"""Tests for the Obok (Kobo) plugin core."""

import io

import dedrm_test_utils as U

obok = U.load("obok")


def test_unpad_strips_trailing_pad_length():
    # obok.unpad trusts the final byte as the pad length; it is not a validating
    # PKCS#7 implementation, so the name reflects what it actually does.
    assert obok.unpad(b"data\x04\x04\x04\x04") == b"data"


def test_kobo_hash_keys_are_stable_ascii_salts():
    # These four salts are baked into Kobo's userkey derivation
    # (sha256(hash + macaddr) -> deviceid). Pinning the exact values is
    # intentional: a silent typo here would break decryption for every user, so
    # we want a hard regression guard rather than only a shape check.
    keys = obok.KOBO_HASH_KEYS
    assert keys == ["88b3a2e13", "XzUhGYdFp", "NoCanLook", "QJhwzAtXL"]
    # The derivation feeds each salt to ``.encode('ascii')``; pin that contract.
    for k in keys:
        assert isinstance(k, str) and k
        k.encode("ascii")


class _FakeStream:
    encoding = "utf-8"

    def __init__(self):
        self.buffer = io.BytesIO()


def test_safeunbuffered_encodes_str():
    fake = _FakeStream()
    obok.SafeUnbuffered(fake).write("héllo")
    assert fake.buffer.getvalue() == "héllo".encode("utf-8")


def test_safeunbuffered_passes_bytes_through():
    fake = _FakeStream()
    obok.SafeUnbuffered(fake).write(b"\x00\x01\x02")
    assert fake.buffer.getvalue() == b"\x00\x01\x02"