using System; 


namespace ReflectionIT.System { 

    public enum DateInterval { 
        Year, 
        Month, 
        Weekday, 
        Day, 
        Hour, 
        Minute, 
        Second 
    } 

    public class DateTimeUtil { 

        public static long DateDiff(DateInterval interval, DateTime date1, DateTime date2) { 

            TimeSpan ts = ts = date2 - date1; 

            switch (interval) { 
                case DateInterval.Year: 
                    return date2.Year - date1.Year; 
                case DateInterval.Month: 
                    return (date2.Month - date1.Month) + (12 * (date2.Year - date1.Year)); 
                case DateInterval.Weekday: 
                    return Fix(ts.TotalDays) / 7; 
                case DateInterval.Day: 
                    return Fix(ts.TotalDays); 
                case DateInterval.Hour: 
                    return Fix(ts.TotalHours); 
                case DateInterval.Minute: 
                    return Fix(ts.TotalMinutes); 
                default: 
                    return Fix(ts.TotalSeconds); 
            } 
        } 

        private static long Fix(double Number) { 
            if (Number >= 0) { 
                return (long)Math.Floor(Number); 
            } 
            return (long)Math.Ceiling(Number); 
        } 
    } 
}