/**
 * Retry Queue - Exponential Backoff (PostHog-style)
 *
 * Retries failed requests with jittered exponential backoff.
 * Detects online/offline status and pauses retries when offline.
 *
 * Features:
 * - Exponential backoff: 3s, 6s, 12s, 24s... up to 30 minutes
 * - Jitter: +/- 50% to prevent thundering herd
 * - Online/offline detection
 * - Max 10 retries before giving up
 * - Uses sendBeacon on page unload for final attempt
 */
import type { BatchedRequest } from "./request-queue";
/**
 * Generates a jittered exponential backoff delay in milliseconds
 *
 * Base value is 3 seconds, doubled with each retry up to 30 minutes max.
 * Each value has +/- 50% jitter.
 *
 * @param retriesPerformedSoFar - Number of retries already attempted
 * @returns Delay in milliseconds
 */
export declare function pickNextRetryDelay(retriesPerformedSoFar: number): number;
export interface RetryQueueConfig {
    sendRequest: (req: BatchedRequest) => Promise<{
        statusCode: number;
    }>;
    sendBeacon: (req: BatchedRequest) => void;
}
export declare class RetryQueue {
    private _isPolling;
    private _poller?;
    private _pollIntervalMs;
    private _queue;
    private _areWeOnline;
    private _sendRequest;
    private _sendBeacon;
    constructor(config: RetryQueueConfig);
    /**
     * Get current queue length
     */
    get length(): number;
    /**
     * Enqueue a failed request for retry
     */
    enqueue(request: BatchedRequest, retriesPerformedSoFar?: number): void;
    /**
     * Attempt to send a request with retry on failure
     */
    retriableRequest(request: BatchedRequest): Promise<void>;
    /**
     * Start polling for retries
     */
    private _poll;
    /**
     * Flush ready items from the queue
     */
    private _flush;
    /**
     * Flush all queued requests using sendBeacon on page unload
     */
    unload(): void;
}