commit d8e9106a40fe6983c64cf4bcca1ac30e3736d39a
Author: sumit <sumit.kumar@digimantra.com>
Date:   Thu Sep 26 16:53:48 2024 +0530

    initial commit with tested code

diff --git a/README.md b/README.md
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+# Rate Limiter
+
+A customizable rate-limiting and throttling middleware for Node.js applications. It allows you to limit the number of requests a client can make to your server within a specified time window.
+
+## Features
+
+- Flexible request limiting based on time windows.
+- Easily configurable for IP-based or user-based rate limiting.
+- Simple integration as middleware in Node.js apps (e.g., with Express).
+- Supports both **rate limiting** and **throttling**.
+
+## Installation
+
+You can install the package via npm:
+
+```bash
+npm install rate-limiter
+```
+
+## Usage
+
+### Basic Usage
+
+The package can be used as middleware in your Node.js/Express applications to limit requests. Here's an example to allow **10 requests per second**.
+
+```javascript
+const express = require('express');
+const rateLimiter = require('rate-limiter');
+
+const app = express();
+
+// Apply rate limiter middleware
+app.use(rateLimiter({
+  windowMs: 1000,   // 1 second
+  maxRequests: 10   // Limit each client to 10 requests per windowMs
+}));
+
+app.get('/', (req, res) => {
+  res.send('Hello, world!');
+});
+
+app.listen(3000, () => {
+  console.log('Server is running on port 3000');
+});
+```
+
+### Options
+
+The `rateLimiter` function accepts an options object to configure the behavior:
+
+- **`windowMs`**: The time frame (in milliseconds) to allow `maxRequests`. For example, `1000` will enforce the limit per second.
+- **`maxRequests`**: The maximum number of requests allowed during the `windowMs` period.
+
+### Example: 100 Requests per 15 Minutes
+
+```javascript
+app.use(rateLimiter({
+  windowMs: 15 * 60 * 1000,  // 15 minutes
+  maxRequests: 100           // Limit each client to 100 requests per windowMs
+}));
+```
+
+## Advanced Features
+
+### IP-Based Limiting
+
+By default, the middleware identifies clients by their IP address (`req.ip` in Express). This ensures that requests from each client IP are tracked separately.
+
+### User-Based Limiting
+
+You can also implement user-based rate limiting by passing a user identifier (such as an API key or user ID) to the rate limiter.
+
+```javascript
+app.use((req, res, next) => {
+  const clientId = req.user.id; // Assuming you have user authentication
+  rateLimiter({
+    windowMs: 60000,   // 1 minute
+    maxRequests: 30    // Limit to 30 requests per minute per user
+  })(req, res, next);
+});
+```
+
+## Development
+
+If you'd like to contribute or modify the package, you can clone the repository and run it locally:
+
+```bash
+git clone https://github.com/yourusername/rate-limiter.git
+cd rate-limiter
+npm install
+```
+
+### Testing Locally
+
+To run the Express example:
+
+1. Create a file `app.js` as shown in the example above.
+2. Run the server:
+
+```bash
+node app.js
+```
+
+## Contributing
+
+Contributions are welcome! Please open issues and submit pull requests on GitHub if you'd like to improve the package.
+
+## Issues
+
+If you encounter any problems or have any questions, feel free to open an issue on GitHub.
+
+## Links
+
+- **GitHub**: [https://github.com/yourusername/rate-limiter](https://github.com/yourusername/rate-limiter)
+- **NPM**: [https://www.npmjs.com/package/rate-limiter](https://www.npmjs.com/package/rate-limiter)
+
+---
diff --git a/index.js b/index.js
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+// index.js
+const RateLimiter = require('./lib/rateLimiter');
+
+// Middleware wrapper for Express.js or any other Node.js framework
+const rateLimiterMiddleware = (options) => {
+  const limiter = new RateLimiter(options);
+
+  return (req, res, next) => {
+    const clientId = req.ip; // Use IP-based rate limiting
+    const result = limiter.handleRequest(clientId);
+
+    if (!result.allowed) {
+      return res.status(429).json({
+        message: 'Too many requests. Please try again later.',
+        retryAfter: result.remainingTime / 1000, // Retry after (seconds)
+      });
+    }
+
+    // If allowed, proceed to the next middleware or route handler
+    next();
+  };
+};
+
+module.exports = rateLimiterMiddleware;
diff --git a/lib/rateLimiter.js b/lib/rateLimiter.js
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+// lib/rateLimiter.js
+
+class RateLimiter {
+  constructor({ windowMs, maxRequests }) {
+    // windowMs is the time window in milliseconds (e.g., 15 minutes = 15 * 60 * 1000)
+    this.windowMs = windowMs;
+    // maxRequests is the number of allowed requests in the given window
+    this.maxRequests = maxRequests;
+    // in-memory store to keep track of requests per client
+    this.clients = new Map();
+  }
+
+  // Function to handle a request
+  handleRequest(clientId) {
+    const currentTime = Date.now();
+
+    // Check if the client has made requests in the current window
+    if (this.clients.has(clientId)) {
+      const clientData = this.clients.get(clientId);
+      const { requestCount, startTime } = clientData;
+
+      // If the current time is within the window, check the request count
+      if (currentTime - startTime < this.windowMs) {
+        if (requestCount >= this.maxRequests) {
+          return { allowed: false, remainingTime: (startTime + this.windowMs - currentTime) };
+        }
+        // If not exceeding the maxRequests, increment the count
+        clientData.requestCount += 1;
+        this.clients.set(clientId, clientData);
+        return { allowed: true, remainingRequests: this.maxRequests - clientData.requestCount };
+      }
+    }
+
+    // Reset or start a new window for the client
+    this.clients.set(clientId, { requestCount: 1, startTime: currentTime });
+    return { allowed: true, remainingRequests: this.maxRequests - 1 };
+  }
+
+  // Function to clear expired clients from the store (optional for memory optimization)
+  clearExpiredClients() {
+    const currentTime = Date.now();
+    this.clients.forEach((clientData, clientId) => {
+      if (currentTime - clientData.startTime > this.windowMs) {
+        this.clients.delete(clientId);
+      }
+    });
+  }
+}
+
+module.exports = RateLimiter;
diff --git a/package.json b/package.json
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+{
+  "name": "rate-limiter",
+  "version": "1.0.0",    
+  "description": "Custom rate limiting middleware for Node.js",
+  "main": "index.js",    
+  "keywords": [          
+    "rate-limiting",
+    "rate-limiter",
+    "secure-api",
+    "throttling",
+    "middleware",
+    "node"
+  ],
+  "author": "Digimantra Labs",
+  "license": "MIT"
+}