import os
from functools import partial


def mod_time(path):
    return os.stat(path).st_mtime


def find_newest_cert(root_dir, hostname):
    look_for = {
        "{}.key.pem".format(hostname): None,
        "{}.chain.pem".format(hostname): None,
    }
    for root, _, files in os.walk(root_dir):
        for file in files:
            if file in look_for.keys():
                fullpath = os.path.join(root, file)
                if look_for[file] is None:
                    look_for[file] = fullpath
                elif mod_time(fullpath) > mod_time(look_for[file]):
                    look_for[file] = fullpath
    return look_for


def ensure_keys(key_dir, hostname):
    files = (part.format(hostname) for part in ("{}.key.pem", "{}.chain.pem"))