Google Apps Scripts: Calendar Utils

calendar-utils.gs

function colorBy(calId, colorRules) {
  const cal = CalendarApp.getCalendarById(calId);
  const startDate = new Date(); // now
  const endDate = new Date();
  endDate.setMonth(endDate.getMonth()+1);

  const events = cal.getEvents(startDate, endDate);

  for (const [ftype, param, color] of colorRules) {
    let filtered = [];
    switch (ftype) {
      case 'guest': 
        filtered = events.filter(event => event.getGuestByEmail(param));
        break;
      case 'title':
        filtered = events.filter(event => event.getTitle() == param);
        break;
    }
    for (event of filtered) {
      Logger.log(`Coloring ${event.getTitle()} ${color}`)
      event.setColor(color);
    }
  }
}

function blockFrom(srcCalId, dstCalId, eventsFilter=function(e) { return true; }) {
  const BLOCKED_FROM_KEY = 'X-Blocked-From';

  const srcCal = CalendarApp.getCalendarById(srcCalId);
  const dstCal = CalendarApp.getCalendarById(dstCalId);

  const startDate = new Date(); // now
  const endDate = new Date();
  endDate.setMonth(endDate.getMonth()+1);
  
  const srcEventsById = new Map(srcCal.getEvents(startDate, endDate).filter(eventsFilter).map(event => [event.getId(), event]));
  const dstEventsBySrcId = new Map(dstCal.getEvents(startDate, endDate).filter(event => event.getTag(BLOCKED_FROM_KEY))
      .map(event => [event.getTag(BLOCKED_FROM_KEY), event]));
      
  // Delete events that can't be found in the source
  const deleted = [...dstEventsBySrcId].
    flatMap(([srcEventId, event]) => srcEventsById.has(srcEventId) ? [] : event);

  for (event of deleted) {
    Logger.log(`Deleting: ${event.getTitle}`, event);
    try {
      event.deleteEvent()
    } catch (error) {
          Logger.log(`Error when deleting: ${error}`);
    }
  }

  // Add or update events
  for ([eventId, event] of [...srcEventsById]) {    
    const existingDstEvent = dstEventsBySrcId.get(eventId);    
    
    try {
      if (existingDstEvent === undefined) {
        Logger.log(`Blocking: ${event.getStartTime()} - ${event.getEndTime()}`)
          dstCal.createEvent('busy', event.getStartTime(), event.getEndTime())
            .setTag(BLOCKED_FROM_KEY, event.getId())
            .setColor(CalendarApp.EventColor.BLUE)
            .removeAllReminders();        
        continue;
      }
    
      // The only property we care about updating is the time, every other property is fixed
      Logger.log(`Updating: ${existingDstEvent.getStartTime()} -> ${event.getStartTime()} - ${existingDstEvent.getEndTime()} -> ${event.getEndTime()}`)
      existingDstEvent.setTime(event.getStartTime(), event.getEndTime());
    } catch (error) {
      Logger.log(`Error when updating ${event.getTitle()}: ${error}`);
    }
  }
}