/**
 * tina4js/i18n — Internationalization and localization. Reactive, zero deps.
 *
 * The active locale is a SIGNAL. t() and the Intl-backed formatters read it,
 * so when you switch locale every translated string and every formatted
 * number/date re-renders in place — as long as you use them in the reactive
 * function form inside a template:
 *
 *     html`<h1>${() => i18n.t('greeting')}</h1>`
 *     html`<p>${() => i18n.currency(19.99, 'USD')}</p>`
 *     i18n.setLocale('fr');   // both update, no reload
 *
 * Formatting is delegated to the browser's native Intl APIs, so there is no
 * locale data to ship. Translations are key-based JSON bundles, mirroring the
 * backend tina4 I18n API (t / setLocale / getLocale / addMessages /
 * availableLocales) so the frontend and backend speak the same shape.
 */
import { type Signal } from '../core/signal';
/** A bundle of messages for one locale. Nested objects are allowed. */
export type Messages = Record<string, unknown>;
/** Message bundles keyed by locale code, e.g. { en: {...}, fr: {...} }. */
export type LocaleMessages = Record<string, Messages>;
export interface I18nOptions {
    /** Active locale. Default: the browser's navigator.language, else 'en'. */
    locale?: string;
    /** Locale used when a key is missing in the active locale. Default: the initial locale. */
    fallbackLocale?: string;
    /** Initial bundles keyed by locale. Nested objects are flattened (dot-path + leaf alias). */
    messages?: LocaleMessages;
    /** Extra base codes (e.g. 'ar') to treat as right-to-left, on top of the built-in set. */
    rtlLocales?: string[];
}
export interface I18n {
    /** The active locale as a reactive signal. Set `.value` or call setLocale(). */
    readonly locale: Signal<string>;
    /** Translate a key, with optional {placeholder} interpolation. Reactive when read in a function block. */
    t(key: string, params?: Record<string, unknown>): string;
    /** Switch the active locale (updates the signal, so dependents re-render). */
    setLocale(locale: string): void;
    /** The active locale code. */
    getLocale(): string;
    /** Merge a bundle into a locale (nested objects flattened). Existing keys are overwritten. */
    addMessages(locale: string, messages: Messages): void;
    /** True if any messages are loaded for the locale. */
    hasLocale(locale: string): boolean;
    /** Sorted list of locale codes that have messages loaded. */
    availableLocales(): string[];
    /** Fetch a JSON bundle from a URL and merge it into the locale. */
    loadMessages(locale: string, url: string): Promise<void>;
    /** Format a number for the active locale via Intl.NumberFormat. */
    number(value: number, options?: Intl.NumberFormatOptions): string;
    /** Format a currency amount for the active locale. */
    currency(value: number, currency: string, options?: Intl.NumberFormatOptions): string;
    /** Format a date for the active locale via Intl.DateTimeFormat. Accepts Date, epoch ms, or a parseable string. */
    date(value: Date | number | string, options?: Intl.DateTimeFormatOptions): string;
    /** Format a relative time (e.g. -1, 'day' -> "yesterday") via Intl.RelativeTimeFormat. */
    relativeTime(value: number, unit: Intl.RelativeTimeFormatUnit, options?: Intl.RelativeTimeFormatOptions): string;
    /** True when the active locale is right-to-left. Reactive when read in a function block. */
    isRTL(): boolean;
    /** "rtl" or "ltr" for the active locale — bind to a container's `dir`. */
    dir(): 'rtl' | 'ltr';
}
/**
 * Create an isolated i18n instance. Most apps use the default `i18n` singleton,
 * but multiple instances are supported (e.g. per-widget or for testing).
 */
export declare function createI18n(options?: I18nOptions): I18n;
/** The default i18n instance. Configure with i18n.addMessages(...) / i18n.setLocale(...). */
export declare const i18n: I18n;
/** Translate via the default instance. Reactive when read in a function block. */
export declare function t(key: string, params?: Record<string, unknown>): string;
/** Switch the default instance's locale. */
export declare function setLocale(locale: string): void;
/** The default instance's active locale. */
export declare function getLocale(): string;
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