/**
 * Virtual Scroll Utility for NA-Kit UI
 *
 * Provides efficient rendering for large lists and tables by only
 * rendering visible items plus a small buffer.
 *
 * @module virtual-scroll
 */
export interface VirtualScrollConfig {
    /** Total number of items */
    itemCount: number;
    /** Height of each item in pixels (or estimated average for variable heights) */
    itemHeight: number;
    /** Height of the container viewport in pixels */
    containerHeight: number;
    /** Number of extra items to render above/below the visible area */
    overscan?: number;
    /** Whether items have variable heights */
    variableHeights?: boolean;
}
export interface VirtualScrollState {
    /** Index of the first visible item */
    startIndex: number;
    /** Index of the last visible item */
    endIndex: number;
    /** Offset from top for the first visible item */
    offsetTop: number;
    /** Total height of all items */
    totalHeight: number;
    /** Items currently visible (indices) */
    visibleIndices: number[];
    /** Number of visible items */
    visibleCount: number;
}
export interface ScrollPosition {
    scrollTop: number;
    scrollLeft: number;
}
/**
 * Core virtual scroll logic — framework-agnostic
 *
 * @example
 * ```ts
 * const vs = new VirtualScrollController({
 *   itemCount: 10000,
 *   itemHeight: 40,
 *   containerHeight: 500,
 *   overscan: 5,
 * });
 *
 * // On scroll event:
 * const state = vs.update(scrollTop);
 * // Render items from state.startIndex to state.endIndex
 * // Apply state.offsetTop as transform on the items container
 * ```
 */
export declare class VirtualScrollController {
    private _config;
    private _state;
    private _itemHeights;
    private _listeners;
    constructor(config: VirtualScrollConfig);
    /** Get current state */
    get state(): VirtualScrollState;
    /** Update configuration (e.g. when item count changes) */
    updateConfig(config: Partial<VirtualScrollConfig>): void;
    /** Set a specific item's actual height (for variable-height items) */
    setItemHeight(index: number, height: number): void;
    /** Update scroll position and return new state */
    update(scrollTop: number): VirtualScrollState;
    /** Scroll to a specific item index */
    getScrollTopForIndex(index: number): number;
    /** Subscribe to state changes */
    subscribe(listener: (state: VirtualScrollState) => void): () => void;
    private _getItemHeight;
    private _calculateState;
    private _notify;
}
export interface LazyLoadOptions {
    /** Root element for intersection (default: viewport) */
    root?: Element | null;
    /** Margin around root */
    rootMargin?: string;
    /** Threshold for triggering */
    threshold?: number | number[];
    /** Callback when element becomes visible */
    onVisible?: (entry: IntersectionObserverEntry) => void;
    /** Whether to unobserve after first intersection */
    once?: boolean;
}
/**
 * Create a lazy loading observer for elements
 */
export declare class LazyLoader {
    private _observer;
    private _callbacks;
    private _once;
    constructor(options?: LazyLoadOptions);
    /** Observe an element */
    observe(element: Element, callback?: (entry: IntersectionObserverEntry) => void): void;
    /** Stop observing an element */
    unobserve(element: Element): void;
    /** Disconnect the observer */
    destroy(): void;
}
export interface InfiniteScrollOptions {
    /** The scrollable container */
    container: HTMLElement;
    /** Distance from bottom to trigger load (px) */
    threshold?: number;
    /** Callback when more items should be loaded */
    onLoadMore: () => void | Promise<void>;
    /** Whether loading is in progress */
    isLoading?: () => boolean;
    /** Whether all items have been loaded */
    hasMore?: () => boolean;
}
/**
 * Infinite scroll helper — triggers loading when near the bottom
 */
export declare class InfiniteScroll {
    private _container;
    private _threshold;
    private _onLoadMore;
    private _isLoading;
    private _hasMore;
    private _handleScroll;
    constructor(options: InfiniteScrollOptions);
    private _onScroll;
    /** Remove event listener and clean up */
    destroy(): void;
}
//# sourceMappingURL=virtual-scroll.d.ts.map