from django.db import models
from django.urls import reverse

from whoisdb.models import MntdObject, WhoisObject, Contact, InetNum

import ipaddress

# generally allow domains for .dn to be created
# allow owners of a subnet to create reverse dns record?


class Nameserver(MntdObject):
	handleSuffix = "NS"
	# dns name
	# ip address, if glue
	#	ipv4/ipv6 address?
	handle = None
	name = models.CharField(max_length=256)
	glueIPv4 = models.GenericIPAddressField(protocol='IPv4', blank=True, null=True)
	glueIPv6 = models.GenericIPAddressField(protocol='IPv6', blank=True, null=True)

	admin_c = models.ManyToManyField(Contact)

	def getPK(self):
		return self.pk

	def get_absolute_url(self):
		return reverse("domains:nameserver-show", args=(self.pk,))

	def __str__(self):
		return self.name

	def getAppName(self):
		return "domains"

	def getNoDeleteReasons(self):
		# nameservers can always be deleted
		return []


class Domain(MntdObject):
	handle = None
	handleSuffix = "DOM"
	name = models.CharField(max_length=67, unique=True, db_index=True)

	nameservers = models.ManyToManyField(Nameserver, blank=True)
	admin_c = models.ManyToManyField(Contact)

	def getPK(self):
		return self.name

	def getZone(self):
		return self.name

	def get_absolute_url(self):
		return reverse("domains:domain-show", args=(self.name,))

	def __str__(self):
		return self.name

	def getAppName(self):
		return "domains"

	def getNoDeleteReasons(self):
		reasons = []

		nameservers = Nameserver.objects.filter(name__endswith="." + self.name)
		for ns in nameservers:
			# FIXME: check if the nameserver has a glue record.... and also if it is maintained by us
			reasons.append("Nameserver %s depends on this domain" % ns.name)

		return reasons

	@classmethod
	def fixName(clazz, name):
		if not name.endswith("."):
			name += "."
		return name.lower()


class ReverseZone(WhoisObject):
	handle = None

	parentNet = models.ForeignKey(InetNum)
	address = models.GenericIPAddressField(db_index=True)
	netmask = models.PositiveIntegerField()

	nameservers = models.ManyToManyField(Nameserver)

	def getPK(self):
		return self.pk

	def prefix(self):
		""" Helper function, mainly used in templates """
		return "%s/%s" % (self.address, self.netmask)

	def getNetwork(self):
		return ipaddress.ip_network(self.prefix())

	def getZone(self):
		net = self.parentNet.getNetwork()
		if net.version == 4:
			# does not work with python3.4
			## for these we delegate the full domain
			#if 0 < net.prefixlen < 32 and net.prefixlen % 8 == 0:
			#	zoneParts = net.reverse_pointer.split(".")

			#	return ".".join(zoneParts[1:])
			#else:
			#	# return RFC2317 compliant zone
			#	return net.reverse_pointer
			parts = list(reversed(str(net.network_address).split(".")))
			domain = ".".join(parts[4 - net.prefixlen // 8:]) + ".in-addr.arpa."
			if net.prefixlen % 8 == 0:
				# clean cut!
				return domain
			else:
				# RFC2317 compliant!
				rfc2317Domain = "%s/%s.%s" % (parts[4 - net.prefixlen // 8 - 1], net.prefixlen, domain)
				return rfc2317Domain
		else:
			## does not work with python3.4
			## ipv6
			## thefuck ipaddress lib... _the_ _fuck_
			#zoneParts = net.reverse_pointer.split(".")[-2 - net.prefixlen // 4:]
			#return ".".join(zoneParts)

			parts = list(reversed(net.exploded.split("/")[0].replace(":", "")))[32 - net.prefixlen // 4:]
			return ".".join(parts) + ".ip6.arpa."

	def get_absolute_url(self):
		return reverse("domains:reversezone-show", args=(self.pk,))

	def getAppName(self):
		return "domains"

	def __str__(self):
		return "%s @ %s" % (self.prefix(), self.parentNet)

	def getNoDeleteReasons(self):
		return []

	def canEdit(self, user):
		if self.parentNet:
			return self.parentNet.canEdit(user)
		else:
			return False