A little disclaimer: you're going to have a field day with this. It's horrible. Looking at it makes me want to vomit, and don't ask me to explain it, because I've long forgotten what I was thinking when I wrote it. That being said, I can't really find a way to shorten it of make it make sense. Perhaps someone could help me out?

A bit of a background:

This program is meant to install mods for a game called Supreme Commander 2. It is meant to install ANY mod. The following is true of all the mods:

• The only archive type is the .scd. SCD's have the same encoding as .zip's, but with a 0% compression rate.
• The way to install the mod is simple: There will always be at least one scd inside the first, and there may be more scd's inside that one. Any scd with folders inside it should be moved to

C:\Program Files (x86)\Steam\steamapps\common\supreme commander 2\gamedata

There may be more than one scd to be moved per mod.

And that's it. This is something of a "programming challenge," but I am really looking for improvements upon the following code:

import os, zipfile
def installfromdownload(filename):
    global scdlist
    targetfolder = r"C:\Program Files (x86)\Mod Manager\Mods\f_" + filename[:-4]
    lentf = len(targetfolder)
    unzip(r"C:\Program Files (x86)\Mod Manager\Mods\z_" + filename + ".scd", targetfolder)
    if checkdirs(targetfolder) == False:
        os.system("copy C:\Program Files (x86)\Mod Manager\Mods\z_" + filename + ".scd" " C:\Program Files (x86)\Steam\steamapps\common\supreme commander 2\gamedata")
    else:
        newfolderonelist = []
        getscds(targetfolder)
        for file in scdlist:
            newfolderone = targetfolder + "\f_" + file[:-4]
            filepath = targetfolder + "\\" + file
            unzip(filepath, newfolderone)
            newfolderonelist.append(newfolderone)
        for newfolders in newfolderonelist:
            if os.checkdirs(newfolders) == False:
                newfolders = newfolders[lentf + 1:]
                for scds in scdlist:
                    if newfolder in scds == True:
                        scdpath = targetfolder + "\\" + scds
                        os.system("copy " + scdpath + " C:\Program Files (x86)\Steam\steamapps\common\supreme commander 2\gamedata")

Note that there is no error handling here, that is done when I call the function. The function unzip() is here:

def unzip(file, target):
    modscd = zipfile.ZipFile(file)
    makepath(target)
    modscd.extractall(target)

The function checkdirs() is here (note this is pretty bad, it only checks for periods in the file name, so please submit suggestions):

def checkdirs(target):
    isfile = 0
    targetlist = os.listdir(target)
    for files in targetlist:
        for letters in files:
            if letters == ".":
                isfile = isfile + 1
    if isfile == len(os.listdir(target)):
        return False
    else:
        return True

The getscds() function just checks a filename for ".scd".