📅 Mirror your calendars between SMA and MF (and any other Google org)

// CONFIG — edit these four lines
const SOURCE_CALENDAR_ID = 'your-other-email@otherorg.com'; // the calendar to pull FROM
const TARGET_CALENDAR_ID = 'primary'; // your primary calendar in THIS account
const DAYS_AHEAD = 30; // how far into the future to mirror
const MIRROR_TAG = '🧭'; // 🧭 for SMA-sourced, 🧵 for MF-sourced (or pick your own)

function syncCalendars() {
  const now = new Date();
  const end = new Date(now.getTime() + DAYS_AHEAD * 24 * 60 * 60 * 1000);

  const source = CalendarApp.getCalendarById(SOURCE_CALENDAR_ID);
  const target = CalendarApp.getCalendarById(
    TARGET_CALENDAR_ID === 'primary' ? Session.getActiveUser().getEmail() : TARGET_CALENDAR_ID
  );

  if (!source) throw new Error('Source calendar not found. Is it shared and added?');
  if (!target) throw new Error('Target calendar not found.');

  // 1. Delete previously mirrored events in the future window
  const existingMirrors = target.getEvents(now, end)
    .filter(e => e.getTag('mirror') === 'true');
  existingMirrors.forEach(e => e.deleteEvent());

  // 2. Copy current source events (skip ones already mirrored in source = loop protection)
  const sourceEvents = source.getEvents(now, end)
    .filter(e => e.getTag('mirror') !== 'true');

  sourceEvents.forEach(e => {
    if (e.getMyStatus && e.getMyStatus() === CalendarApp.GuestStatus.NO) return;

    const title = `${MIRROR_TAG} ${e.getTitle()}`;
    let mirror;
    if (e.isAllDayEvent()) {
      mirror = target.createAllDayEvent(title, e.getAllDayStartDate(), e.getAllDayEndDate(), {
        description: e.getDescription(),
        location: e.getLocation()
      });
    } else {
      mirror = target.createEvent(title, e.getStartTime(), e.getEndTime(), {
        description: e.getDescription(),
        location: e.getLocation()
      });
    }
    mirror.setTag('mirror', 'true');
    mirror.setVisibility(CalendarApp.Visibility.PRIVATE); // colleagues see "Busy" only
    mirror.removeAllReminders();
  });

  console.log(`Synced ${sourceEvents.length} events.`);
}

function removeAllMirrors() {
  const target = CalendarApp.getCalendarById(Session.getActiveUser().getEmail());
  const start = new Date(2020, 0, 1);
  const end = new Date(2030, 0, 1);
  const mirrors = target.getEvents(start, end).filter(e => e.getTag('mirror') === 'true');
  mirrors.forEach(e => e.deleteEvent());
  console.log(`Deleted ${mirrors.length} mirror events.`);
}