import os
import re


EMPTY_ANNOTATION_FILE = ('<?xml version="1.0" encoding="UTF-8" ?>'
                         '<document><annotations></annotations></document>')


def sanitize_identifier(identifier, replacement='-'):
    return re.sub(r'[^\w-]', replacement, identifier)


def check_is_file_empty(filepath):
    """
    Check whether file is empty or not.

    :param filepath:  Path of a file that will be checked.
    :return:          True if the file empty.
    """
    if os.path.exists(filepath):
        return os.stat(filepath).st_size == 0
    else:
        raise FileNotFoundError("Path '%s' doesn't exist" % filepath)