# Backend API Documentation - Auth Service

Complete API documentation for implementing the backend for the DX Authentication Service.

## 📋 Overview

This authentication service provides QR code-based authentication with comprehensive device tracking for all DX projects (Dexar, Novo Markets, FastCheck, BackOffice).

**Base URL:**
- Development: `http://localhost:3000/api`
- Production: `https://api.dx-projects.com/api`

---

## 🔐 Endpoints

### 1. Generate QR Code

Generate a new QR code session for authentication.

**Endpoint:** `POST /auth/qr/generate`

**Request Body:**
```json
{
  "project": "dexar",
  "deviceInfo": {
    "deviceType": "desktop",
    "deviceOS": "windows",
    "context": "browser",
    "project": "dexar",
    "userAgent": "Mozilla/5.0...",
    "screenResolution": "1920x1080",
    "browserName": "Chrome",
    "browserVersion": "120.0.0"
  }
}
```

**Request Schema:**
| Field | Type | Required | Description |
|-------|------|----------|-------------|
| `project` | string | Yes | Project ID: dexar, novo, fastcheck, backoffice |
| `deviceInfo.deviceType` | string\|null | No | mobile, desktop, tablet |
| `deviceInfo.deviceOS` | string\|null | No | android, ios, windows, macos, linux |
| `deviceInfo.context` | string\|null | No | browser, application, telegram |
| `deviceInfo.project` | string | Yes | Same as root project |
| `deviceInfo.userAgent` | string | No | Browser user agent |
| `deviceInfo.screenResolution` | string | No | e.g. "1920x1080" |
| `deviceInfo.browserName` | string | No | Browser name |
| `deviceInfo.browserVersion` | string | No | Browser version |

**Response:** `200 OK`
```json
{
  "sessionId": "550e8400-e29b-41d4-a716-446655440000",
  "qrCode": "data:image/png;base64,iVBORw0KGgo...",
  "expiresAt": "2026-01-26T15:30:00.000Z",
  "expiresIn": 60
}
```

**QR Code Content Should Be:**
```json
{
  "sessionId": "550e8400-e29b-41d4-a716-446655440000",
  "apiUrl": "https://api.dx-projects.com/api"
}
```

---

### 2. Scan QR Code (Mobile Auth)

Scan and authenticate using a QR code session.

**Endpoint:** `POST /auth/qr/scan`

**Request Body:**
```json
{
  "sessionId": "550e8400-e29b-41d4-a716-446655440000",
  "deviceInfo": {
    "deviceType": "mobile",
    "deviceOS": "android",
    "context": "application",
    "project": "dexar",
    "userAgent": "Mozilla/5.0...",
    "screenResolution": "1080x2400",
    "browserName": "Chrome Mobile",
    "browserVersion": "120.0.0"
  }
}
```

**Response:** `200 OK`
```json
{
  "success": true,
  "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "userId": "user-123",
  "expiresAt": "2026-01-27T14:30:00.000Z",
  "message": "Authentication successful",
  "userInfo": {
    "username": "john_doe",
    "email": "john@example.com",
    "role": "admin"
  }
}
```

---

### 3. Check Auth Status (Polling)

Check if a QR session has been authenticated. Used for polling every 2 seconds.

**Endpoint:** `GET /auth/qr/status/:sessionId`

**Response (Not Authenticated):** `200 OK`
```json
{
  "authenticated": false
}
```

**Response (Authenticated):** `200 OK`
```json
{
  "authenticated": true,
  "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "userId": "user-123",
  "expiresAt": "2026-01-27T14:30:00.000Z",
  "userInfo": {
    "username": "john_doe",
    "email": "john@example.com",
    "role": "admin"
  }
}
```

---

### 4. Traditional Login

Username/password authentication (alternative to QR).

**Endpoint:** `POST /auth/login`

**Request Body:**
```json
{
  "username": "john_doe",
  "password": "secure_password_123",
  "deviceInfo": {
    "deviceType": "desktop",
    "deviceOS": "windows",
    "context": "browser",
    "project": "backoffice"
  }
}
```

**Response:** `200 OK`
```json
{
  "success": true,
  "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "userId": "user-123",
  "expiresAt": "2026-01-27T14:30:00.000Z",
  "message": "Login successful",
  "userInfo": {
    "username": "john_doe",
    "email": "john@example.com",
    "role": "admin"
  }
}
```

---

### 5. Validate Session

Validate an existing JWT token.

**Endpoint:** `POST /auth/validate`

**Headers:**
```
Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
```

**Request Body:**
```json
{
  "deviceInfo": {
    "deviceType": "desktop",
    "deviceOS": "windows",
    "context": "browser",
    "project": "dexar"
  }
}
```

**Response:** `200 OK`
```json
{
  "valid": true,
  "userId": "user-123",
  "expiresAt": "2026-01-27T14:30:00.000Z",
  "userInfo": {
    "username": "john_doe",
    "email": "john@example.com",
    "role": "admin"
  }
}
```

---

### 6. Logout

Invalidate current session.

**Endpoint:** `POST /auth/logout`

**Headers:**
```
Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
```

**Request Body:**
```json
{
  "deviceInfo": {
    "deviceType": "desktop",
    "deviceOS": "windows",
    "context": "browser",
    "project": "dexar"
  }
}
```

**Response:** `200 OK`
```json
{
  "success": true,
  "message": "Logged out successfully"
}
```

---

## 💾 Database Schema

### Sessions Table
```sql
CREATE TABLE auth_sessions (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  session_id VARCHAR(255) UNIQUE NOT NULL,
  project VARCHAR(50) NOT NULL,
  device_type VARCHAR(20),
  device_os VARCHAR(20),
  context VARCHAR(20),
  user_agent TEXT,
  screen_resolution VARCHAR(20),
  browser_name VARCHAR(50),
  browser_version VARCHAR(20),
  authenticated BOOLEAN DEFAULT FALSE,
  user_id UUID,
  ip_address VARCHAR(45),
  created_at TIMESTAMP DEFAULT NOW(),
  expires_at TIMESTAMP NOT NULL,
  authenticated_at TIMESTAMP,
  INDEX idx_session_id (session_id),
  INDEX idx_expires_at (expires_at),
  INDEX idx_user_id (user_id)
);
```

### Auth Logs Table
```sql
CREATE TABLE auth_logs (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID,
  project VARCHAR(50) NOT NULL,
  action VARCHAR(50) NOT NULL, -- login, logout, qr_scan, validate, qr_generate
  device_type VARCHAR(20),
  device_os VARCHAR(20),
  context VARCHAR(20),
  user_agent TEXT,
  ip_address VARCHAR(45),
  success BOOLEAN,
  error_message TEXT,
  created_at TIMESTAMP DEFAULT NOW(),
  INDEX idx_user_id (user_id),
  INDEX idx_created_at (created_at),
  INDEX idx_project (project)
);
```

---

## 🔒 Security Implementation

### Password Hashing
```javascript
const bcrypt = require('bcrypt');
const saltRounds = 12;

// Hash password
const hashedPassword = await bcrypt.hash(password, saltRounds);

// Verify password
const isValid = await bcrypt.compare(password, hashedPassword);
```

### JWT Token Generation
```javascript
const jwt = require('jsonwebtoken');

const token = jwt.sign(
  {
    userId: user.id,
    project: deviceInfo.project,
    deviceType: deviceInfo.deviceType
  },
  process.env.JWT_SECRET,
  { expiresIn: '24h' }
);
```

### QR Code Generation
```javascript
const QRCode = require('qrcode');

const qrData = {
  sessionId: sessionId,
  apiUrl: process.env.API_URL
};

const qrCodeImage = await QRCode.toDataURL(JSON.stringify(qrData));
```

---

## 🚀 Implementation Flow

### QR Authentication Flow

1. **Desktop Browser Requests QR Code**
   - POST `/auth/qr/generate` with desktop device info
   - Backend creates session in database
   - Returns QR code image

2. **Frontend Starts Polling**
   - Every 2 seconds: GET `/auth/qr/status/:sessionId`
   - Backend returns `{ authenticated: false }`

3. **Mobile App Scans QR**
   - Parse QR code to get sessionId
   - POST `/auth/qr/scan` with mobile device info
   - Backend authenticates user
   - Backend updates session as authenticated
   - Returns JWT token

4. **Desktop Polling Detects Auth**
   - Next poll returns `{ authenticated: true, token: "..." }`
   - Frontend stores token
   - Redirects to application

---

## 📊 Device Info Tracking

### When to Send Device Info

**Send device info on:**
- ✅ QR code generation (desktop)
- ✅ QR code scanning (mobile)
- ✅ Traditional login
- ✅ Session validation
- ✅ Logout

**Device Info Rules:**
- All fields except `project` are optional
- Send `null` for unknown values
- Never fail request if device info is incomplete
- Log all device info for analytics

---

## ⚠️ Error Handling

### Error Response Format
```json
{
  "error": true,
  "message": "Invalid credentials",
  "code": "INVALID_CREDENTIALS"
}
```

### Error Codes
| Code | HTTP Status | Description |
|------|-------------|-------------|
| `INVALID_PROJECT` | 400 | Unknown project identifier |
| `INVALID_SESSION` | 401 | Session not found or expired |
| `INVALID_CREDENTIALS` | 401 | Wrong username/password |
| `INVALID_TOKEN` | 401 | JWT token invalid or expired |
| `SESSION_EXPIRED` | 401 | QR code session expired |
| `RATE_LIMIT_EXCEEDED` | 429 | Too many requests |
| `SERVER_ERROR` | 500 | Internal server error |

---

## 🧪 Testing

### Test Data

**Test User:**
```json
{
  "username": "test_user",
  "password": "Test123!",
  "email": "test@dx-projects.com",
  "role": "user"
}
```

### Example cURL Commands

**Generate QR Code:**
```bash
curl -X POST http://localhost:3000/api/auth/qr/generate \
  -H "Content-Type: application/json" \
  -d '{
    "project": "dexar",
    "deviceInfo": {
      "deviceType": "desktop",
      "deviceOS": "windows",
      "context": "browser",
      "project": "dexar"
    }
  }'
```

**Check Status:**
```bash
curl http://localhost:3000/api/auth/qr/status/{sessionId}
```

**Login:**
```bash
curl -X POST http://localhost:3000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{
    "username": "test_user",
    "password": "Test123!",
    "deviceInfo": {
      "deviceType": "desktop",
      "deviceOS": "windows",
      "context": "browser",
      "project": "dexar"
    }
  }'
```

---

## 📌 Important Notes

1. **QR Code Expiration:** 60 seconds (configurable)
2. **JWT Token Expiration:** 24 hours (configurable)
3. **Polling Interval:** 2 seconds
4. **Rate Limiting:** 60 requests/minute per IP
5. **CORS:** Allow all project domains
6. **Session Cleanup:** Delete expired sessions every hour

---

## 🔧 Environment Variables

```env
# API Configuration
PORT=3000
API_URL=http://localhost:3000/api
NODE_ENV=development

# JWT
JWT_SECRET=your-super-secret-jwt-key-change-this
JWT_EXPIRATION=24h

# Database
DB_HOST=localhost
DB_PORT=5432
DB_NAME=dx_auth
DB_USER=postgres
DB_PASSWORD=your-password

# QR Code
QR_EXPIRATION=60
QR_SIZE=240

# CORS
CORS_ORIGINS=http://localhost:4200,http://localhost:4300,http://localhost:4400

# Rate Limiting
RATE_LIMIT_WINDOW=60000
RATE_LIMIT_MAX_REQUESTS=60
```

---

## 📚 Additional Resources

- **Frontend Integration:** See `HOW_TO_USE.md`
- **Project Setup:** See `README.md`
- **FastCheck APIs:** Reference similar implementation in FastCheck project

---

## 🆘 Support

For backend implementation questions:
- Email: backend@dx-projects.com
- Slack: #backend-auth
- Documentation: https://docs.dx-projects.com/auth