codenuk_frontend_mine/AUTH_IMPLEMENTATION.md

Authentication Implementation

Overview

This document describes the authentication system implementation with proper error handling, separate signup/signin routes, and email verification flow.

Architecture

Backend (User Auth Service)

• Port: 8011
• Base URL: http://localhost:8011
• Database: PostgreSQL
• Features: JWT authentication, email verification, session management

Frontend (Next.js App)

• Port: 3001
• Base URL: http://localhost:3001
• Framework: Next.js 15.4.6 with TypeScript
• UI: Tailwind CSS + shadcn/ui components

Routes Structure

Frontend Routes

/signup          - User registration page
/signin          - User login page  
/auth            - Redirects to /signin (legacy support)
/verify-email    - Email verification page (handled by backend redirect)

Backend API Endpoints

POST /api/auth/register     - User registration
POST /api/auth/login        - User login
GET  /api/auth/verify-email - Email verification (redirects to frontend)
POST /api/auth/logout       - User logout
POST /api/auth/refresh      - Token refresh
GET  /api/auth/me           - Get user profile

User Flow

1. Registration Flow

1. User visits /signup
2. Fills out registration form
3. Submits form → POST /api/auth/register
4. Backend creates user account and sends verification email
5. Frontend shows success message and redirects to /signin after 3 seconds
6. User receives email with verification link

2. Email Verification Flow

1. User clicks verification link in email
2. Link points to: http://localhost:8011/api/auth/verify-email?token=<token>
3. Backend verifies token and redirects to: http://localhost:3001/signin?verified=true
4. Frontend displays success message: "Email verified successfully! You can now sign in to your account."

3. Login Flow

1. User visits /signin
2. Fills out login form
3. Submits form → POST /api/auth/login
4. Backend validates credentials and returns JWT tokens
5. Frontend stores tokens and redirects to dashboard (/)

Error Handling

Backend Error Responses

All API endpoints return consistent error format:

{
  "success": false,
  "error": "Error type",
  "message": "Detailed error message"
}

Frontend Error Handling

• Network Errors: Display user-friendly messages
• API Errors: Show specific error messages from backend
• Validation Errors: Client-side validation with immediate feedback
• Authentication Errors: Clear messaging for login/registration issues

Common Error Scenarios

Registration Errors

• Email already exists: "An account with this email already exists"
• Username taken: "Username is already taken"
• Invalid email format: "Please enter a valid email address"
• Weak password: "Password must be at least 8 characters long"
• Missing fields: "Please fill in all required fields"

Login Errors

• Invalid credentials: "Invalid email or password"
• Email not verified: "Please verify your email before signing in"
• Account locked: "Account is temporarily locked due to multiple failed attempts"

Email Verification Errors

• Invalid token: "Verification link is invalid or has expired"
• Already verified: "Email is already verified"
• Token expired: "Verification link has expired. Please request a new one"

Components Structure

Signup Flow

/signup
├── SignUpPage (main container)
├── SignUpForm (form component)
└── Success State (after registration)

Signin Flow

/signin
├── SignInPage (main container)
├── SignInForm (form component)
└── Verification Messages (from URL params)

API Integration

Authentication Handler (authenticationHandler.tsx)

• Handles API calls to backend
• Proper error propagation
• TypeScript interfaces for type safety

Key Functions

registerUser(data: RegisterData): Promise<ApiResponse>
loginUser(email: string, password: string): Promise<ApiResponse>

Security Features

Backend Security

• JWT token authentication
• Password hashing (bcrypt)
• Rate limiting on auth endpoints
• CORS configuration
• Helmet security headers
• Session management

Frontend Security

• Token storage in localStorage
• Automatic token refresh
• Secure API communication
• Input validation and sanitization

Environment Configuration

Backend (.env)

PORT=8011
FRONTEND_URL=http://localhost:3001
POSTGRES_HOST=localhost
POSTGRES_DB=user_auth
JWT_SECRET=your-secret-key
SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USER=your-email@gmail.com
SMTP_PASS=your-app-password

Frontend (.env.local)

NEXT_PUBLIC_API_URL=http://localhost:8011
NEXT_PUBLIC_FRONTEND_URL=http://localhost:3001

Testing the Implementation

1. Start Services

# Backend
cd automated-dev-pipeline
docker-compose up user-auth

# Frontend
cd codenuk-frontend-dark-theme
npm run dev

2. Test Registration

1. Visit http://localhost:3001/signup
2. Fill out registration form
3. Submit and check for success message
4. Check email for verification link

3. Test Email Verification

1. Click verification link in email
2. Should redirect to http://localhost:3001/signin?verified=true
3. Verify success message appears

4. Test Login

1. Visit http://localhost:3001/signin
2. Enter credentials
3. Should redirect to dashboard on success

Troubleshooting

Common Issues

1. CORS Errors

   • Check backend CORS configuration
   • Verify frontend URL in allowed origins

2. Email Not Sending

   • Check SMTP configuration in backend
   • Verify email credentials

3. Verification Link Not Working

   • Check frontend URL in backend configuration
   • Verify token expiration settings

4. Login Fails After Verification

   • Check if user is properly verified in database
   • Verify JWT token generation

Debug Steps

1. Check browser network tab for API calls
2. Check backend logs for errors
3. Verify database connections
4. Test API endpoints directly with Postman/curl

Future Enhancements

1. Password Reset Flow
2. Two-Factor Authentication
3. Social Login Integration
4. Account Lockout Protection
5. Session Management Dashboard
6. Audit Logging