import os, shutil
src = "res" #from
dest = "D:/test/" #to
backup = "D:/test/backup"

def walker(src):
    list = {"+files":[]} #create dict with reserved space for files
    for file in os.listdir(src):
        fullPath = os.path.join(src, file)
        if os.path.isdir(fullPath):
            list[file] = walker(fullPath) #if item is dir - move deeper
        else:
            list["+files"].append(file) #else add as filename

    if not len(list["+files"]):#on no files in directory - remove empty item
        del list["+files"]
    return list


def install(tree, src, dest, backup):
    for folder, data in tree.iteritems():
        nextSrc = os.path.join(src, folder)
        nextDest = os.path.join(dest, folder)
        nextBackup = os.path.join(backup, folder)

        #for files in current folder backup original and replace
        if folder == "+files":
            for file in data:
                fileFrom = os.path.join(src, file)
                fileTo = os.path.join(dest, file)
                fileBackup = os.path.join(backup, file)
                shutil.copyfile(fileTo, fileBackup)
                shutil.copyfile(fileFrom, fileTo)
        #else if this is folder - dig down
        else:
            install(tree[data], nextSrc, nextDest, nextBackup)


tree = walker(src)
install(tree, src, dest, backup)

print 'ok!'

else:
    install(data, nextSrc, nextDest, nextBackup) # fixed