#!/usr/bin/env python
import os, sys, re

STATUS = ["OK", "WARNING", "CRITICAL", "UNKNOWN"]
status = "UNKNOWN"
service = "DHCP"

warn_level = .8
crit_level = .9

used = free = total = 0
used_percent = 1

check_cmd = r'/usr/bin/ssh %(server)s "netsh dhcp server show mibinfo"' % {"server": sys.argv[1]}
subnet = sys.argv[2]
ss = None

for ll in os.popen3(check_cmd)[1].readlines():
    rr = re.match(r"\s*Subnet = (?P<ss>[\d\.]+)\.", ll)
    if (rr):
        ss = rr.group("ss")
        if (ss != subnet):
            ss = None
    rr = re.match(r"\s*(?P<kk>[^=]+) = (?P<vv>[\d]+)", ll)
    if (ss and rr):
        if (rr.group("kk") == "No. of Addresses in use"):
            used = int(rr.group("vv"))
        if (rr.group("kk") == "No. of free Addresses"):
            free = int(rr.group("vv"))

total = used + free
if (total > 0):
    used_percent = float(used) / total
detail = "%d of %d addresses in use; %d%% utilization" % (used, total, used_percent * 100)

if (used_percent >= crit_level):
    status = "CRITICAL"
elif (used_percent >= warn_level):
    status = "WARNING"
elif (used_percent == 0):
    status = "UNKNOWN"
else:
    status = "OK"

print "%s %s: (%s) %s" % (service, status, subnet, detail)
sys.exit(STATUS.index(status))