adobe / spectrum-web-components / 12802187570

/*

Copyright 2020 Adobe. All rights reserved.

This file is licensed to you under the Apache License, Version 2.0 (the "License");

you may not use this file except in compliance with the License. You may obtain a copy

of the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under

the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS

OF ANY KIND, either express or implied. See the License for the specific language

governing permissions and limitations under the License.

*/

import { ReactiveElement } from '@spectrum-web-components/base';

import { MutationController } from '@lit-labs/observers/mutation-controller.js';

const slotContentIsPresent = Symbol('slotContentIsPresent');

type Constructor<T = Record<string, unknown>> = {

    // eslint-disable-next-line @typescript-eslint/no-explicit-any

    new (...args: any[]): T;

    prototype: T;

};

export interface SlotPresenceObservingInterface {

    slotContentIsPresent: boolean;

    getSlotContentPresence(selector: string): boolean;

    managePresenceObservedSlot(): void;

}

export function ObserveSlotPresence<T extends Constructor<ReactiveElement>>(

    constructor: T,

    lightDomSelector: string | string[]

): T & Constructor<SlotPresenceObservingInterface> {

    const lightDomSelectors = Array.isArray(lightDomSelector)

        ? lightDomSelector

        : [lightDomSelector];

    class SlotPresenceObservingElement

        extends constructor

        implements SlotPresenceObservingInterface

    {

        // eslint-disable-next-line @typescript-eslint/no-explicit-any

        constructor(...args: any[]) {

            super(args);

            new MutationController(this, {

                config: {

                    childList: true,

                    subtree: true,

                },

                callback: () => {

                    this.managePresenceObservedSlot();

                },

            });

            this.managePresenceObservedSlot();

        }

        /**

         *  @private

         */

        public get slotContentIsPresent(): boolean {

            if (lightDomSelectors.length === 1) {

                return (

                    this[slotContentIsPresent].get(lightDomSelectors[0]) ||

                    false

                );

            } else {

        }

        private [slotContentIsPresent]: Map<string, boolean> = new Map();

        public getSlotContentPresence(selector: string): boolean {

            if (this[slotContentIsPresent].has(selector)) {

                return this[slotContentIsPresent].get(selector) || false;

            }

        }

        public managePresenceObservedSlot = (): void => {

            let changes = false;

            lightDomSelectors.forEach((selector) => {

                const nextValue = !!this.querySelector(`:scope > ${selector}`);

                const previousValue =

                    this[slotContentIsPresent].get(selector) || false;

                changes = changes || previousValue !== nextValue;

                this[slotContentIsPresent].set(

                    selector,

                    !!this.querySelector(`:scope > ${selector}`)

                );

            });

            if (changes) {

                this.updateComplete.then(() => {

                    this.requestUpdate();

                });

            }

        };

    }

    return SlotPresenceObservingElement;

}