import hashlib
import hmac
import secrets
from dataclasses import dataclass


PBKDF2_ITERATIONS = 120_000


@dataclass(frozen=True)
class AuthenticatedUser:
    id: str
    username: str
    nickname: str


def hash_password(password: str) -> str:
    salt = secrets.token_hex(16)
    digest = hashlib.pbkdf2_hmac(
        "sha256",
        password.encode("utf-8"),
        salt.encode("ascii"),
        PBKDF2_ITERATIONS,
    ).hex()
    return f"pbkdf2_sha256${PBKDF2_ITERATIONS}${salt}${digest}"


def verify_password(password: str, stored: str) -> bool:
    try:
        algorithm, iterations, salt, digest = stored.split("$", 3)
        if algorithm != "pbkdf2_sha256":
            return False
        calculated = hashlib.pbkdf2_hmac(
            "sha256",
            password.encode("utf-8"),
            salt.encode("ascii"),
            int(iterations),
        ).hex()
        return hmac.compare_digest(calculated, digest)
    except (TypeError, ValueError):
        return False


def new_token() -> str:
    return secrets.token_urlsafe(48)


def hash_token(token: str) -> str:
    return hashlib.sha256(token.encode("utf-8")).hexdigest()