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

	def __str__(self):
		return self.name

	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


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

	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