import { ClientOptions, HttpClient } from "./models";
/**
 * Http client implementation based on the native Fetch API (available in Node 18+).
 * This keeps the SDK dependency-free while preserving the previous error handling contract.
 */
export declare class FetchHttpClient extends HttpClient {
    client: ClientOptions.FetchImplementation;
    private errorHandler;
    constructor(configOptions?: ClientOptions.Configuration);
    /**
     * Create http client instance with default settings.
     */
    initHttpClient(configOptions?: ClientOptions.Configuration): void;
    /**
     * Process http request.
     *
     * @param method - Which type of http request will be executed.
     * @param path - API URL endpoint.
     * @param queryParameters - Querystring parameters used for http request.
     * @param body - Data sent with http request.
     * @param requestHeaders - Headers sent with http request.
     */
    httpRequest<T>(method: ClientOptions.HttpMethod, path: string, queryParameters: object, body: (null | object), requestHeaders: any): Promise<T>;
    /**
     * Build the full request URL from the base URL, path and query parameters.
     *
     * @private
     */
    private buildRequestURL;
    /**
     * Serialize query parameters into a querystring, ignoring undefined and null values.
     *
     * Every current *FilteringParameters query value is a string, number, boolean or enum, so
     * primitive serialization is sufficient today. Arrays are still expanded to repeated keys and
     * Date values to ISO strings (as axios used to do) so that adding such a filter param later
     * cannot silently produce a malformed URL via String([1,2]) or String(new Date()).
     *
     * @private
     */
    private serializeQueryParameters;
    private stringifyQueryValue;
    /**
     * Read and parse the response body. Postmark responses are JSON, but empty bodies are tolerated.
     *
     * @private
     */
    private parseResponseBody;
    /**
     * Build a Postmark error from a non-2xx response.
     *
     * @param data - parsed response body.
     * @param status - http response status code.
     *
     * @return {PostmarkError} - formatted Postmark error
     * @private
     */
    private buildRequestError;
    /**
     * Transform a thrown error (network failure, timeout, abort) into a proper Postmark error.
     *
     * @param errorThrown - error thrown while performing the request.
     *
     * @return {PostmarkError} - formatted Postmark error
     * @private
     */
    private transformError;
    /**
     * Build an AbortSignal that aborts the request once the configured timeout elapses.
     *
     * AbortSignal.timeout() is available at runtime in Node 18+, but is not present in the
     * lib.dom typings shipped with the TypeScript version this project pins, so it is
     * referenced through an explicit cast.
     *
     * @private
     */
    private buildTimeoutSignal;
    /**
     * Timeout in seconds is adjusted to milliseconds.
     *
     * @private
     */
    private getRequestTimeoutInMilliseconds;
    private adjustValue;
}