// *****************************************************************************
// Copyright (C) 2018 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
// *****************************************************************************

import { BackendApplicationConfig, deepmerge } from '@theia/application-package/lib/application-props';

export class BackendApplicationConfigProvider {

    private static KEY = Symbol('BackendApplicationConfigProvider');

    static get(): BackendApplicationConfig {
        const config = BackendApplicationConfigProvider.doGet();
        if (config === undefined) {
            throw new Error('The configuration is not set. Did you call BackendApplicationConfigProvider#set?');
        }
        return config;
    }

    static set(config: BackendApplicationConfig.Partial): void {
        if (BackendApplicationConfigProvider.doGet() !== undefined) {
            throw new Error('The configuration is already set.');
        }
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        const globalObject = global as any;
        const key = BackendApplicationConfigProvider.KEY;
        globalObject[key] = deepmerge(BackendApplicationConfig.DEFAULT, config);
    }

    private static doGet(): BackendApplicationConfig | undefined {
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        const globalObject = global as any;
        const key = BackendApplicationConfigProvider.KEY;
        return globalObject[key];
    }

}
