# List of domains that should point to the current IP
freedns_domains = set(["foo.example.com"])

# FreeDNS API endpoint, accessible from https://freedns.afraid.org/api/ (use the ASCII one)
freedns_check_url = "https://freedns.afraid.org/api/?action=getdyndns&sha=REDACTED"

# It is assumed that this address responds with a page containing only the IP address
ip_check_url = "https://ident.me/"


def log(message):
    """
    Appends a string to the logfile (hardcoded as log.txt).
    :param message: The message to be appended. Linebreaks are your responsibility.
    """
    with open("log.txt", "a") as f:
        f.write(message)


import datetime
now = datetime.datetime.now()
log("nn" + str(now) + ": Script executing,")
import urllib.request
current_ip = urllib.request.urlopen(ip_check_url).read().decode("utf-8")
log(" IP: " + current_ip)

log("ntGetting FreeDNS records...")
import urllib.request
records_raw = urllib.request.urlopen(freedns_check_url).read().decode("utf-8").split("n")
log(" Found " + str(len(records_raw)) + ".")

for raw_record in records_raw:
    parts = raw_record.split("|")

    domain = parts[0]
    current_freedns_ip = parts[1]
    freedns_update_url = parts[2]

    if domain not in freedns_domains:
        log("ntt" + domain + " is not on the watch list, skipping.")
    else:
        log("ntt" + domain + " (" + current_freedns_ip + ") is on the watch list...")

        if current_ip == current_freedns_ip:
            log(" IPs already match, moving on.")
        else:
            log(" IPs don't match, updating...")
            urllib.request.urlopen(freedns_update_url)
            log(" done.")


log("ntScript exited gracefully.")