calculate-start-of-week-from-end.py

from datetime import datetime, timedelta


def calculate_start_date_and_months(end_date_str, num_weeks):
    # Convert end_date_str to a datetime object
    end_date = datetime.strptime(end_date_str, "%Y-%m-%d")

    # Calculate the number of days to subtract
    num_days = num_weeks * 7

    # Calculate the start date
    start_date = end_date - timedelta(days=num_days)

    # Calculate the number of months between start_date and end_date
    num_months = (
        (end_date.year - start_date.year) * 12 + end_date.month - start_date.month
    )

    # Return the start date and number of months in the desired format
    return start_date.strftime("%Y-%m-%d"), num_months


# Example usage
end_date = "2025-06-29"
num_weeks = 26
start_date, num_months = calculate_start_date_and_months(end_date, num_weeks)
print(f"Start date: {start_date}, Number of months: {num_months}")