import locale
import re
from collections.abc import Iterable
from typing import TypeVar

T = TypeVar("T")

# Set to user's default locale:
locale.setlocale(locale.LC_ALL, "")

# Or set to a specific locale:
# locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')


def format_number(number: float) -> str:
    return locale.format_string("%d", number, grouping=True)


def flatten(list_: Iterable[list[T]]) -> list[T]:
    """
    Flattens a list of lists into a single list.
    """
    return [item for sublist in list_ for item in sublist]


def create_valid_filename(filename: str) -> str:
    """
    Create a valid filename by removing invalid characters.
    """
    # Remove invalid characters for filenames
    invalid_chars = r'[<>:"/\\|?*]'
    filename = re.sub(invalid_chars, "_", filename)

    # Remove leading/trailing spaces and dots
    filename = filename.strip(" .")

    # Ensure filename is not empty
    if not filename:
        filename = "unnamed"

    return filename


class classproperty(property):
    """
    A class property decorator.
    """

    def __get__(self, owner_self, owner_cls):
        if self.fget:
            return self.fget(owner_cls)