Question

The purpose of the code below is to determine if a particular date qualifies as a “weekend” i.e after 12:00 PM on Thursday, minimum 2 days and before Monday 12:00 PM

Is there a better way? If-Else turns ugly and the Strategy pattern is way too much work for this.

public bool ValidateWeekend(DateTime pickupDate, DateTime dropoffDate)
    {
        TimeSpan ts = dropoffDate.Subtract(pickupDate);

        if (ts.TotalDays >= 2 && ts.TotalDays <= 4)
        {
            switch (pickupDate.DayOfWeek)
            {
                case DayOfWeek.Thursday:
                    if (pickupDate.Hour >= 12)
                    {
                        switch (dropoffDate.DayOfWeek)
                        {
                            case DayOfWeek.Sunday:
                                return true;
                            case DayOfWeek.Monday:
                                if (dropoffDate.Hour <= 12)
                                {
                                    return true;
                                }
                                return false;
                        }
                    }
                    break;
                case DayOfWeek.Friday:
                    switch (dropoffDate.DayOfWeek)
                    {
                        case DayOfWeek.Sunday:
                            return true;
                        case DayOfWeek.Monday:
                            if (dropoffDate.Hour <= 12)
                            {
                                return true;
                            }
                            return false;
                    }
                    break;
                case DayOfWeek.Saturday:
                    switch (dropoffDate.DayOfWeek)
                    {
                        case DayOfWeek.Sunday:
                            return true;
                        case DayOfWeek.Monday:
                            if (dropoffDate.Hour <= 12)
                            {
                                return true;
                            }
                            return false;
                    }
                    return false;
            }
        }
        return false;
    }

Answer 1

You definitely should refactor the dropoffDate out – because the code is duplicated 3 times! The simplest cleanup: I would introduce a function to check the pickupDate and another to check the dropoffDate:

private bool IsPickupWeekend(DateTime pickupDate)
{
    switch (pickupDate.DayOfWeek)
            {
                case DayOfWeek.Thursday:
                    return pickupDate.Hour >= 12;
                case DayOfWeek.Friday:                    
                case DayOfWeek.Saturday:
                    return true;
            }
        }
        return false;
}

private bool IsWeekendDropOff(DateTime dropoffDate)
{
    switch (dropoffDate.DayOfWeek)
                    {
                        case DayOfWeek.Sunday:
                            return true;
                        case DayOfWeek.Monday:
                            if (dropoffDate.Hour <= 12)
                            {
                                return true;
                            }
                            return false;
                    }
                    return false;

}

And now your main function is a 2 liner:

if (ts.TotalDays >= 2 && ts.TotalDays <= 4)
{
    return IsPickupWeekend(pickupDate) && IsWeekendDropOff(dropoffDate);
}