import * as _backstage_frontend_plugin_api from '@backstage/frontend-plugin-api';
import { JsonObject } from '@backstage/types';

/** @public */
declare const signalApiRef: _backstage_frontend_plugin_api.ApiRef<SignalApi>;
/** @public */
interface SignalSubscriber {
    unsubscribe(): void;
}
/** @public */
interface SignalApi {
    subscribe<TMessage extends JsonObject = JsonObject>(channel: string, onMessage: (message: TMessage) => void): SignalSubscriber;
}

/** @public */
declare const useSignal: <TMessage extends JsonObject = JsonObject>(channel: string) => {
    lastSignal: TMessage | null;
    isSignalsAvailable: boolean;
};

export { signalApiRef, useSignal };
export type { SignalApi, SignalSubscriber };