nginx-proxy-manager/frontend/src/locale/IntlProvider.tsx

import { createIntl, createIntlCache } from "react-intl";
import langDe from "./lang/de.json";
import langEn from "./lang/en.json";
import langEs from "./lang/es.json";
import langIt from "./lang/it.json";
import langJa from "./lang/ja.json";
import langList from "./lang/lang-list.json";
import langNl from "./lang/nl.json";
import langPl from "./lang/pl.json";
import langRu from "./lang/ru.json";
import langSk from "./lang/sk.json";
import langVi from "./lang/vi.json";
import langZh from "./lang/zh.json";

// first item of each array should be the language code,
// not the country code
// Remember when adding to this list, also update check-locales.js script
const localeOptions = [
	["en", "en-US", langEn],
	["de", "de-DE", langDe],
	["es", "es-ES", langEs],
	["ja", "ja-JP", langJa],
	["it", "it-IT", langIt],
	["nl", "nl-NL", langNl],
	["pl", "pl-PL", langPl],
	["ru", "ru-RU", langRu],
	["sk", "sk-SK", langSk],
	["vi", "vi-VN", langVi],
	["zh", "zh-CN", langZh],
];

const loadMessages = (locale?: string): typeof langList & typeof langEn => {
	const thisLocale = (locale || "en").slice(0, 2);

	// ensure this lang exists in localeOptions above, otherwise fallback to en
	if (thisLocale === "en" || !localeOptions.some(([code]) => code === thisLocale)) {
		return Object.assign({}, langList, langEn);
	}

	return Object.assign({}, langList, langEn, localeOptions.find(([code]) => code === thisLocale)?.[2]);
};

const getFlagCodeForLocale = (locale?: string) => {
	const thisLocale = (locale || "en").slice(0, 2);

	// only add to this if your flag is different from the locale code
	const specialCases: Record<string, string> = {
		ja: "jp", // Japan
		zh: "cn", // China
		vi: "vn, // Vietnam
	};

	if (specialCases[thisLocale]) {
		return specialCases[thisLocale].toUpperCase();
	}
	return thisLocale.toUpperCase();
};

const getLocale = (short = false) => {
	let loc = window.localStorage.getItem("locale");
	if (!loc) {
		loc = document.documentElement.lang;
	}
	if (short) {
		return loc.slice(0, 2);
	}
	// finally, fallback
	if (!loc) {
		loc = "en";
	}
	return loc;
};

const cache = createIntlCache();

const initialMessages = loadMessages(getLocale());
let intl = createIntl({ locale: getLocale(), messages: initialMessages }, cache);

const changeLocale = (locale: string): void => {
	const messages = loadMessages(locale);
	intl = createIntl({ locale, messages }, cache);
	window.localStorage.setItem("locale", locale);
	document.documentElement.lang = locale;
};

// This is a translation component that wraps the translation in a span with a data
// attribute so devs can inspect the element to see the translation ID
const T = ({
	id,
	data,
	tData,
}: {
	id: string;
	data?: Record<string, string | number | undefined>;
	tData?: Record<string, string>;
}) => {
	const translatedData: Record<string, string> = {};
	if (tData) {
		// iterate over tData and translate each value
		Object.entries(tData).forEach(([key, value]) => {
			translatedData[key] = intl.formatMessage({ id: value });
		});
	}
	return (
		<span data-translation-id={id}>
			{intl.formatMessage(
				{ id },
				{
					...data,
					...translatedData,
				},
			)}
		</span>
	);
};

console.log("L:", localeOptions);

export { localeOptions, getFlagCodeForLocale, getLocale, createIntl, changeLocale, intl, T };