hippofish/packages/client/src/scripts/language-utils.ts

import { supportedLangs } from "@/scripts/langmap";
import { detect } from "tinyld";
import * as mfm from "mfm-js";

export function detectLanguage(text: string): string {
	const nodes = mfm.parse(text);
	const filtered = mfm.extract(nodes, (node) => {
		return node.type === "text" || node.type === "quote";
	});
	const purified = mfm.toString(filtered);
	return detect(purified);
}

export function isSupportedLang(langCode: string | null) {
	if (!langCode) return false;
	return supportedLangs[langCode] ?? false;
}

/**
 * Compare two language codes to determine whether they are decisively different
 * @returns false if they are close enough
 */
export function isSameLanguage(
	langCode1: string | null,
	langCode2: string | null,
) {
	return (
		languageContains(langCode1, langCode2) ||
		languageContains(langCode2, langCode1)
	);
}

/**
 * Returns true if langCode1 contains langCode2
 */
export function languageContains(
	langCode1: string | null,
	langCode2: string | null,
) {
	if (!langCode1 || !langCode2) return false;

	return parentLanguage(langCode2) === langCode1;
}

export function parentLanguage(langCode: string | null) {
	if (!langCode) return null;
	if (["zh-hant", "zh-hans", "yue", "nan"].includes(langCode)) {
		return "zh";
	}
	if (["nb", "nn"].includes(langCode)) {
		return "no";
	}
	return langCode;
}