import hashlib

def rule_id(service_name: str, kind: str) -> int:
	h = hashlib.sha1(f"{service_name}:{kind}".encode()).hexdigest()
	return(int(h[:4], 16))  # here's hoping

def build_nat_rules(services, cfg):
	rules = []

	for s in services:
		rid_wan = rule_id(s.name, "dnat_wan")
		rid_hairpin = rule_id(s.name, "dnat_hairpin")

		rules.append({
			"id": rid_wan,
			"service": s,
			"cfg": cfg,
			"kind": "dnat_wan",
		})

		if "nat" in s.exposure:
			rules.append({
				"id": rid_hairpin,
				"service": s,
				"cfg": cfg,
				"kind": "dnat_hairpin",
			})

	return(rules)