/**
 * The UI locales that actually ship — regional BCP 47 tags, per docs/localization.md D2. This is the
 * one list `I18nBridge` merges catalogs for and `Languages.tsx` offers for UI localization; it is
 * deliberately separate from the broader "languages you speak" / "translate to" lists, which are a
 * different feature (see the doc's open question 4) and are not limited to locales with a catalog.
 */
export type ShippedLocale = { code: string; label: string };

/**
 * The label is an AUTONYM — each language named in its own language, so "Português" reads as Portuguese
 * whichever locale the UI is currently in. That is the convention for a language picker and it is the
 * useful behaviour: somebody who cannot read the current language still has to find theirs.
 *
 * Computed rather than written down, for the same reason the spoken-language list is (see Languages.tsx):
 * `Intl` already knows every language's name in every locale, including its own.
 */
const autonym = (code: string): string => {
  const name = new Intl.DisplayNames([code], { type: 'language', fallback: 'code' }).of(code) ?? code;
  return name.charAt(0).toUpperCase() + name.slice(1);
};

export const SHIPPED_LOCALES: ShippedLocale[] = ['en-GB', 'pt-PT'].map((code) => ({
  code,
  label: autonym(code),
}));

export const FALLBACK_LOCALE = 'en-GB';