#!/usr/bin/env python3
"""Набор почти полного HDD для проверки ENOSPC и удаления copy-temp."""

from __future__ import annotations

import pathlib
import sys


SOURCE_SIZE = 262_181
FILLER_SIZE = 32_850_000


def source_content() -> bytes:
    return bytes(((index * 37 + (index >> 8) * 11 + 0xA7) & 0xFF)
                 for index in range(SOURCE_SIZE))


def write_filler(path: pathlib.Path) -> None:
    chunk = bytes(((index * 17 + 0x53) & 0xFF) for index in range(65536))
    remaining = FILLER_SIZE
    with path.open("wb") as stream:
        while remaining:
            part = min(remaining, len(chunk))
            stream.write(chunk[:part])
            remaining -= part


def create(root: pathlib.Path) -> None:
    source = root / "SOURCE"
    target = root / "TARGET"
    source.mkdir(parents=True)
    target.mkdir(parents=True)
    (source / "FULL.BIN").write_bytes(source_content())
    write_filler(root / "FILLER.BIN")


def verify_initial(root: pathlib.Path) -> None:
    failures = []
    source = root / "SOURCE" / "FULL.BIN"
    target = root / "TARGET"
    filler = root / "FILLER.BIN"
    if not source.is_file() or source.read_bytes() != source_content():
        failures.append("повреждён SOURCE/FULL.BIN")
    if not filler.is_file() or filler.stat().st_size != FILLER_SIZE:
        failures.append("неверный FILLER.BIN")
    if not target.is_dir() or list(target.iterdir()):
        failures.append("TARGET не пуст до теста")
    if failures:
        for failure in failures:
            print(f"FAIL: {failure}")
        raise SystemExit(1)
    print("PASS: ENOSPC fixture готов, SOURCE/FULL.BIN сохранён.")


def verify(root: pathlib.Path) -> None:
    failures = []
    source = root / "SOURCE" / "FULL.BIN"
    target = root / "TARGET"
    filler = root / "FILLER.BIN"
    if not source.is_file() or source.read_bytes() != source_content():
        failures.append("исходный FULL.BIN изменён")
    if not filler.is_file() or filler.stat().st_size != FILLER_SIZE:
        failures.append("FILLER.BIN изменён")
    if (target / "FULL.BIN").exists():
        failures.append("после ENOSPC остался конечный TARGET/FULL.BIN")
    temporaries = sorted(target.glob("~SC*.TMP"))
    if temporaries:
        failures.append("после ENOSPC остался временный файл")
    if failures:
        for failure in failures:
            print(f"FAIL: {failure}")
        raise SystemExit(1)
    print("PASS: ENOSPC не изменил source/filler и не оставил target/temp.")


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


if __name__ == "__main__":
    main()