Google Apps Script: how to create calendar events from contact's dates

contactDates2Calendar.js

// This script uses the underscoreGS library: https://sites.google.com/site/scriptsexamples/custom-methods/underscoregs

var MONTHS = [ ContactsApp.Month.JANUARY, 
              ContactsApp.Month.FEBRUARY, 
              ContactsApp.Month.MARCH, 
              ContactsApp.Month.APRIL, 
              ContactsApp.Month.MAY, 
              ContactsApp.Month.JUNE, 
              ContactsApp.Month.JULY, 
              ContactsApp.Month.AUGUST, 
              ContactsApp.Month.SEPTEMBER, 
              ContactsApp.Month.OCTOBER, 
              ContactsApp.Month.NOVEMBER, 
              ContactsApp.Month.DECEMBER ];

// Take a date from Contact and make it usable for Calendar
function convertDate(dateFromContact) {
  var now = new Date();
  var monthAsInt = underscore._indexOf(MONTHS, dateFromContact.getMonth());
  if (monthAsInt == -1) {
    return false;
  } 
  return new Date( now.getFullYear(), monthAsInt, dateFromContact.getDay() );
}


function rebuild() {
  
  // [ contact1, ..., contactN ]
  var contactCache = ContactsApp.getContacts();
  
  // { 'calendar1': calendar1, ..., 'calendarN': calendarN }
  var calendarCache = {};
  
  // { 'calendar1': [ event1, event2, ..., eventN ], ..., 'calendarN': [ event1, event2, ..., eventN ] }
  var eventCache = {};
  
  var now = new Date();
  var aYearFromNow = new Date(now.getFullYear() + 1, now.getMonth(), now.getDate());
  
  if (contactCache.length > 0) {
    
    // Iterate over all Contacts:
    
    for (var i = 0; i < contactCache.length; i++) {
      var currentContact = contactCache[i];
      var allDatesOfCurrentContact = currentContact.getDates();
      if (allDatesOfCurrentContact.length > 0) {
        
        // Iterate over all Dates of the current Contact:
        
        for (var j = 0; j < allDatesOfCurrentContact.length; j++) {
          var currentDateFromContact = allDatesOfCurrentContact[j];
          
          // Has this Calendar already been retrieved?
          
          if (underscore._has(calendarCache, currentDateFromContact.getLabel())) {
            var calendarForCurrentDate = calendarCache[currentDateFromContact.getLabel()];
            
            // This should be true since we wouldn't retrieve a calendar without its events:
            
            if (underscore._has(eventCache, currentDateFromContact.getLabel())) {
              
              // If this Date has already been retrieved there's obviously a CalendarEvent for it. It that case our work here is done...  
              
              if (underscore._any(eventCache[currentDateFromContact.getLabel()], function(eventToLookFor){
                var dateToLookFor = eventToLookFor.getStartTime();
                if ( eventToLookFor.getTag('contactId') == currentContact.getId() && eventToLookFor.isAllDayEvent() ) {
                  if ( currentDateFromContact.getDay() == dateToLookFor.getDate() && dateToLookFor.getMonth() == underscore._indexOf(MONTHS, currentDateFromContact.getMonth()) ) {
                    return true
                  }
                }
                return false
              })) {
                Logger.log('EVENT EXISTS');
              } 
              
              // If there isn't a CalendarEvent for this Date we need to create it: 
              
              else {
                var dateForNewEvent = new Date( now.getFullYear(), underscore._indexOf(MONTHS, currentDateFromContact.getMonth()), currentDateFromContact.getDay() );
                var dateForNewEvent = convertDate(currentDateFromContact);
                if ( dateForNewEvent ) {
                  var titleForNewEvent = currentDateFromContact.getLabel() + ': ' + currentContact.getFullName();    
                  var newEventSeriesId = calendarForCurrentDate.createAllDayEventSeries(titleForNewEvent, dateForNewEvent, CalendarApp.newRecurrence().addYearlyRule()).getId();
                  
                  // To edit our EventSeries we have to reload it from the server to prevent an etag error (http://code.google.com/p/google-apps-script-issues/issues/detail?id=264):
                  
                  calendarForCurrentDate.getEventSeriesById(newEventSeriesId).setTag('contactId', currentContact.getId());
                  calendarForCurrentDate.getEventSeriesById(newEventSeriesId).setVisibility(CalendarApp.Visibility.PRIVATE);
                  calendarForCurrentDate.getEventSeriesById(newEventSeriesId).addEmailReminder(1);
                  
                  Logger.log('EVENT CREATED');
                }
              }
            }
          } 
          
          // Seems like we didn't retrieve this calendar yet...
          
          else { 
            
            // Let's see if we can find it on the server:
            
            var allMatchingCalendars = CalendarApp.getCalendarsByName(currentDateFromContact.getLabel());
            if (allMatchingCalendars.length > 0) {
              var calendarForCurrentDate = allMatchingCalendars[0];
              Logger.log('CALENDAR EXISTS: ' + calendarForCurrentDate.getName());
            } 
            
            // We couldn't find it. This means we have to create it:
            
            else {
              var calendarForCurrentDate = CalendarApp.createCalendar(currentDateFromContact.getLabel());
              Logger.log('CREATING CALENDAR: ' + calendarForCurrentDate.getName());
            }
            
            // Let's load this Calendar and it's Event into our caching variables:
            Logger.log('CACHING...');
            calendarCache[currentDateFromContact.getLabel()] = calendarForCurrentDate;
            eventCache[currentDateFromContact.getLabel()] = calendarForCurrentDate.getEvents(now, aYearFromNow);
          }
        }
      }
    }
  }
};