import calendar
from datetime import datetime

class Dates:
    def __init__(self, date_time_obj=datetime.now()):
        self.date_time_obj = date_time_obj

    def get_month_range_str(self, year=None, month=None):
        idx_month = self.date_time_obj.month
        idx_year = self.date_time_obj.year

        if month:
            idx_month = month
        if year:
            idx_year = year

        last_date_of_month = calendar.monthrange(idx_year, idx_month)[1]

        start_date_str = f'{idx_year}-{idx_month}-01'
        end_date_str = f'{idx_year}-{idx_month}-{last_date_of_month}'

        return {
            'start_date': start_date_str,
            'end_date': end_date_str
        }