This is the backend server for PrivyDrop. It is built with Node.js, Express, and Socket.IO, and is responsible for handling WebRTC connection signaling, room management, and API requests from the frontend.

✨ Features

WebRTC Signaling: Uses Socket.IO to exchange SDP and ICE candidates.
Room Management: Efficiently creates and manages temporary file-sharing rooms using Redis.
Lightweight API: Provides core HTTP endpoints for frontend interaction.
Temporary Data Storage: All room data in Redis has an automatic expiration time (TTL).

🛠️ Tech Stack

Runtime: Node.js
Framework: Express.js
Language: TypeScript
Real-time Communication: Socket.IO
Database: Redis (using the ioredis client)
Process Management: PM2

🚀 Getting Started (Local Development)

Prerequisites
- Node.js (v18.x or newer)
- A running Redis instance
Navigate to Directory and Install Dependencies
```
cd backend
npm install
```

Configure Environment Variables Create a .env.development.local file in the backend/ directory and populate it with the following variables:

# Server Configuration
BACKEND_PORT=3001
CORS_ORIGIN=http://localhost:3002 # URL of the frontend development server

# Redis Configuration
REDIS_HOST=127.0.0.1
REDIS_PORT=6379
# REDIS_PASSWORD=your_redis_password

Run the Development Server
```
npm run dev
```
The server will start on the port specified by the BACKEND_PORT environment variable (defaults to 3001).

📖 API & Event Summary

This service provides a set of API endpoints and Socket.IO events to support the frontend application.

API Endpoints: Primarily include room creation (/api/get_room), joining, and checking.
Socket.IO Events: Responsible for handling clients joining rooms (join) and forwarding WebRTC signaling messages (offer, answer, ice-candidate).

📚 Detailed Documentation

To understand the backend's code structure, module design, and Redis data model in depth, please read the Backend Architecture Deep Dive.
To learn about how the frontend and backend collaborate, refer to the Overall Project Architecture.
For instructions on deploying in a production environment, please see the Deployment Guide.