import { NodeOperationError } from 'n8n-workflow';
/**
 * Zalo OA Transport Layer
 *
 * Shared utilities for making API requests, handling errors,
 * and verifying webhook signatures.
 */
/**
 * Zalo API Error Response Structure
 */
export interface IZaloApiError {
    error: number;
    message: string;
}
/**
 * HTTP Request options for Zalo API
 */
export interface IRequestOptions {
    method: 'GET' | 'POST' | 'PUT' | 'DELETE';
    url: string;
    headers?: Record<string, string>;
    body?: any;
    qs?: Record<string, string>;
    formData?: any;
    timeout?: number;
}
/**
 * Make HTTP request with exponential backoff retry for rate limits (429)
 *
 * @param requestFn - Function that returns a promise for the HTTP request
 * @param maxRetries - Maximum number of retries (default: 3)
 * @param initialDelay - Initial delay in milliseconds (default: 1000ms)
 * @returns Promise with the response data
 */
export declare function makeRequestWithRetry<T>(requestFn: () => Promise<T>, maxRetries?: number, initialDelay?: number): Promise<T>;
/**
 * Handle Zalo API errors and wrap them in NodeOperationError
 *
 * @param error - The error object from the API request
 * @returns NodeOperationError with clear error message
 */
export declare function handleZaloError(error: any): NodeOperationError;
/**
 * Verify Zalo webhook signature using HMAC-SHA256
 *
 * @param payload - The webhook payload (as string or buffer)
 * @param signature - The signature from X-Zalo-Signature header
 * @param secret - The App Secret from Zalo credentials
 * @returns true if signature is valid, false otherwise
 */
export declare function verifyWebhookSignature(payload: string | Buffer, signature: string, secret: string): boolean;
/**
 * Calculate exponential backoff delay
 * @param attempt - Current attempt number (0-indexed)
 * @param initialDelay - Initial delay in milliseconds
 * @returns Delay in milliseconds
 */
export declare function calculateBackoffDelay(attempt: number, initialDelay?: number): number;