#!/usr/bin/env python3
"""Детерминированный набор для P5: 20 copy и граничные размеры."""

from __future__ import annotations

import pathlib
import sys


SIZES = [
    0,
    1,
    4095,
    4096,
    65535,
    65536,
    37,
    511,
    512,
    513,
    1023,
    1024,
    2047,
    2048,
    8191,
    8192,
    16383,
    16384,
    32769,
    1024 * 1024 + 37,
]


def content(index: int, size: int) -> bytes:
    seed = (0x31 + index * 13) & 0xFF
    return bytes(((position * 37 + (position >> 8) * 11 + seed) & 0xFF)
                 for position in range(size))


def create(root: pathlib.Path) -> None:
    source = root / "SOURCE"
    target = root / "TARGET"
    source.mkdir(parents=True)
    target.mkdir(parents=True)
    for index, size in enumerate(SIZES):
        (source / f"F{index:02d}.BIN").write_bytes(content(index, size))


def verify_initial(root: pathlib.Path) -> None:
    source = root / "SOURCE"
    target = root / "TARGET"
    failures = []
    for index, size in enumerate(SIZES):
        path = source / f"F{index:02d}.BIN"
        if not path.is_file() or path.read_bytes() != content(index, size):
            failures.append(f"повреждён SOURCE/{path.name}")
    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: P5 fixture содержит 20 источников, TARGET пуст.")


def verify(root: pathlib.Path) -> None:
    source = root / "SOURCE"
    target = root / "TARGET"
    failures = []
    for index, size in enumerate(SIZES):
        name = f"F{index:02d}.BIN"
        source_path = source / name
        target_path = target / name
        if not target_path.is_file():
            failures.append(f"нет TARGET/{name}")
        elif target_path.read_bytes() != source_path.read_bytes():
            failures.append(f"TARGET/{name} не совпадает с источником")
        elif target_path.stat().st_size != size:
            failures.append(f"неверный размер TARGET/{name}")
    temporaries = sorted(target.glob("~SC*.TMP"))
    if temporaries:
        failures.append("остались временные файлы: " +
                        ", ".join(path.name for path in temporaries))
    if failures:
        for failure in failures:
            print(f"FAIL: {failure}")
        raise SystemExit(1)
    print("PASS: 20/20 файлов совпали; все граничные размеры и >1 МБ пройдены.")


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()