const DEFAULT_LOCALE = "en-US" as const;
function hasOwn<T extends Record<string, unknown>>(
obj: T,
key: PropertyKey
): key is keyof T {
return Object.prototype.hasOwnProperty.call(obj, key);
}
export function resolveLocale<T extends Record<string, unknown>>(messages: T): keyof T {
if (typeof document !== "undefined") {
const lang = document.documentElement.lang;
if (lang && hasOwn(messages, lang)) {
return lang;
}
}
if (hasOwn(messages, DEFAULT_LOCALE)) {
return DEFAULT_LOCALE as keyof T;
}
const [fallback] = Object.keys(messages);
return (fallback ?? DEFAULT_LOCALE) as keyof T;
}
export const FALLBACK_LOCALE = DEFAULT_LOCALE;
