; final SharedPreferences _prefs; MockBillingService(this._prefs); @override Future purchasePro() async { await Future.delayed(const Duration(seconds: 1)); await _prefs.setString(_key, 'vip'); return true; } @override Future restorePurchases() async { await Future.delayed(const Duration(seconds: 1)); return false; } @override Future getCurrentPlan() async { final value = _prefs.getString(_key); return value == 'vip' ? UserPlan.vip : UserPlan.free; } }