#!/usr/bin/python3
# get target temperature from AVM/Comet Dect Heizkoerperregler (Heating Device)
# need Fritz!OS 6.50+

import getopt
import re
import requests
import sys
import xml.etree.ElementTree as etree
import urllib.parse
from hashlib import md5

DEBUG=False

def OK(text):
  print("OK: " + text)
  sys.exit()

def Warning(text):
  print("WARNING: " + text)
  sys.exit()

def Critical(text):
  print("CRITICAL: " + text)
  sys.exit()

def OptionsError():
  Critical("Error: not all required options are given.\n -H <hostname>\n -U <username>\n -P <password>\n -A <ID of device>")

def debug(text):
  if DEBUG == True:
    print("DEBUG: " + text)

def get_sid(loginurl, username, password):
  if not username:
    username=''

  # get challenge string
  response = requests.get(loginurl)

  if response.status_code == 200:
    tree = etree.fromstring(response.content)
    challenge = tree.find("Challenge").text
    sid = tree.find("SID").text
    debug("challenge: " + challenge)
    debug("sid: " + sid)
  else:  
    Critical("Error: GetSid failed")

  if len(sid) > 0 and re.search("^0+$", sid) and challenge:
    debug("Get new SID")
    # sid is null, got challenge
    sid = ""
    # build password response
    pwd = challenge + "-" + password
    # UTF-16LE encoding as required
    pwd = pwd.encode("UTF-16LE")
    # md5hash on top
    m = md5()
    m.update(pwd)
    # final answer string
    challenge_response = challenge + "-" + m.hexdigest()
    debug("challenge_response: " + challenge_response)
    # send to box
    url = loginurl + "?username=" + username + "&response=" + challenge_response
    response = requests.get(url)
    #print(response.content)
    # check answer
    tree = etree.fromstring(response.content)
    sid2 = tree.find("SID").text
    debug("SID: " + sid2)
    if (len(sid2) > 0) and not re.search("^0+$", sid2):
      # is not null, bingo!
      return sid2
  else:
    # use existing sid if sid matches an hex string
    if (len(sid) > 0) and re.search("^[0-9a-f]+$", sid):
      return sid

host = None
username = None
password = None
ain = None

try:
  opts, args = getopt.gnu_getopt(sys.argv[1:], 'H:U:P:A:')
except getopt.GetoptError as err:
  OptionsError()

for opt, arg in opts:
  if opt == "-H":
    host = arg
  elif opt == "-U":
    username = arg
  elif opt == "-P":
    password = arg
  elif opt == "-A":
    ain = arg

if not host or not username or not password or not ain:
  OptionsError()

# build urls and login
# - login_sid.lua for fritzos 5.50+
loginurl = "http://" + host + "/login_sid.lua"
ahaurl = "http://" + host + "/webservices/homeautoswitch.lua"
sid = get_sid(loginurl, username, password);
if not sid:
  Critical("Error: Login invalid or failed")

#query actual state
rain = urllib.parse.quote(ain)
url = ahaurl + '?ain=' + rain + '&sid=' + sid + '&switchcmd=gettemperature';

http_response = requests.get(url)

if http_response.status_code == 200:
  # check answer
  answer = http_response.content.decode().strip()
  debug("Antwort: " + answer)
  temperatur = float(answer) / 10
  temp_str = "{0:<3.1f}".format(temperatur)
  OK("Temperatur: " + temp_str + " | temp=" + temp_str)
else:
  Critical("Error: Query failed.")