"""Date range validation functions."""
from oto import response as oto_response

from analytics.consts import error
from analytics.utils import date as analytics_date


def validate_date_range(from_date, to_date, days_threshold,
                        date_format='%Y-%m-%d'):
    """Validate date range to be not greater than threshold provided.

    Args:
        from_date (str): start of the date range.
        to_date (str): end of the date ranege.
        days_threshold (int): threshold number of days in the date range
            to validate
        date_format (str) optional: string representation of date format
    Returns:
        Response: the response object.

    """
    if days_threshold <= 0:
        return oto_response.create_error_response(
            code=error.VALIDATION_ERROR_CODE,
            message=error.INVALID_DAYS_THRESHOLD_MESSAGE)

    from_date = analytics_date.get(from_date, date_format)
    to_date = analytics_date.get(to_date, date_format)
    if not all((from_date, to_date)):
        return oto_response.create_error_response(
            code=error.VALIDATION_ERROR_CODE,
            message=error.INVALID_DATE_RANGE_FORMAT_MESSAGE)

    delta = to_date - from_date

    if not 0 < delta.days <= days_threshold:
        return oto_response.create_error_response(
            code=error.VALIDATION_ERROR_CODE,
            message=error.INVALID_DATE_RANGE_VALUES_MESSAGE)

    return oto_response.Response()