// *****************************************************************************
// 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
// *****************************************************************************

import { injectable, inject } from '@theia/core/shared/inversify';
import { FileSystemWatcherServer, WatchOptions, FileSystemWatcherClient, FileSystemWatcherService } from '../common/filesystem-watcher-protocol';
import { FileSystemWatcherServiceDispatcher } from './filesystem-watcher-dispatcher';

/**
 * Wraps the watcher singleton service for each frontend.
 */
@injectable()
export class FileSystemWatcherServerClient implements FileSystemWatcherServer {

    protected static clientIdSequence = 0;

    /**
     * Track allocated watcherIds to de-allocate on disposal.
     */
    protected watcherIds = new Set<number>();

    /**
     * @todo make this number precisely map to one specific frontend.
     */
    protected readonly clientId = FileSystemWatcherServerClient.clientIdSequence++;

    @inject(FileSystemWatcherServiceDispatcher)
    protected readonly watcherDispatcher: FileSystemWatcherServiceDispatcher;

    @inject(FileSystemWatcherService)
    protected readonly watcherService: FileSystemWatcherService;

    async watchFileChanges(uri: string, options?: WatchOptions): Promise<number> {
        const watcherId = await this.watcherService.watchFileChanges(this.clientId, uri, options);
        this.watcherIds.add(watcherId);
        return watcherId;
    }

    async unwatchFileChanges(watcherId: number): Promise<void> {
        this.watcherIds.delete(watcherId);
        return this.watcherService.unwatchFileChanges(watcherId);
    }

    setClient(client: FileSystemWatcherClient | undefined): void {
        if (client !== undefined) {
            this.watcherDispatcher.registerClient(this.clientId, client);
        } else {
            this.watcherDispatcher.unregisterClient(this.clientId);
        }
    }

    dispose(): void {
        this.setClient(undefined);
        for (const watcherId of this.watcherIds) {
            this.unwatchFileChanges(watcherId);
        }
    }
}