what's in this zip file

whatsinthiszipfile.py

# encoding: utf-8

import os.path
import sys
import zipfile


def file_to_gamenames(filename, f):
    extension = filename.split(".")[-1].lower()

    if extension == "spr":
        return ("C1",)
    if extension == "s16":
        return ("C2", "C3")
    if extension == "c16":
        return ("C3",)
    if extension == "blk":
        return ("C3",)
    if extension == "rcb":
        return ("C1",)

    if extension == "cob":
        if f.read(4) == "COB2":
            return ("C2",)
        else:
            return ("C1",)

    return ()


def main():
    if len(sys.argv) != 3 or sys.argv[1] != "--gamename":
        sys.stderr.write("USAGE: {} --gamename FILE\n".format(sys.argv[0]))
        exit(1)

    filename = sys.argv[2]
    sys.stderr.write("Checking file {}...\n".format(repr(filename)))

    if not os.path.exists(filename):
        sys.stderr.write("File {} does not exist!\n".format(repr(filename)))
        exit(1)

    if filename.lower().endswith(".zip"):
        is_c1 = True
        is_c2 = True
        is_c3 = True
        with zipfile.ZipFile(filename) as zf:
            for name in zf.namelist():
                with zf.open(name) as f:
                    gamenames = file_to_gamenames(name, f)
                    sys.stderr.write("- {} -> {}\n".format(repr(name), gamenames))
                    if gamenames:
                        is_c1 = is_c1 and "C1" in gamenames
                        is_c2 = is_c2 and "C2" in gamenames
                        is_c3 = is_c3 and "C3" in gamenames

        if int(is_c1) + int(is_c2) + int(is_c3) != 1:
            print("Unknown")
        elif is_c1:
            print("C1")
        elif is_c2:
            print("C2")
        elif is_c3:
            print("C3")

    else:
        sys.stderr.write("File {} is not a zip file".format(repr(filename)))


if __name__ == "__main__":
    main()