Holiday lights that come on at a different time each night

1// Holiday lights: switches a light on and off at a different time each evening, so2// the house looks lived in while you're away. Runs on any Gen2 or newer Shelly relay or dimmer.3 4let CONFIG = {5  onFrom: "18:30",6  onSpreadMin: 45,7  offFrom: "22:30",8  offSpreadMin: 60,9  switchId: 0,10  dimmer: false,11  brightness: 60,12  fadeSec: 0,13};14 15// Check the clock every 20 seconds, so each change lands within the minute picked.16let CHECK_EVERY_SEC = 20;17 18// Tonight's plan: the local date it's for and the minutes past midnight to switch.19let plan = { date: -1, onAt: 0, offAt: 0 };20let isOn = null;21let waitingForClock = false;22 23function toMinutes(hhmm) {24  let p = hhmm.split(":");25  return Number(p[0]) * 60 + Number(p[1]);26}27 28function hhmm(m) {29  m = m % 1440;30  let h = Math.floor(m / 60);31  let mm = m % 60;32  return (h < 10 ? "0" : "") + h + ":" + (mm < 10 ? "0" : "") + mm;33}34 35// Local date (days since 1970) and minutes past midnight, or null before the36// clock has synced.37function localNow() {38  let s = Shelly.getComponentStatus("sys");39  if (s === null || typeof s.unixtime !== "number" || s.time === null) return null;40  let t = s.unixtime + (s.utc_offset || 0);41  return { date: Math.floor(t / 86400), min: Math.floor((t % 86400) / 60) };42}43 44// An evening runs from midday to midday, so times after midnight belong to the45// evening before.46let MIDDAY = 720;47 48function evening(t) {49  return t < MIDDAY ? t + 1440 : t;50}51 52function newPlan(date) {53  let onAt = evening(toMinutes(CONFIG.onFrom)) + Math.floor(Math.random() * (CONFIG.onSpreadMin + 1));54  let offAt = evening(toMinutes(CONFIG.offFrom)) + Math.floor(Math.random() * (CONFIG.offSpreadMin + 1));55  plan = { date: date, onAt: onAt, offAt: offAt };56  print("Tonight: on at " + hhmm(onAt) + ", off at " + hhmm(offAt) + ".");57}58 59function setLight(on) {60  if (isOn === on) return;61  isOn = on;62  print(on ? "Light on." : "Light off.");63  if (!CONFIG.dimmer) {64    Shelly.call("Switch.Set", { id: CONFIG.switchId, on: on });65    return;66  }67  let p = { id: CONFIG.switchId, on: on };68  if (on) p.brightness = CONFIG.brightness;69  if (CONFIG.fadeSec > 0) p.transition_duration = CONFIG.fadeSec;70  Shelly.call("Light.Set", p);71}72 73function check() {74  let now = localNow();75  // Without the clock it can't tell the time, so it leaves the light alone.76  if (now === null) {77    if (!waitingForClock) print("Waiting for the clock to sync.");78    waitingForClock = true;79    return;80  }81  waitingForClock = false;82  let date = now.min < MIDDAY ? now.date - 1 : now.date;83  if (plan.date !== date) newPlan(date);84  // Minutes since midnight at the start of this evening.85  let m = now.min + (now.date - date) * 1440;86  setLight(m >= plan.onAt && m < plan.offAt);87}88 89Timer.set(CHECK_EVERY_SEC * 1000, true, check);90print("Holiday lights started. Stop the script when you're home.");91check();