import { Observable } from 'rxjs';
import * as i0 from "@angular/core";
export type LiveReadFetch<T> = () => Observable<T> | Promise<T>;
export type LiveReadWatch<T> = () => Observable<T>;
export interface LiveReadFallbackOptions<T> {
    /**
     * One-time source of truth. Usually an HTTP API read.
     */
    fetch: LiveReadFetch<T>;
    /**
     * Realtime source. Usually Firestore watch(). If it errors, polling takes over.
     */
    watch?: LiveReadWatch<T>;
    /**
     * Polling interval used when realtime is unavailable or fails.
     */
    pollIntervalMs?: number;
    /**
     * Called when the realtime stream fails and the helper switches to polling.
     */
    onRealtimeError?: (error: unknown) => void;
    /**
     * Called on individual polling failures. Polling keeps running.
     */
    onPollingError?: (error: unknown) => void;
    /**
     * Called when the initial fetch fails. Realtime/polling still starts.
     */
    onInitialFetchError?: (error: unknown) => void;
    /**
     * Keep polling even when realtime is active. Useful when the mirror is
     * best-effort and the API must periodically correct stale data.
     */
    pollWhileWatching?: boolean;
}
/**
 * Combines a truth-source fetch with an optional realtime stream and polling
 * fallback. Use it for public mirrors where Firestore improves UX, but the API
 * remains the authoritative path.
 */
export declare class LiveReadFallbackService {
    watch<T>(options: LiveReadFallbackOptions<T>): Observable<T>;
    static ɵfac: i0.ɵɵFactoryDeclaration<LiveReadFallbackService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<LiveReadFallbackService>;
}