"""Tests for topazextract, including the path-traversal regression test."""

from io import BytesIO

import dedrm_test_utils as U

tz = U.load("topazextract", package="dedrm")


def test_book_read_encoded_number():
    assert tz.bookReadEncodedNumber(BytesIO(bytes([0x05]))) == 5
    assert tz.bookReadEncodedNumber(BytesIO(bytes([0x81, 0x00]))) == 128


def test_book_read_string():
    assert tz.bookReadString(BytesIO(bytes([0x03]) + b"abc")) == b"abc"


def _bare_book(outdir):
    """A TopazBook instance with just the attributes extractFiles() needs."""
    book = tz.TopazBook.__new__(tz.TopazBook)
    book.outdir = str(outdir)
    return book


def test_extractfiles_strips_path_traversal(tmp_path):
    """A malicious Topaz header tag must not write outside the output dir.

    Regression test for the arbitrary-file-write fix: the record name is read
    verbatim from the (untrusted) book file, so ``../../evil`` must be reduced
    to a basename inside ``outdir`` rather than escaping it.
    """
    outdir = tmp_path / "out"
    outdir.mkdir()
    book = _bare_book(outdir)

    evil_tag = b"../../evil"
    book.bookHeaderRecords = {evil_tag: [[0, 5, 0]]}
    # Attacker-controlled payload bytes, no key required.
    book.getBookPayloadRecord = lambda name, index: b"PWNED"

    book.extractFiles()

    # Primary oracle (independent of traversal depth): with the fix, basename()
    # strips every "../" so the record always lands INSIDE outdir. The pre-fix
    # code did os.path.join(outdir, "../../evil0000.dat"), writing OUTSIDE outdir,
    # so this assertion fails without the fix no matter how deep tmp_path nests.
    assert (outdir / "evil0000.dat").read_bytes() == b"PWNED"
    # outdir contains exactly that one sanitised file, nothing unexpected.
    assert sorted(p.name for p in outdir.iterdir()) == ["evil0000.dat"]
    # Defense in depth: nothing escaped to the dirs the "../../" payload targets.
    assert not (tmp_path / "evil0000.dat").exists()
    assert not (tmp_path.parent / "evil0000.dat").exists()


def test_extractfiles_writes_normal_record(tmp_path):
    outdir = tmp_path / "out"
    outdir.mkdir()
    book = _bare_book(outdir)
    book.bookHeaderRecords = {b"spam": [[0, 4, 0]]}
    book.getBookPayloadRecord = lambda name, index: b"eggs"

    book.extractFiles()

    assert (outdir / "spam0000.dat").read_bytes() == b"eggs"