from django import forms
from django.db.models import Case, When, IntegerField

from .models import Maintainer, Contact, InetNum, ASBlock, ASNumber

import re
import ipaddress


class WhoisObjectFormMixin(object):
	def __init__(self, user, *args, **kwargs):
		super(WhoisObjectFormMixin, self).__init__(*args, **kwargs)
		self._user = user

		instance = getattr(self, 'instance', None)
		if instance and instance.pk:
			self.fields['handle'].widget.attrs['readonly'] = True

		# only show users contacts and already present contacts
		if 'admin_c' in self.fields:
			self.fields['admin_c'].queryset = Contact.objects.filter(mnt_by__in=self._user.maintainer_set.all())
			if instance and instance.pk:
				self.fields['admin_c'].queryset |= instance.admin_c.all()

	def clean_handle(self):
		instance = getattr(self, 'instance', None)
		if instance and instance.pk:
			return instance.handle
		else:
			return self.cleaned_data['handle']

	def clean(self):
		cleaned_data = super(WhoisObjectFormMixin, self).clean()
		if cleaned_data.get("handle") == "AUTO" and not self.errors:
			cleaned_data['handle'] = self._meta.model.genGenericHandle(cleaned_data.get("name"))

		return cleaned_data


class MntFormMixin(object):
	protectedFields = []
	def __init__(self, lower=False, *args, **kwargs):
		super(MntFormMixin, self).__init__(*args, **kwargs)

		self._editLower = lower

		if self._editLower:
			for key in self.protectedFields:
				self.fields[key].disabled = True

		#self.fields["mnt_by"].widget.attrs["data-role"] = "tagsinput"
		instance = getattr(self, "instance", None)
		mntWhens = [When(auth=self._user, then=2)]
		if instance and instance.pk:
			mntWhens.append(When(handle__in=instance.mnt_by.all().values_list("handle"), then=1))
		mntQs = Maintainer.objects.annotate(card=Case(*mntWhens, default=0, output_field=IntegerField())).order_by("-card")
		self.fields["mnt_by"].queryset = mntQs

class MntForm(forms.ModelForm):
	class Meta:
		model = Maintainer
		fields = ['handle', 'description', 'admin_c']

	def __init__(self, user, *args, **kwargs):
		super(MntForm, self).__init__(*args, **kwargs)
		self._user = user
		if 'admin_c' in self.fields:
			self.fields['admin_c'].queryset = Contact.objects.filter(mnt_by=user.maintainer_set.all())


class MntInitialForm(MntForm):
	class Meta:
		model = Maintainer
		fields = ['handle', 'description']


class ContactForm(WhoisObjectFormMixin, forms.ModelForm):
	class Meta:
		model = Contact
		fields = ['handle', 'name', 'mnt_by']

	def __init__(self, *args, **kwargs):
		super(ContactForm, self).__init__(*args, **kwargs)

		self.fields['mnt_by'].queryset = Maintainer.objects.filter(auth=self._user)


class ContactInitialForm(ContactForm):
	class Meta:
		model = Contact
		fields = ['handle', 'name']


class InetNumForm(MntFormMixin, WhoisObjectFormMixin, forms.ModelForm):
	prefix = forms.CharField()
	protectedFields = ['handle', 'protocol', 'parent_range', 'mnt_by', 'prefix']

	class Meta:
		model = InetNum
		fields = ['handle', 'protocol', 'parent_range', 'prefix', 'name', 'description', 'mnt_by', 'mnt_lower']

	def __init__(self, *args, **kwargs):
		super(InetNumForm, self).__init__(*args, **kwargs)
		if 'admin_c' in self.fields:
			self.fields['admin_c'].queryset = Contact.objects.filter(mnt_by__in=self.user.maintainer_set.all())
			instance = getattr(self, "instance", None)
			if instance and instance.pk:
				self.fields['admin_c'].queryset |= instance.admin_c.all()

		if self._editLower:
			for key in self.protectedFields:
				self.fields[key].disabled = True
				self.fields[key].widget.attrs['readonly'] = False

	def clean_prefix(self):
		# make sure this is a subnet we're getting
		net = self.cleaned_data['prefix']
		if not re.match(r"[0-9:.]+/[0-9]+", net):
			raise forms.ValidationError("Address needs to be a subnet in the format of ip/cidr")
		try:
			net = ipaddress.ip_network(net)
		except ValueError as e:
			raise forms.ValidationError(str(e))

		return net

	def clean_parent_range(self):
		parent_range = self.cleaned_data.get('parent_range', None)
		
		# allow parent range to be unset for already present objects
		if not (self.instance and self.instance.pk) and not parent_range:
			raise forms.ValidationError("Parent range must be set")

	def clean(self):
		cleaned_data = super(InetNumForm, self).clean()

		if not self._editLower:
			if not self.errors:
				prefix = cleaned_data['prefix']
				parent = cleaned_data['parent_range']
				if parent:
					parentNet = parent.getNetwork()

					if cleaned_data['protocol'] != parent.protocol:
						raise forms.ValidationError("Protocol type for prefix must be same as parent network")

					# check if in parent block
					if prefix.network_address not in parentNet or prefix.prefixlen < parentNet.prefixlen:
						raise forms.ValidationError("Prefix must be inside parent network range")

					# check if parent block has net that overlaps with us
					for otherNet in parent.inetnum_set.all():
						if self.instance and self.instance.pk == otherNet.pk:
							continue

						if otherNet.getNetwork().overlaps(prefix):
							raise forms.ValidationError("The given prefix overlaps with network %s" % otherNet.handle)

				self.instance.address = str(prefix.network_address)
				self.instance.netmask = prefix.prefixlen

		return cleaned_data

class ASBlockForm(MntFormMixin, WhoisObjectFormMixin, forms.ModelForm):
	protectedFields = ['handle', 'parent_block', 'asBegin', 'asEnd', 'mnt_by']

	# FIXME: Filter blocks
	class Meta:
		model = ASBlock
		fields = ['handle', 'parent_block', 'asBegin', 'asEnd', 'name', 'description', 'mnt_by', 'mnt_lower']

	def __init__(self, *args, **kwargs):
		super(ASBlockForm, self).__init__(*args, **kwargs)

		if not self.instance or self.instance and self.instance and self.instance.parent_block:
			self.fields["parent_block"].required = True
		if self.instance and self.instance.pk:
			self.fields["parent_block"].disabled = True

	def clean(self):
		cleaned_data = super(ASBlockForm, self).clean()

		if not self.errors:
			asBegin = cleaned_data['asBegin']
			asEnd = cleaned_data['asEnd']
			parent = cleaned_data['parent_block']
			# check if somebody is already using this block
			
			# check if in range
			if asBegin > asEnd:
				raise forms.ValidationError("AS beginning must be smaller or equal to AS end")

			if parent:
				if parent.asnumber_set.count() > 0:
					raise forms.ValidationError("The parent AS block is already references by following AS number objects: %s" % (", ".join(map(lambda _x: _x.handle, parent.asnumber_set.all())),))


				# check if same range
				if not (asBegin >= parent.asBegin and asEnd <= parent.asEnd):
					raise forms.ValidationError("AS beginning and end must be inside the range of the parent AS block")

				if parent.asBegin == asBegin and parent.asEnd == asEnd:
					raise forms.ValidationError("The range of this block cannot be the same range AS the parent AS block")

				# check for overlap with other asblocks
				for block in parent.asblock_set.all():
					if self.instance and self.instance.pk and block.pk == self.instance.pk:
						continue

					if block.asBegin <= asBegin <= block.asEnd or block.asBegin <= asEnd <= block.asEnd or \
					   asBegin <= block.asBegin <= asEnd or asBegin <= block.asEnd <= asEnd:
					   raise forms.ValidationError("Block overlaps with block %s" % block.handle)


		return cleaned_data

class ASNumberForm(MntFormMixin, WhoisObjectFormMixin, forms.ModelForm):
	protectedFields = ['handle', 'asblock', 'number', 'mnt_by']

	class Meta:
		model = ASNumber
		fields = ['handle', 'asblock', 'number', 'volatile', 'name', 'description', 'mnt_by', 'mnt_lower', 'admin_c']

	def __init__(self, *args, **kwargs):
		super(ASNumberForm, self).__init__(*args, **kwargs)

		if not (self.instance and self.instance.pk):
			self.fields["asblock"].required = True
		else:
			self.fields["asblock"].disabled = True

	def clean(self):
		cleaned_data = super(ASNumberForm, self).clean()

		if not self.errors:
			number = cleaned_data['number']
			block = cleaned_data['asblock']

			# belongs to asblock?
			if number < block.asBegin or number > block.asEnd:
				raise forms.ValidationError("AS number is not inside AS block")

			# does an entry already exist?
			try:
				otherAS = ASNumber.objects.get(number=number)
				if not (self.instance and self.instance.pk and self.instance.pk == otherAS.pk):
					raise forms.ValidationError("This AS number is already represented by %s" % otherAS.handle)
			except ASNumber.DoesNotExist:
				pass

			# has already other asblock?
			if block.asblock_set.count() > 0:
				raise forms.ValidationError("The given AS block is already references by following sub AS blocks: %s" % (", ".join(map(lambda _x: _x.handle, block.asblock_set.all())),))