/********************************************************************************
 * 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 WITH Classpath-exception-2.0
 ********************************************************************************/

import { inject, injectable } from 'inversify';
import { CancellationToken } from 'vscode-jsonrpc';
import { ProgressClient, ProgressMessage, ProgressUpdate } from '@gedit/connection';
import { StatusBar, StatusBarAlignment } from '../status-bar';
import { PromiseDeferred } from '@gedit/utils';
import throttle = require('lodash.throttle');

@injectable()
export class ProgressStatusBarItem implements ProgressClient {

  protected readonly id = 'theia-progress-status-bar-item';

  @inject(StatusBar)
  protected readonly statusBar: StatusBar;

  protected messagesByProgress = new Map<string, string | undefined>();

  protected incomingQueue = new Array<string>();
  protected readonly triggerUpdate = throttle(() => this.update(this.currentProgress), 250, {
    leading: true,
    trailing: true
  });

  get currentProgress(): string | undefined {
    return this.incomingQueue.slice(-1)[0];
  }

  showProgress(progressId: string, message: ProgressMessage, cancellationToken: CancellationToken): Promise<string | undefined> {
    const result = new PromiseDeferred<string | undefined>();
    cancellationToken.onCancellationRequested(() => {
      this.processEvent(progressId, 'done');
      result.resolve(ProgressMessage.Cancel);
    });
    this.processEvent(progressId, 'start', message.text);
    return result.promise;
  }

  async reportProgress(progressId: string, update: ProgressUpdate, originalMessage: ProgressMessage, _cancellationToken: CancellationToken): Promise<void> {
    const newMessage = update.message ? `${originalMessage.text}: ${update.message}` : originalMessage.text;
    this.messagesByProgress.set(progressId, newMessage);
    this.triggerUpdate();
  }

  protected processEvent(progressId: string, event: 'start' | 'done', message?: string): void {
    if (event === 'start') {
      this.incomingQueue.push(progressId);
      this.messagesByProgress.set(progressId, message);
    } else {
      this.incomingQueue = this.incomingQueue.filter(id => id !== progressId);
      this.messagesByProgress.delete(progressId);
    }
    this.triggerUpdate();
  }

  protected update(progressId: string | undefined): void {
    const message = progressId && this.messagesByProgress.get(progressId);
    if (!progressId || !message) {
      this.statusBar.removeElement(this.id);
      return;
    }
    const text = `$(refresh~spin) ${message}`;
    this.statusBar.setElement(this.id, {
      text,
      alignment: StatusBarAlignment.LEFT,
      priority: 1
    });
  }

}