/**
 * Returns a substring of an HTML string while preserving HTML structure.
 *
 * Core rules:
 * - Element nodes are re-serialized as tags (start/end) to keep structure.
 * - Text nodes are always HTML-escaped on output. This prevents that previously
 *   escaped text (like "<div>") turns into real tags during the DOM round trip.
 * - Attribute values are HTML-escaped on output.
 * - Void elements are serialized without closing tags.
 * - For TWIGNORE/TW-IGNORE elements, the innerHTML is passed through so that
 *   their content (including real HTML) remains untouched.
 * - On early cutoff (once the length limit is reached), already opened tags are
 *   properly closed to keep the result valid HTML.
 *
 * Note on length counting:
 * - The length is based on the decoded textContent length (as the DOM provides),
 *   not on byte length nor escaped entity length. This mirrors how the text is perceived.
 *
 * @param html   The input HTML string; may contain a mix of real HTML and already escaped HTML.
 * @param length The maximum number of text characters (based on textContent) to include.
 * @returns A valid HTML string containing up to the specified number of text characters,
 *          preserving HTML tags and keeping escaped text escaped.
 */
export declare const getSubTextFromHTML: (html: string, length: number) => string;
export declare const getCharactersCount: (html: string) => number;
export declare const shuffleArray: <T>(array: T[]) => T[];
export declare const calculateAutoSpeed: (ema: number) => {
    speed: number;
    steps: number;
};
interface CalculateEMAProps {
    currentEMA: number;
    newValue: number;
    alpha?: number;
}
export declare const calculateEMA: ({ currentEMA, newValue, alpha }: CalculateEMAProps) => number;
export interface ChunkStreamingSpeedState {
    lastTimestamp?: number;
    lastLength: number;
    ema: number;
}
interface ChunkStreamingSpeedProps {
    currentLength: number;
    state: ChunkStreamingSpeedState;
}
export declare const updateChunkStreamingSpeedEMA: ({ currentLength, state, }: ChunkStreamingSpeedProps) => ChunkStreamingSpeedState;
export {};