import {ExchangeService} from "../Core/ExchangeService";
import {GetEventsResults} from "./GetEventsResults";

import {SubscriptionBase} from "./SubscriptionBase";
/**
 * Represents a pull subscription.
 * 
 * @sealed
 */
export class PullSubscription extends SubscriptionBase {

	private moreEventsAvailable: boolean = null;
	
	/**
	 * Gets a value indicating whether more events are available on the server.
	 * MoreEventsAvailable is undefined (null) until GetEvents is called.
	 */
	get MoreEventsAvailable(): boolean {
		return this.moreEventsAvailable;
	}

	/**
	 * @internal Initializes a new instance of the **PullSubscription** class.
	 *
	 * @param   {ExchangeService}   service     The service.
	 */
    constructor(service: ExchangeService) {
        super(service);
    }

	/**
	 * Obtains a collection of events that occurred on the subscribed folders since the point in time defined by the Watermark property. When GetEvents succeeds, Watermark is updated.
	 *
	 * @return  {Promise<GetEventsResults>}      Returns a collection of events that occurred since the last watermark	:Promise.
	 */
	GetEvents(): Promise<GetEventsResults> {
		return this.Service.GetEvents(this.Id, this.Watermark).then((results: GetEventsResults) => {

            this.Watermark = results.NewWatermark;
            this.moreEventsAvailable = results.MoreEventsAvailable;

            return results;
		});
	}

	/**
	 * Unsubscribes from the pull subscription.
	 */
	Unsubscribe(): Promise<void> { return this.Service.Unsubscribe(this.Id); }
}