/**
 * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/IntersectionObserver}
 */
type ObserverOptions = {
    root?: HTMLElement;
    rootMargin: string;
    threshold: number[];
};
type PostTrackerConfig = {
    options?: ObserverOptions;
    query: string;
    returnVisibleElement: boolean;
    minMillisecondsToReport?: number;
    observerUpdateEventString?: string;
    liveBlogWrapperQuery?: string;
    liveBlogWrapper?: HTMLElement;
    onEntersViewport: (args: {
        timestamp: string;
        element?: HTMLElement;
    }) => void;
    onRead: (args: {
        post: object;
        viewport: ViewPort;
        summary: object[];
    }) => void;
    onError: (event: Error) => void;
};
type ViewPort = {
    height: number;
    width: number;
};
/**
 * A class representing an intersection observer tracker.
 *
 * Used to track how a user reads through articles on FT pages.
 *
 * If no elements are found IntersectionObserverTracker the onError callback is called.
 */
export declare class PostTracker {
    config: PostTrackerConfig;
    currentlyObservedElements: Set<Element>;
    visibleElements: Set<HTMLElement>;
    wrapperElement: HTMLElement | null;
    defaultOptions: {
        root: null;
        rootMargin: string;
        threshold: number[];
    };
    onEntersViewport: PostTrackerConfig['onEntersViewport'];
    onRead: PostTrackerConfig['onRead'];
    onError: PostTrackerConfig['onError'];
    observer: IntersectionObserver;
    constructor(config: PostTrackerConfig);
    setUp(): void;
    /**
     * checks if the PostTrackerConfig passed in is valid
     *
     * @returns {Boolean}
     */
    isValidConfig(): boolean;
    /**
     * Handles reporting when a DOM element gets into the view
     * Also reports when a post has been on the viewport for more than 5s
     */
    manageIntersection(entries: IntersectionObserverEntry[]): void;
    /**
     * Adds window visibility data to dataset.visibilityData for all DOM elements if this.visibleElements
     */
    handleVisibilityChange(event: Event): void;
    /**
     * Starts observing a list of elements that match query.
     * Calls the on error callback if no element is found.
     */
    observeElements(query: string): void;
    /**
     * Observes new post rendered in the wrapper
     */
    observeNewElements(): void;
    /**
     * Disconnects the intersection observer and stops watching for visibility changes
     * @returns
     */
    stopObservation(): void;
    /**
     * Stops observing element visibility and cleans up resources
     */
    destroy(): void;
    /**
     * Calls the onEntersViewport callback only once when the target element of an IntersectionObserverEntry enters the user's viewPort.
     */
    reportOnEntersViewport(entry: IntersectionObserverEntry): void;
    summariseAndReport(entry: IntersectionObserverEntry): void;
    /**
     * Gets the summary data from the IntersectionObserverEntry and stores it
     * in the IntersectionObserverEntry.target.dataset.visibilityData as a
     * JSON.stringified object (refers to an Array).
     */
    summariseAndStoreViewData(entry: IntersectionObserverEntry): void;
    /**
     * Emits the View data to the consumer
     */
    reportRead(element: HTMLElement): void;
    /**
     * Adds or removes a DOM element from the this.visibleElements depending on if
     * the element is intersecting
     */
    updateVisibleElements(entry: IntersectionObserverEntry): void;
    /**
     * Processes the times for when the DOM element was in view
     *
     * @param {(VisibilityData|TabVisibilityData)[]} summary - NB not working when try this in typescript
     */
    processTime(summary: any): {
        summary: any[];
        duration: number;
        start: any;
        end: any;
    };
    /**
     * Emits the read event for all visible elements when the user closes the browser window
     * this function doesn't exist, unclear whether anything should happen or not
     */
    handleWindowClose(): void;
    /**
     * runs read report for all visible elements
     */
    runFinalReadReport(): void;
    /**
     * Calls the onError callback if a function is passed to the
     */
    triggerError(error: Error): void;
    /**
     * checks if an element is currently being observed
     * @returns {boolean}
     */
    isElementBeingObserved(element: Element): boolean;
}
export {};