from hashlib import pbkdf2_hmac
from random import choices
from string import ascii_letters
from datetime import datetime, timedelta

from typing import Optional, Union
from jose import jwt

from ..schemas.tokens import TokenData
from ..schemas.users import UserData

from .users import get_user_by_username

from calculate.utils.files import Process


def make_secret_key() -> str:
    openssl_process = Process("/usr/bin/openssl", "rand", "-hex", "32")
    secret_key = openssl_process.read()
    return secret_key.strip()


# SECRET_KEY =\
#     "efe90242c1c221b20fc718edc3aa5da4f78147eb2f4e81e809e945bbcdf0710e"
SECRET_KEY = make_secret_key()
ALGORITHM = "HS256"


async def auth_user(username: str, password: str) -> Union[UserData, bool]:
    user_row = await get_user_by_username(username)
    if not user_row:
        return False
    user = UserData(**user_row)
    if not validate_password(password, user.password):
        return False
    return user


def decode_jwt(token: str) -> Union[TokenData, None]:
    payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
    username: str = payload.get("sub")
    expire = payload.get("exp")
    if username is None:
        return None
    return TokenData(username=username,
                     expire=expire)


def create_access_token(data: dict,
                        expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


def get_salt(length=12):
    """Метод для получения случайной строки символов используемой как соль
    при кэшировании."""
    return "".join(choices(ascii_letters, k=length))


def validate_password(password: str, hashed_password: str) -> bool:
    salt, db_hash = hashed_password.split("$")
    hashed = hash_password(password, salt)
    return hashed == db_hash


def hash_password(password: str, salt: str) -> str:
    if salt is None:
        salt = get_salt()
    enc = pbkdf2_hmac("sha256", password.encode(), salt.encode(), 100_000)
    return enc.hex()