import { ChangeStream, ChangeStreamOptions, Collection, Document, Filter } from 'mongodb';
import { ErrorEvents } from './ErrorEvents';
import { PromiseTracker } from './PromiseTracker';
import { Subscription, SubscriptionCallback, SubscriptionOptions } from './Subscription';
import { TypedEventEmitter } from './TypedEventEmitter';
export interface SubscriberOptions<TMessage extends Document> {
    /** Global MongoDB filter to apply on change stream. */
    filter?: Filter<TMessage>;
    changeStreamOptions?: ChangeStreamOptions;
}
export type SubscriberEvents<TMessage extends Document> = ErrorEvents<TMessage>;
export declare class Subscriber<TMessage extends Document> extends TypedEventEmitter<SubscriberEvents<TMessage>> {
    protected collection: Collection<TMessage>;
    protected filter: Filter<TMessage>;
    protected changeStreamOptions: ChangeStreamOptions;
    protected subscriptions: Set<Subscription<TMessage>>;
    protected changeStream?: ChangeStream;
    protected promises: PromiseTracker;
    protected closed: boolean;
    constructor(collection: Collection<TMessage>, options?: SubscriberOptions<TMessage>);
    /**
     * Subscribes to matching messages in the future.
     *
     * - All active subscribers will receive all future matching messages.
     * - Events are delivered at most once.
     * - Events are delivered in database insertion order.
     * - Past messages are ignored.
     * - Each `Subscriber` instance creates one MongoDB change stream.
     *  - Change streams occupy one connection,
     *  - so you'll usually want only one `Subscriber` instance,
     *  - and multiple `.subscribe()` calls with local filters.
     */
    subscribe<TSpecificMessage extends TMessage>(callback: SubscriptionCallback<TSpecificMessage>, options?: SubscriptionOptions<TSpecificMessage>): Subscription<TSpecificMessage>;
    close(): Promise<void>;
    protected init(): void;
}