# -*- coding: utf-8 -*-

##########################################
# Shared Abstract classes and interfaces #
##########################################

# Imports
from abc import ABC, abstractmethod
from os import environ


class IValidatable(ABC):
    """
    Interface initializing a class with a magic method for
    checking the validity of its objects
    """

    @abstractmethod
    async def __validate__(self) -> bool:
        """
        Checks if the object of the class is valid

        :return: Object validity boolean
        """
        raise NotImplementedError


class ENV(object):
    _name: str | None = None
    DEFAULT: str

    def __init__(self) -> None:
        if self._name is None or self.DEFAULT is None:
            raise NotImplementedError

    @property
    def from_os(self) -> str | None:
        if self._name is not None:
            return environ.get(self._name)

    @property
    def value(self) -> str:
        val = self.from_os
        if val is not None:
            return val
        return self.DEFAULT

    def __call__(self) -> str:
        return self.value