import { type Locale } from './types.js';
/**
 * Header-like source for {@link resolveLocale}. Pass a `Request` (its `cookie` and
 * `accept-language` headers are read) or a plain object with the raw header
 * strings — keeps the helper framework-agnostic.
 */
export interface LocaleSource {
    /** Raw `Cookie` request header, e.g. `theme=dark; urbicon-locale=de`. */
    cookie?: string | null;
    /** Raw `Accept-Language` request header, e.g. `de-DE,de;q=0.9,en;q=0.8`. */
    acceptLanguage?: string | null;
}
export interface ResolveLocaleOptions {
    /**
     * Locales the app actually ships data for. Resolution never returns a locale
     * outside this set. Defaults to the locales currently registered in the
     * registry (so it tracks "data optional"), falling back to all
     * {@link SUPPORTED_LOCALES} if nothing is registered yet.
     */
    supportedLocales?: readonly Locale[];
    /** Returned when neither cookie nor Accept-Language yields a supported locale. @default 'en' */
    defaultLocale?: Locale;
    /** Name of the cookie holding the persisted locale choice. @default 'urbicon-locale' */
    cookieName?: string;
}
/**
 * Resolve the initial locale for a request, server-side: persisted cookie first,
 * then the browser's `Accept-Language`, then the default. Feed the result to
 * `<I18nProvider locale={…}>` so SSR and hydration agree (no client-only
 * `navigator.language` guess, no hydration mismatch).
 *
 * ```ts
 * // +layout.server.ts
 * export const load = ({ request }) => ({ locale: resolveLocale(request) });
 * ```
 *
 * Detection is the consumer's choice — this helper is optional. Persisting the
 * cookie on switch is the consumer's job too (e.g. in the provider's
 * `onLocaleChange`); this only reads it back.
 */
export declare function resolveLocale(source: Request | LocaleSource, options?: ResolveLocaleOptions): Locale;