import PageViewport from '~/interfaces/PageViewport';
/**
 * Zoom navigation controller for the PDF viewer.
 *
 * Manages all zoom-related interactions: the zoom dropdown menu, zoom in/out buttons,
 * direct percentage input, Ctrl+wheel zooming, and automatic re-zoom on window resize.
 * The controller emits zoom factor changes through a registered callback via {@link onChange}.
 */
export default class ZoomNav {
    /** Intrinsic page viewport size at the base scale, used for fit-to-page/width calculations. */
    private readonly pageViewport;
    /** Toggle button/area that opens and closes the zoom dropdown menu. */
    private readonly zoomToggle;
    /** The zoom dropdown menu element. */
    private readonly zoomMenu;
    /** All selectable zoom preset buttons (percentage values and fit modes). */
    private readonly zoomSelects;
    /** Button to decrease the zoom level by one step. */
    private readonly zoomOutButton;
    /** Button to increase the zoom level by one step. */
    private readonly zoomInButton;
    /** Form element wrapping the zoom input field. */
    private readonly zoomForm;
    /** Input field displaying and accepting the current zoom percentage. */
    private readonly zoomInput;
    /** The scrollable page view container, used for fit-to-page/width calculations. */
    private readonly pageView;
    /** Timer ID for debouncing window resize events. */
    private resizeTimeout;
    /** Last known zoom percentage value (e.g. 100 for 100%). Used as fallback for invalid input. */
    private lastZoomFactor;
    /** Last selected zoom value string (e.g. "100", "pageWidth"). */
    private lastZoomValue;
    /** Sorted list of numeric zoom percentages available in the dropdown (e.g. [50, 75, 100, ...]). */
    private readonly zoomFactorList;
    /** Minimum zoom percentage available in the dropdown. */
    private readonly minZoomFactor;
    /** Maximum zoom percentage available in the dropdown. */
    private readonly maxZoomFactor;
    /** Callback invoked when the zoom factor changes. */
    private changeListener;
    /**
     * Initializes the zoom navigation by querying dependent DOM nodes,
     * determining the initial zoom level, and binding all event listeners.
     *
     * If the PDF's intrinsic width exceeds the viewer container width,
     * the initial zoom is set to "fit to width"; otherwise it defaults to 100%.
     *
     * @param context      - The root element containing all zoom-related elements.
     * @param pageViewport - The intrinsic page viewport size at the base scale.
     */
    constructor(context: HTMLElement, pageViewport: PageViewport);
    /**
     * Opens the zoom dropdown menu.
     */
    open(): void;
    /**
     * Closes the zoom dropdown menu.
     */
    close(): void;
    /**
     * Returns the current zoom factor as a ratio (e.g. `1.5` for 150%).
     *
     * @returns The current zoom factor.
     */
    getZoomFactor(): number;
    /**
     * Registers a callback that is invoked whenever the zoom factor changes.
     *
     * @param listener - Callback receiving the new zoom factor as a ratio.
     * @returns This instance for chaining.
     */
    onChange(listener: (zoomFactor: number) => void): ZoomNav;
    /**
     * Positions the zoom dropdown menu below the toggle button using absolute coordinates.
     */
    private layoutZoomMenuLayout;
    /**
     * Calculates the zoom factor for the given zoom value and updates the input display.
     *
     * @param strZoom - The zoom value (numeric percentage string or fit mode name).
     */
    private updateInputZoom;
    /**
     * Removes the selection highlight from the currently selected zoom menu item.
     */
    private deselectZoom;
    /**
     * Highlights the zoom menu item matching the given zoom value, if one exists.
     *
     * @param zoomValue - The zoom value to match against menu item `data-value` attributes.
     */
    private activateZoom;
    /**
     * Parses the zoom percentage from the input field, clamps it to the valid range,
     * and applies the resulting zoom. If the input is not a valid number,
     * it is reverted to the last known valid zoom percentage.
     */
    private enterZoom;
    /**
     * Steps the zoom level up or down to the nearest preset value in the dropdown list.
     *
     * @param zoomDir - Direction to zoom: {@link constants.ZOOM_OUT} or {@link constants.ZOOM_IN}.
     */
    private calcNextZoom;
    /**
     * Returns the zoom menu button that is currently selected (highlighted), if any.
     *
     * @returns The selected zoom button element, or `undefined` if none is selected.
     */
    private getSelectedZoomNode;
    /**
     * Returns the `data-value` of the currently selected zoom menu item.
     *
     * @returns The zoom value string (e.g. `"100"`, `"pageWidth"`), or `null` if none is selected.
     */
    private getSelectedZoomValue;
}