Resident Evil 4 HD Switch Save Converter

#!/usr/bin/env python3

from io import BytesIO
from os.path import isfile
from argparse import ArgumentParser

SWITCH_SETTINGS_OFFSET = 0x1E40
SWITCH_DEFAULT_SETTINGS = bytes([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x02, 0x40, 0x02, 0x02, 0x00, 0x5F, 0x00])


def read_file(filename: str) -> bytes:
    with open(filename, "rb") as f:
        data = f.read()
    return data

def write_file(filename: str, data: (bytes, bytearray)) -> None:
    with open(filename, "wb") as f:
        f.write(data)

if __name__ == "__main__":
    parser = ArgumentParser(description="A script to port RE:4 HD (Xbox 360, PS3, PS4, and PC) saves to Switch")
    parser.add_argument("input", type=str, help="The input filename")
    parser.add_argument("output", type=str, help="The output filename")
    args = parser.parse_args()

    assert isfile(args.input), "The specified input file doesn't exist"

    save_data = read_file(args.input)
    with BytesIO(save_data) as bio:
        bio.seek(SWITCH_SETTINGS_OFFSET)
        bio.write(SWITCH_DEFAULT_SETTINGS)
        bio.flush()
        write_file(args.output, bio.getvalue())
    print("Done!")