src/index.js

// This script is from https://github.com/shadowmoose/GHA-LoC-Badge/blob/master/src/index.js

const { badgen } = require('badgen');
const fs = require('fs').promises;
const path = require('path');
const core = require('@actions/core');
const { glob } = require('glob-gitignore');


const st = Date.now();
const dir = core.getInput('directory') || './';
const debug = core.getInput('debug') === 'true';
const badge = core.getInput('badge') || './badge.svg';
const patterns = (core.getInput('patterns')||'').split('|').map(s => s.trim()).filter(s=>s);
const ignore = (core.getInput('ignore') || '').split('|').map(s => s.trim()).filter(s=>s);

const badgeOpts = {};
for (const en of Object.keys(process.env)) {
	if (en.startsWith('INPUT_BADGE_')) {
		badgeOpts[en.replace('INPUT_BADGE_', '').toLowerCase()] = process.env[en]
	}
}

if (debug) core.info('Debugging enabled.');


async function countLines(fullPath) {
	return new Promise((res, rej) => {
		let count = 1;
		require('fs').createReadStream(fullPath)
			.on('data', function(chunk) {
				let index = -1;
				while((index = chunk.indexOf(10, index + 1)) > -1) count++
			})
			.on('end', function() {
				res(count);
			})
			.on('error', function(err) {
				rej(err)
			});
	})
}

const countThrottled = throttle(countLines, 10);

/**
 * Recursively count the lines in all matching files within the given directory.
 *
 * @param dir {string} The path to check.
 * @param patterns {string[]} array of patterns to match against.
 * @param negative {string[]} array of patterns to NOT match against.
 * @return {Promise<{ignored: number, lines: number, counted: number}>} An array of all files located, as absolute paths.
 */
async function getFiles (dir, patterns = [], negative = []) {
	let lines = 0, ignored=0, counted=0;

	await glob(patterns, {
		cwd: dir,
		ignore: negative,
		nodir: true
	}).then(files => {
		counted = files.length;
		return Promise.all(files.map( async f => {
			try {
				if (debug) core.info(`Counting: ${f}`);
				return await countThrottled(f);
			} catch (err) {
				core.error(err);
				return 0;
			}
		}))
	}).then(res => res.map(r => lines += r));

	return { lines, ignored, counted };
}

function throttle(callback, limit=5) {
	let idx = 0;
	const queue = new Array(limit);

	return async (...args) => {
		const offset = idx++ % limit;
		const blocker = queue[offset];
		let cb = null;
		queue[offset] = new Promise((res) => cb = res);  // Next call waits for this call's resolution.

		if (blocker) await blocker;
		try {
			return await callback.apply(this, args);
		} finally {
			cb();
		}
	}
}


function makeBadge(text, config) {
	return badgen({
    label: "lines of code",
		status: `${text}`,               // <Text>, required
	});
}


getFiles(dir, patterns, ignore).then( async ret => {
	await fs.mkdir(path.dirname(badge), { recursive: true })
	await fs.writeFile(badge, makeBadge(ret.lines.toLocaleString(), badgeOpts));
})