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Inventory Management

Manajemen inventori dengan stock tracking dan low stock alerts

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🎯 Overview

Inventory adalah salah satu fitur utama dalam MStore Mobile yang menyediakan fungsionalitas untuk manajemen inventori dengan stock tracking dan low stock alerts.

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📋 Features

  • ✅ Product CRUD operations
  • ✅ Stock tracking
  • ✅ Low stock alerts
  • ✅ Stock adjustment
  • ✅ Stock opname
  • ✅ Batch operations
  • ✅ Category management
  • ✅ Barcode scanning

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🏗️ Architecture

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BLoC Implementation

BLoC: InventoryBloc, CashierInventoryBloc, CreateInventoryBloc, DetailInventoryBloc 
// Events
abstract class InventoryEvent extends Equatable {}

class LoadInventory extends InventoryEvent {}
class CreateInventory extends InventoryEvent {}
class UpdateInventory extends InventoryEvent {}
class DeleteInventory extends InventoryEvent {}

// States
abstract class InventoryState extends Equatable {}

class InventoryInitial extends InventoryState {}
class InventoryLoading extends InventoryState {}
class InventoryLoaded extends InventoryState {}
class InventoryError extends InventoryState {}

// BLoC
class InventoryBloc extends Bloc<InventoryEvent, InventoryState> {
  final InventoryRepository _repository;
  
  InventoryBloc({required InventoryRepository repository})
      : _repository = repository,
        super(InventoryInitial()) {
    on<LoadInventory>(_onLoad);
    on<CreateInventory>(_onCreate);
    on<UpdateInventory>(_onUpdate);
    on<DeleteInventory>(_onDelete);
  }
  
  Future<void> _onLoad(
    LoadInventory event,
    Emitter<InventoryState> emit,
  ) async {
    emit(InventoryLoading());
    
    final result = await _repository.getInventorys();
    
    result.fold(
      (failure) => emit(InventoryError(failure.message)),
      (data) => emit(InventoryLoaded(data)),
    );
  }
}

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Repository Pattern

abstract class InventoryRepository {
  Future<Either<Failure, List<Inventory>>> getInventorys();
  Future<Either<Failure, Inventory>> getInventoryById(String id);
  Future<Either<Failure, Inventory>> createInventory(Inventory data);
  Future<Either<Failure, Inventory>> updateInventory(String id, Inventory data);
  Future<Either<Failure, void>> deleteInventory(String id);
}

class InventoryRepositoryImpl implements InventoryRepository {
  final InventoryApi _api;
  final InventoryLocalRepository _localRepo;
  
  @override
  Future<Either<Failure, List<Inventory>>> getInventorys() async {
    try {
      // Try local first (offline-first)
      final local = await _localRepo.getInventorys();
      
      // Sync with API in background
      final result = await _api.getInventorys();
      result.fold(
        (failure) => null,
        (data) => _localRepo.saveInventorys(data),
      );
      
      return Right(local.isNotEmpty ? local : result.getOrElse(() => []));
    } catch (e) {
      return Left(UnexpectedFailure(e.toString()));
    }
  }
}

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📡 API Integration

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Endpoints

  • /api/v1/inventory/*
  • /api/v1/products/*

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Request/Response Examples

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Get List

GET /api/v1/inventory/*
Authorization: Bearer {access_token}
Response: 
{
  "success": true,
  "data": [
    {
      "id": "123",
      "name": "Example",
      "created_at": "2024-10-14T10:00:00Z"
    }
  ],
  "pagination": {
    "page": 1,
    "limit": 20,
    "total": 100
  }
}

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💾 Local Database (Isar)

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Schema

  • ProductLocal
  • InventoryLocal
@collection
class InventoryLocal {
  Id id = Isar.autoIncrement;
  
  @Index()
  String? inventoryId;
  
  String? name;
  DateTime? createdAt;
  DateTime? updatedAt;
  DateTime? syncedAt;
  
  bool? isSynced;
  bool? isDeleted;
}

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Queries

// Get all
final items = await isar.inventoryLocals.where().findAll();

// Get by ID
final item = await isar.inventoryLocals
    .filter()
    .inventoryIdEqualTo(id)
    .findFirst();

// Search
final results = await isar.inventoryLocals
    .filter()
    .nameContains(query, caseSensitive: false)
    .findAll();

// Get unsynced
final unsynced = await isar.inventoryLocals
    .filter()
    .isSyncedEqualTo(false)
    .findAll();

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🔄 Offline-First Strategy

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Write Operations

  1. Save to local Isar immediately
  2. Show success to user
  3. Add to sync queue
  4. Background sync when online
  5. Update with server response

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Read Operations

  1. Read from local Isar (fast)
  2. Show to user immediately
  3. Background fetch from API
  4. Update local cache if changed
  5. Notify UI if data updated

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Conflict Resolution

  • Strategy: Last-write-wins
  • Timestamp: Server timestamp as source of truth
  • Logging: All conflicts logged for audit

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🎨 UI Components

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Main Screen

class InventoryPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => getIt<InventoryBloc>()..add(LoadInventory()),
      child: Scaffold(
        appBar: AppBar(title: Text('Inventory Management')),
        body: BlocBuilder<InventoryBloc, InventoryState>(
          builder: (context, state) {
            if (state is InventoryLoading) {
              return Center(child: CircularProgressIndicator());
            }
            
            if (state is InventoryError) {
              return ErrorWidget(message: state.message);
            }
            
            if (state is InventoryLoaded) {
              return InventoryListView(items: state.items);
            }
            
            return SizedBox.shrink();
          },
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () => _navigateToCreate(context),
          child: Icon(Icons.add),
        ),
      ),
    );
  }
}

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🧪 Testing

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Unit Tests

void main() {
  group('InventoryBloc', () {
    late InventoryBloc bloc;
    late MockInventoryRepository mockRepository;

    setUp(() {
      mockRepository = MockInventoryRepository();
      bloc = InventoryBloc(repository: mockRepository);
    });

    tearDown(() {
      bloc.close();
    });

    test('initial state is InventoryInitial', () {
      expect(bloc.state, equals(InventoryInitial()));
    });

    blocTest<InventoryBloc, InventoryState>(
      'emits [Loading, Loaded] when Load succeeds',
      build: () {
        when(() => mockRepository.getInventorys()).thenAnswer(
          (_) async => Right([Inventory(id: '1', name: 'Test')]),
        );
        return bloc;
      },
      act: (bloc) => bloc.add(LoadInventory()),
      expect: () => [
        InventoryLoading(),
        isA<InventoryLoaded>(),
      ],
    );
  });
}

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📊 Performance Considerations

  • Lazy Loading: Load data on demand
  • Pagination: Implement pagination for large datasets
  • Caching: Cache frequently accessed data
  • Indexing: Use Isar indexes for fast queries
  • Background Sync: Sync in background to avoid blocking UI

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🔐 Security

  • Authorization: Check user permissions before operations
  • Data Encryption: Sensitive data encrypted in Isar
  • Input Validation: Validate all user inputs
  • Audit Trail: Log all operations for audit

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📱 Platform-Specific

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iOS

  • Use Cupertino widgets
  • Follow iOS HIG
  • Handle safe area insets

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Android

  • Use Material widgets
  • Follow Material Design
  • Handle back button
Last Updated: October 14, 2024
Status: ✅ Production Ready