index.js

const crypto = require("crypto");
const fs = require("node:fs");
const fsp = fs.promises;

const DEFAULT_ALGORITHM = "md5";

async function safeStat(path) {
    const stat = await fsp.stat(path);
    return `${stat.mode}:${stat.uid}:${stat.gid}:${stat.size}:${stat.dev}:${stat.ino}:${stat.rdev}:${stat.blksize}:${stat.blocks}`;
}

// inspired by https://stackoverflow.com/a/44643479/2860309
function checksumFile(path, { algorithm = DEFAULT_ALGORITHM } = {}) {
    return new Promise(async (resolve, reject) => {
        const hash = crypto.createHash(algorithm);
        const stream = fs.createReadStream(path);
        stream.on("error", (err) => reject(err));
        stream.on("data", (chunk) => hash.update(chunk));
        stream.on("end", () => resolve(hash.digest("hex")));
    });
}

function checksumDirectory(path, { algorithm = DEFAULT_ALGORITHM } = {}) {
    return new Promise(async (resolve, reject) => {
        const hash = crypto.createHash(algorithm);

        hash.update(await safeStat(path));
        fsp.readdir(path, { withFileTypes: true })
            .then(async (files) => {
                files.sort((a, b) => a.name.localeCompare(b.name));
                for (let file of files) {
                    const filePath = `${path}/${file.name}`;
                    hash.update(file.name);
                    hash.update(await safeStat(filePath));

                    if (file.isDirectory()) {
                        hash.update(
                            await checksumDirectory(
                                path + "/" + file.name,
                                algorithm
                            )
                        );
                    } else if (file.isFile()) {
                        hash.update(
                            await checksumFile(
                                path + "/" + file.name,
                                algorithm
                            )
                        );
                    } else {
                        // file is not a file or directory, not evaluating
                    }
                }
                resolve(hash.digest("hex"));
            })
            .catch((err) => reject(err));
    });
}

module.exports = {
    checksumFile,
    checksumDirectory,
};