from datetime import timedelta, datetime, timezone

def get_start_date_for_dag():
    return datetime.combine(datetime.utcnow() - timedelta(days=7),
                                  datetime.min.time())

def get_next_day_date(date_to_download):
    format_str = '%Y-%m-%d'
    next_date_to_run = datetime.strptime(date_to_download, format_str)
    return next_date_to_run + timedelta(days=1)

def get_date_range(no_of_days):
    dates = []
    for day in range(no_of_days):
        date_str = (datetime.utcnow() - timedelta(day)).strftime('%Y-%m-%d')
        dates.append(date_str)
    return dates

def get_yesterday():
    today = datetime.combine(datetime.today() - timedelta(1),
                                      datetime.min.time())
    return today

def get_today():
    today = datetime.combine(datetime.today(),
                                      datetime.min.time())
    return today

def get_tomorrow():
    tomorrow = datetime.combine(datetime.today() + timedelta(1),
                                      datetime.min.time())
    return tomorrow