# Dashboard Backend

Real-time cryptocurrency price streaming server built with Express.js and Socket.IO

## 🎯 Features

- ✅ Real-time cryptocurrency prices via WebSocket
- ✅ CoinGecko API integration (free, no API key needed)
- ✅ Automatic data refresh every 5 seconds
- ✅ CORS enabled for cross-origin requests
- ✅ Connection tracking and client count broadcasting
- ✅ Graceful error handling
- ✅ Automatic reconnection support

## 🛠 Tech Stack

- **Framework**: Express.js v4.18+
- **Real-time**: Socket.IO v4.5+
- **HTTP Client**: Axios v1.5+
- **Environment**: Dotenv v16+
- **CORS**: CORS middleware v2.8+

## 📋 Prerequisites

- Node.js v16.0.0 or higher
- npm v8.0.0 or higher

## 🚀 Quick Start

### 1. Installation

```bash
npm install
```

### 2. Environment Setup

Create a `.env` file:

```env
PORT=5000
NODE_ENV=development
CORS_ORIGIN=http://localhost:3000
```

### 3. Start Development Server

```bash
npm run dev
```

Server will run on `http://localhost:5000`

### 4. Start Production Server

```bash
npm start
```

## 📡 WebSocket Events

### Client → Server

**requestData**
- Payload: `{ dataType: 'crypto' }`
- Description: Client requests crypto data

### Server → Client

**data**
- Payload: Real-time cryptocurrency data
- Emitted: Every 5 seconds

**clientCount**
- Payload: `{ count: number }`
- Description: Total connected clients

**error**
- Payload: `{ message: string, details: string }`
- Description: Error occurred

## 📊 Data Response Format

```json
{
  "type": "crypto",
  "timestamp": "2025-10-28T12:00:00.000Z",
  "prices": {
    "bitcoin": {
      "usd": 42500.50,
      "usd_market_cap": 850000000000,
      "usd_24h_vol": 25000000000,
      "usd_24h_change": 2.5
    },
    "ethereum": {
      "usd": 2300.75,
      "usd_market_cap": 280000000000,
      "usd_24h_vol": 15000000000,
      "usd_24h_change": 1.8
    }
  }
}
```

## 🔄 Supported Cryptocurrencies

- Bitcoin (BTC)
- Ethereum (ETH)
- Cardano (ADA)
- Solana (SOL)
- Ripple (XRP)

## 🔒 Security

- Environment variables for sensitive data
- CORS restrictions configurable
- Input validation on events
- Error messages sanitized
- No sensitive data exposed

## 🐛 Debugging

### Enable Verbose Logging

The server logs all important events:
- Client connections/disconnections
- Data requests
- API calls
- Errors

Check console output for troubleshooting

### Common Issues

**Port Already in Use**
```bash
# Mac/Linux
lsof -i :5000

# Windows
netstat -ano | findstr :5000
```

**CORS Errors**
- Check CORS_ORIGIN in .env matches frontend URL
- Verify frontend is running on http://localhost:3000

**API Not Responding**
- Check internet connection
- CoinGecko API may be rate-limited
- Server will auto-retry

## 📈 Performance

- Lightweight and fast
- Handles multiple concurrent connections
- Efficient data updates (5-second intervals)
- Minimal bandwidth usage

## 🚀 Deployment Ready

Tested and ready for deployment on:
- Railway.app ✅
- Render.com ✅
- Heroku ✅
- DigitalOcean ✅
- AWS ✅

## 📝 API Health Check

```bash
curl http://localhost:5000/health
```

Response:
```json
{
  "status": "OK",
  "message": "Server is running",
  "timestamp": "2025-10-28T12:00:00.000Z"
}
```

## 📄 License

ISC

## 👤 Author

CloudForge Dev Team

---

**Status**: Production Ready
**Last Updated**: 2025-10-28