import type { Actor, IAction, IActorOutput, IActorTest } from './Actor';
import type { Bus } from './Bus';
/**
 * An ActionObserver can passively listen to {@link Actor#run} inputs and outputs for all actors on a certain bus.
 *
 * ActionObserver should not edit inputs and outputs,
 * they should be considered immutable.
 *
 * @see Actor
 * @see Bus
 *
 * @template I The input type of an actor.
 * @template O The output type of an actor.
 */
export declare abstract class ActionObserver<I extends IAction, O extends IActorOutput> {
    readonly name: string;
    readonly bus: Bus<Actor<I, IActorTest, O>, I, IActorTest, O>;
    /**
     * All enumerable properties from the `args` object are inherited to this observer.
     *
     * The observer will NOT automatically subscribe to the given bus when this constructor is called.
     *
     * @param {IActionObserverArgs<I extends IAction, O extends IActorOutput>} args Arguments object
     * @throws When required arguments are missing.
     */
    protected constructor(args: IActionObserverArgs<I, O>);
    /**
     * Invoked when an action was run by an actor.
     *
     * @param actor               The action on which the {@link Actor#run} method was invoked.
     * @param {I}          action The original action input.
     * @param {Promise<O>} output A promise resolving to the final action output.
     */
    abstract onRun(actor: Actor<I, IActorTest, O>, action: I, output: Promise<O>): void;
}
export interface IActionObserverArgs<I extends IAction, O extends IActorOutput> {
    /**
     * The name for this observer.
     * @default {<rdf:subject>}
     */
    name: string;
    /**
     * The bus this observer can subscribe to.
     */
    bus: Bus<Actor<I, IActorTest, O>, I, IActorTest, O>;
}