Python date utils for building ranges and periods

date_utils.py

from datetime import date, datetime, timedelta
from dateutil.relativedelta import relativedelta


def build_formatted_range(interval: str, range_start: date | datetime = None, range_end: date | datetime = None,
                          period: str = None):
    new_start = range_start
    new_end = range_end

    if range_end is None:
        new_end = date.today()
    if range_start is None:
        new_start = backdate(date=new_end, period=period)

    if new_start is not None and (isinstance(new_start, date) or isinstance(new_start, datetime)):
        new_start = convert_date_to_str(new_start, interval)
    if new_end is not None and (isinstance(new_end, date) or isinstance(new_end, datetime)):
        new_end = convert_date_to_str(new_end, interval)

    return new_start, new_end


def backdate(to_date: date | datetime, period: str):
    new_date = to_date
    periods = int(''.join([s for s in period if s.isdigit()]))
    if periods > 0:
        if 'm' in period:
            new_date = new_date - timedelta(minutes=periods)
        elif 'h' in period:
            new_date = new_date - timedelta(hours=periods)
        elif 'w' in period:
            new_date = new_date - timedelta(weeks=periods)
        elif 'M' in period:
            new_date = new_date - relativedelta(months=periods)
        elif 'y' in period:
            new_date = new_date - relativedelta(years=periods)
        else:  # days
            new_date = new_date - timedelta(days=periods)

    return new_date


FORMAT_RANGE_DICT = {'d': '%Y-%m-%d', 'h': '%Y-%m-%d %H:%M:%S'}


def convert_date_to_str(range_date: date | datetime, interval='1d'):
    return range_date.strftime(FORMAT_RANGE_DICT.get(interval[-1]))