import { join, dirname } from 'path';
import { readdir } from 'fs/promises';
import { Dirent } from 'fs';

const ALLOWED_VERSIONED_DIRNAME_LENGTH = [2, 3]; // v1, v10

function isVersionedDirname(dirent: Dirent) {
	if (!dirent.isDirectory()) return false;

	return (
		ALLOWED_VERSIONED_DIRNAME_LENGTH.includes(dirent.name.length) &&
		dirent.name.toLowerCase().startsWith('v')
	);
}

async function getMaxVersion(from: string) {
	const entries = await readdir(from, { withFileTypes: true });

	const dirnames = entries.reduce<string[]>((acc, cur) => {
		if (isVersionedDirname(cur)) acc.push(cur.name);
		return acc;
	}, []);

	if (!dirnames.length) return null;

	return Math.max(...dirnames.map((d) => parseInt(d.charAt(1), 10)));
}

export async function getNodeTranslationPath(
	nodeSourcePath: string,
	language: string,
): Promise<string> {
	const nodeDir = dirname(nodeSourcePath);
	const maxVersion = await getMaxVersion(nodeDir);

	return maxVersion
		? join(nodeDir, `v${maxVersion}`, 'translations', `${language}.js`)
		: join(nodeDir, 'translations', `${language}.js`);
}