import { createIntl, createIntlCache } from "react-intl";
import langEn from "./lang/en.json";
import langRu from "./lang/ru.json";
import langList from "./lang/lang-list.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"], ["ru", "ru-RU"]];

const loadMessages = (locale?: string): typeof langList & typeof langEn => {
	const thisLocale = locale || "en";
	switch (thisLocale.slice(0, 2)) {
		case "ru":
			return Object.assign({}, langList, langRu);
		default:
			return Object.assign({}, langList, langEn);
	}
};

const getFlagCodeForLocale = (locale?: string) => {
	switch (locale) {
		case "ru":
			return "RU";
		default:
			return "EN";
	}
};

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>
	);
};

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