domotz-remote-pawn/src/discovery/bonjour/service_accumulator.js

Domotz Agent

/** This file is part of Domotz Agent.
 * Copyright (C) 2018  Domotz Ltd
 *
 * Domotz Agent is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Domotz Agent is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Domotz Agent.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 *
 * Stores the discovered Bonjour services indexed by MAC address because Bonjour discovery tends to be unreliable
 * between different runs.
 *
 * That is, one run a device may report SERVICE_A and SERVICE_B, the following run it may report only SERVICE_A.
 *
 * This class provides a way to enrich the latest discovery with the previous discovered services, replaying a service
 * if it is missing for up to 'inertia' cycles: if a service is missing for more than 'inertia' cycles it is not reported
 * anymore.
 **/

var bonjourServicesAccumulator = function (inertia) {
    var servicesByMac = {};

    function updateServicesByMacWithNewValues(result) {
        keys(result).forEach(function (mac) {
            var device = result[mac];
            if (servicesByMac[mac] === undefined) {
                servicesByMac[mac] = {};
            }

            keys(device).forEach(function (service) {
                if (service !== '$') {
                    servicesByMac[mac][service] = { age: 0, serviceData: device[service] };
                }
            });
        });
    }

    function enrichResultWithStoredData(result) {
        keys(result).forEach(function (mac) {
            var stored = servicesByMac[mac];
            keys(stored).forEach(function (service) {
                result[mac][service] = result[mac][service] || stored[service].serviceData;
            });
        });

        return result;
    }

    function cleanupExpired() {
        keys(servicesByMac).forEach(function (mac) {
            var stored = servicesByMac[mac];
            keys(stored).forEach(function (service) {
                stored[service].age++;
                if (stored[service].age > inertia) {
                    delete stored[service];
                }
            });
        });
    }

    function getActualServices(result) {
        // 1 - set new results with age = 0
        updateServicesByMacWithNewValues(result);
        // 2 - prepare result to send by mixing new and old but still valid values
        result = enrichResultWithStoredData(result);
        // 3 - delete old and not still valid data
        cleanupExpired();
        return result;
    }

    return getActualServices;
};

function keys(object) {
    var k = [];
    for (var key in object) {
        if (object.hasOwnProperty(key)) {
            k.push(key);
        }
    }
    return k;
}

module.exports._accumulator = bonjourServicesAccumulator;