import type { Charity, LocaleMessages } from './types.js';
import { type SupportedLocale } from './locales/index.js';
export type { SupportedLocale } from './locales/index.js';
/**
 * Detect the user's preferred locale from browser APIs.
 *
 * Resolution order:
 * 1. Explicit `locale` option
 * 2. First match from `navigator.languages[]` (user-ordered preference list)
 * 3. `navigator.language` base tag (e.g. "es" from "es-MX")
 * 4. Fallback: "en"
 */
export declare function detectLocale(preferred?: string): SupportedLocale;
/**
 * Load locale messages for the given language code.
 * Returns cached result on repeat calls. Falls back to 'en' on error.
 */
export declare function loadLocale(lang: string): Promise<LocaleMessages>;
/**
 * Merge base charities with locale-specific translations.
 *
 * For each charity: use the locale tagline if available, otherwise keep
 * the English default from the base data.
 */
export declare function mergeCharities(base: readonly Charity[], locale: LocaleMessages): Charity[];
/**
Returns true if the locale uses right-to-left script.
*/
export declare function isRTL(lang: string): boolean;
/**
 * Build a translated banner text line for a charity.
 *
 * @returns The formatted string "UA_FLAG supportUkraine name: tagline"
 */
export declare function formatBannerText(charity: Charity, messages: LocaleMessages): string;
/**
 * Eagerly pre-load the English locale so it is always available synchronously.
 * Other locales are loaded on demand via `loadLocale()`.
 */
export declare function preloadDefault(): Promise<LocaleMessages>;