import { ElementRef, OnDestroy, OnInit, Renderer2 } from '@angular/core';
import { CdkVirtualScrollViewport } from '@angular/cdk/scrolling';
import { DropDownEventMessagesService } from '../services/drop-down-event-messages/drop-down-event-messages.service';
import * as i0 from "@angular/core";
export declare class DropDownArrowManagerDirective implements OnInit, OnDestroy {
    private elementRef;
    renderer: Renderer2;
    private dropDownEventMessagesService;
    private readonly ACTIVE_ITEM_CSS_CLASS;
    private readonly DATA_ITEM_INDEX_ATTRIBUTE;
    private readonly DATA_SING_TRIGGER_BUTTON_ATTRIBUTE;
    private readonly ngUnSubscribe;
    private currentActive;
    private currentActiveItemIndex;
    private allowIncrementalOrDecrementIndex;
    private lockedUpdateHighlightItemOnScroll;
    private allowFocusForActiveItem;
    private subscriptionToScrolledIndexChange;
    _viewport: CdkVirtualScrollViewport;
    set viewport(viewport: CdkVirtualScrollViewport);
    get viewport(): CdkVirtualScrollViewport;
    lastItemIndex: number;
    constructor(elementRef: ElementRef, renderer: Renderer2, dropDownEventMessagesService: DropDownEventMessagesService);
    ngOnInit(): void;
    ngOnDestroy(): void;
    /**
     * on arrow down move to the next enable item.
     * in case nothing active it set the first item as active.
     *
     * we are using the preventDefault inorder to prevent from outer scroll
     * on the viewport to move which will close the dropdown
     */
    onArrowDown(event: KeyboardEvent): void;
    /**
     * on arrow up move to the previous enable item.
     * in case nothing active it set the first item as active.
     *
     * we are using the preventDefault inorder to prevent from outer scroll
     * on the viewport to move which will close the dropdown
     */
    onArrowUp(event: KeyboardEvent): void;
    /**
     * Emulate click on the current active item
     */
    onEnter(event: KeyboardEvent): void;
    /**
     * unset the current active item.
     * we use it on search change.
     */
    private unsetCurrentActive;
    /**
     * before we active item we check if the item in the dom
     * and if not scroll to it first
     */
    private preActiveItem;
    /**
     * set active item.
     */
    private activeItem;
    /**
     * get the item element index as number
     */
    private getItemIndexAsNumber;
    /**
     * check if we need to use the scroll to index of the cdk virtual scroll.
     * this use for a case where the user move to one of the items and then he scroll to a place where our active
     * item is not in the dom and once the user click on one of the arrow (up | down) we should first scroll to the active item
     * and only then active the next or previous item
     */
    private useScrollToIndex;
    /**
     * listen to scroll index changes in order to decide
     * if we need to update the highlighted item.
     *
     * in case lockedUpdateHighlightItemOnScroll is true it mean
     * the scroll is not by user scrolling (it programmatically) so on those case
     * we want to locked this functionality
     */
    private listenToScrolledIndexChange;
    /**
     * update the highlighted item on scroll.
     * we need to add or remove the highlighted item when scroll since the
     * virtual scroll not change the element item and when user scroll we will see
     * the wrong highlighted item. in order to fix it we are listening to scroll
     * and check if the real item is in doom and add back the item to be highlighted
     * and if it not we remove the highlighted.
     */
    private updateHighlightItemOnScroll;
    /**
     * In case we have search input return the focus to the search input
     */
    private backFocusToSearch;
    /**
     * select item.
     * we call this method on enter clicked and there is active item.
     * in case search input exist we return the focus to it
     */
    private selectItem;
    static ɵfac: i0.ɵɵFactoryDeclaration<DropDownArrowManagerDirective, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<DropDownArrowManagerDirective, "[singDropDownArrowManager]", never, { "viewport": "singDropDownArrowManagerViewport"; "lastItemIndex": "singDropDownArrowManagerLastItemIndex"; }, {}, never, never, false, never>;
}
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