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Welcome to the IntraChat-Android-FastAPI wiki!

🔧 API Endpoints

Authentication

Method	Endpoint	Description
POST	/register	Register new user
POST	/login	Login and get JWT token
POST	/delete_account	Delete user account (requires password)

Chat

Method	Endpoint	Description
WebSocket	/ws/{username}	Real-time messaging
GET	/messages	Get recent messages (last 100)
GET	/users	Get all registered users with profile photos

Files

Method	Endpoint	Description
POST	/upload	Upload a file (chat attachments)
GET	/uploads/{filename}	Download/view uploaded file
POST	/profile/upload_profile	Upload profile photo
GET	/uploads/profiles/{filename}	Get user profile photo

Static Files

Method	Endpoint	Description
GET	/	Web client (index.html)
GET	/chat.html	Chat interface
GET	/style.css	Stylesheets
GET	/app.js	JavaScript logic

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🛠️ Technologies Used

Backend

• FastAPI - Modern, fast web framework
• Uvicorn - ASGI server
• WebSockets - Real-time communication
• SQLite - Lightweight database
• JWT - Secure authentication
• Passlib - Password hashing
• Pillow - Image processing for profile photos
• Aiofiles - Async file operations

Web Client

• HTML5 - Semantic markup
• CSS3 - Modern styling with CSS variables (dark/light themes)
• Vanilla JavaScript - No frameworks, pure JS
• WebSocket API - Real-time messaging
• Fetch API - RESTful API calls
• LocalStorage - Client-side session management
• Responsive Design - Mobile-first approach

Android App

• Kotlin - Modern Android development
• Jetpack Compose - Declarative UI
• Room Database - Local data persistence
• Retrofit - HTTP client
• OkHttp - WebSocket client
• Coroutines - Asynchronous programming
• Material Design 3 - Modern UI components
• Coil - Image loading library

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🔒 Security Features

• 🔐 Password hashing with PBKDF2-SHA256
• 🎫 JWT token-based authentication (30-day expiry)
• 🛡️ CORS protection configured for LAN access
• 📝 Input sanitization for file uploads
• 🔒 Secure WebSocket connections
• 🚫 SQL injection prevention via parameterized queries
• 📁 File upload size limits and type validation
• 🗑️ Secure account deletion with password verification

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🐛 Troubleshooting

Server Issues

Problem: Server won't start

# Check if port 8000 is already in use
sudo lsof -i :8000

# Kill the process if needed
sudo kill -9 <PID>

Problem: Can't access from other devices

• ✅ Ensure server is running with --host 0.0.0.0
• ✅ Check firewall settings:

  sudo ufw allow 8000/tcp

• ✅ Verify all devices are on the same Wi-Fi network

Problem: Profile photos not loading

# Check uploads folder permissions
ls -la uploads/
chmod 755 uploads/
chmod 755 uploads/profiles/

Web Client Issues

Problem: Can't connect to server

• ✅ Check browser console (F12) for errors
• ✅ Verify server IP address is correct in URL
• ✅ Ensure server is running (http://IP:8000 should show login page)

Problem: WebSocket connection fails

• ✅ Check browser console for WebSocket errors
• ✅ Some browsers block ws:// on HTTPS pages (use HTTP for both)
• ✅ Restart server if WebSocket hangs

Problem: Theme not switching

• ✅ Clear browser cache (Ctrl+Shift+Delete)
• ✅ Check LocalStorage in DevTools (F12 → Application → LocalStorage)

Android App Issues

Problem: Build errors in Android Studio

# Clean and rebuild
./gradlew clean
./gradlew build

Problem: App can't connect to server

• ✅ Check ApiClient.kt for correct server IP (or use in-app settings)
• ✅ Ensure server is running and reachable
• ✅ Test connection in browser first: http://SERVER_IP:8000
• ✅ Check Logcat for detailed error messages

Problem: Profile photos not showing

• ✅ Grant storage permissions in Android settings
• ✅ Clear app cache: Settings → Apps → Intra → Storage → Clear Cache
• ✅ Re-upload photo from Settings screen

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