fileUtil.js

const folder = process.env.SAVED_FOLDER;
const nodezip = require('node-zip');
const fs = require('fs');

module.exports = {
	/** 
	 * 
	 * @param {number} n 
	 * @param {number} l
	 * @returns {string}
	 */
	padZero(n, l = process.env.FILE_NUM_WIDTH) {
		return ('' + n).padStart(l, '0');
	},
	/**
	 * 
	 * @param {string} temp 
	 * @param {string} info
	 * @returns {string}
	 */
	fillTemplate(temp, info) {
		return temp.replace(/%s/g, info);
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} l
	 * @returns {string}
	 */
	getNextFile(s, suf = '.xml', l = 7) {
		const regex = new RegExp(`${s}[0-9]*${suf}$`);
		const dir = fs.readdirSync(folder).filter(v => v && regex.test(v));
		return `${folder}/${s}${this.padZero(dir.length, l)}${suf}`;
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} l
	 * @returns {number}
	 */
	getNextFileId(s, suf = '.xml', l = 7) {
		const indicies = this.getValidFileIndicies(s, suf, l);
		return indicies.length ? indicies[indicies.length - 1] + 1 : 0;
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} l
	 * @returns {number}
	 */
	fillNextFileId(s, suf = '.xml', l = 7) {
		const id = this.getNextFileId(s, suf);
		const fn = this.getFileIndex(s, suf, id, l);
		fs.writeFileSync(fn, '');
		return id;
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} n
	 * @param {number} l
	 * @returns {string}
	 */
	getFileIndex(s, suf = '.xml', n, l = 7) {
		return this.getFileString(s, suf, this.padZero(n, l));
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {string} name
	 * @returns {string}
	 */
	getFileString(s, suf = '.xml', name) {
		return `${folder}/${s}${name}${suf}`;
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} l
	 * @returns {number[]}
	 */
	getValidFileIndicies(s, suf = '.xml', l = 7) {
		const regex = new RegExp(`${s}[0-9]{${l}}${suf}$`);
		return fs.readdirSync(folder).
			filter(v => v && regex.test(v)).
			map(v => Number.parseInt(v.substr(s.length, l)));
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} l
	 * @returns {string[]}
	 */
	getValidFileNames(s, suf = '.xml', l = 7) {
		const regex = new RegExp(`${s}[0-9]{${l}}${suf}$`);
		return fs.readdirSync(folder).
			filter(v => v && regex.test(v)).
			map(v => `${folder}/${v}`);
	},
	/**
	 * @param {string} s
	 * @param {string} suf
	 * @param {number} l
	 * @returns {string[]}
	 */
	getLastFileIndex(s, suf = '.xml', l = 7) {
		const regex = new RegExp(`${s}[0-9]{${l}}${suf}$`);
		const list = fs.readdirSync(folder).filter(v => v && regex.test(v));
		return list.length ? Number.parseInt(list.pop().substr(s.length, l)) : -1;
	},
	/**
	 * 
	 * @param {string} fileName 
	 * @param {string} zipName 
	 */
	zippy(fileName, zipName) {
		if (!fs.existsSync(fileName)) return Promise.reject();
		const buffer = fs.readFileSync(fileName);
		const zip = nodezip.create();
		this.addToZip(zip, zipName, buffer);
		return zip.zip();
	},
	/**
	 * 
	 * @param {nodezip.ZipFile} zip 
	 * @param {string} zipName 
	 * @param {string} buffer 
	 */
	addToZip(zip, zipName, buffer) {
		zip.add(zipName, buffer);
		if (zip[zipName].crc32 < 0)
			zip[zipName].crc32 += 4294967296;
	},
}