/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import { Direction } from '@angular/cdk/bidi';
/**
 * Function that is used to determine whether an item can be sorted into a particular index.
 * @docs-private
 */
export type SortPredicate<T> = (index: number, item: T) => boolean;
/**
 * Item that can be sorted within `DropListSortStrategy`. This is a limited representation of
 * `DragRef` used to avoid circular dependencies. It is intended to only be used within
 * `DropListSortStrategy`.
 * @docs-private
 */
export interface DropListSortStrategyItem {
    isDragging(): boolean;
    getPlaceholderElement(): HTMLElement;
    getRootElement(): HTMLElement;
    _sortFromLastPointerPosition(): void;
    getVisibleElement(): HTMLElement;
}
/**
 * Strategy used to sort and position items within a drop list.
 * @docs-private
 */
export interface DropListSortStrategy<T extends DropListSortStrategyItem> {
    direction: Direction;
    start(items: readonly T[]): void;
    nest(item: T, nestIndex: number, currentNestIndex: number): void;
    unnest(item: T, nestIndex: number): void;
    sort(item: T, pointerX: number, pointerY: number, pointerDelta: {
        x: number;
        y: number;
    }): {
        previousIndex: number;
        currentIndex: number;
    } | null;
    enter(item: T, pointerX: number, pointerY: number, index?: number): void;
    withItems(items: readonly T[]): void;
    withSortPredicate(predicate: SortPredicate<T>): void;
    reset(): void;
    getActiveItemsSnapshot(): readonly T[];
    getItemIndex(item: T): number;
    getActiveItem(index: number): T;
    updateOnScroll(topDifference: number, leftDifference: number): void;
}