Block out work calendar from personal calendar

README.md

Steps

1. Create a new Apps Script project
2. Copy-paste in Code.gs
   • Change srcId to the address for your source calendar
3. Add Google Calendar API as a Service in the left sidebar
4. Add a Trigger via the left sidebar:
   • Function to run: sync
   • Event source: time-driven, hour timer, every hour
   • Notify me of failures: daily
5. Change timezone to UTC in Project Settings

Code.gs

function sync() {
  const srcId = "you@example.com";
  const syncWindowInDays = 7;
  
  const now = new Date();
  const startDate = new Date(now);
  startDate.setDate(now.getDate() - syncWindowInDays);
  const endDate = new Date(now);
  endDate.setDate(now.getDate() + syncWindowInDays);
  
  const sourceCal = CalendarApp.getCalendarById(srcId);
  const destCal = CalendarApp.getDefaultCalendar();

  const sourceEvents = new Map(
    sourceCal
      .getEvents(startDate, endDate)
      .filter(e => !e.isAllDayEvent())
      .map(e => [eventId(e), e])
  );
  
  const TAG_ID = "block.id";
  const existingEvents = destCal.getEvents(startDate, endDate)
    .map(e => [e.getTag(TAG_ID), e])
    .filter(([id, _]) => id != null)
    .reduce((acc, [id, e]) => {
      if (!sourceEvents.has(id)) {
        Logger.log("Deleting stale event: %s [id=%s]", e.getTitle(), id);
        e.deleteEvent();
      } else if (acc.has(id)) {
        Logger.log("Deleting duplicate event: %s [id=%s]", e.getTitle(), id);
        e.deleteEvent();
      } else {
        acc.set(id, e);
      }

      return acc;
    }, new Map());

  for (const [id, sourceEvent] of sourceEvents) {
    let destEvent = existingEvents.get(id);
  
    if (!destEvent) {
      Logger.log("Creating new event: %s [id=%s]", sourceEvent.getTitle(), eventId(sourceEvent))

      destEvent = destCal
        .createEvent("Blocked", sourceEvent.getStartTime(), sourceEvent.getEndTime())
        .setTag(TAG_ID, eventId(sourceEvent))
        .setVisibility(CalendarApp.Visibility.PRIVATE)
        .removeAllReminders();
    }
    
    if ((destEvent.getStartTime().valueOf() != sourceEvent.getStartTime().valueOf()) || (destEvent.getEndTime().valueOf() != sourceEvent.getEndTime().valueOf())) {
      Logger.log("Correcting event: %s [sourceId=%s destId=%s]", sourceEvent.getTitle(), eventId(sourceEvent), eventId(destEvent))
      destEvent.setTime(sourceEvent.getStartTime(), sourceEvent.getEndTime())
    }
  }
}

function eventId(event) {
  if (event.isRecurringEvent()) {
    return event.getId() + "-" + event.getStartTime().toISOString() + "-" + event.getEndTime().toISOString();
  }
  
  return event.getId();
}