compress hash example

import hashlib
import mmap
import subprocess
import sys
from argparse import ArgumentParser
from bz2 import BZ2File
from gzip import GzipFile
from lzma import LZMAFile
from pathlib import Path


def compressor(source: Path, target: Path, CompressClass, buffer_size=1024 ** 2):
    with CompressClass(target, "w") as target, source.open("rb") as source:
        buffer = bytearray(buffer_size)
        view = memoryview(buffer)
        while True:
            size = source.readinto(buffer)
            if size == 0:
                break

            target.write(view[:size])


def hasher(algo, files):
    result = []
    for file in files:
        with file.open("rb") as fd:
            with mmap.mmap(fd.fileno(), 0, access=mmap.ACCESS_READ) as mm:
                dig = hashlib.new(algo, mm).hexdigest()
                result.append(f"{dig}  {file.name}")

    result = "\n".join(result)
    with open(f"{files[0].stem}.{algo}", "w") as hash_file:
        hash_file.write(result)


def compress(image):
    bz2 = image.with_suffix(".img.bz2")
    xz = image.with_suffix(".img.xz")
    gz = image.with_suffix(".img.gz")
    md5 = image.with_suffix(".md5")
    sha256 = image.with_suffix(".sha256")

    print(f"Komprimiere {bz2}")

    # with bz2.open("wb") as fd:
    #    subprocess.run(["bzip2", "-c", "-9", "-k", str(image)], stdout=fd)

    compressor(image, bz2, BZ2File)

    print(f"Komprimiere {xz}")

    # with xz.open("wb") as fd:
    #     subprocess.run(["xz", "-c", "-9", "-k", str(image)], stdout=fd)

    compressor(image, xz, LZMAFile)

    print(f"Komprimiere {gz}")
    compressor(image, gz, GzipFile)

    print("Erstelle md5sum")
    hasher("md5", [image, bz2, gz, xz])

    # with md5.open("wb") as fd:
    #     subprocess.run(["md5sum", str(image), str(bz2), str(xz)], stdout=fd)

    print("Erstelle sha256sum")
    hasher("sha256", [image, bz2, gz, xz])

    # with sha256.open("wb") as fd:
    #     subprocess.run(["sha256sum", str(image), str(bz2), str(xz)], stdout=fd)


def main(image):
    if not image.exists():
        raise ValueError("Image file does not exist.")
    compress(image)


def get_args():
    parser = ArgumentParser()
    parser.add_argument("file", type=Path, help="Image to compress")
    return parser.parse_args()


if __name__ == "__main__":
    args = get_args()
    main(args.file)