Code.gs

/* Trying to solve two problems here:
 *  1. gcal won't import remote calendars nicely (into a calendar I can edit)
 *  2. gcal only makes one calendar public
 * 
 * Thus, there are "remote" calendars in my gcal that pull from an icloud
 * calendar. Then, this script runs nightly and copies everything over to
 * my public calendar up to a certain range (a week, a month, etc.)
 */

var daysToCopy = 90;

var cal_default = CalendarApp.getCalendarById("PUBLIC CALENDAR ID HERE");
var cals = [
  CalendarApp.getCalendarById("PRIVATE CALENDAR ID HERE"),
  CalendarApp.getCalendarById("PRIVATE CALENDAR ID HERE"),
];

// Event labeling library

function templateAutogenLabel(date) {
  return `Autogenerated at ${date} by Calendar Curator\n\n`;  // also interpreted as a regex
}

function initAutogen() {
  // Updates global state!
  PropertiesService.getScriptProperties().setProperty('last_updated', Date().toString());
}

function getAutogenLabel() {
  let last_updated = PropertiesService.getScriptProperties().getProperty('last_updated')
  return templateAutogenLabel(last_updated);
}

function isAutogenerated(event) {
  let autogenRegex = templateAutogenLabel(".*?");  // any date
  return event.getDescription().match(autogenRegex);
}

function isNewlyAutogenerated(event) {
  return event.getDescription().match(getAutogenLabel());
}

function setAutogenLabel(event) {
  let desc = event.getDescription();

  while (isAutogenerated(event)) {  // in case there are multiple labels?
    let autogenRegex = templateAutogenLabel(".*?");  // any date
    desc = desc.replace(autogenRegex,"");
    desc = desc.trim();
  }

  event.setDescription(getAutogenLabel() + desc);
}

// main

function main() {
  initAutogen();

  removeAutogen(cal_default);

  for (c in cals) {
    copyCalendarContents(cals[c], cal_default);
  }
}

function removeAutogen(cal) {
  var dayInMS = 24 * 60 * 60 * 1000
  var today = new Date();
  var endDate = new Date(today.getTime() + (daysToCopy * dayInMS));

  var events = cal.getEvents(today, endDate);
  for (e in events) {
    var event = events[e];

    if (isAutogenerated(event)) {
      event.deleteEvent();
    }
  }
}

function copyCalendarContents(fromCal, toCal) {
  // Requires that autogenerated events are removed

  var dayInMS = 24 * 60 * 60 * 1000
  var today = new Date();
  var endDate = new Date(today.getTime() + (daysToCopy * dayInMS));

  var events = fromCal.getEvents(today, endDate);
  for (e in events) {
    var event = events[e];

    copyEvent(fromCal, toCal, event);
  }
}

function copyEvent(fromCal, toCal, event) {
  // We don't bother with recurring events
  // because it is too hard to determine the recurrence
  // and we can just copy everything anyways...

  if (event.isAllDayEvent()) {
    return copyAllDayEvent(fromCal, toCal, event);
  } else {
    return copyHourlyEvent(fromCal, toCal, event);
  }
}

function copyAllDayEvent(fromCal, toCal, event) {
  return toCal.createAllDayEvent(
    event.getTitle(),
    event.getAllDayStartDate(),
    event.getAllDayEndDate(),
    {
      "description": getAutogenLabel() + event.getDescription(),
      "location": event.getLocation()
    }
  );
}

function copyHourlyEvent(fromCal, toCal, event) {
  return toCal.createEvent(
    event.getTitle(),
    event.getStartTime(),
    event.getEndTime(),
    {
      "description": getAutogenLabel() + event.getDescription(),
      "location": event.getLocation()
    }
  );
}