import os
import string
import pathlib

class aleatory_file_name:
    """
    That create new random file name, with given size and given extension.
    File name is returned as a string. Creating new instance of that class
    does not return an instance, but only string result.
    """

    def __new__(cls, extension: str = "", size: int = 32) -> str:
        """
        That create new random file name from system random number 
        generator, extension and size. Resulted file name have given size,
        given extension but name is fully random. Name could contain small
        letters, big letters and digits.

        Parameters
        ----------
        extension : str (default: "")
            Extension of the file.
        
        size : int (default: 32)
            Lenght of the file name.

        Returns
        -------
        str 
            Random name of the file.
        """

        name_lenght = size
       
        if len(extension) > 0:
            name_lenght -= 1 + len(extension)

        name = cls.__get_random_name(name_lenght)
        return cls.__get_file_name(name, extension)

    @classmethod
    def path(cls, *args, **kwargs) -> pathlib.Path:
        """
        That function work same as initializer, but return pathlib.Path,
        instread of string.

        Parameters
        ----------
        *args, **kwargs
            Same as __new__ parameters.

        Returns
        -------
        pathlib.Path
            Path instread of string.
        """

        return pathlib.Path(cls(*args, **kwargs))

    @classmethod
    def __get_chars(cls) -> str:
        """
        It return full aphabet with small and big letters. To letters it 
        add also digits.

        Returns
        -------
        str
            Full alphabet with digits, big and small letters.
        """
        return str(string.ascii_letters + string.digits)

    @classmethod
    def __get_random_name(cls, size: int) -> str:
        """
        That generate random name (random string wich letters from alphabet
        generated in __get_chars) with size passed by intiger parameter.

        Parameters
        ----------
        size : int
            Lenght of random name.

        Returns
        -------
        str
            Random name with given lenght.
        """
        
        chars = cls.__get_chars()
        result = str()

        for count in range(size):
            random = os.urandom(1)[0]
            random = random % len(chars)

            result = result + chars[random]

        return result

    @classmethod
    def __get_file_name(cls, name: str, extension: str) -> str:
        """
        That create file name from name and extension. When extension is
        blank, then it return file name without extension. When extension 
        is passed then return file name as "name.extension".

        Parameters
        ----------
        name : str
            Name of the file.

        extensions : str
            Extension of the file.

        Returns
        -------
        str
            Full file name from name and extension.
        """

        if len(extension) > 0:
            return name + "." + extension
        
        return name