// *****************************************************************************
// Copyright (C) 2017 TypeFox and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0.
//
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License v. 2.0 are satisfied: GNU General Public License, version 2
// with the GNU Classpath Exception which is available at
// https://www.gnu.org/software/classpath/license.html.
//
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
// *****************************************************************************
/* eslint-disable @typescript-eslint/no-explicit-any */

import { injectable } from 'inversify';
import { Emitter, Event } from '../common/event';

/**
 * `SelectionProvider` is implemented by services to notify listeners about selection changes.
 */
export interface SelectionProvider<T> {
    onSelectionChanged: Event<T | undefined>;
}

/**
 * Singleton service that is used to share the current selection globally in a Theia application.
 * On each change of selection, subscribers are notified and receive the updated selection object.
 */
@injectable()
export class SelectionService implements SelectionProvider<Object | undefined> {

    private currentSelection: Object | undefined;

    protected readonly onSelectionChangedEmitter = new Emitter<any>();
    readonly onSelectionChanged: Event<any> = this.onSelectionChangedEmitter.event;

    get selection(): Object | undefined {
        return this.currentSelection;
    }

    set selection(selection: Object | undefined) {
        this.currentSelection = selection;
        this.onSelectionChangedEmitter.fire(this.currentSelection);
    }

}