"""Contain logic for checking standard error files"""
import re
from typing import Union

from .errors import InvalidValue

def invalid_value(
        line_number: int, column_number: int, val: str) -> Union[
            InvalidValue, None]:
    """
    Returns a `quality_control.errors.InvalidValue` object in the case where
    `val` is not a valid input for standard error files, otherwise, it returns
    `None`.
    """
    if re.search(r"(^[0-9]+\.[0-9]{6,}$|^[0-9]+\.[0-9]{6,}[eE]-[0-9]+$)", val):
        return None
    return InvalidValue(
        line_number, column_number, val, (
            f"Invalid value '{val}'. "
            "Expected string representing a number with at least six decimal "
            "places."))