/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

const {
  TYPES: { CSS_CHANGE },
} = require("devtools/server/actors/resources/index");
const TrackChangeEmitter = require("devtools/server/actors/utils/track-change-emitter");

/**
 * Start watching for all css changes related to a given Target Actor.
 *
 * @param TargetActor targetActor
 *        The target actor from which we should observe css changes.
 * @param Object options
 *        Dictionary object with following attributes:
 *        - onAvailable: mandatory function
 *          This will be called for each resource.
 */
class CSSChangeWatcher {
  constructor() {
    this.onTrackChange = this.onTrackChange.bind(this);
  }

  async watch(targetActor, { onAvailable }) {
    this.onAvailable = onAvailable;
    TrackChangeEmitter.on("track-change", this.onTrackChange);
  }

  onTrackChange(change) {
    change.resourceType = CSS_CHANGE;
    this.onAvailable([change]);
  }

  destroy() {
    TrackChangeEmitter.off("track-change", this.onTrackChange);
  }
}

module.exports = CSSChangeWatcher;
