Add JWT authentication with password reset and 15 coding problems, and Google OAuth

[Aishwarya011k]

📋 Description

✨ What's Included

Authentication System

• User signup with email validation
• Secure login with JWT tokens (7-day expiration)
• Password hashing with bcrypt (10 rounds)
• Protected user profile endpoint
• Logout functionality

Password Reset

• Forgot password email request
• Secure token generation and hashing
• 15-minute token expiration
• SendGrid email integration with fallback
• Password update functionality

Coding Problems

• 15 problems across 5 test categories
• 5 test cases per problem (75 total)
• 3 difficulty levels: Easy, Medium, Hard
• Multi-language support: JavaScript, Python, Java, C, C++

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🧪 How to Test

Prerequisites

• Node.js 14+
• PostgreSQL 12+
• SendGrid API key (optional)

Setup Steps

1. Install dependencies

   npm install
   cd server && npm install && cd ..

2. Create database

   psql -U postgres
   CREATE DATABASE "coding-platform";

3. Create server/.env

   PORT=3001
   NODE_ENV=development
   DATABASE_URL=postgresql://postgres:YOUR_PASSWORD@localhost:5432/coding-platform
   JWT_SECRET=dev-secret-key
   SENDGRID_API_KEY=your-key-optional
   EMAIL_FROM=Coding Platform <noreply@codingplatform.com>
   FRONTEND_URL=http://localhost:3000
   
   # Google OAuth Configuration
   GOOGLE_CLIENT_ID=your-google-client-id.apps.googleusercontent.com
   GOOGLE_CLIENT_SECRET=your-google-client-secret

4. Start backend (Terminal 1)

   cd server && npm run dev

   Expected: ✅ Server listening on port 3001

5. Start frontend (Terminal 2)

   npm start

   Expected: App opens at http://localhost:3000

Test Cases

Test 1: Sign Up

• Click "Sign in" → "Create new account"
• Enter name, email, password
• Verify: Account page shows user info

Test 2: Sign In

• Enter email and password
• Verify: Logged in, profile visible

Test 3: Google OAuth Sign In

• Click "Continue with Google"
• Complete Google authentication
• Verify: Logged in with profile picture and "Signed in with Google"

Test 4: Account Linking

• Sign up with email/password
• Sign out, then sign in with Google using same email
• Verify: Account linked, both methods work

Test 5: View Profile

• After login, verify name and email displayed
• For Google users: verify profile picture shows

Test 6: Forgot Password

• Click "Forgot password?" → Enter email
• Verify: Reset link appears in terminal/email
• Note: Only works for email/password users

Test 7: Reset Password

• Use reset link, enter new password
• Verify: Login works with new password

Test 8: View Problems

• After login, scroll to "Browse Problems"
• Verify: All 15 problems visible with difficulty levels

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🔒 Security

✅ Passwords encrypted with bcrypt (10 rounds)
✅ JWT tokens expire after 7 days
✅ Reset tokens expire after 15 minutes
✅ Google OAuth 2.0 secure authentication
✅ Account linking prevents duplicate accounts
✅ Profile data securely retrieved from Google
✅ .env file gitignored (no secrets exposed)
✅ SQL injection prevented (parameterized queries)
✅ Input validation on all endpoints
✅ Helmet security headers enabled
✅ CORS configured

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📊 Database Schema

CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name VARCHAR(100),
  email VARCHAR(100) UNIQUE NOT NULL,
  password VARCHAR(255),
  google_id VARCHAR(255),
  profile_picture TEXT,
  auth_provider VARCHAR(20) DEFAULT 'local',
  password_reset_token VARCHAR(255),
  password_reset_expiry TIMESTAMP,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

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New OAuth Fields:

• google_id: Google OAuth unique identifier
• profile_picture: User's profile image URL
• auth_provider: "local" or "google" (determines auth method)

🎯 API Endpoints

Method	Path	Protected	Description
POST	/api/auth/signup	No	Register new user
POST	/api/auth/signin	No	Login, get JWT token
POST	/api/auth/signout	No	Logout
GET	/api/auth/profile	Yes	Get user profile
POST	/api/auth/forgot-password	No	Request password reset
POST	/api/auth/reset-password	No	Complete password reset
GET	/api/auth/google	No	Initiate Google OAuth
GET	/api/auth/google/callback	No	Handle Google OAuth callback

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✅ Conclusion

This PR introduces a complete authentication system with secure password reset functionality, 15 comprehensive coding problems, and seamless Google OAuth integration. Users can now register, login securely with email/password or Google, reset forgotten passwords, and access coding challenges.