private DateTime GetHolidayDate(int year, HolidayDefinition holidayDefinition)
{
return(Enum.Parse <HolidayPlacementStrategy>(holidayDefinition.PlacementStrategy) switch
{
HolidayPlacementStrategy.FixedDate => DateUtils.CalculateFixedDatePlacement(year,
holidayDefinition.Month, holidayDefinition.Day),
HolidayPlacementStrategy.FixedDay => DateUtils.CalculateFixedDayPlacement(year, holidayDefinition.Month,
holidayDefinition.DayOfWeek, holidayDefinition.WeekOfMonth),
HolidayPlacementStrategy.FixedDateNonWeekend => DateUtils.CalculateFixedDateNonWeekendPlacement(year,
holidayDefinition.Month, holidayDefinition.Day),
_ => throw new InvalidOperationException($"'{holidayDefinition.PlacementStrategy}' is not handled")
});
/// <inheritdoc />
public async Task <long> CalculateWorkingDays(DateTime from, DateTime to)
{
var totalDays = (long)(to - from).TotalDays + 1;
if (totalDays <= 0)
{
return(0);
}
// Retrieve all relevant holidays definitions from data source, pull all if the total days elapses a year
var holidays = await _holidayDefinitionRepository.Query
.Where(totalDays < 365?HolidayDefinition.BetweenMonths(from, to) : h => true)
.ToListAsync();
// Efficiently calculate whole years, removing in batch. Skipping the last remainder of a year
// Additional performance could be achieved with asynchronous batching
var removalDays = 0L;
var fullYears = totalDays / 365;
for (var y = 0; y < fullYears; y++)
{
// Determine the count of all holidays that rest on a weekday
removalDays = holidays
.Select(h => GetHolidayDate(from.Year + y, h).DayOfWeek)
.Aggregate(removalDays, (days, holidayDay) =>
days + (holidayDay != DayOfWeek.Saturday && holidayDay != DayOfWeek.Sunday ? 1 : 0));
}
// Calculate the overflow of days
var excessDays = totalDays % (DateTime.IsLeapYear(to.Year) ? 366 : 365);
if (excessDays > 0)
{
// Sum all holidays that exist within the partial range that are not on a weekend
removalDays += holidays
.Where(h => h.Month >= to.AddDays(-excessDays).Month)
.Count(h =>
{
// Conditional as to what year the holiday falls on, i.e. 1/06/2020 - 1/05/2021
var holidayDate = GetHolidayDate(to.Year, h);
// Assume that if it isn't within the last year, it is in the previous year
if (holidayDate > to)
{
holidayDate = GetHolidayDate(to.Year - 1, h);
}
return(holidayDate >= from && holidayDate <= to &&
holidayDate.DayOfWeek != DayOfWeek.Saturday &&
holidayDate.DayOfWeek != DayOfWeek.Sunday);
});
}
// Account for weekends in bulk
var weekends = totalDays / 7 * 2;
// Cycle through remaining days (Maximum 6) to determine how many additional weekends
var remainingWeekOverflow = totalDays % 7;
if (remainingWeekOverflow > 0)
{
var lastProcessedDate = to.AddDays(-remainingWeekOverflow);
// TODO : There is a more optimal way, but in the interest of time the performance increase is negligible
for (var d = 1; d <= remainingWeekOverflow; d++)
{
var day = lastProcessedDate.AddDays(d).DayOfWeek;
if (day == DayOfWeek.Saturday || day == DayOfWeek.Sunday)
{
weekends++;
}
}
}
removalDays += weekends;
return(totalDays - removalDays);
}
static HolidayUtils()
{
HolidayDefinitions = new HolidayDefinition[] {
new HolidayDefinition()
{
Title = "元日", Month = 1, Day = 1
},
new HolidayDefinition()
{
Title = "成人の日", Month = 1, Day = 15, EndYear = 1999
},
new HolidayDefinition()
{
Title = "成人の日", Month = 1, HappyMondayWeek = 2, StartYear = 2000
},
new HolidayDefinition()
{
Title = "建国記念の日", Month = 2, Day = 11, StartYear = 1967
},
new HolidayDefinition()
{
Title = "天皇誕生日", Month = 4, Day = 29, EndYear = 1988
},
new HolidayDefinition()
{
Title = "みどりの日", Month = 4, Day = 29, StartYear = 1989, EndYear = 2006
},
new HolidayDefinition()
{
Title = "昭和の日", Month = 4, Day = 29, StartYear = 2007
},
new HolidayDefinition()
{
Title = "憲法記念日", Month = 5, Day = 3
},
new HolidayDefinition()
{
Title = "みどりの日", Month = 5, Day = 4, StartYear = 2007
},
new HolidayDefinition()
{
Title = "こどもの日", Month = 5, Day = 5
},
new HolidayDefinition()
{
Title = "海の日", Month = 7, Day = 20, StartYear = 1996, EndYear = 2002
},
new HolidayDefinition()
{
Title = "海の日", Month = 7, HappyMondayWeek = 3, StartYear = 2003
},
new HolidayDefinition()
{
Title = "山の日", Month = 8, Day = 11, StartYear = 2016
},
new HolidayDefinition()
{
Title = "敬老の日", Month = 9, Day = 15, StartYear = 1966, EndYear = 2002
},
new HolidayDefinition()
{
Title = "敬老の日", Month = 9, HappyMondayWeek = 3, StartYear = 2003
},
new HolidayDefinition()
{
Title = "体育の日", Month = 10, Day = 10, EndYear = 1999
},
new HolidayDefinition()
{
Title = "体育の日", Month = 10, HappyMondayWeek = 2, StartYear = 2000
},
new HolidayDefinition()
{
Title = "文化の日", Month = 11, Day = 3
},
new HolidayDefinition()
{
Title = "勤労感謝の日", Month = 11, Day = 23
},
new HolidayDefinition()
{
Title = "天皇誕生日", Month = 12, Day = 23, StartYear = 1989
},
};
}
