"""Service to handle user_token operations."""
import uuid
from datetime import datetime
from typing import Optional

from atheneum.db import db
from atheneum.model import User, UserToken


def generate_token() -> uuid.UUID:
    """
    Generate a unique token.

    :return:
    """
    return uuid.uuid4()


def create(
        user: User,
        note: Optional[str] = None,
        enabled: bool = True,
        expiration_time: Optional[datetime] = None) -> UserToken:
    """
    Create and save a UserToken.

    :param user: The User object to bind the token to
    :param note: An optional field to store additional information about a
    token
    :param enabled: A boolean to indicate whether a token can be considered
    eligible for authentication
    :param expiration_time: An optional argument to determine when the token
    becomes invalid as a means of authentication. Defaults to None, which means
    no expiration
    :return:
    """
    token = generate_token()
    user_token = UserToken(
        user_id=user.id,
        token=token.__str__(),
        note=note,
        enabled=enabled,
        creation_time=datetime.now(),
        expiration_time=expiration_time,
        version=0)

    db.session.add(user_token)
    db.session.commit()

    return user_token


def delete(user_token: UserToken) -> bool:
    """
    Delete a user_token.

    :param user_token:
    :return:
    """
    existing_user_token = db.session.delete(user_token)
    if existing_user_token is None:
        db.session.commit()
        return True
    return False


def find_by_user_and_token(user: User, token: str) -> Optional[UserToken]:
    """
    Lookup a user_token by user and token string.

    :param user:
    :param token:
    :return:
    """
    return UserToken.query.filter_by(user_id=user.id, token=token).first()