retail/docs/RIVERPOD_DI_MIGRATION.md

# Riverpod Dependency Injection Migration

**Date**: October 10, 2025
**Status**: ✅ **COMPLETE**

---

## Problem

The authentication system was trying to use GetIt for dependency injection, causing the following error:

```
Bad state: GetIt: Object/factory with type AuthRepository is not registered inside GetIt.
```

Additionally, there was a circular dependency error in the auth provider:

```
Bad state: Tried to read the state of an uninitialized provider.
This generally means that have a circular dependency, and your provider end-up depending on itself.
```

---

## Solution

Migrated from GetIt to **pure Riverpod dependency injection**. All dependencies are now managed through Riverpod providers.

---

## Changes Made

### 1. Updated Auth Provider (`lib/features/auth/presentation/providers/auth_provider.dart`)

**Before:**
```dart
import '../../../../core/di/injection_container.dart';

@riverpod
AuthRepository authRepository(Ref ref) {
  return sl<AuthRepository>();  // Using GetIt
}

@riverpod
class Auth extends _$Auth {
  @override
  AuthState build() {
    _checkAuthStatus();  // Circular dependency - calling async in build
    return const AuthState();
  }
}
```

**After:**
```dart
import '../../../../core/network/dio_client.dart';
import '../../../../core/storage/secure_storage.dart';
import '../../data/datasources/auth_remote_datasource.dart';
import '../../data/repositories/auth_repository_impl.dart';

/// Provider for DioClient (singleton)
@Riverpod(keepAlive: true)
DioClient dioClient(Ref ref) {
  return DioClient();
}

/// Provider for SecureStorage (singleton)
@Riverpod(keepAlive: true)
SecureStorage secureStorage(Ref ref) {
  return SecureStorage();
}

/// Provider for AuthRemoteDataSource
@Riverpod(keepAlive: true)
AuthRemoteDataSource authRemoteDataSource(Ref ref) {
  final dioClient = ref.watch(dioClientProvider);
  return AuthRemoteDataSourceImpl(dioClient: dioClient);
}

/// Provider for AuthRepository
@Riverpod(keepAlive: true)
AuthRepository authRepository(Ref ref) {
  final remoteDataSource = ref.watch(authRemoteDataSourceProvider);
  final secureStorage = ref.watch(secureStorageProvider);
  final dioClient = ref.watch(dioClientProvider);

  return AuthRepositoryImpl(
    remoteDataSource: remoteDataSource,
    secureStorage: secureStorage,
    dioClient: dioClient,
  );
}

@riverpod
class Auth extends _$Auth {
  @override
  AuthState build() {
    // Don't call async operations in build
    return const AuthState();
  }

  /// Initialize auth state - call this on app start
  Future<void> initialize() async {
    // Auth initialization logic moved here
  }
}
```

### 2. Removed GetIt Setup (`lib/main.dart`)

**Before:**
```dart
import 'core/di/service_locator.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Hive.initFlutter();

  // Setup dependency injection
  await setupServiceLocator();  // GetIt initialization

  runApp(const ProviderScope(child: RetailApp()));
}
```

**After:**
```dart
void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Hive.initFlutter();

  // Run the app with Riverpod (no GetIt needed - using Riverpod for DI)
  runApp(const ProviderScope(child: RetailApp()));
}
```

### 3. Initialize Auth State on App Start (`lib/app.dart`)

**Before:**
```dart
class RetailApp extends ConsumerWidget {
  const RetailApp({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return MaterialApp(/* ... */);
  }
}
```

**After:**
```dart
class RetailApp extends ConsumerStatefulWidget {
  const RetailApp({super.key});

  @override
  ConsumerState<RetailApp> createState() => _RetailAppState();
}

class _RetailAppState extends ConsumerState<RetailApp> {
  @override
  void initState() {
    super.initState();
    // Initialize auth state on app start
    WidgetsBinding.instance.addPostFrameCallback((_) {
      ref.read(authProvider.notifier).initialize();
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(/* ... */);
  }
}
```

---

## Dependency Injection Architecture

### Provider Hierarchy

```
DioClient (singleton)
    ↓
SecureStorage (singleton)
    ↓
AuthRemoteDataSource (uses DioClient)
    ↓
AuthRepository (uses AuthRemoteDataSource, SecureStorage, DioClient)
    ↓
Auth State Notifier (uses AuthRepository)
```

### Provider Usage

```dart
// Access DioClient
final dioClient = ref.read(dioClientProvider);

// Access SecureStorage
final secureStorage = ref.read(secureStorageProvider);

// Access AuthRepository
final authRepository = ref.read(authRepositoryProvider);

// Access Auth State
final authState = ref.watch(authProvider);

// Call Auth Methods
await ref.read(authProvider.notifier).login(email: '...', password: '...');
await ref.read(authProvider.notifier).logout();
```

---

## Benefits of Riverpod DI

1. **No Manual Registration**: Providers are automatically available
2. **Type Safety**: Compile-time type checking
3. **Dependency Graph**: Riverpod manages dependencies automatically
4. **Testability**: Easy to override providers in tests
5. **Code Generation**: Auto-generates provider code
6. **No Circular Dependencies**: Proper lifecycle management
7. **Singleton Management**: Use `keepAlive: true` for singletons

---

## GetIt Files (Now Unused)

These files are no longer needed but kept for reference:

- `lib/core/di/service_locator.dart` - Old GetIt setup
- `lib/core/di/injection_container.dart` - Old GetIt container

You can safely delete these files if GetIt is not used anywhere else in the project.

---

## Migration Checklist

- [x] Create Riverpod providers for DioClient
- [x] Create Riverpod providers for SecureStorage
- [x] Create Riverpod providers for AuthRemoteDataSource
- [x] Create Riverpod providers for AuthRepository
- [x] Remove GetIt references from auth_provider.dart
- [x] Fix circular dependency in Auth.build()
- [x] Remove GetIt setup from main.dart
- [x] Initialize auth state in app.dart
- [x] Regenerate code with build_runner
- [x] Test compilation (0 errors)

---

## Build Status

```
✅ Errors: 0
✅ Warnings: 61 (info-level only)
✅ Build: SUCCESS
✅ Code Generation: COMPLETE
```

---

## Testing the App

1. **Run the app**:
   ```bash
   flutter run
   ```

2. **Expected behavior**:
   - App starts and shows login page (if not authenticated)
   - Login with valid credentials
   - Token is saved and added to Dio headers automatically
   - Navigate to Settings to see user profile
   - Logout button works correctly
   - After logout, back to login page

---

## Key Takeaways

1. **Riverpod providers replace GetIt** for dependency injection
2. **Use `keepAlive: true`** for singleton providers (DioClient, SecureStorage)
3. **Never call async operations in `build()`** - use separate initialization methods
4. **Initialize auth state in app.dart** using `addPostFrameCallback`
5. **All dependencies are managed through providers** - no manual registration needed

---

## Next Steps (Optional)

If you want to further clean up:

1. Delete unused GetIt files:
   ```bash
   rm lib/core/di/service_locator.dart
   rm lib/core/di/injection_container.dart
   ```

2. Remove GetIt from dependencies in `pubspec.yaml`:
   ```yaml
   # Remove this line:
   get_it: ^8.0.2
   ```

3. Run `flutter pub get` to update dependencies

---

**Status**: ✅ **MIGRATION COMPLETE - NO ERRORS**

The app now uses pure Riverpod for all dependency injection!