from trezor.crypto import random

if False:
    from typing import Optional

_cached_seed = None  # type: Optional[bytes]
_cached_seed_without_passphrase = None  # type: Optional[bytes]  # Needed for SLIP-21
_cached_session_id = None  # type: Optional[bytes]


def get_session_id() -> bytes:
    global _cached_session_id
    if not _cached_session_id:
        _cached_session_id = random.bytes(32)
    return _cached_session_id


def set_seed(seed: Optional[bytes]) -> None:
    global _cached_seed
    _cached_seed = seed


def get_seed() -> Optional[bytes]:
    return _cached_seed


def set_seed_without_passphrase(seed: Optional[bytes]) -> None:
    global _cached_seed_without_passphrase
    _cached_seed_without_passphrase = seed


def get_seed_without_passphrase() -> Optional[bytes]:
    return _cached_seed_without_passphrase


def clear() -> None:
    global _cached_session_id
    _cached_session_id = None

    set_seed(None)
    set_seed_without_passphrase(None)