Merge C# files into a single one

merge.ts

/**
 * Usage: node --experimental-strip-types merge.ts
 */

"use strict";
import fs from 'node:fs/promises';
import path from 'node:path';

const usingRe = /^using ([A-Za-z0-9.= ]+);?/;

const sanitizeMultilineStr = (str: string) => str.replace(/\t+/gm, '').replace(/\{tab\}/g, '\t');

async function writeFile(dir: string, filename: string, data: string)
{
	await fs.mkdir(dir, { recursive: true });
	return fs.writeFile(path.join(dir, filename), data, 'utf8');
}

async function readFiles(dir: string)
{
	const parsedContent: string[] = [];
	const usingLibs = new Set();

	const files = (await fs.readdir(dir, { withFileTypes: true, recursive: true }))
		.filter((x) => x.isFile() && x.name.endsWith('.cs')) // filter .cs files only
		.map((x) => path.join(x.parentPath, x.name)); // return an array of paths

	const contents = await Promise.all(files.map((file) => fs.readFile(file, 'utf8')));

	contents.forEach((content, idx) =>
	{
		const filteredContent = content
			.split('\n') // split lines
			.filter((line) =>
			{
				const usingsFound = line.trim().match(usingRe);
				if (usingsFound)
				{
					usingLibs.add(usingsFound[1]);
					return false; // exclude the line with the "using directive"
				}
				return true;
			})
			.join('\n'); // join all "lines" again

		const contentWithNewLines = content.endsWith('\n') ? `${filteredContent.trim()}\n` : `${filteredContent.trim()}\n\n`;

		parsedContent.push(`// Content of: ${files.at(idx)}\n${contentWithNewLines}`);
	});

	return {
		using: usingLibs,
		contents: parsedContent,
	};
};

(async () =>
{
	const args = process.argv.splice(2);
	const srcPath = args[0];
	const className = args[1];

	if (args.length === 0)
	{
		console.log('Parameters: <source path> <class name>');
		process.exit(1);
	}

	if (!srcPath) throw new Error('You must set a source path!');
	if (!className) throw new Error('You must set the main class name!');

	const res = await readFiles(srcPath);

	let output = sanitizeMultilineStr(`
		// This file was autogenerated using the merge tool
		// ${new Date().toString()}

		{usings}

		{contents}
	`);

	output = output
		.replace('{usings}', Array.from(res.using).map((x) => `using ${x};`).join('\n'))
		.replace('{contents}', res.contents.join('\n'));

	await writeFile('dist', `${className}.cs`, output);
})();