import ctypes
import pathlib
import secrets

_lib = ctypes.CDLL(pathlib.Path(__file__).parent / "ext.so")

# crypto_key_exchange
x25519_ty = ctypes.c_uint8 * 32
_lib.crypto_x25519_public_key.restype = None
_lib.crypto_x25519_public_key.argtypes = [x25519_ty, x25519_ty]


def crypto_key_exchange_make_key() -> bytes:
    secret = bytearray(secrets.token_bytes(32))
    secret[0] &= 248
    secret[31] = (secret[31] & 127) | 64
    return bytes(secret)


def crypto_key_exchange_public_key(secret: bytes) -> bytes:
    public = x25519_ty()
    _lib.crypto_x25519_public_key(public, x25519_ty(*secret))
    return bytes(public)

# and.... that's all for now