# Architecture - spotlight.cam

**Technical architecture and implementation details**

---

## System Architecture

```
┌─────────────────┐
│   Web Browser   │  (PWA - React + Vite + Tailwind)
│   (Android/iOS) │
└────────┬────────┘
         │ HTTPS
         ▼
┌─────────────────┐
│     nginx       │  (Reverse Proxy, Port 8080)
│   (Port 8080)   │
└────────┬────────┘
         │
    ┌────┴────┐
    │         │
    ▼         ▼
┌────────┐ ┌────────────┐
│Frontend│ │  Backend   │  (Node.js + Express + Socket.IO)
│(Vite)  │ │  (planned) │
│:5173   │ │  :3000     │
└────────┘ └──────┬─────┘
                  │
                  ▼
           ┌─────────────┐
           │ PostgreSQL  │  (Database)
           │  (planned)  │
           └─────────────┘

WebRTC P2P Connection:
Browser A ←──────────────────────→ Browser B
          (Direct P2P via WebRTC)
               ↑
               │ (Signaling only via WebSocket)
               │
           Backend
```

---

## Docker Compose Services

### Current Setup

**nginx:**
- Image: `nginx:alpine`
- Port: 8080 (host) → 80 (container)
- Volumes: nginx config files
- Purpose: Reverse proxy, serves frontend, will proxy `/api/*` to backend

**frontend:**
- Build: `./frontend/Dockerfile`
- Internal port: 5173 (Vite dev server)
- Volumes: hot reload support
- Environment: `NODE_ENV=development`, `VITE_HOST=0.0.0.0`

### Planned Services

**backend:**
- Build: `./backend/Dockerfile`
- Internal port: 3000
- Environment: DB credentials, JWT secret, etc.
- Depends on: `db`

**db:**
- Image: `postgres:15-alpine`
- Port: 5432 (internal only)
- Volumes: PostgreSQL data persistence
- Environment: POSTGRES_USER, POSTGRES_PASSWORD, POSTGRES_DB

---

## nginx Configuration

**File:** `nginx/conf.d/default.conf`

### Upstream
```nginx
upstream frontend {
    server frontend:5173;
}

upstream backend {
    server backend:3000;  # planned
}
```

### Routes
- `/` → frontend (React app)
- `/api/*` → backend (REST API) - planned
- `/socket.io/*` → backend (WebSocket) - planned

### Features
- WebSocket support (Upgrade headers for Vite HMR and future Socket.IO)
- Client max body size: 500M (for large video uploads via link)
- Proxy headers: X-Real-IP, X-Forwarded-For, etc.

---

## Frontend Architecture

### Tech Stack
- **React 18** - UI library
- **Vite** - Build tool, dev server
- **Tailwind CSS v3.4.0** - Styling (NOT v4 - compatibility issues)
- **React Router** - Client-side routing
- **Context API** - State management (will add Socket.IO client, WebRTC logic)

### Folder Structure
```
frontend/
├── public/               # Static assets
├── src/
│   ├── main.jsx         # Entry point
│   ├── App.jsx          # Router setup
│   ├── pages/           # Page components
│   │   ├── LoginPage.jsx
│   │   ├── RegisterPage.jsx
│   │   ├── EventsPage.jsx
│   │   ├── EventChatPage.jsx
│   │   ├── MatchChatPage.jsx    # ← Main WebRTC mockup
│   │   ├── RatePartnerPage.jsx
│   │   └── HistoryPage.jsx
│   ├── components/
│   │   └── layout/
│   │       ├── Layout.jsx
│   │       └── Navbar.jsx
│   ├── contexts/
│   │   └── AuthContext.jsx      # Mock auth (will become real)
│   ├── mocks/           # Mock data (will be replaced by API calls)
│   │   ├── users.js
│   │   ├── events.js
│   │   ├── messages.js
│   │   ├── matches.js
│   │   └── ratings.js
│   └── index.css        # Tailwind imports
├── tailwind.config.js   # Tailwind v3.4.0 config
├── vite.config.js       # Vite config
└── package.json
```

### State Management

**Current (Mock):**
- AuthContext: mock login/register/logout with localStorage
- Local state in components

**Planned:**
- Socket.IO client for real-time chat
- WebRTC connection state
- Redux/Zustand (if needed for complex state)

---

## Backend Architecture (Planned)

### Tech Stack
- **Node.js** - Runtime
- **Express** - Web framework
- **Socket.IO** - WebSocket for chat and WebRTC signaling
- **PostgreSQL** - Database
- **Prisma/Knex** - ORM/Query builder
- **bcrypt** - Password hashing
- **JWT** - Authentication tokens

### Folder Structure (Proposed)
```
backend/
├── src/
│   ├── server.js        # Entry point
│   ├── app.js           # Express app setup
│   ├── routes/          # REST API routes
│   │   ├── auth.js      # POST /api/auth/register, /login
│   │   ├── users.js     # GET /api/users/me, etc.
│   │   ├── events.js    # GET /api/events, etc.
│   │   ├── matches.js   # POST /api/matches, etc.
│   │   └── ratings.js   # POST /api/ratings, etc.
│   ├── controllers/     # Business logic
│   ├── models/          # Database models (Prisma schema or Knex queries)
│   ├── middleware/      # Auth, validation, error handling
│   ├── socket/          # Socket.IO event handlers
│   │   ├── chat.js      # Event chat, private chat
│   │   └── webrtc.js    # WebRTC signaling (SDP/ICE)
│   └── utils/           # Helpers
├── prisma/              # (if using Prisma)
│   └── schema.prisma    # Database schema
├── migrations/          # Database migrations
├── .env.example
└── package.json
```

### API Endpoints (Planned)

**Auth:**
- `POST /api/auth/register` - Create account
- `POST /api/auth/login` - Login, get JWT
- `POST /api/auth/logout` - Logout (optional, JWT is stateless)

**Users:**
- `GET /api/users/me` - Get current user
- `PATCH /api/users/me` - Update profile
- `GET /api/users/:id` - Get user profile

**Events:**
- `GET /api/events` - List all events
- `GET /api/events/:id` - Event details
- `POST /api/events/:id/join` - Join event

**Matches:**
- `GET /api/matches` - User's match history
- `POST /api/matches` - Create match
- `PATCH /api/matches/:id` - Update match status

**Ratings:**
- `POST /api/ratings` - Rate partner
- `GET /api/ratings/user/:id` - User's ratings
- `GET /api/ratings/stats/:id` - Rating statistics

**Reports:**
- `POST /api/reports` - Report user

---

## Database Schema

### Tables

**users:**
```sql
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  username VARCHAR(50) UNIQUE NOT NULL,
  email VARCHAR(255) UNIQUE NOT NULL,
  password_hash VARCHAR(255) NOT NULL,
  avatar VARCHAR(255),
  created_at TIMESTAMP DEFAULT NOW(),
  updated_at TIMESTAMP DEFAULT NOW()
);
```

**events:**
```sql
CREATE TABLE events (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  location VARCHAR(255) NOT NULL,
  start_date DATE NOT NULL,
  end_date DATE NOT NULL,
  worldsdc_id VARCHAR(100) UNIQUE,
  participants_count INT DEFAULT 0,
  description TEXT,
  created_at TIMESTAMP DEFAULT NOW()
);
```

**chat_rooms:**
```sql
CREATE TABLE chat_rooms (
  id SERIAL PRIMARY KEY,
  event_id INT REFERENCES events(id),
  type VARCHAR(20) NOT NULL, -- 'event' or 'private'
  created_at TIMESTAMP DEFAULT NOW()
);
```

**messages:**
```sql
CREATE TABLE messages (
  id SERIAL PRIMARY KEY,
  room_id INT REFERENCES chat_rooms(id) ON DELETE CASCADE,
  user_id INT REFERENCES users(id),
  content TEXT NOT NULL,
  type VARCHAR(20) NOT NULL, -- 'text', 'link', 'video'
  created_at TIMESTAMP DEFAULT NOW()
);
```

**matches:**
```sql
CREATE TABLE matches (
  id SERIAL PRIMARY KEY,
  user1_id INT REFERENCES users(id),
  user2_id INT REFERENCES users(id),
  event_id INT REFERENCES events(id),
  room_id INT REFERENCES chat_rooms(id),
  status VARCHAR(20) DEFAULT 'pending', -- 'pending', 'accepted', 'completed'
  created_at TIMESTAMP DEFAULT NOW(),
  CONSTRAINT unique_match UNIQUE (user1_id, user2_id, event_id)
);
```

**ratings:**
```sql
CREATE TABLE ratings (
  id SERIAL PRIMARY KEY,
  match_id INT REFERENCES matches(id),
  rater_id INT REFERENCES users(id),
  rated_id INT REFERENCES users(id),
  score INT CHECK (score >= 1 AND score <= 5),
  comment TEXT,
  would_collaborate_again BOOLEAN DEFAULT FALSE,
  created_at TIMESTAMP DEFAULT NOW(),
  CONSTRAINT unique_rating UNIQUE (match_id, rater_id, rated_id)
);
```

### Indexes (Performance)
```sql
CREATE INDEX idx_messages_room_id ON messages(room_id);
CREATE INDEX idx_messages_created_at ON messages(created_at);
CREATE INDEX idx_matches_user1_id ON matches(user1_id);
CREATE INDEX idx_matches_user2_id ON matches(user2_id);
CREATE INDEX idx_matches_event_id ON matches(event_id);
CREATE INDEX idx_ratings_rated_id ON ratings(rated_id);
```

---

## WebSocket (Socket.IO) Events

### Client → Server

**Connection:**
- `connect` - Client connects
- `disconnect` - Client disconnects

**Event Chat:**
- `join_event_room` - Join event chat room
  - Payload: `{ eventId: number }`
- `leave_event_room` - Leave event chat room
  - Payload: `{ eventId: number }`
- `send_event_message` - Send message to event chat
  - Payload: `{ eventId: number, content: string }`

**Private Chat:**
- `join_private_room` - Join private match room
  - Payload: `{ matchId: number }`
- `send_private_message` - Send message to match partner
  - Payload: `{ matchId: number, content: string }`

**Matchmaking:**
- `send_match_request` - Request match with user
  - Payload: `{ targetUserId: number, eventId: number }`
- `accept_match_request` - Accept match request
  - Payload: `{ matchId: number }`

**WebRTC Signaling:**
- `webrtc_offer` - Send SDP offer
  - Payload: `{ matchId: number, offer: RTCSessionDescriptionInit }`
- `webrtc_answer` - Send SDP answer
  - Payload: `{ matchId: number, answer: RTCSessionDescriptionInit }`
- `webrtc_ice_candidate` - Send ICE candidate
  - Payload: `{ matchId: number, candidate: RTCIceCandidate }`

### Server → Client

**Event Chat:**
- `event_message` - New message in event chat
  - Payload: `{ id, roomId, userId, username, avatar, content, createdAt }`
- `active_users` - List of active users in event
  - Payload: `{ users: Array }`

**Private Chat:**
- `private_message` - New message from partner
  - Payload: `{ id, matchId, userId, username, content, createdAt }`

**Matchmaking:**
- `match_request_received` - Someone wants to match
  - Payload: `{ matchId, fromUser }`
- `match_accepted` - Match request accepted
  - Payload: `{ matchId, partner }`

**WebRTC Signaling:**
- `webrtc_offer` - Received SDP offer from partner
- `webrtc_answer` - Received SDP answer from partner
- `webrtc_ice_candidate` - Received ICE candidate from partner

---

## WebRTC P2P Architecture

### Components

**RTCPeerConnection:**
- Manages P2P connection between two browsers
- Handles ICE candidate gathering
- Manages connection state (new, connecting, connected, failed)

**RTCDataChannel:**
- Binary data transfer channel
- Ordered, reliable delivery (like TCP)
- Max message size: 16KB-64KB (browser dependent)
- Used for video file chunks

**STUN Server:**
- Public STUN server (e.g., Google: `stun:stun.l.google.com:19302`)
- Discovers public IP address
- Helps with NAT traversal

**TURN Server (Optional):**
- Relay server for difficult NAT/firewall scenarios
- Only ~10% of connections need TURN
- Can use free services or self-host

### File Transfer Flow

**1. Initiate Connection:**
```javascript
// Sender creates offer
const pc = new RTCPeerConnection({ iceServers: [{ urls: 'stun:stun.l.google.com:19302' }] });
const dataChannel = pc.createDataChannel('fileTransfer');
const offer = await pc.createOffer();
await pc.setLocalDescription(offer);
// Send offer to receiver via Socket.IO
socket.emit('webrtc_offer', { matchId, offer });
```

**2. Exchange SDP/ICE:**
```javascript
// Receiver receives offer via Socket.IO
socket.on('webrtc_offer', async ({ offer }) => {
  await pc.setRemoteDescription(offer);
  const answer = await pc.createAnswer();
  await pc.setLocalDescription(answer);
  socket.emit('webrtc_answer', { matchId, answer });
});

// Both peers exchange ICE candidates
pc.onicecandidate = (event) => {
  if (event.candidate) {
    socket.emit('webrtc_ice_candidate', { matchId, candidate: event.candidate });
  }
};
```

**3. Transfer File:**
```javascript
// Chunk file and send
const CHUNK_SIZE = 16384; // 16KB
const file = selectedFile;
const totalChunks = Math.ceil(file.size / CHUNK_SIZE);

// Send metadata first
dataChannel.send(JSON.stringify({
  type: 'metadata',
  name: file.name,
  size: file.size,
  mimeType: file.type,
  totalChunks
}));

// Send chunks
for (let i = 0; i < totalChunks; i++) {
  const start = i * CHUNK_SIZE;
  const end = Math.min(start + CHUNK_SIZE, file.size);
  const chunk = file.slice(start, end);
  const arrayBuffer = await chunk.arrayBuffer();
  dataChannel.send(arrayBuffer);

  // Update progress
  const progress = ((i + 1) / totalChunks) * 100;
  setTransferProgress(progress);
}
```

**4. Receive File:**
```javascript
// Receiver assembles chunks
let receivedChunks = [];
let metadata = null;

dataChannel.onmessage = (event) => {
  if (typeof event.data === 'string') {
    // Metadata
    metadata = JSON.parse(event.data);
  } else {
    // Chunk
    receivedChunks.push(event.data);

    if (receivedChunks.length === metadata.totalChunks) {
      // All chunks received, create file
      const blob = new Blob(receivedChunks, { type: metadata.mimeType });
      const url = URL.createObjectURL(blob);
      // Trigger download
      const a = document.createElement('a');
      a.href = url;
      a.download = metadata.name;
      a.click();
    }
  }
};
```

### Error Handling

**Connection Failed:**
- Fallback to link sharing (Google Drive, Dropbox)
- Show user-friendly error message
- Log error for debugging

**Transfer Interrupted:**
- Detect connection state change
- Offer retry option
- Consider implementing resume capability (future)

---

## Security

### Backend Security

**Authentication:**
- bcrypt for password hashing (salt rounds: 10-12)
- JWT for session management (httpOnly cookies recommended)
- Token expiration (e.g., 24 hours)
- Refresh token mechanism (optional)

**API Security:**
- Rate limiting (express-rate-limit)
- Helmet.js for security headers
- CORS configuration (allow only frontend origin)
- Input validation (express-validator)
- SQL injection prevention (prepared statements, ORM)
- XSS prevention (sanitize user input)

### Frontend Security

**Storage:**
- JWT in httpOnly cookie (recommended) OR secure localStorage
- Never store passwords
- Clear sensitive data on logout

**Input Validation:**
- Client-side validation for UX
- Server-side validation for security
- Sanitize before displaying user content

### WebRTC Security

**Native Encryption:**
- DTLS (Datagram Transport Layer Security) for data channels
- SRTP (Secure Real-time Transport Protocol) for media
- Enabled by default, no configuration needed

**Additional Measures:**
- Verify signaling server (HTTPS + WSS)
- Optional: end-to-end encryption for chat (WebCrypto API, libsodium)
- No video files stored on server

---

## Deployment Architecture (Future)

### Production Stack

**Option 1: Single VPS**
- Ubuntu/Debian server
- Docker Compose
- nginx as reverse proxy + SSL (Let's Encrypt)
- PostgreSQL on same server
- Backup strategy

**Option 2: Cloud (Recommended)**
- Frontend: Vercel/Netlify (CDN, auto-scaling)
- Backend: AWS EC2/DigitalOcean/Render
- Database: AWS RDS/DigitalOcean Managed PostgreSQL
- nginx on backend for API
- Redis for session storage (optional)

**Option 3: Kubernetes (Overkill for MVP)**
- GKE/EKS/AKS
- Helm charts
- Auto-scaling
- Load balancing

### SSL/TLS

**Let's Encrypt:**
- Free SSL certificates
- Auto-renewal with Certbot
- Required for WebRTC (getUserMedia requires HTTPS)

### Environment Variables

**Backend:**
```env
NODE_ENV=production
PORT=3000
DATABASE_URL=postgresql://user:pass@host:5432/dbname
JWT_SECRET=random-secret-key
CORS_ORIGIN=https://spotlight.cam
STUN_SERVER=stun:stun.l.google.com:19302
TURN_SERVER=turn:your-turn-server.com (optional)
```

**Frontend:**
```env
VITE_API_URL=https://api.spotlight.cam
VITE_WS_URL=wss://api.spotlight.cam
```

---

## Performance Considerations

### Frontend
- Code splitting (React.lazy)
- Image optimization
- Service worker caching (PWA)
- Minimize bundle size

### Backend
- Database connection pooling
- Query optimization (indexes)
- Caching (Redis for frequently accessed data)
- Compression (gzip/brotli)

### WebRTC
- Adaptive chunk size based on bandwidth
- Buffer management (avoid overwhelming DataChannel)
- Connection quality monitoring
- Automatic reconnection on failure

---

## Monitoring & Logging (Future)

**Backend:**
- Winston/Pino for logging
- Log levels: error, warn, info, debug
- Structured logging (JSON format)

**Database:**
- Query performance monitoring
- Slow query log
- Connection pool metrics

**WebRTC:**
- Connection success rate
- Transfer speed metrics
- Failure reasons
- Browser compatibility stats

---

**Last Updated:** 2025-11-12