import { type RefObject } from 'react';
/**
 * Minimum difference between the layout and the visual viewport that is treated as an opened
 * on-screen keyboard. Small differences come from browser UI (URL bar, toolbars) and must not
 * shrink the container.
 */
export declare const KEYBOARD_MIN_INSET = 80;
export interface KeyboardViewportMetrics {
    /** `visualViewport.height` - height of the area not covered by the keyboard. */
    viewportHeight: number;
    /** `visualViewport.offsetTop` - offset of the visual viewport inside the layout viewport. */
    viewportOffsetTop: number;
    /** `visualViewport.scale` - pinch-zoom factor, `1` when the page is not zoomed. */
    scale: number;
    /** `window.innerHeight` - layout viewport height, unaffected by the keyboard on iOS Safari. */
    layoutHeight: number;
    /** Top of the container in layout viewport coordinates (`getBoundingClientRect().top`). */
    containerTop: number;
}
export interface KeyboardViewportFit {
    /** Whether the on-screen keyboard currently covers part of the layout viewport. */
    isKeyboardOpen: boolean;
    /**
     * Height limit that keeps the bottom of the container right above the keyboard.
     * `undefined` while the keyboard is closed - the container keeps its natural height.
     */
    maxHeight?: number;
}
/**
 * Height limit for a container whose bottom would otherwise end up under the on-screen keyboard.
 *
 * Browsers keep the layout viewport at full height while the keyboard is open (iOS Safari always,
 * Chrome and Firefox since the `interactive-widget=resizes-visual` default), so `100vh` / `100dvh` /
 * `height: 100%` keep the original height and the bottom of the chat (prompt input, disclaimer)
 * stays hidden. The visible area is reported by `visualViewport` instead, and the limit is its
 * bottom edge measured from the top of the container.
 */
export declare function resolveKeyboardViewportFit(metrics: KeyboardViewportMetrics, minInset?: number): KeyboardViewportFit;
/**
 * Tracks the on-screen keyboard through `visualViewport` and returns the height limit that keeps
 * the referenced container inside the visible area.
 *
 * @param containerRef - element to fit into the visual viewport
 * @param enabled - disables tracking (e.g. outside mobile mode)
 */
export declare function useKeyboardViewportFit(containerRef: RefObject<HTMLElement>, enabled?: boolean): KeyboardViewportFit;