app.js

const bodyParser = require("body-parser");
const rateLimit = require("express-rate-limit");
const cors = require('cors');
const express = require('express');
const app = express();
const mongooseConnection = require('./db');

const users = require("./routes/api/users");

// Config from Environment variables
let keys = {};
keys.clientUrl = process.env.APP_CLIENTURL;

/**
 * Index.js does the following:
 * 1. Sets up middleware for Rate Limiting & Body Parser (used for JSON).
 * 2. Connects to the MongoDB for CRUD operations.
 * 3. Express server to serve API endpoints & /resetpassword webpage
 * 4. Connects socket.io to Express server to enable realtime
 * bidirectional communication for chat messaging functionality.
 */

// Enable CORS
app.use(cors({
  origin:['http://localhost:3000', keys.clientUrl],
  methods:['GET','POST'],
}));

// Rate Limiter Middleware
const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100 // limit each IP to 100 requests per windowMs
});
//  apply limiter to all requests
app.use(limiter);

// Bodyparser middleware
app.use(bodyParser.urlencoded({extended: false}));
app.use(bodyParser.json());

// Routes
app.use("/api/users", users);

module.exports = app;