/// <reference types="node" />
import IOperationQueue from './interfaces/IOperationQueue';
/**
 * Operation queue used by the Batch Writer implemented using MongoDB.
 */
export default class MongoDbOperationQueue implements IOperationQueue {
    private serverUrl;
    /** Collection name for queued operations. */
    static readonly collectionName: string;
    private collection;
    /**
     * MongoDb database name where the operations are stored
     */
    private databaseName;
    private db;
    constructor(serverUrl: string, databaseName?: string);
    /**
     * Initialize the MongoDB operation store.
     */
    initialize(): Promise<void>;
    enqueue(didUniqueSuffix: string, operationBuffer: Buffer): Promise<void>;
    dequeue(count: number): Promise<Buffer[]>;
    peek(count: number): Promise<Buffer[]>;
    /**
     * Checks to see if the queue already contains an operation for the given DID unique suffix.
     */
    contains(didUniqueSuffix: string): Promise<boolean>;
    /**
     * * Clears the unresolvable transaction store. Mainly used in tests.
     */
    clearCollection(): Promise<void>;
    /**
     * Creates the queued operation collection with indexes if it does not exists.
     * @returns The existing collection if exists, else the newly created collection.
     */
    private static createCollectionIfNotExist;
}