public class VerifyDate {
    
    //method to handle potential checks against two dates
    public static Date CheckDates(Date date1, Date date2) {
        //if date2 is within the next 30 days of date1, use date2.  Otherwise use the end of the month
        if(DateWithin30Days(date1,date2)) {
            return date2;
        } else {
            return SetEndOfMonthDate(date1);
        }
    }
    
    //method to check if date2 is within the next 30 days of date1
    @TestVisible
    private static Boolean DateWithin30Days(Date date1, Date date2) {
        //check for date2 being in the past
            if( date2 < date1) { return false; }
        
            //check that date2 is within (>=) 30 days of date1
            Date date30Days = date1.addDays(30); //create a date 30 days away from date1
        if( date2 >= date30Days ) { return false; }
        else { return true; }
    }

    //method to return the end of the month of a given date
    @TestVisible
    private static Date SetEndOfMonthDate(Date date1) {
        Integer totalDays = Date.daysInMonth(date1.year(), date1.month());
        Date lastDay = Date.newInstance(date1.year(), date1.month(), totalDays);
        return lastDay;
    }

}