import * as React from 'react';
import { IRefObject, IRectangle, IRenderFunction } from '../../Utilities';
import { List } from './List';
/**
 * {@docCategory List}
 */
export declare const ScrollToMode: {
    /**
     * Does not make any consideration to where in the viewport the item should align to.
     */
    auto: 0;
    /**
     * Attempts to scroll the list so the top of the desired item is aligned with the top of the viewport.
     */
    top: 1;
    /**
     * Attempts to scroll the list so the bottom of the desired item is aligned with the bottom of the viewport.
     */
    bottom: 2;
    /**
     * Attempts to scroll the list so the desired item is in the exact center of the viewport.
     */
    center: 3;
};
/**
 * {@docCategory List}
 */
export declare type ScrollToMode = typeof ScrollToMode[keyof typeof ScrollToMode];
/**
 * Props passed to the render override for the list root.
 * {@docCategory List}
 */
export interface IListOnRenderRootProps<T> {
    /**
     * The ref to be applied to the list root.
     * The `List` uses this element to track scroll position and sizing.
     */
    rootRef: React.Ref<HTMLDivElement>;
    /**
     * Props to apply to the list root element.
     */
    divProps: React.HTMLAttributes<HTMLDivElement>;
    /**
     * The active pages to be rendered into the list.
     * These will have been rendered using `onRenderPage`.
     */
    pages: IPage<T>[];
    /**
     * The content to be rendered as the list surface element.
     * This will have been rendered using `onRenderSurface`.
     */
    surfaceElement: JSX.Element | null;
}
/**
 * Props passed to the render override for the list surface.
 * {@docCategory List}
 */
export interface IListOnRenderSurfaceProps<T> {
    /**
     * A ref to be applied to the surface element.
     * The `List` uses this element to track content size and focus.
     */
    surfaceRef: React.Ref<HTMLDivElement>;
    /**
     * Props to apply to the list surface element.
     */
    divProps: React.HTMLAttributes<HTMLDivElement>;
    /**
     * The active pages to be rendered into the list.
     * These will have been rendered using `onRenderPage`.
     */
    pages: IPage<T>[];
    /**
     * The content to be rendered representing all active pages.
     */
    pageElements: JSX.Element[];
}
/**
 * {@docCategory List}
 */
export interface IList {
    /**
     * Force the component to update.
     */
    forceUpdate: () => void;
    /**
     * Get the current height the list and it's pages.
     */
    getTotalListHeight?: () => number;
    /**
     * Scroll to the given index. By default will bring the page the specified item is on into the view. If a callback
     * to measure the height of an individual item is specified, will only scroll to bring the specific item into view.
     *
     * Note: with items of variable height and no passed in `getPageHeight` method, the list might jump after scrolling
     * when windows before/ahead are being rendered, and the estimated height is replaced using actual elements.
     *
     * @param index - Index of item to scroll to
     * @param measureItem - Optional callback to measure the height of an individual item
     * @param scrollToMode - Optional defines the behavior of the scrolling alignment. Defaults to auto.
     *  Note: The scrollToMode requires the measureItem callback is provided to function.
     */
    scrollToIndex: (index: number, measureItem?: (itemIndex: number) => number, scrollToMode?: ScrollToMode) => void;
    /**
     * Get the start index of the page that is currently in view
     */
    getStartItemIndexInView: () => number;
}
/**
 * {@docCategory List}
 */
export interface IListProps<T = any> extends React.HTMLAttributes<List<T> | HTMLDivElement> {
    /**
     * Optional callback to access the IList interface. Use this instead of ref for accessing
     * the public methods and properties of the component.
     */
    componentRef?: IRefObject<IList>;
    /** Optional classname to append to root list. */
    className?: string;
    /** Items to render. */
    items?: T[];
    /**
     * Method to call when trying to render an item.
     * @param item - The data associated with the cell that is being rendered.
     * @param index - The index of the cell being rendered.
     * @param isScrolling - True if the list is being scrolled. May be useful for rendering a placeholder if your cells
     * are complex.
     */
    onRenderCell?: (item?: T, index?: number, isScrolling?: boolean) => React.ReactNode;
    /**
     * Method to call when trying to render an item conditionally.
     *
     * When this method returns `null` the cell will be skipped in the render.
     *
     * This prop is mutually exclusive with `onRenderCell` and when `onRenderCellConditional` is set,
     * `onRenderCell` will not be called.
     *
     * @param item - The data associated with the cell that is being rendered.
     * @param index - The index of the cell being rendered.
     * @param isScrolling - True if the list is being scrolled. May be useful for rendering a placeholder if your cells
     * are complex.
     */
    onRenderCellConditional?: (item?: T, index?: number, isScrolling?: boolean) => React.ReactNode | null;
    /**
     * Optional callback invoked when List rendering completed.
     * This can be on initial mount or on re-render due to scrolling.
     * This method will be called as a result of changes in List pages (added or removed),
     * and after ALL the changes complete.
     * To track individual page Add / Remove use onPageAdded / onPageRemoved instead.
     * @param pages - The current array of pages in the List.
     */
    onPagesUpdated?: (pages: IPage<T>[]) => void;
    /** Optional callback for monitoring when a page is added. */
    onPageAdded?: (page: IPage<T>) => void;
    /** Optional callback for monitoring when a page is removed. */
    onPageRemoved?: (page: IPage<T>) => void;
    /** Optional callback to get the item key, to be used on render. */
    getKey?: (item: T, index?: number) => string;
    /**
     * Called by the list to get the specification for a page.
     * Use this method to provide an allocation of items per page,
     * as well as an estimated rendered height for the page.
     * The list will use this to optimize virtualization.
     */
    getPageSpecification?: (itemIndex?: number, visibleRect?: IRectangle) => IPageSpecification;
    /**
     * Method called by the list to get how many items to render per page from specified index.
     * In general, use `getPageSpecification` instead.
     */
    getItemCountForPage?: (itemIndex?: number, visibleRect?: IRectangle) => number;
    /**
     * Method called by the list to get the pixel height for a given page. By default, we measure the first
     * page's height and default all other pages to that height when calculating the surface space. It is
     * ideal to be able to adequately predict page heights in order to keep the surface space from jumping
     * in pixels, which has been seen to cause browser performance issues.
     * In general, use `getPageSpecification` instead.
     */
    getPageHeight?: (itemIndex?: number, visibleRect?: IRectangle, itemCount?: number) => number;
    /**
     * Method called by the list to derive the page style object. For spacer pages, the list will derive
     * the height and passed in heights will be ignored.
     */
    getPageStyle?: (page: IPage<T>) => any;
    /**
     * In addition to the visible window, how many windowHeights should we render ahead.
     * @defaultvalue 2
     */
    renderedWindowsAhead?: number;
    /**
     * In addition to the visible window, how many windowHeights should we render behind.
     * @defaultvalue 2
     */
    renderedWindowsBehind?: number;
    /** Index in items array to start rendering from. Defaults to 0. */
    startIndex?: number;
    /** Number of items to render. Defaults to items.length. */
    renderCount?: number;
    /**
     * Boolean value to enable render page caching. This is an experimental performance optimization
     * that is off by default.
     * @defaultvalue false
     */
    usePageCache?: boolean;
    /**
     * Optional callback to determine whether the list should be rendered in full, or virtualized.
     * Virtualization will add and remove pages of items as the user scrolls them into the visible range.
     * This benefits larger list scenarios by reducing the DOM on the screen, but can negatively affect performance for
     * smaller lists.
     * The default implementation will virtualize when this callback is not provided.
     */
    onShouldVirtualize?: (props: IListProps<T>) => boolean;
    /**
     * The role to assign to the list root element.
     * Use this to override the default assignment of 'list' to the root and 'listitem' to the cells.
     */
    role?: string;
    /**
     * Called when the List will render a page.
     * Override this to control how cells are rendered within a page.
     */
    onRenderPage?: IRenderFunction<IPageProps<T>>;
    /**
     * Render override for the element at the root of the `List`.
     * Use this to apply some final attributes or structure to the content
     * each time the list is updated with new active pages or items.
     */
    onRenderRoot?: IRenderFunction<IListOnRenderRootProps<T>>;
    /**
     * Render override for the element representing the surface of the `List`.
     * Use this to alter the structure of the rendered content if necessary on each update.
     */
    onRenderSurface?: IRenderFunction<IListOnRenderSurfaceProps<T>>;
    /**
     * An object which can be passed in as a fresh instance to 'force update' the list.
     */
    version?: {};
    /**
     * Whether to disable scroll state updates. This causes the isScrolling arg in onRenderCell to always be undefined.
     * This is a performance optimization to let List skip a render cycle by not updating its scrolling state.
     */
    ignoreScrollingState?: boolean;
}
/**
 * {@docCategory List}
 */
export interface IPage<T = any> {
    key: string;
    items: T[] | undefined;
    startIndex: number;
    itemCount: number;
    style: React.CSSProperties;
    top: number;
    height: number;
    data?: any;
    isSpacer?: boolean;
    isVisible?: boolean;
}
/**
 * {@docCategory List}
 */
export interface IPageProps<T = any> extends React.HTMLAttributes<HTMLDivElement>, React.ClassAttributes<HTMLDivElement> {
    /**
     * The role being assigned to the rendered page element by the list.
     */
    role?: string;
    /**
     * The allocation data for the page.
     */
    page: IPage<T>;
}
/**
 * {@docCategory List}
 */
export interface IPageSpecification {
    /**
     * The number of items to allocate to the page.
     */
    itemCount?: number;
    /**
     * The estimated pixel height of the page.
     */
    height?: number;
    /**
     * Data to pass through to the page when rendering.
     */
    data?: any;
    /**
     * The key to use when creating the page.
     */
    key?: string;
}