import dns.name
import dns.message
import dns.query
import dns.resolver

#from collections import defaultdict
# FIXME: DNS timeouts

def compareRecords(rrset, expected):
	result = {
		"nameMissing": [],
		"rrMissing": [],
		"rrExtra": [],
	}

	for domain, rrtype, content in expected:
		for rrrec in rrset:
			if domain == rrrec.name.to_text() and dns.rdatatype.from_text(rrtype) == rrrec.rdtype:
				for name in content:
					if name not in map(lambda _x: _x.to_text(), rrrec.items):
						# record missing
						result["rrMissing"].append((domain, rrtype, name))

				for item in rrrec.items:
					if item.to_text() not in content:
						# superfluous record
						result["rrExtra"].append((domain, rrtype, item.to_text()))

				break
		else:
			# domain +  rr nicht in nameserver
			result["nameMissing"].append((domain, rrtype))

	success = not any(len(_x) > 0 for _x in result.values())

	return success, result


def dnsQuery(domain, rrType, nameserverIp):
	dname = dns.name.from_text(domain)
	req = dns.message.make_query(dname, dns.rdatatype.from_text(rrType))
	resp = dns.query.udp(req, nameserverIp, timeout=2.0)

	if resp.rcode() != dns.rcode.NXDOMAIN:
		rrset = resp.answer + resp.authority + resp.additional
		return True, rrset
	else:
		return False, []


def checkDomain(domain, tldNameserver, nameservers):
	result = []

	# build record set
	nsRecords = [(domain, "NS", list(ns.name for ns in nameservers))]
	glueRecords = []
	for ns in nameservers:
		if ns.name.endswith("." + domain):
			if ns.glueIPv4 or ns.glueIPv6:
				if ns.glueIPv4:
					glueRecords.append((ns.name, "A", [ns.glueIPv4]))
				if ns.glueIPv6:
					glueRecords.append((ns.name, "AAAA", [ns.glueIPv6]))
			else:
				result.append(("err", "Nameserver %s is under domain %s, but has no glue entries." % (ns.name, domain)))

	# 1. TLD nameserver
	try:
		found, rrset = dnsQuery(domain, "ANY", tldNameserver)
		if found:
			success, errors = compareRecords(rrset, nsRecords + glueRecords)
			if success:
				result.append(("succ", "All records present in TLD nameserver"))
			else:
				result.append(("err", "Record mismatch between TLD nameserver and WHOIS database", errors))
		else:
			result.append(("err", "Domain %s not found in TLD nameserver" % (domain,)))
	except (dns.exception.Timeout, OSError):
		result.append(("err", "TLD nameserver is currently not reachable"))

	# find other records...

	# 2. your nameservers
	for ns in nameservers:
		addr = None
		if ns.glueIPv4:
			addr = ns.glueIPv4
		elif ns.glueIPv6:
			addr = ns.glueIPv6
		else:
			for rrType in ("A", "AAAA"):
				try:
					r = dns.resolver.Resolver()
					r.timeout = 2.0
					q = r.query(ns.name, rdtype=dns.rdatatype.from_text(rrType))
					addr = q.response.answer[0].items[0].address
				except (dns.exception.DNSException, OSError):
					pass

		if addr:
			err = False
			errDict = {"nameMissing": [], "rrMissing": [], "rrExtra": []}
			try:
				for rec in (nsRecords + glueRecords):
					found, rrset = dnsQuery(rec[0], rec[1], addr)

					#success, errors = compareRecords(rrset, nsRecords + glueRecords)
					success, errors = compareRecords(rrset, [rec])
					if not success:
						err = True
						for k in errors.keys():
							errDict[k].extend(errors[k])

				if not err:
					result.append(("succ", "Nameserver %s is configured correctly" % ns.name))
				else:
					result.append(("err", "Nameserver %s (via %s) recordset does not match the database" % (ns.name, addr), errDict))
			except (dns.exception.DNSException, OSError):
				result.append(("err", "Nameserver %s is not reachable (via %s)" % (ns.name, addr)))
				
		else:
			result.append(("err", "Can't resolv an ip address for nameserver %s" % ns.name))

	return result