worker/lib/features/favorites/README.md

# Favorites Feature

A complete favorites state management system for the Worker app using **Riverpod 3.0** with code generation and **Hive** for local persistence.

---

## 📁 File Structure

```
lib/features/favorites/
├── data/
│   ├── datasources/
│   │   └── favorites_local_datasource.dart      # Hive operations
│   └── models/
│       ├── favorite_model.dart                  # Hive model (TypeId: 28)
│       └── favorite_model.g.dart                # Generated adapter
├── domain/
│   └── entities/
│       └── favorite.dart                        # Business entity
├── presentation/
│   └── providers/
│       ├── favorites_provider.dart              # Riverpod providers
│       └── favorites_provider.g.dart            # Generated providers
├── INTEGRATION_SUMMARY.md                       # Complete documentation
├── USAGE_EXAMPLES.md                            # Code examples
└── README.md                                    # This file
```

---

## 🚀 Quick Start

### 1. Import Provider
```dart
import 'package:worker/features/favorites/presentation/providers/favorites_provider.dart';
```

### 2. Check if Product is Favorited
```dart
final isFavorited = ref.watch(isFavoriteProvider(productId));
```

### 3. Toggle Favorite
```dart
ref.read(favoritesProvider.notifier).toggleFavorite(productId);
```

### 4. Get Favorites Count
```dart
final count = ref.watch(favoriteCountProvider);
```

---

## 📦 Available Providers

| Provider | Type | Description |
|----------|------|-------------|
| `favoritesProvider` | `AsyncNotifier<Set<String>>` | Main favorites state |
| `isFavoriteProvider(productId)` | `Provider<bool>` | Check if product is favorited |
| `favoriteCountProvider` | `Provider<int>` | Total count of favorites |
| `favoriteProductIdsProvider` | `Provider<List<String>>` | All favorite product IDs |
| `favoritesLocalDataSourceProvider` | `Provider<DataSource>` | Database access |
| `currentUserIdProvider` | `Provider<String>` | Current user ID (TODO: auth) |

---

## 🎯 Common Use Cases

### Favorite Button in Product Card
```dart
class ProductCard extends ConsumerWidget {
  final String productId;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final isFavorited = ref.watch(isFavoriteProvider(productId));

    return IconButton(
      icon: Icon(
        isFavorited ? Icons.favorite : Icons.favorite_border,
        color: isFavorited ? Colors.red : Colors.grey,
      ),
      onPressed: () {
        ref.read(favoritesProvider.notifier).toggleFavorite(productId);
      },
    );
  }
}
```

### Favorites Count Badge
```dart
class FavoriteBadge extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final count = ref.watch(favoriteCountProvider);

    return Badge(
      label: Text('$count'),
      child: Icon(Icons.favorite),
    );
  }
}
```

### Display All Favorites
```dart
class FavoritesPage extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final favoritesAsync = ref.watch(favoritesProvider);

    return favoritesAsync.when(
      data: (favorites) => ListView.builder(
        itemCount: favorites.length,
        itemBuilder: (context, index) {
          final productId = favorites.elementAt(index);
          return ProductTile(productId: productId);
        },
      ),
      loading: () => const CustomLoadingIndicator(),
      error: (error, stack) => ErrorWidget(error),
    );
  }
}
```

---

## 🔧 Provider Methods

### Main Provider (`favoritesProvider.notifier`)

| Method | Description |
|--------|-------------|
| `addFavorite(productId)` | Add product to favorites |
| `removeFavorite(productId)` | Remove product from favorites |
| `toggleFavorite(productId)` | Toggle favorite status |
| `refresh()` | Reload favorites from database |
| `clearAll()` | Remove all favorites |

---

## 💾 Data Persistence

- **Storage**: Hive local database
- **Box**: `favorite_box` (HiveBoxNames.favoriteBox)
- **Model**: `FavoriteModel` (TypeId: 28)
- **Fields**:
  - `favoriteId`: Unique ID (userId_productId_timestamp)
  - `productId`: Product reference
  - `userId`: User reference
  - `createdAt`: Timestamp

---

## ⚠️ Important Notes

### TODO: Auth Integration
Currently using hardcoded userId (`'user_001'`). Replace when auth is ready:

```dart
// In favorites_provider.dart
@riverpod
String currentUserId(Ref ref) {
  // TODO: Replace with actual auth provider
  final user = ref.watch(authProvider).user;
  return user?.id ?? 'guest';
}
```

### Hive Box Initialization
Ensure the favorites box is opened in `main.dart`:

```dart
await Hive.openBox<FavoriteModel>(HiveBoxNames.favoriteBox);
```

---

## 📚 Documentation

- **[INTEGRATION_SUMMARY.md](./INTEGRATION_SUMMARY.md)** - Complete technical documentation
- **[USAGE_EXAMPLES.md](./USAGE_EXAMPLES.md)** - Comprehensive code examples

---

## ✅ Features

- ✅ Add/remove favorites
- ✅ Toggle favorite status
- ✅ Persistent storage (Hive)
- ✅ Multi-user support
- ✅ Optimistic updates
- ✅ Error handling
- ✅ Loading states
- ✅ Debug logging
- ✅ Auto-dispose providers

---

## 🧪 Testing

```dart
test('should add favorite', () async {
  final container = ProviderContainer();
  addTearDown(container.dispose);

  await container.read(favoritesProvider.notifier)
      .addFavorite('product_1');

  final favorites = await container.read(favoritesProvider.future);
  expect(favorites, contains('product_1'));
});
```

---

## 🎨 UI Integration Examples

See **[USAGE_EXAMPLES.md](./USAGE_EXAMPLES.md)** for:
- Favorite buttons with loading states
- Favorites page with pull-to-refresh
- Empty state handling
- Error state handling
- App lifecycle management
- Performance optimization

---

## 🐛 Debugging

All operations log to console:
```
[FavoritesProvider] Added favorite: product_123
[FavoritesLocalDataSource] Loaded 5 favorites for user: user_001
[FavoritesProvider] Error adding favorite: ...
```

---

## 📈 Performance

- **O(1)** favorite lookup using `Set<String>`
- **Auto-dispose** providers when not in use
- **Selective rebuilds** with `isFavoriteProvider`
- **Database compaction** available

---

## 🔮 Future Enhancements

- [ ] Remote API sync
- [ ] Offline queue
- [ ] Cross-device sync
- [ ] Batch operations
- [ ] Favorites collections
- [ ] Share favorites
- [ ] Analytics tracking

---

## 🆘 Troubleshooting

| Issue | Solution |
|-------|----------|
| Favorites not persisting | Check Hive box initialization in `main.dart` |
| State not updating | Use `ref.read()` for mutations, `ref.watch()` for listening |
| Performance issues | Use `isFavoriteProvider` instead of watching full `favoritesProvider` |

---

## 📞 Support

For detailed examples and advanced use cases, see:
- **[USAGE_EXAMPLES.md](./USAGE_EXAMPLES.md)**
- **[INTEGRATION_SUMMARY.md](./INTEGRATION_SUMMARY.md)**

---

**Status**: ✅ Ready for integration
**Version**: 1.0.0
**Last Updated**: 2024-10-24