unrange.py

from ipaddress import ip_address, ip_network, summarize_address_range, collapse_addresses
from itertools import chain
import sys


def parse_net_or_range(s):
	if '-' in s:
		start, end = s.split('-', 1)
		start = ip_address(start)
		end = ip_address(end)
		return summarize_address_range(start, end)
	return [ip_network(s)]


def smallest_containing_net(a, b):
	while not a.supernet_of(b):
		a = a.supernet()
	return a


def merge_cost(a, b):
	return smallest_containing_net(a, b).num_addresses - a.num_addresses - b.num_addresses


def main(args):
	_, *args = args
	addrs = list(collapse_addresses(chain.from_iterable(map(parse_net_or_range, args))))
	ads = set(addrs)
	gaps = sorted((merge_cost(a, b), a, b) for a, b in zip(addrs, addrs[1:]))
	merged = []
	n = len(ads)
	while gaps:
		_, a, b = gaps.pop(0)
		merged.append(smallest_containing_net(a, b))
		ads.discard(a)
		ads.discard(b)
		l = list(collapse_addresses(chain(merged, ads)))
		if len(l) < n:
			print('%d:' % len(l))
			print('\t' + ' '.join(str(n) for n in l))
			n = len(l)


if __name__ == '__main__':
	main(sys.argv)