#!/usr/bin/env python3

import re
from slugify import slugify


_REGEX_PART_ALLOWED_FILE_NAME_CHARACTERS = r"-_a-zA-Z0-9 ()."
_DISALLOWED_FILE_NAME_CHARACTERS = re.compile(rf"[^{_REGEX_PART_ALLOWED_FILE_NAME_CHARACTERS}]+")
ALLOWED_FILE_NAMES = re.compile(rf"^[{_REGEX_PART_ALLOWED_FILE_NAME_CHARACTERS}]+$")


def set_extension(file_name, extension):
	m = re.fullmatch(r"""
^
(.*?)             # Match anything, non-greedily because otherwise it would also match extension
(?:
	(?:\.tar)?     # Optionally match .tar
	\.[^.]{0,5}
)?                # Optionally match an extension (0 to 5 long)
$
""", file_name, flags=re.VERBOSE)
	if not m:
		return file_name + extension
	else:
		return m.group(1) + extension



def sanitize(file_name):
	# Strip dots
	while file_name.startswith("."):
		file_name = file_name[1:]

	if not file_name:
		return None

	if ALLOWED_FILE_NAMES.fullmatch(file_name):
		return file_name
	else:
		return slugify(file_name, lowercase=False, regex_pattern=_DISALLOWED_FILE_NAME_CHARACTERS)