link-unlink/dist/esm/unlink.js

Link and unlink with saving and restoring the previous file or directory

import fs from 'fs';
import { Lock } from 'lock';
import path from 'path';
import Queue from 'queue-cb';
import rimraf2 from 'rimraf2';
const lock = Lock();
function restoreLink(previous, target, callback) {
    rimraf2(target, {
        disableGlob: true
    }, (err)=>{
        err ? callback(err) : fs.rename(previous, target, callback);
    });
}
function worker(target, callback) {
    lock(target, (release)=>{
        callback = release(callback);
        const dirname = path.dirname(target);
        const basename = path.basename(target);
        fs.readdir(dirname, (err, files)=>{
            if (err) return callback(err);
            const matches = files.filter((x)=>x.indexOf(basename) === 0 && x.slice(basename.length)[0] === '.').map((x)=>path.join(dirname, x));
            if (matches.length === 0) return rimraf2(target, {
                disableGlob: true
            }, callback);
            if (matches.length === 1) return restoreLink(matches[0], target, callback);
            const stats = [];
            const queue = new Queue();
            matches.forEach((match)=>queue.defer((cb)=>{
                    fs.lstat(match, (err, stat)=>{
                        if (err) return callback(err);
                        stats.push({
                            match,
                            stat
                        });
                        cb();
                    });
                }));
            queue.await((err)=>{
                if (err) return callback(err);
                const sorted = stats.sort((a, b)=>b.stat.ctime.valueOf() - a.stat.ctime.valueOf());
                restoreLink(sorted[0].match, target, callback);
            });
        });
    });
}
export default function link(target, callback) {
    if (typeof callback === 'function') return worker(target, callback);
    return new Promise((resolve, reject)=>worker(target, (err, restore)=>err ? reject(err) : resolve(restore)));
}