from __future__ import annotations

import hashlib
import secrets
from base64 import urlsafe_b64decode, urlsafe_b64encode

PBKDF2_ALGORITHM = "sha256"
PBKDF2_ITERATIONS = 120_000
SALT_BYTES = 16


def hash_password(password: str) -> str:
    salt = secrets.token_bytes(SALT_BYTES)
    digest = hashlib.pbkdf2_hmac(
        PBKDF2_ALGORITHM,
        password.encode("utf-8"),
        salt,
        PBKDF2_ITERATIONS,
    )
    encoded_salt = urlsafe_b64encode(salt).decode("utf-8")
    encoded_digest = urlsafe_b64encode(digest).decode("utf-8")
    return f"pbkdf2_{PBKDF2_ALGORITHM}${PBKDF2_ITERATIONS}${encoded_salt}${encoded_digest}"


def verify_password(password: str, password_hash: str) -> bool:
    try:
        scheme, iterations, encoded_salt, encoded_digest = password_hash.split("$", 3)
    except ValueError:
        return False

    if scheme != f"pbkdf2_{PBKDF2_ALGORITHM}":
        return False

    salt = urlsafe_b64decode(encoded_salt.encode("utf-8"))
    expected_digest = urlsafe_b64decode(encoded_digest.encode("utf-8"))
    computed_digest = hashlib.pbkdf2_hmac(
        PBKDF2_ALGORITHM,
        password.encode("utf-8"),
        salt,
        int(iterations),
    )
    return secrets.compare_digest(computed_digest, expected_digest)