// *****************************************************************************
// Copyright (C) 2019 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 { environment } from '@theia/application-package/lib/environment';
import { injectable } from 'inversify';
import { MaybePromise } from '../common/types';
import URI from '../common/uri';
import { Endpoint } from './endpoint';

export interface AddressPort {
    address: string
    port: number
}

@injectable()
export class ExternalUriService {

    /**
     * Maps local to remote URLs.
     * Should be no-op if the given URL is not a localhost URL.
     *
     * By default maps to an origin serving Theia.
     *
     * Use `parseLocalhost` to retrieve localhost address and port information.
     */
    resolve(uri: URI): MaybePromise<URI> {
        const address = this.parseLocalhost(uri);
        if (address) {
            return this.toRemoteUrl(uri, address);
        }
        return uri;
    }

    parseLocalhost(uri: URI): AddressPort | undefined {
        if (uri.scheme !== 'http' && uri.scheme !== 'https') {
            return;
        }
        const localhostMatch = /^(localhost|127\.0\.0\.1|0\.0\.0\.0):(\d+)$/.exec(uri.authority);
        if (!localhostMatch) {
            return;
        }
        return {
            address: localhostMatch[1],
            port: +localhostMatch[2],
        };
    }

    protected toRemoteUrl(uri: URI, address: AddressPort): URI {
        return new Endpoint({ host: this.toRemoteHost(address) })
            .getRestUrl()
            .withPath(uri.path)
            .withFragment(uri.fragment)
            .withQuery(uri.query);
    }

    protected toRemoteHost(address: AddressPort): string {
        return `${this.getRemoteHost()}:${address.port}`;
    }

    /**
     * @returns The remote host (where the backend is running).
     */
    protected getRemoteHost(): string {
        return environment.electron.is() ? 'localhost' : window.location.hostname;
    }
}