retail-nest/docs/IMPLEMENTATION_SUMMARY.md

Authentication System Implementation Summary

Completed Components

1. Auth Module (src/modules/auth/)

• AuthController - Register, Login, Profile, Refresh endpoints
• AuthService - User validation, JWT generation, password hashing
• DTOs - LoginDto, RegisterDto, AuthResponseDto
• Strategies - JwtStrategy, LocalStrategy (Passport.js)
• Guards - JwtAuthGuard, LocalAuthGuard
• Interfaces - JwtPayload interface

2. Users Module (src/modules/users/)

• UsersController - CRUD operations (Admin only)
• UsersService - Business logic, validation
• UsersRepository - Data access layer
• User Entity - TypeORM entity with UserRole enum
• DTOs - CreateUserDto, UpdateUserDto, UserResponseDto

3. Common Module (src/common/)

• Decorators:

  • @CurrentUser() - Extract authenticated user
  • @Public() - Mark routes as public
  • @Roles(...) - Specify required roles

• Guards:

  • JwtAuthGuard - Global JWT authentication (respects @Public)
  • RolesGuard - Role-based access control

4. Database

• Migration - CreateUsersTable migration
• Seed - Default users (Admin, Manager, Cashier)
• DataSource - TypeORM configuration

5. Configuration

• Environment Variables - JWT_SECRET, DB config
• JWT Config - Token expiration, secret
• Database Config - PostgreSQL connection

---

Key Features Implemented

Security Features

• Bcrypt password hashing (10 rounds)
• JWT token authentication (1 day expiration)
• Password validation (min 8 chars, uppercase, lowercase, number)
• Password exclusion from API responses (@Exclude)
• Global authentication guards
• Role-based access control

User Roles

• ADMIN - Full access to all endpoints
• MANAGER - Product and category management
• CASHIER - Transaction processing
• USER - Read-only access

API Features

• Swagger documentation
• Global validation pipe
• CORS enabled
• Class serializer (excludes sensitive fields)
• Comprehensive error handling

---

File Structure

src/
├── modules/
│   ├── auth/
│   │   ├── dto/
│   │   │   ├── login.dto.ts
│   │   │   ├── register.dto.ts
│   │   │   ├── auth-response.dto.ts
│   │   │   └── index.ts
│   │   ├── guards/
│   │   │   ├── jwt-auth.guard.ts
│   │   │   └── local-auth.guard.ts
│   │   ├── interfaces/
│   │   │   └── jwt-payload.interface.ts
│   │   ├── strategies/
│   │   │   ├── jwt.strategy.ts
│   │   │   └── local.strategy.ts
│   │   ├── auth.controller.ts
│   │   ├── auth.service.ts
│   │   └── auth.module.ts
│   │
│   └── users/
│       ├── dto/
│       │   ├── create-user.dto.ts
│       │   ├── update-user.dto.ts
│       │   ├── user-response.dto.ts
│       │   └── index.ts
│       ├── entities/
│       │   └── user.entity.ts
│       ├── users.controller.ts
│       ├── users.service.ts
│       ├── users.repository.ts
│       └── users.module.ts
│
├── common/
│   ├── decorators/
│   │   ├── current-user.decorator.ts
│   │   ├── public.decorator.ts
│   │   ├── roles.decorator.ts
│   │   └── index.ts
│   └── guards/
│       ├── jwt-auth.guard.ts
│       ├── roles.guard.ts
│       └── index.ts
│
├── database/
│   ├── migrations/
│   │   └── 1704470000000-CreateUsersTable.ts
│   ├── seeds/
│   │   ├── users.seed.ts
│   │   └── run-seeds.ts
│   └── data-source.ts
│
├── config/
│   ├── app.config.ts
│   ├── database.config.ts
│   ├── jwt.config.ts
│   └── redis.config.ts
│
├── app.module.ts (updated with Auth & Users modules)
├── main.ts (updated with global pipes, guards, swagger)
└── app.controller.ts (marked as @Public)

---

API Endpoints

Public Endpoints

• GET / - Health check
• GET /health - Health status
• POST /api/auth/register - Register new user
• POST /api/auth/login - Login user

Protected Endpoints

• GET /api/auth/profile - Get current user (Authenticated)
• POST /api/auth/refresh - Refresh token (Authenticated)
• GET /api/users - List users (Admin/Manager)
• GET /api/users/:id - Get user (Admin/Manager)
• POST /api/users - Create user (Admin only)
• PATCH /api/users/:id - Update user (Admin only)
• DELETE /api/users/:id - Delete user (Admin only)

---

Environment Variables Required

# Application
NODE_ENV=development
PORT=3000
API_PREFIX=api

# Database
DB_HOST=localhost
DB_PORT=5432
DB_USERNAME=postgres
DB_PASSWORD=postgres
DB_DATABASE=retail_pos

# JWT
JWT_SECRET=retail-pos-super-secret-key-change-in-production-2025
JWT_EXPIRES_IN=1d

# CORS
CORS_ORIGIN=http://localhost:3000,capacitor://localhost

# Rate Limiting
THROTTLE_TTL=60
THROTTLE_LIMIT=100

# Bcrypt
BCRYPT_ROUNDS=10

---

Setup & Run Instructions

1. Install Dependencies (Already Done)

All required packages are installed:

• @nestjs/jwt
• @nestjs/passport
• passport, passport-jwt
• bcrypt
• class-validator, class-transformer

2. Run Database Migration

npm run migration:run

3. Seed Default Users

npm run seed:run

Default credentials:

• Admin: admin@retailpos.com / Admin123!
• Manager: manager@retailpos.com / Manager123!
• Cashier: cashier@retailpos.com / Cashier123!

4. Start Development Server

npm run start:dev

5. Access Swagger Documentation

http://localhost:3000/api/docs

---

Testing the System

1. Test Registration

curl -X POST http://localhost:3000/api/auth/register \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Test User",
    "email": "test@example.com",
    "password": "Test123!"
  }'

2. Test Login

curl -X POST http://localhost:3000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{
    "email": "admin@retailpos.com",
    "password": "Admin123!"
  }'

3. Test Protected Endpoint

curl -X GET http://localhost:3000/api/auth/profile \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"

4. Test Admin Endpoint

curl -X GET http://localhost:3000/api/users \
  -H "Authorization: Bearer YOUR_ADMIN_TOKEN"

---

Usage Examples

Protecting a Controller

@Controller('products')
@UseGuards(JwtAuthGuard)  // Protect entire controller
export class ProductsController {
  // All routes require authentication
}

Public Route

@Get('products')
@Public()  // Skip authentication
async findAll() {
  return this.productsService.findAll();
}

Role-Based Authorization

@Post('products')
@Roles(UserRole.ADMIN, UserRole.MANAGER)  // Only admin and manager
async create(@Body() dto: CreateProductDto) {
  return this.productsService.create(dto);
}

Get Current User

@Get('profile')
async getProfile(@CurrentUser() user: User) {
  // user contains: id, email, name, roles
  return user;
}

---

Implementation Details

Password Hashing

• Passwords are hashed in AuthService.register() using bcrypt
• Hash rounds: 10
• Validation: AuthService.validateUser() uses bcrypt.compare()

JWT Token Structure

{
  "sub": "user-uuid",
  "email": "user@example.com",
  "roles": ["admin"],
  "iat": 1704470400,
  "exp": 1704556800
}

Global Guards

Registered in app.module.ts:

1. JwtAuthGuard - Applied to all routes, respects @Public()
2. RolesGuard - Checks @Roles() decorator

Error Handling

• 400: Validation failed
• 401: Unauthorized (invalid credentials)
• 403: Forbidden (insufficient permissions)
• 409: Conflict (email already exists)
• 404: Not found

---

Best Practices Implemented

1. Password never returned in responses (@Exclude)
2. Proper separation of concerns (Controller → Service → Repository)
3. DTO validation with class-validator
4. Repository pattern for data access
5. Global guards for authentication
6. Role-based access control
7. Environment-based configuration
8. Swagger API documentation
9. TypeScript strict mode
10. Error handling and proper HTTP status codes

---

Next Steps / Enhancements

1. Refresh Token Implementation

   • Add refresh_token table
   • Implement token rotation
   • Add /auth/logout endpoint

2. Email Verification

   • Send verification email on registration
   • Add email_verified flag
   • Create verification endpoint

3. Password Reset

   • Forgot password flow
   • Reset token generation
   • Password reset endpoint

4. Two-Factor Authentication

   • TOTP implementation
   • QR code generation
   • 2FA verification

5. Rate Limiting

   • Add @Throttle() to auth endpoints
   • Implement IP-based rate limiting
   • Add account lockout after failed attempts

6. Audit Logging

   • Log all authentication events
   • Track login attempts
   • Monitor suspicious activity

7. Session Management

   • Track active sessions
   • Implement force logout
   • Session timeout handling

---

Documentation

• AUTH_SYSTEM.md - Complete authentication system documentation
• Swagger Docs - Interactive API documentation at /api/docs
• Code Comments - Inline documentation for all components

---

Summary

The authentication system is fully implemented and ready for use. All endpoints are functional, secure, and documented. The system follows NestJS best practices and provides a solid foundation for building the rest of the Retail POS API.

Key Achievements:

• JWT authentication with Passport.js
• Role-based access control (4 roles)
• Secure password handling
• Global authentication guards
• Comprehensive API documentation
• Database migrations and seeds
• Proper error handling
• TypeScript type safety
• Production-ready security features

The system is ready for integration with Products, Categories, Transactions, and Sync modules.