genieacs_probability_upgrades

/*
Start upgrading x routers per day, double that number until max router upgrades reached.

Eg: With starting upgrade number of 200 routers, total of 5000 and max per day of 1000:
Day 1 upgrade 200 routers,
Day 2 uprade 400 routers,
Day 3 upgrade 800 routers,
Day 4 upgrade 1000 routers
Day 5 upgrade 1000 routers
Day 6 upgrade 1000 routers
Day 7 upgrade 600 routers and finish.

A start day in the future will return 0 chance of router upgrade 
*/

var STARTING_UPGRADE_AMOUNT = 200
var MAX_UPGRADES_PER_DAY = 1000
// number of routers that are informing (in a 2 hour period for example)
var TOTAL_DEVICES_TO_UPDATE = 10000
var FIRMWARE_VERSION = 'IMAGE FILENAME HERE'

class RouterCalculator {
  /** A class to manage router upgrade probability for Genieacs */
  constructor(maxUpgradesPerDay, startingUpgradeAmount, totalDevicesToUpdate) {
    this.maxUpgradesPerDay = maxUpgradesPerDay;
    this.startingUpgradeAmount = startingUpgradeAmount;
    this.totalDevicesToUpdate = totalDevicesToUpdate;
  }
  _todayAtMidnight() {
    let now = new Date();
    now.setHours(0, 0, 0, 0);
    let unixTime = now.getTime();
    return unixTime;
  }

  _getPercentCompleted(startPercentage, maxPercentage, daysCompleted) {
    let percentCompleted = 0;
    for (let x = 0; x < daysCompleted; x++) {
      percentCompleted += (startPercentage * Math.pow(2, x) < maxPercentage) ? startPercentage * Math.pow(2, x) : maxPercentage
    }
    return percentCompleted < 100 ? percentCompleted : 100;
  }

  daysToComplete() {
    let daysCompleted = 0;
    let maxPercentage = (this.maxUpgradesPerDay / this.totalDevicesToUpdate) * 100;
    let startPercentage = (this.startingUpgradeAmount / this.totalDevicesToUpdate) * 100;
    while (this._getPercentCompleted(startPercentage, maxPercentage, daysCompleted) < 100) {
      daysCompleted++
    }
    return daysCompleted
  }

  calculateProbability(startDay) {
    let todayDate = this._todayAtMidnight()
    if (todayDate < startDay) {
      return 0;
    } else {
      let daysCompleted = (todayDate - startDay) / 86400 / 1000;
      let maxPercentage = (this.maxUpgradesPerDay / this.totalDevicesToUpdate) * 100;
      let startPercentage = (this.startingUpgradeAmount / this.totalDevicesToUpdate) * 100;
      let percentCompleted = this._getPercentCompleted(startPercentage, maxPercentage, daysCompleted);
      let percentRemaining = (100 - percentCompleted) < 0 ? 0 : (100 - percentCompleted);
      let upgradePercent = (startPercentage * Math.pow(2, daysCompleted) < maxPercentage) ? startPercentage * Math.pow(2, daysCompleted) : maxPercentage;
      let upgradeProbability = upgradePercent / 100;
      let actualUpgradeProb = (1 / (percentRemaining / 100)) * upgradeProbability > 1 ? 1 : (1 / (percentRemaining / 100)) * upgradeProbability;
      return actualUpgradeProb;
    }
  }
  generateStartDay(daysInTheFuture = 0) {
    // some validation might be nice
    daysInTheFuture = Math.floor(daysInTheFuture);
    daysInTheFuture = -daysInTheFuture > 0 ? -daysInTheFuture : daysInTheFuture;
    let now = new Date();
    now.setHours(0, 0, 0, 0);
    let unixTime = now.getTime();
    return unixTime + (daysInTheFuture * 86400 * 1000);
  }
}

///////////////////////////////////////////

function xmur3(str) {
  for (var i = 0, h = 1779033703 ^ str.length; i < str.length; i++)
    h = Math.imul(h ^ str.charCodeAt(i), 3432918353),
      h = h << 13 | h >>> 19;
  return function () {
    h = Math.imul(h ^ h >>> 16, 2246822507);
    h = Math.imul(h ^ h >>> 13, 3266489909);
    return (h ^= h >>> 16) >>> 0;
  }
}

function mulberry32(a) {
  return function () {
    var t = a += 0x6D2B79F5;
    t = Math.imul(t ^ t >>> 15, t | 1);
    t ^= t + Math.imul(t ^ t >>> 7, t | 61);
    return ((t ^ t >>> 14) >>> 0) / 4294967296;
  }
}

let rc = new RouterCalculator(MAX_UPGRADES_PER_DAY, STARTING_UPGRADE_AMOUNT, TOTAL_DEVICES_TO_UPDATE);
// let startDate = rc.generateStartDay();
let upgradeProbability = rc.calculateProbability(1582455600000);
// let daysToComplete = rc.daysToComplete();
// console.log("Start date generated " + startDate);
// console.log("Probability required to hit upgrade target: " + upgradeProbability);
// console.log("Total days required to complete router upgrades (once started): " + daysToComplete);

var date = new Date();
date.setHours(0, 0, 0, 0);
var dateIntSeed = date.getTime();
// Math.random is seeded with device. (returns same every time)
var deviceSeed = Math.random();
var seedString = Math.round(deviceSeed * dateIntSeed).toString();

var seed = xmur3(seedString);
var rand = mulberry32(seed());
var r = rand();

if (r <= upgradeProbability) {
  console.log("Device probabilty: " + r + " , is less than " + upgradeProbability);
  // declare("Downloads.[FileType:1 Firmware Upgrade Image]", { path: 1 }, { path: 1 });
  // declare("Downloads.[FileType:1 Firmware Upgrade Image].FileName", { value: 1 }, { value: FIRMWARE_VERSION });
  // declare("Downloads.[FileType:1 Firmware Upgrade Image].Download", { value: 1 }, { value: Date.now() });
  // log("Firmware updated");
}