Restringir los recursos de servicio a modificar turnos para dos semanas con un desencadenador de Apex

//Because the next two weeks of time slots are visible to customers and are bookable,
//we want to prevent any updates to those shifts.
//This trigger doesn't allow to create a shift
//where either start time or end time falls under
// 1. Older than today's date
// 2. Two weeks after today's date
 
trigger TwoWeeksLimitTrigger on Shift (before insert,before update) {
    if(trigger.isInsert || trigger.isUpdate){
        if (Trigger.isBefore) {
            for(Shift shift : Trigger.New) {
                Date todayDate = date.today();
                Date twoWeekDate = todayDate.addDays(14);
                if(shift.StartTime < todayDate || shift.StartTime > twoWeekDate){
                    trigger.new[0].StartTime.addError('Customers are already booking slots for this time period and so changing Shifts is not allowed.');
                }
                else if(shift.EndTime < todayDate || shift.EndTime > twoWeekDate){
                    trigger.new[0].EndTime.addError('Customers are already booking slots for this time period and so changing Shifts is not allowed.');
                }
            }
        }
    }
}