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

from dncore.models import User
from .validators import HandleValidator, HandleValidatorWithSuffix

import ipaddress


class WhoisObject(models.Model):
	class Meta:
		abstract = True
	handleSuffix = ""

	handle = models.SlugField(max_length=32, unique=True, verbose_name='handle', validators=[HandleValidator()])
	created = models.DateTimeField(auto_now_add=True)
	last_modified = models.DateTimeField(auto_now_add=True)

	def __str__(self):
		return self.handle

	def genHandle(self, main=None):
		if not main:
			main = self.name
		return self.genGenericHandle(main)

	@classmethod
	def genGenericHandle(clazz, main):
		prefix = ""
		if " " in main:
			parts = main.split(" ")
			prefix = "".join(map(lambda _x: _x[0], parts))
			if len(prefix) < 3 and len(parts[-1]) > 1:
				prefix += parts[-1][1:4 - len(prefix)]
		else:
			prefix = main[0:3]
		prefix = prefix.upper()

		i = 1
		handle = "%s%%d-%s" % (prefix, clazz.handleSuffix)
		while True:
			try:
				prefix
				clazz.objects.get(handle=handle % i)
				i += 1
			except clazz.DoesNotExist:
				break

		return handle % i

	def getNoDeleteReasons(self):
		raise NotImplementedError()

	def canBeDeleted(self):
		return not bool(self.getNoDeleteReasons())

	def handleAuto(self, name=None):
		if self.handle == "AUTO":
			self.handle = self.genHandle(name)


class Maintainer(WhoisObject):
	handleSuffix = "MNT"

	auth = models.ManyToManyField(User)
	handle = models.SlugField(max_length=32, unique=True, verbose_name='handle', validators=[HandleValidatorWithSuffix('MNT')], help_text="Must end with -MNT, eg FOO3-MNT")
	description = models.CharField(max_length=64, blank=True, help_text="Short description what this maintainer is for")

	admin_c = models.ManyToManyField("Contact")

	# autoInclude = models.BooleanField(default=True)

	def get_absolute_url(self):
		return reverse("whoisdb:mnt-detail", kwargs={"handle": self.handle})

	def getNoDeleteReasons(self):
		reasons = []

		mntables = [Contact, ASBlock, ASNumber, InetNum]
		for mntable in mntables:
			candidates = mntable.objects.filter(mnt_by=self).annotate(mntCount=models.Count('mnt_by')).filter(mntCount__lte=1)
			for candidate in candidates:
				reasons.append("Object %s would have no maintainers left." % candidate.handle)

		return reasons


class MntdObject(WhoisObject):
	class Meta:
		abstract = True

	mnt_by = models.ManyToManyField(Maintainer)


class Contact(MntdObject):
	handleSuffix = "DN"
	TYPE_PERSON = 'PERSON'
	TYPE_ROLE = 'ROLE'
	TYPE = (('person', TYPE_PERSON), ('role', TYPE_ROLE))
	TYPE = (('person', TYPE_PERSON),)

	name = models.CharField(max_length=128)
	type = models.CharField(max_length=10, choices=TYPE)

	def get_absolute_url(self):
		return reverse("whoisdb:contact-detail", kwargs={"handle": self.handle})

	def getNoDeleteReasons(self):
		reasons = []

		contactables = [Maintainer]
		for contactable in contactables:
			candidates = contactable.objects.filter(admin_c=self).annotate(contactCount=models.Count('admin_c')).filter(contactCount__lte=1)
			for candidate in candidates:
				reasons.append("Object %s would have no contact left." % candidate.handle)

		return reasons


class ASBlock(MntdObject):
	handleSuffix = "ASB"

	parent_block = models.ForeignKey("ASBlock", models.CASCADE, null=True, blank=True, default=None)
	description = models.CharField(max_length=64, blank=True)

	mnt_lower = models.ManyToManyField(Maintainer, related_name='lower_asblock_set', blank=True)


class ASNumber(MntdObject):
	handleSuffix = "AS"

	number = models.PositiveIntegerField(unique=True, db_index=True)
	volatile = models.BooleanField(default=False)
	asblock = models.ForeignKey(ASBlock, models.CASCADE)
	description = models.CharField(max_length=64, blank=True)

	mnt_lower = models.ManyToManyField(Maintainer, related_name='lower_asnumber_set', blank=True)


class InetNum(MntdObject):
	handleSuffix = "NET"

	IPv4 = "ipv4"
	IPv6 = "ipv6"

	PROTO = ((IPv4, 'IPv4'), (IPv6, 'IPv6'))
	protocol = models.CharField(max_length=4, choices=PROTO)
	address = models.GenericIPAddressField(db_index=True)
	netmask = models.PositiveIntegerField()
	parent_range = models.ForeignKey("InetNum", models.CASCADE, null=True, blank=True, default=None)
	name = models.CharField(max_length=64)
	description = models.CharField(max_length=64, blank=True)

	mnt_lower = models.ManyToManyField(Maintainer, related_name='lower_inetnum_set', blank=True)

	def getNetwork(self):
		return ipaddress.ip_network("%s/%s" % (self.address, self.netmask))

	def get_absolute_url(self):
		return reverse("whoisdb:inetnum-detail", kwargs={"handle": self.handle})

	def getNoDeleteReasons(self):
		reasons = []
		if self.inetnum_set.all().count() > 0:
			reasons.append("The following networks depend on this network: %s" % ", ".join(map(lambda _x: _x.handle, self.inetnum_set.all())))

		return reasons