/* eslint-disable import/prefer-default-export */

import { readFile } from 'fs-extra';
import yargs = require('yargs');

export const isAutoGeneratedFile = (content: string) => {
	content = content
		.replace(/\r\n/g, '\n')
		.trim();

	type Quotes = '"'|'\'';
	const fileStart = (quotes: Quotes) => `${quotes}use strict${quotes};`;

	// Check both quote formats: If the file has been processed by eslint, it will use single quotes,
	// while files generated by tsc usually use double quotes.
	const matchesStart = content.startsWith(fileStart('"')) || content.startsWith(fileStart('\''));
	const hasSourceMap = !!content.match(/\/\/\s?# sourceMappingURL=.+\.map$/);
	const hasIgnore = content.includes('// ignore: generated check');

	return matchesStart && hasSourceMap && !hasIgnore;
};

const main = async () => {
	const argv = await yargs.argv;
	const filePaths = argv._ as string[];
	if (!filePaths || !filePaths.length) return;

	const generatedFiles = [];
	for (const filePath of filePaths) {
		const content = await readFile(filePath, 'utf8');
		if (isAutoGeneratedFile(content)) {
			generatedFiles.push(filePath);
		}
	}

	if (generatedFiles.length) {
		throw new Error([
			'The following .js file(s) appear to be generated from .ts files:',
			`\t${generatedFiles.join(', ')}`,
			'If any of the above files are not auto-generated, please add a brief comment (e.g. // ignore: generated check)',
			'to disable this check.',
		].join('\n'));
	}
};

if (require.main === module) {
	void (async () => {
		try {
			await main();
		} catch (error) {
			console.error(error);
			process.exit(1);
		}
	})();
}