/**
 * @module botbuilder-m365
 */
/**
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */
import { TurnState } from './TurnState';
export declare class ConversationHistory {
    /**
     * Name of the conversation state property used to hold the list of entires.
     */
    static readonly StatePropertyName = "__history__";
    /**
     * Adds a new line of text to conversation history
     *
     * @param {TurnState} state Applications turn state.
     * @param {string} line Line of text to add to history.
     * @param {number} maxLines Optional. Maximum number of lines to store. Defaults to 10.
     */
    static addLine(state: TurnState, line: string, maxLines?: number): void;
    static appendToLastLine(state: TurnState, text: string): void;
    static clear(state: TurnState): void;
    static hasMoreLines(state: TurnState): boolean;
    static getLastLine(state: TurnState): string;
    static getLastSay(state: TurnState): string;
    static removeLastLine(state: TurnState): string | undefined;
    static replaceLastLine(state: TurnState, line: string): void;
    static replaceLastSay(state: TurnState, newResponse: string, botPrefix?: string): void;
    /**
     * Returns the current conversation history as a string of text.
     *
     *
     * The length of the returned text is gated by `maxCharacterLength` and only whole lines of
     * history entries will be returned. That means that if the length of the most recent history
     * entry is greater then `maxCharacterLength` no text will be returned.
     *
     * @param {TurnState} state Applications turn state.
     * @param {number} maxTokens Optional. Maximum length of the text returned. Defaults to 1000 tokens.
     * @param {string} lineSeparator Optional. Separator used between lines. Defaults to '\n'.
     * @returns {string} The most recent lines of conversation history as a text string.
     */
    static toString(state: TurnState, maxTokens?: number, lineSeparator?: string): string;
    static toArray(state: TurnState, maxTokens?: number): string[];
}
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