# DHCPd Leases
#
# Douglas Thrift
#
# $Id$

from datetime import datetime
from pyparsing import *
import pytz

open_brace = Suppress('{')
close_brace = Suppress('}')
date = oneOf(list('0123456')) \
	+ Combine(Word(nums, exact = 4) + '/' + Word(nums, exact = 2) + '/' + Word(nums, exact = 2)) \
	+ Combine(Word(nums, exact = 2) + ':' + Word(nums, exact = 2) + ':' + Word(nums, exact = 2)) \
	| Literal('never')
semi_colon = Suppress(';')
my_state = Literal('my') \
	+ Suppress('state') \
	+ Word(alphas, alphas + '-') \
	+ Suppress('at') \
	+ date \
	+ semi_colon
peer_state = Literal('partner') \
	+ Suppress('state') \
	+ Word(alphas, alphas + '-') \
	+ Suppress('at') \
	+ date \
	+ semi_colon
mclt = Literal('mclt') + Word(nums) + semi_colon
failover = Literal('failover') \
	+ Suppress('peer') \
	+ QuotedString('"') \
	+ Suppress('state') \
	+ open_brace \
	+ Dict(ZeroOrMore(Group(my_state | peer_state | mclt))) \
	+ close_brace
ip_address = Combine(Word(nums) + '.' + Word(nums) + '.' + Word(nums) + '.' + Word(nums))
starts = Literal('starts') + date + semi_colon
ends = Literal('ends') + date + semi_colon
tstp = Literal('tstp') + date + semi_colon
tsfp = Literal('tsfp') + date + semi_colon
atsfp = Literal('atsfp') + date + semi_colon
cltt = Literal('cltt') + date + semi_colon
binding_state = Literal('active') \
	| Literal('free') \
	| Literal('backup') \
	| Literal('expired') \
	| Literal('abandoned')
binding = Literal('binding') + Suppress('state') + binding_state + semi_colon
next = Literal('next') + binding
mac_address = Combine(Word(hexnums, exact = 2) + ':' + Word(hexnums, exact = 2) + ':' + Word(hexnums, exact = 2) + ':' + Word(hexnums, exact = 2) + ':' + Word(hexnums, exact = 2) + ':' + Word(hexnums, exact = 2))
hardware = Literal('hardware') \
	+ Suppress('ethernet') \
	+ mac_address \
	+ semi_colon
uid = Literal('uid') + QuotedString('"', '\\') + semi_colon
set = Literal('set') + Word(alphas, alphas + '-') + Suppress('=') + QuotedString('"') + semi_colon
client_hostname = Literal('client-hostname') + QuotedString('"') + semi_colon
statements = starts \
	| ends \
	| tstp \
	| tsfp \
	| atsfp \
	| cltt \
	| binding \
	| next \
	| hardware \
	| uid \
	| set \
	| client_hostname
lease = Literal('lease') \
	+ ip_address \
	+ open_brace \
	+ Dict(ZeroOrMore(Group(statements))) \
	+ close_brace
server_duid = Literal('server-duid') + QuotedString('"', '\\') + semi_colon
leases = Dict(ZeroOrMore(Group(failover | lease | server_duid)))
comment = '#' + Optional(restOfLine)

leases.ignore(comment)

def date_parse_action(tokens):
	when = ' '.join(tokens)

	return pytz.utc.localize(datetime.strptime(when, '%w %Y/%m/%d %H:%M:%S')) if when != 'never' else datetime.max

date.setParseAction(date_parse_action)

if __name__ == '__main__':
	leases.parseFile('/var/db/dhcpd.leases', parseAll = True)