/// <reference types="node" resolution-mode="require"/>
import { parentPort } from 'worker_threads';
import type { TransferListItem } from 'worker_threads';
import type { Awaitable } from '../types/utilities.js';
import type { Messenger } from '../messenger/index.js';
import type { RemoveListenerFunction } from '../types/messages.js';
import type { OnStreamCallback } from '../types/streams.js';
declare function sendMessage<Data = any>(data: Data, transferList?: readonly TransferListItem[]): void;
declare function waitForMessage<Data = any>(callback: (body: Data) => Awaitable<boolean>): Promise<Data>;
declare function onMessage<Data = any>(callback: (body: Data) => Awaitable<void>): RemoveListenerFunction;
declare function onMessengerReceived(callback: (messenger: Messenger) => Awaitable<any>): () => import("worker_threads").MessagePort;
declare function onStream(callback: OnStreamCallback<Exclude<typeof parentPort, null>>): RemoveListenerFunction;
declare function createStream(metaData?: Record<string | number, any>): Promise<import("../streams/index.js").WritableToPort<import("worker_threads").MessagePort>>;
/**
 * An object containing functions to be used within workers when communicating with the main thread.
 *
 * @example
 * ParentThread.sendMessage('hello from worker!');
 *
 * ParentThread.onMessage<Record<string, string>>((data) => {
 *     console.log(Object.values(data));
 * });
 */
export declare const ParentThread: Readonly<{
    /**
     * @param data The data to send to the main thread.
     * @param transferList An optional array of {@link TransferListItem}s. See the
     * [Node.js documentation](https://nodejs.org/api/worker_threads.html#workerpostmessagevalue-transferlist) for more information.
     *
     * @example
     * ParentThread.sendMessage('foo');
     * ParentThread.sendMessage({ hello: 'world' });
     */
    sendMessage: typeof sendMessage;
    /**
     * Listen for messages coming from the main thread.
     *
     * @param callback A function to run each time a message is received from the main thread.
     *
     * @returns A function that will remove the listener when called.
     *
     * @example
     * ParentThread.onMessage<string>((data) => console.log(data, 'received!'));
     */
    onMessage: typeof onMessage;
    /**
     * Listen for {@link Messenger}s being sent to the worker from the main thread.
     *
     * @param callback A function to run each time a `Messenger` is received from the main thread.
     *
     * @returns A function that will remove the listener when called.
     *
     * @example
     * ParentThread.onMessengerReceived((messenger) => console.log(messenger.ID));
     */
    onMessengerReceived: typeof onMessengerReceived;
    /**
     * Wait for specific messages coming from the main thread.
     *
     * @param callback A function returning a boolean that will be run each time a message is received the main thread.
     * Once the condition is met and the function returns `true`, the promise will resolve with the data received.
     *
     * @returns A promise of the received data.
     *
     * @example
     * const data = await ParentThread.waitForMessage<{ foo: string }>(({ foo }) => foo === 'bar');
     *
     * console.log(data);
     */
    waitForMessage: typeof waitForMessage;
    /**
     * Receive data streams from the main thread.
     *
     * @param callback The callback to run once the stream has been initialized and is ready to consume.
     */
    onStream: typeof onStream;
    /**
     * Create a {@link Writable} instance that can be piped into in order to stream data to
     * the main thread. The main thread can listen for incoming streams with the
     * `service.onStream()` listener.
     *
     * @param metaData Any specific data about the stream that should be accessible when
     * using it.
     */
    createStream: typeof createStream;
}>;
export {};