Creating a Simple API Proxy with Node.js Express for Security and Aggregation

const express = require('express');
const fetch = require('node-fetch'); // Requires 'node-fetch' for older Node.js versions, built-in in Node.js 18+
require('dotenv').config(); // For managing environment variables

const app = express();
const PORT = process.env.PORT || 3000;

// Middleware to parse JSON request bodies
app.use(express.json());

// Simple proxy endpoint for an external API
app.get('/api/external-data', async (req, res) => {
  try {
    const externalApiKey = process.env.EXTERNAL_API_KEY; // Keep API key hidden from client
    const externalApiUrl = 'https://api.thirdparty.com/data';
    
    // Construct query parameters if needed
    const queryParams = new URLSearchParams(req.query).toString();
    const url = `${externalApiUrl}?api_key=${externalApiKey}&${queryParams}`;

    const response = await fetch(url);
    const data = await response.json();
    res.json(data);
  } catch (error) {
    console.error('Proxy Error:', error);
    res.status(500).json({ error: 'Failed to fetch data from external API' });
  }
});

// Example of aggregating multiple APIs
app.get('/api/aggregated-dashboard', async (req, res) => {
    try {
        const userResponse = await fetch('https://api.internal.com/users/1');
        const productResponse = await fetch('https://api.external.com/products?limit=5&api_key=' + process.env.EXTERNAL_API_KEY);

        const [userData, productData] = await Promise.all([
            userResponse.json(),
            productResponse.json()
        ]);

        res.json({ user: userData, recentProducts: productData });

    } catch (error) {
        console.error('Aggregation Error:', error);
        res.status(500).json({ error: 'Failed to aggregate data' });
    }
});

app.listen(PORT, () => {
  console.log(`API Proxy running on port ${PORT}`);
});