xml_date.py

from datetime import datetime, timedelta
import re


class DateOffset:
    years: int
    months: int
    days: int

    def __init__(self, years: int, months: int, days: int):
        self.years = years
        self.months = months
        self.days = days

    @staticmethod
    def from_datetime(date: datetime):
        now = datetime.now()
        years = date.year - now.year
        months = date.month - now.month
        days = date.day - now.day
        return DateOffset(years, months, days)

    def _format_diff_numeric(self, num: int, suffix: str) -> str:
        if num < 0:
            return str(num) + suffix
        elif num == 0:
            return ""
        else:
            return "+" + str(num) + suffix

    def __add__(self, other):
        return DateOffset(self.years + other.years, self.months + other.months, self.days + other.days)

    def __sub__(self, other):
        return DateOffset(self.years - other.years, self.months - other.months, self.days - other.days)

    def __str__(self):
        days = self._format_diff_numeric(self.days, "d")
        months = self._format_diff_numeric(self.months, "M")
        years = self._format_diff_numeric(self.years, "y")
        return f"[now{years}{months}{days}]"


class XMLDate:
    xml_str: str
    date: datetime

    def __init__(self, xml_str):
        self.xml_str = xml_str
        self._parse_date()

    @staticmethod
    def now():
        now = datetime.now()
        xml_str = now.strftime('"%Y-%m-%d %H:%M:%S"')
        return XMLDate(xml_str)

    def _parse_date(self):
        datetime_str = self.xml_str.replace('"', '')
        if re.fullmatch(r'\d{4}-\d{2}-\d{2}', datetime_str):
            self.date = datetime.strptime(datetime_str, "%Y-%m-%d")
        elif re.fullmatch(r'\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}', datetime_str):
            self.date = datetime.strptime(datetime_str, "%Y-%m-%d %H:%M:%S")
        elif re.fullmatch(r'\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d', datetime_str):
            self.date = datetime.strptime(datetime_str, "%Y-%m-%d %H:%M:%S.%f")
        else:
            raise ValueError("Invalid date string: {}".format(datetime_str))

    def get_relative_date_str(self, diff: DateOffset = DateOffset(0, 0, 0)) -> str:
        rel_diff = DateOffset.from_datetime(self.date) + diff
        return str(rel_diff)

    def __str__(self):
        return self.date.strftime("%Y-%m-%d %H:%M:%S.%f")

    def __gt__(self, other):
        return self.date > other.date

    def __lt__(self, other):
        return self.date < other.date

    def __eq__(self, other):
        return self.date == other.date