#!/usr/bin/env python3
"""Создаёт и проверяет fixture отмены рекурсивного F5."""

from __future__ import annotations

import pathlib
import sys


def payload(size: int) -> bytes:
    return bytes(((index * 29 + 17) & 0xFF) for index in range(size))


BIG = payload(4 * 1024 * 1024)
AFTER = b"may be committed before traversal reaches BIG\r\n"


def create(root: pathlib.Path) -> None:
    tree = root / "CSRC" / "TREE"
    tree.mkdir(parents=True)
    (root / "CDST").mkdir()
    (tree / "BIG.BIN").write_bytes(BIG)
    (tree / "AFTER.TXT").write_bytes(AFTER)


def verify(root: pathlib.Path) -> None:
    source = root / "CSRC" / "TREE"
    target = root / "CDST" / "TREE"
    failures: list[str] = []

    if (source / "BIG.BIN").read_bytes() != BIG:
        failures.append("source BIG.BIN изменён")
    if (source / "AFTER.TXT").read_bytes() != AFTER:
        failures.append("source AFTER.TXT изменён")
    if not target.is_dir():
        failures.append("root target-каталог не был создан до cancel")
    else:
        big_target = target / "BIG.BIN"
        if big_target.exists():
            failures.append("BIG.BIN committed несмотря на ранний cancel")
        after_target = target / "AFTER.TXT"
        if after_target.exists() and after_target.read_bytes() != AFTER:
            failures.append("частично завершённый AFTER.TXT повреждён")
        temporary = [path.name for path in target.iterdir()
                     if path.name.upper().endswith(".TMP")]
        if temporary:
            failures.append(f"после cancel остались temp: {temporary}")

    if failures:
        for failure in failures:
            print(f"FAIL: {failure}")
        raise SystemExit(1)
    print("PASS: tree cancel removed active temp; source intact; no BIG commit.")


def main() -> None:
    if len(sys.argv) != 3 or sys.argv[1] not in {"create", "verify"}:
        raise SystemExit(f"usage: {sys.argv[0]} create|verify DIR")
    root = pathlib.Path(sys.argv[2])
    if sys.argv[1] == "create":
        create(root)
    else:
        verify(root)


if __name__ == "__main__":
    main()