# 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

```bash
# 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
```bash
npm run migration:run
```

### 3. Seed Default Users
```bash
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
```bash
npm run start:dev
```

### 5. Access Swagger Documentation
```
http://localhost:3000/api/docs
```

---

## Testing the System

### 1. Test Registration
```bash
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
```bash
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
```bash
curl -X GET http://localhost:3000/api/auth/profile \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"
```

### 4. Test Admin Endpoint
```bash
curl -X GET http://localhost:3000/api/users \
  -H "Authorization: Bearer YOUR_ADMIN_TOKEN"
```

---

## Usage Examples

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

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

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

### Get Current User
```typescript
@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
```json
{
  "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.