from hashlib import sha256
from typing import Union, Optional
from string import ascii_letters, digits

from src.ez_lan_manager.services.DatabaseService import DatabaseService
from src.ez_lan_manager.types.User import User


class NameNotAllowedError(Exception):
    def __init__(self, disallowed_char: str) -> None:
        self.disallowed_char = disallowed_char

class UserService:
    ALLOWED_USER_NAME_SYMBOLS = ascii_letters + digits + "!#$%&*+,-./:;<=>?[]^_{|}~"

    def __init__(self, db_service: DatabaseService) -> None:
        self._db_service = db_service

    def get_user(self, accessor: Optional[Union[str, int]]) -> Optional[User]:
        if accessor is None:
            return
        if isinstance(accessor, int):
            return self._db_service.get_user_by_id(accessor)
        accessor = accessor.lower()
        if "@" in accessor:
            return self._db_service.get_user_by_mail(accessor)
        return self._db_service.get_user_by_name(accessor)

    def set_profile_picture(self, user_id: int, picture: bytes) -> None:
        self._db_service.set_user_profile_picture(user_id, picture)

    def get_profile_picture(self, user_id: int) -> bytes:
        return self._db_service.get_user_profile_picture(user_id)

    def create_user(self, user_name: str, user_mail: str, password_clear_text: str) -> User:
        disallowed_char = self._check_for_disallowed_char(user_name)
        if disallowed_char:
            raise NameNotAllowedError(disallowed_char)

        user_name = user_name.lower()

        hashed_pw = sha256(password_clear_text.encode(encoding="utf-8")).hexdigest()
        return self._db_service.create_user(user_name, user_mail, hashed_pw)

    def update_user(self, user: User) -> User:
        disallowed_char = self._check_for_disallowed_char(user.user_name)
        if disallowed_char:
            raise NameNotAllowedError(disallowed_char)
        user.user_name = user.user_name.lower()
        return self._db_service.update_user(user)

    def is_login_valid(self, user_name_or_mail: str, password_clear_text: str) -> bool:
        user = self.get_user(user_name_or_mail)
        if not user:
            return False
        return user.user_password == sha256(password_clear_text.encode(encoding="utf-8")).hexdigest()


    def _check_for_disallowed_char(self, name: str) -> Optional[str]:
        for c in name:
            if c not in self.ALLOWED_USER_NAME_SYMBOLS:
                return c