Server-Side Caching for External API Responses

const NodeCache = require('node-cache');
const axios = require('axios');

// Initialize cache with a 10-minute (600 seconds) TTL
const apiCache = new NodeCache({ stdTTL: 600, checkperiod: 120 });

async function getCachedExternalData(url, cacheKey) {
    let data = apiCache.get(cacheKey);
    if (data) {
        console.log(`Cache hit for ${cacheKey}`);
        return data;
    }

    console.log(`Cache miss for ${cacheKey}, fetching data...`);
    try {
        const response = await axios.get(url);
        data = response.data;
        apiCache.set(cacheKey, data); // Cache the data
        console.log(`Data for ${cacheKey} cached.`);
        return data;
    } catch (error) {
        console.error(`Error fetching data from ${url}:`, error.message);
        throw error;
    }
}

// Example Usage (e.g., in an Express route)
/*
const express = require('express');
const app = express();

app.get('/api/posts', async (req, res) => {
    try {
        const posts = await getCachedExternalData('https://jsonplaceholder.typicode.com/posts', 'allPosts');
        res.json(posts);
    } catch (error) {
        res.status(500).json({ error: 'Failed to fetch posts' });
    }
});

app.listen(3000, () => console.log('Server running on port 3000'));
*/

// To test without Express:
(async () => {
    console.log('--- First call (should miss cache) ---');
    await getCachedExternalData('https://jsonplaceholder.typicode.com/todos/1', 'todo1');
    console.log('--- Second call (should hit cache) ---');
    await getCachedExternalData('https://jsonplaceholder.typicode.com/todos/1', 'todo1');
    // Wait for TTL to expire and check again (optional, for demo)
    // setTimeout(async () => {
    //     console.log('--- Call after TTL (should miss cache again) ---');
    //     await getCachedExternalData('https://jsonplaceholder.typicode.com/todos/1', 'todo1');
    // }, 610 * 1000);
})();