A script to watch the cats at Battersea (https://www.battersea.org.uk/cats/cat-rehoming-gallery) and notify us by email when a new one shows up

cat-watcher.js

const fs = require('fs');
const https = require('https')
const { execSync } = require('child_process');

const queryFrequencyMs = 5 * 60 * 1000;

let seenNids = {};

const generateEmail = (() => {
	const footer = `<h1>New cat alert!</h1>`;

	return cats => {
		let body = `<p>Hi humans!</p><p>You're getting this email because you're watching for new unreserved, unrehomed cats at the Battersea centre. If you want to stop receiving this email, talk to Yousef.</p><p>Also, click the cat thumbnails for full info.</p>`;

		for(let c of cats) {
			let age = new Date(new Date() - new Date(c.field_animal_age)).getFullYear() - 1970;
			body += `<div style="overflow: auto">
					<h2>${c.title}</h2>
					<div style="float: left"><a href="https://www.battersea.org.uk${c.path}" target="_blank"><img src="${c.field_animal_thumbnail}"/></a></div>
					<ul style="overflow: hidden">
						<li>Sex: ${c.field_animal_sex}</li>
						<li>Birthday: ${c.field_animal_age} (${age} years old)</li>
						<li>Type: ${c.field_animal_size}-sized, ${c.field_animal_breed}</li>
					</ul>
				</div>`;
		}

		return body;
	};
})();

setInterval(async () => {
	console.log('Querying battersea...');
	https.get('https://www.battersea.org.uk/api/animals/cats', res => {
		let body = '';

		res.on('data', chunk => body += chunk);

		res.on('end', () => {
			let json = JSON.parse(body);
			let cats = json.animals.filter(a => a.field_animal_centre === 'battersea' && !a.field_animal_reserved && !a.field_animal_rehomed);
			let newCats = [];

			for (let c of cats) {
				if (c.nid in seenNids)
					continue;
				seenNids[c.nid] = true;
				newCats.push(c);
			}

			if (newCats.length) {
				console.log('New cats!');
				fs.writeFileSync('/tmp/catmail.txt', generateEmail(newCats));
				execSync(`cat /tmp/catmail.txt | mail -s "New cat alert!" -a "From: Watchdog <watchdog@amar.io>" -a "Content-type: text/html" yousefamar@gmail.com veronicanacci97@gmail.com`);
				return;
			}
			console.log('No new cats.');
		});
	}).on('error', e => {
		console.error(e);
	});
}, queryFrequencyMs);