/*****************************************************************************
 * Open MCT, Copyright (c) 2014-2024, United States Government
 * as represented by the Administrator of the National Aeronautics and Space
 * Administration. All rights reserved.
 *
 * Open MCT is licensed under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * Open MCT includes source code licensed under additional open source
 * licenses. See the Open Source Licenses file (LICENSES.md) included with
 * this source code distribution or the Licensing information page available
 * at runtime from the About dialog for additional information.
 *****************************************************************************/

export default function StateGeneratorProvider() {}

function pointForTimestamp(timestamp, duration, name) {
  return {
    name: name,
    utc: Math.floor(timestamp / duration) * duration,
    value: Math.floor(timestamp / duration) % 2
  };
}

StateGeneratorProvider.prototype.supportsSubscribe = function (domainObject) {
  return domainObject.type === 'example.state-generator';
};

StateGeneratorProvider.prototype.subscribe = function (domainObject, callback) {
  var duration = domainObject.telemetry.duration * 1000;

  var interval = setInterval(function () {
    var now = Date.now();
    var datum = pointForTimestamp(now, duration, domainObject.name);
    datum.value = String(datum.value);
    callback(datum);
  }, duration);

  return function () {
    clearInterval(interval);
  };
};

StateGeneratorProvider.prototype.supportsRequest = function (domainObject, options) {
  return domainObject.type === 'example.state-generator';
};

StateGeneratorProvider.prototype.request = function (domainObject, options) {
  var start = options.start;
  var end = Math.min(Date.now(), options.end); // no future values
  var duration = domainObject.telemetry.duration * 1000;
  if (options.strategy === 'latest' || options.size === 1) {
    start = end;
  }

  var data = [];
  while (start <= end && data.length < 5000) {
    data.push(pointForTimestamp(start, duration, domainObject.name));
    start += duration;
  }

  return Promise.resolve(data);
};