"""Service to handle authentication."""
import re
from typing import Optional

from nacl import pwhash
from nacl.exceptions import InvalidkeyError

from corvus import errors
from corvus.model import User, UserToken
from corvus.service import user_token_service


def validate_password_strength(proposed_password: str) -> str:
    """Validate that a password meets minimum strength requirements."""
    # calculating the length
    length_error = len(proposed_password) < 8

    # searching for digits
    digit_error = re.search(r"\d", proposed_password) is None

    # searching for uppercase
    uppercase_error = re.search(r"[A-Z]", proposed_password) is None

    # searching for lowercase
    lowercase_error = re.search(r"[a-z]", proposed_password) is None

    if length_error or digit_error or uppercase_error or lowercase_error:
        raise errors.ValidationError(
            ' '.join(['The password must be at least 8 characters long.',
                      'Contain one or more digits,',
                      'one or more uppercase characters,',
                      'and one or more lowercase characters']))

    return proposed_password


def is_valid_password(user: User, password: str) -> bool:
    """
    User password must pass pwhash verify.

    :param user:
    :param password:
    :return:
    """
    assert user

    try:
        return pwhash.verify(
            user.password_hash.encode('utf8'), password.encode('utf8'))
    except InvalidkeyError:
        pass
    return False


def logout(user_token: Optional[UserToken] = None) -> None:
    """
    Remove a user_token associated with a client session.

    :param user_token:
    :return:
    """
    if user_token is not None:
        user_token_service.delete(user_token)