// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

Audits2.ProtocolService = class extends Common.Object {
  constructor() {
    super();
    /** @type {?Protocol.InspectorBackend.Connection} */
    this._rawConnection = null;
    /** @type {?Services.ServiceManager.Service} */
    this._backend = null;
    /** @type {?Promise} */
    this._backendPromise = null;
    /** @type {?function(string)} */
    this._status = null;
  }

  /**
   * @return {!Promise<undefined>}
   */
  attach() {
    return InspectorMain.interceptMainConnection(this._dispatchProtocolMessage.bind(this)).then(rawConnection => {
      this._rawConnection = rawConnection;
    });
  }

  /**
   * @param {string} auditURL
   * @param {!Array<string>} categoryIDs
   * @param {!Object} flags
   * @return {!Promise<!ReportRenderer.RunnerResult>}
   */
  startLighthouse(auditURL, categoryIDs, flags) {
    return this._send('start', {url: auditURL, categoryIDs, flags});
  }

  /**
   * @return {!Promise<!Object|undefined>}
   */
  detach() {
    return Promise.resolve().then(() => this._send('stop')).then(() => this._backend.dispose()).then(() => {
      delete this._backend;
      delete this._backendPromise;
      return this._rawConnection.disconnect();
    });
  }

  /**
   *  @param {function (string): undefined} callback
   */
  registerStatusCallback(callback) {
    this._status = callback;
  }

  /**
   * @param {string} message
   */
  _dispatchProtocolMessage(message) {
    this._send('dispatchProtocolMessage', {message: message});
  }

  _initWorker() {
    this._backendPromise =
        Services.serviceManager.createAppService('audits2_worker', 'Audits2Service').then(backend => {
          if (this._backend)
            return;
          this._backend = backend;
          this._backend.on('statusUpdate', result => this._status(result.message));
          this._backend.on('sendProtocolMessage', result => this._sendProtocolMessage(result.message));
        });
  }

  /**
   * @param {string} message
   */
  _sendProtocolMessage(message) {
    this._rawConnection.sendMessage(message);
  }

  /**
   * @param {string} method
   * @param {!Object=} params
   * @return {!Promise<!ReportRenderer.RunnerResult>}
   */
  _send(method, params) {
    if (!this._backendPromise)
      this._initWorker();

    return this._backendPromise.then(_ => this._backend.send(method, params));
  }
};