import { IMessageActivity, ITypingActivity, SentActivity } from '@microsoft/teams.api';
import { IEventEmitter } from '@microsoft/teams.common';
/**
 * Raised when Teams cancels a stream (403) or when a stream operation is attempted after cancellation.
 */
export declare class StreamCancelledError extends Error {
    constructor(message?: string);
}
/**
 * the minimum events a streamer
 * should support
 */
export interface IStreamerEvents {
    /**
     * emitted for each chunk sent
     */
    readonly chunk: SentActivity;
    /**
     * emitted once on stream close
     */
    readonly close: SentActivity;
}
/**
 * component that can send streamed chunks of an activity
 */
export interface IStreamer {
    readonly events: Omit<IEventEmitter<IStreamerEvents>, 'emit'>;
    /**
     * whether the stream has been canceled.
     * For example when the user pressed the Stop button or the 2-minute timeout has exceeded.
     */
    readonly canceled: boolean;
    /**
     * emit an activity chunk
     * @param activity the activity to send
     */
    emit(activity: Partial<IMessageActivity | ITypingActivity> | string): void;
    /**
     * send status updates before emitting (ex. "Thinking...")
     * @param text the status text to send
     */
    update(text: string): void;
    /**
     * close the stream
     */
    close(): SentActivity | undefined | Promise<SentActivity | undefined>;
}