# REST API with Authentication

## Vision

Build a production-ready REST API with robust authentication, demonstrating best practices for security, error handling, and API design.

## Goals

### Primary Goals
- **Secure authentication**: JWT-based auth with refresh tokens
- **Protected routes**: Middleware-based authorization
- **RESTful design**: Clean, consistent API endpoints
- **Production ready**: Proper error handling, validation, logging

### Success Metrics
- All endpoints respond in < 200ms
- 100% test coverage on auth logic
- Zero security vulnerabilities (npm audit)
- Clear API documentation with examples

## Target Users

- **API consumers**: Frontend apps, mobile clients, third-party integrations
- **Developers**: Building on top of this API infrastructure
- **Operations**: Deploying and monitoring in production

## Architecture

### Layers
1. **Route Layer**: Express routes and request handling
2. **Middleware Layer**: Authentication, validation, error handling
3. **Service Layer**: Business logic and data operations
4. **Data Layer**: Database access and models

### Technology Choices

**Why PostgreSQL?**
- ACID compliance for user data
- Excellent performance for relational queries
- Industry standard with great tooling

**Why JWT?**
- Stateless authentication (scales horizontally)
- Standard format (RFC 7519)
- Easy to implement and validate

**Why bcrypt?**
- Industry standard for password hashing
- Built-in salt generation
- Configurable cost factor

## API Design

### Endpoints

**Authentication**
- `POST /api/auth/register` - Create new user
- `POST /api/auth/login` - Login and get JWT
- `POST /api/auth/refresh` - Refresh expired token
- `POST /api/auth/logout` - Invalidate token

**Users**
- `GET /api/users/me` - Get current user (protected)
- `PUT /api/users/me` - Update current user (protected)
- `DELETE /api/users/me` - Delete account (protected)

### Security Measures
- Password strength requirements
- Rate limiting on auth endpoints
- JWT expiration (15 min access, 7 day refresh)
- HTTPS only in production
- Input validation and sanitization
- SQL injection prevention via parameterized queries

## Non-Goals

Out of scope for this project:

- ❌ Social login (OAuth, SAML)
- ❌ Email verification
- ❌ Password reset flow
- ❌ Multi-factor authentication
- ❌ Role-based access control (RBAC)
- ❌ API versioning (v1, v2)

These are valuable features but not in scope for this foundational implementation.

## Technical Requirements

### Performance
- API response time < 200ms (p95)
- Support 1000 concurrent connections
- Database connection pooling

### Reliability
- Graceful error handling with proper HTTP codes
- Database transaction support
- Health check endpoint
- Structured logging

### Security
- Passwords hashed with bcrypt (cost 12)
- JWT signed with RS256 or HS256
- Secrets in environment variables
- CORS configuration
- Helmet.js security headers

## Development Approach

### Phase 1: Database Setup
Establish database schema, migrations, and connection pooling.

### Phase 2: API Endpoints
Build core endpoints with proper validation and error handling.

### Phase 3: Authentication
Implement JWT-based authentication with middleware.

### Testing Strategy
- Unit tests for business logic
- Integration tests for API endpoints
- Security testing for auth flows

## Future Enhancements

Potential v2.0 features:

- OAuth social login
- Email verification flow
- Password reset with token
- Rate limiting per user
- API key authentication for services
- Audit logging for security events