from django.contrib.auth import get_user_model

User = get_user_model()


class EmailOrUsernameModelBackend(object):
    """
    Change UsernameModelBackend.

    Login via email.
    """

    def authenticate(self, username=None, password=None, email=None):
        """
        Authenticate method.

        Change login to email instead username.
        """
        if email:
            kwargs = {'email': email}
        else:
            kwargs = {'username': username}
        try:
            user = User.objects.get(**kwargs)
            if user.check_password(password):
                return user
        except User.DoesNotExist:
            return None

    def get_user(self, username):
        """
        Get_user method.

        Get user by username.
        """
        try:
            return User.objects.get(pk=username)
        except User.DoesNotExist:
            return None