#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
from subprocess import run
import getopt, sys

""" The program assumes there is a rule in the OUTPUT chain
    creatd by the following command:
    ip6tables -A OUTPUT -p tcp --dest srv01.libre.space 
    or
    iptables -A OUTPUT -p tcp --dest srv01.libre.space
    depending on yout netwprk setup 
    The default setting is for IPv6
    Author: Bent Bagger, OZ6BL. (c) 2021.
    """

status_file_name = '/root/bin/status.file'

def usage():
  print("""Usage: check_satnogs_polls [-h | --help]
Options:
 -h, --help
    There are no options but '-h' or '--help' :-(
    """)

def init():
  try:
      opts, args = getopt.getopt(sys.argv[1:], "h", "help")
  except getopt.GetoptError as err:
    # print help information and exit:
    print(err)  # will print something like "option -a not recognized"
    usage()
    sys.exit(2)
  for o, a in opts:
    if o in ("-h", "--help"):
      usage()
      sys.exit()
    else:
      assert False, "unhandled option"
  #print("crit: %d, warn: %d, period: %d" % (critical, warning, period))

def get_status():
  status_file = open(status_file_name, mode = 'r')
  status = status_file.readline()
  status_file.close()
  return status

def set_status(status):
  status_file = open(status_file_name, mode = 'w')
  status_file.write(status)
  status_file.close()
  return 

init()  # get command line arguments

# Get the OUTPUT chain
try:
    text = run(['/usr/sbin/ip6tables', '-xvL', 'OUTPUT'], capture_output=True, check=True)
except Exception as X:
     print(f'CRITICAL - Exception: {X}')
     sys.exit(2)
finally:
    pass
# Decode to a string with lines separated by new line
lines = text.stdout.decode().split('\n')
# Find the line for the SatNOGS server
my_line = ''
for line in lines:
    if 'libre.space' in line:
        my_line =line
if my_line != '':
    count = my_line.split()[0] # no. packets seen
else:
    print("Rule for the SatNOGS server not found\nDid you forget to add it to your firewall?")
    sys.exit(1)

# Get the previous reading

try:
    prev_count = get_status()
    #logger('got status')
except IOError:
    prev_count = '0'

# Save current reading

set_status(count)

if int(prev_count) < int(count):
    # Good - some datagrams have been sent
    print(f"OK: {count} datagrams seen so far")
    sys.exit(0)
else:
    # No change since last probe
    print("CRITICAL: No change")
    sys.exit(2)