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const express = require('express');
const cors = require('cors'); // npm install cors

const app = express();
const port = 3000;

// Define allowed origins
const allowedOrigins = [
    'https://yourfrontend.com',
    'https://sub.yourfrontend.com',
    // Add more specific origins as needed
    // For development, you might temporarily allow localhost, but remove for production
    // 'http://localhost:8080'
];

// Configure CORS middleware
const corsOptions = {
    origin: function (origin, callback) {
        // Allow requests with no origin (like mobile apps or curl requests)
        if (!origin) return callback(null, true);
        if (allowedOrigins.indexOf(origin) === -1) {
            const msg = `The CORS policy for this site does not allow access from the specified Origin: ${origin}`;
            return callback(new Error(msg), false);
        }
        return callback(null, true);
    },
    methods: ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS'], // Allowed HTTP methods
    allowedHeaders: ['Content-Type', 'Authorization', 'X-Requested-With'], // Allowed request headers
    credentials: true, // Allow cookies to be sent
    optionsSuccessStatus: 204 // Some legacy browsers (IE11, various SmartTVs) choke on 200
};

// Apply CORS middleware
app.use(cors(corsOptions));

// Your API routes
app.get('/api/data', (req, res) => {
    res.json({ message: 'This is secure data!' });
});

app.post('/api/submit', (req, res) => {
    res.json({ message: 'Data submitted securely!' });
});

// Start the server
app.listen(port, () => {
    console.log(`Server listening at http://localhost:${port}`);
});