Calculate Day of Weeks by Given Date

calendar_calculate_day_of_weeks.py

import datetime
from collections import namedtuple
import math
import re

Day = namedtuple('Day', 'code title')
MonthCode = namedtuple('MonthCode', 'number code')
CenturyCode = namedtuple('CenturyCode', 'year code')


class GetDay(object):
    def __init__(self) -> None:
        super().__init__()

        self.day_of_week = [
            Day(0,  'Sunday'),
            Day(1, 'Monday'),
            Day(2,  'Tuesday'),
            Day(3,  'Wednesday'),
            Day(4,  'Thursday'),
            Day(5,  'Friday'),
            Day(6,  'Saturday')]

        self.centuryCodes = [
            CenturyCode(1700,  4),
            CenturyCode(1800,  2),
            CenturyCode(1900,  0),
            CenturyCode(2000,  6),
            CenturyCode(2100,  4),
            CenturyCode(2200,  2),
            CenturyCode(2300,  0)]

        self.monthCodes = [
            MonthCode(1, 0),
            MonthCode(2, 3),
            MonthCode(3, 3),
            MonthCode(4, 6),
            MonthCode(5, 1),
            MonthCode(6, 4),
            MonthCode(7, 6),
            MonthCode(8, 2),
            MonthCode(9, 5),
            MonthCode(10, 0),
            MonthCode(11, 3),
            MonthCode(12, 5)]

    def dayOf(self, date: str):
        date = datetime.datetime.strptime(
            re.sub(r'\W', '-', date), '%d-%m-%Y')
        return self.calculate(date)

    def calculate(self, date: datetime.datetime):
        year = date.year
        month = date.month
        day = date.day
        yearCode = self.getYearCode(year)
        monthCode = self.getMonthCode(month)
        centuryCode = self.getCenturyCode(year)
        leapYear = self.getLeapYearCode(year)

        result = (yearCode + monthCode + centuryCode + day - leapYear) % 7
        day_index = math.floor(result)
        return self.day_of_week[day_index].title

    def getYearCode(self, year: int):
        yy = int(str(year)[-2:])
        result = (yy + (yy/4)) % 7
        return math.floor(result)

    def getMonthCode(self, month):
        return self.monthCodes[month - 1].code

    def getCenturyCode(self, year):
        if year >= 1700 and year < 1800:
            return self.centuryCodes[0].code
        elif year >= 1800 and year < 1900:
            return self.centuryCodes[1].code
        elif year >= 1900 and year < 2000:
            return self.centuryCodes[2].code
        elif year >= 2000 and year < 2100:
            return self.centuryCodes[3].code
        elif year >= 2100 and year < 2200:
            return self.centuryCodes[4].code
        elif year >= 2200 and year < 2300:
            return self.centuryCodes[5].code
        elif year >= 2300 and year < 2400:
            return self.centuryCodes[6].code
        else:
            raise ValueError('Year is not eligible!')

    def getLeapYearCode(self, year):
        return 0 if ((year % 4) > 0 or (year % 100) > 0 or (year % 400) > 0) else 1


if __name__ == "__main__":
    getDay = GetDay()
    dateDMY = '09-12-2020'
    day = getDay.dayOf(dateDMY)
    print('-------------------------------')
    print(f"🐔. What day of the week is it on {dateDMY}?")
    print(f"🐣. It's \"{day}\"!")
    print('-------------------------------')