Convert spaces to tabs

tabify.js

/**
 * Converts spaces to tab on all files within a folder, recursively.
 * Rodrigo Dias <rcesar@gmail.com>
 * Friday, December 13, 2024.
 */

const fs = require('fs');
const path = require('path');

const skipDir = ['.git', 'node_modules'];
const NC = '\x1b[0m';
const RED = '\x1b[31m';
const GRE = '\x1b[32m';
const BLU = '\x1b[34m';

const target = process.argv[2];
if (!target) {
	console.log('Usage: node tabify.js FOLDER [--crlf]\n');
	console.log('Options:');
	console.log('    --crlf    Uses CR/LF for linebreaks; default is LF.');
	process.exit(1);
} else if (!fs.lstatSync(target).isDirectory()) {
	console.log(`${RED}Not a folder: ${target}${NC}`);
	process.exit(1);
}
const useCrLf = process.argv[3] === '--crlf';

let numSubFolders = 0;
let numFiles = 0;
let numFilesDone = 0;
recursivePass(target);
console.log(`${BLU}Summary:${NC}`)
console.log(`${GRE}  Found ${numFiles} file(s) and ${numSubFolders} subfolder(s).${NC}`);
console.log(`${GRE}  Tabs replaced in ${numFilesDone} file(s).${NC}`);

/**
 * @param {string} target
 */
function recursivePass(target) {
	if (target.endsWith('/') || target.endsWith('\\'))
		target = target.substring(0, target.length - 1); // remove trailing slash

	fs.readdirSync(target, {}).forEach(name => {
		const thisPath = target + path.sep + name;
		if (fs.lstatSync(thisPath).isDirectory()) {
			if (skipDir.indexOf(name) === -1) {
				++numSubFolders;
				recursivePass(thisPath);
			}
		} else {
			++numFiles;
			if (processFile(thisPath)) ++numFilesDone;
		}
	});
}

/**
 * @param {string} filePath
 * @returns {boolean}
 */
function processFile(filePath) {
	const lines = fs.readFileSync(filePath, {encoding: 'utf8'}).split(/\r?\n/g);
	let wasTreated = false;
	if (!fileHasTabs(lines)) {
		const indents = getIndents(lines);
		if (indents.length) {
			const lowestIndent = findLowestIndent(indents);
			swapSpacesWithTabs(lines, indents, lowestIndent);
			wasTreated = true;
		}
	}
	const newText = lines.join(useCrLf ? '\r\n' : '\n');
	fs.writeFileSync(filePath, newText);
	return wasTreated;
}

/**
 * @param {string[]} lines
 * @returns {boolean}
 */
function fileHasTabs(lines) {
	for (const line of lines) {
		if (line.startsWith('\t'))
			return true;
	}
	return false;
}

/**
 * @param {string[]} lines
 * @returns {{line: number; spaces: number}[]}
 */
function getIndents(lines) {
	const indents = [];
	for (let i = 0; i < lines.length; ++i) {
		if (lines[i].startsWith(' ')) {
			indents.push({
				line: i,
				spaces: (line => {
					let c = 0;
					while (line.charAt(c) === ' ') ++c;
					return c;
				})(lines[i]),
			});
		}
	}
	return indents;
}

/**
 * @param {{line: number; spaces: number}[]} indents
 * @returns {number}
 */
function findLowestIndent(indents) {
	let lowest = Number.MAX_VALUE;
	for (const indent of indents) {
		if (indent.spaces < lowest)
			lowest = indent.spaces;
	}
	return lowest;
}

/**
 * @param {string[]} lines
 * @param {{line: number; spaces: number}[]} indents
 * @param {number} numSpaces
 */
function swapSpacesWithTabs(lines, indents, numSpaces) {
	for (const indent of indents) {
		const numTabs = (indent.spaces - (indent.spaces % numSpaces)) / numSpaces;
		lines[indent.line] = '\t'.repeat(numTabs)
			+ lines[indent.line].substring(numTabs * numSpaces); // in-place modification
	}
}