#!/usr/bin/env python3
"""Создаёт и проверяет HDD-fixture рекурсивного группового F8."""

from __future__ import annotations

import pathlib
import sys


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


def create(root: pathlib.Path) -> None:
    panel = root / "RDEL"
    adir = panel / "ADIR"
    bdir = panel / "BDIR"
    keepdir = panel / "KEEPDIR"

    (adir / "EMPTY").mkdir(parents=True)
    bdir.mkdir(parents=True)
    keepdir.mkdir(parents=True)

    # Несколько файлов в одном каталоге проверяют, что F_NEXT продолжает
    # перечисление после удаления только что возвращённой записи.
    for index, size in enumerate((0, 1, 16, 4097)):
        (adir / f"A{index}.BIN").write_bytes(payload(size, index + 3))

    deep = adir
    for depth in range(1, 13):
        deep = deep / f"D{depth:02d}"
        deep.mkdir()
        (deep / f"F{depth:02d}.TXT").write_bytes(
            payload(depth * 7, depth + 19)
        )

    (bdir / "B0.TXT").write_bytes(b"delete second root\r\n")
    (bdir / "B1.BIN").write_bytes(payload(513, 71))
    (panel / "TOP.BIN").write_bytes(payload(33, 91))

    (panel / "KEEP.TXT").write_bytes(b"keep top-level payload\r\n")
    (keepdir / "SAFE.BIN").write_bytes(payload(257, 111))


def verify(root: pathlib.Path) -> None:
    panel = root / "RDEL"
    failures: list[str] = []

    for name in ("ADIR", "BDIR", "TOP.BIN"):
        if (panel / name).exists():
            failures.append(f"выбранный объект не удалён: {name}")

    keep_file = panel / "KEEP.TXT"
    if not keep_file.is_file() or keep_file.read_bytes() != b"keep top-level payload\r\n":
        failures.append("невыбранный KEEP.TXT отсутствует или изменён")

    safe = panel / "KEEPDIR" / "SAFE.BIN"
    if not safe.is_file() or safe.read_bytes() != payload(257, 111):
        failures.append("невыбранное дерево KEEPDIR изменено")

    remaining = sorted(
        path.relative_to(panel).as_posix().upper()
        for path in panel.rglob("*")
    )
    if remaining != ["KEEP.TXT", "KEEPDIR", "KEEPDIR/SAFE.BIN"]:
        failures.append(f"неожиданный остаток RDEL: {remaining}")

    if failures:
        for failure in failures:
            print(f"FAIL: {failure}")
        raise SystemExit(1)
    print("PASS: selected file and two directory trees deleted; KEEP preserved.")


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()