/*****************************************************************************
 * Open MCT, Copyright (c) 2014-2020, 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.
 *****************************************************************************/

function updateLatestTimeStamp(timestamp, timeSystems) {
    let latest = {};

    timeSystems.forEach(timeSystem => {
        latest[timeSystem.key] = timestamp[timeSystem.key];
    });

    return latest;
}

export function getLatestTimestamp(
    currentTimestamp,
    compareTimestamp,
    timeSystems,
    currentTimeSystem
) {
    let latest = { ...currentTimestamp };
    const compare = { ...compareTimestamp };
    const key = currentTimeSystem.key;

    if (!latest || !latest[key]) {
        latest = updateLatestTimeStamp(compare, timeSystems);
    }

    if (compare[key] > latest[key]) {
        latest = updateLatestTimeStamp(compare, timeSystems);
    }

    return latest;
}

export function subscribeForStaleness(callback, timeout) {
    let stalenessTimer = setTimeout(() => {
        clearTimeout(stalenessTimer);
        callback();
    }, timeout);

    return {
        update: (data) => {
            if (stalenessTimer) {
                clearTimeout(stalenessTimer);
            }

            stalenessTimer = setTimeout(() => {
                clearTimeout(stalenessTimer);
                callback(data);
            }, timeout);
        },
        clear: () => {
            if (stalenessTimer) {
                clearTimeout(stalenessTimer);
            }
        }
    };
}