#from django.shortcuts import render
from django.http import JsonResponse
from django.core.exceptions import ValidationError
from django.contrib.auth.views import login_required
from django.db.models import Q

from whoisdb.models import ASBlock, ASNumber, InetNum
from domains.models import Domain, ReverseZone
from dnmgmt.settings import TLD_NAMESERVERS
from .dnshelper import checkDomain as helperCheckDomain

import ipaddress


@login_required
def asblockFreeAS(request):

	ret = {
		"success": False,
		"errorMsg": None,
		"number": -1,
	}

	try:
		blockName = request.GET.get('block', None)
		if not blockName:
			raise ValidationError("No block given")

		try:
			mnts = request.user.maintainer_set.all()
			block = ASBlock.objects.filter(mnt_by__in=mnts).distinct().get(handle=blockName)
			if block.asblock_set.count() > 0:
				raise ValidationError("AS Block already has sub AS Blocks")
			if block.asnumber_set.count() > 0:
				num = block.asnumber_set.order_by("-number")[0].number + 1
				if num > block.asEnd:
					num = None
					for n in range(block.asBegin, block.asEnd + 1):
						try:
							ASNumber.objects.get(number=n)
						except ASNumber.DoesNotExist:
							num = n
							break
					if not num:
						raise ValidationError("No free AS Number in block")
				ret["number"] = num
			else:
				ret["number"] = block.asBegin
		except ASBlock.DoesNotExist:
			raise ValidationError("Could not get AS Block")

		ret["success"] = True
	except ValidationError as e:
		ret["errorMsg"] = e.message
	return JsonResponse(ret)


@login_required
def freeSubnet(request):

	ret = {
		"success": False,
		"errorMsg": None,
		"network": None,
	}

	try:
		parentRangeName = request.GET.get('parentRange', None)
		if not parentRangeName:
			raise ValidationError("No subnet given")

		parentRange = None
		try:
			mnts = request.user.maintainer_set.all()
			parentRange = InetNum.objects.filter(mnt_by__in=mnts).distinct().get(handle=parentRangeName)
		except InetNum.DoesNotExist:
			raise ValidationError("Parent range does not exist / is not maintained by you")

		prefixLen = 0
		try:
			prefixLen = request.GET.get("prefixLen", None)
			if not prefixLen:
				if parentRange.protocol == InetNum.IPv4:
					prefixLen = 27
				else:
					prefixLen = 60
			prefixLen = int(prefixLen)

			if prefixLen < 8 or \
				(parentRange.protocol == InetNum.IPv4 and prefixLen > 32) or \
				(parentRange.protocol == InetNum.IPv6 and prefixLen > 128):
				raise ValidationError("Given prefix length is out of range")
		except ValueError:
			raise ValidationError("PrefixLen is not a number")

		usableNet = None
		# FIXME: use first biggest usable netblock...
		#biggestNet = parentRange.inetnum_set.order_by("-address")
		#if biggestNet
		#	candidateNet =
		#	and (biggestNet.getNetwork().broadcast_address.:

		# try using next network in range
		# ordering does not work, as order_by sorts alphabetically
		# ==> the set is short, we can iterate through all. no sense in unpacking the SQL magic
		#biggestNets = parentRange.inetnum_set.order_by("-address")
		biggestNet = None
		for ipRange in parentRange.inetnum_set.all():
			if not biggestNet or ipRange.getNetwork() > biggestNet:
				biggestNet = ipRange.getNetwork()

		if biggestNet:
			candidateNet = ipaddress.ip_network("%s/%s" % (biggestNet.broadcast_address + 1, biggestNet.prefixlen))
			print("biggest net", biggestNet, "candidate", candidateNet)
			if candidateNet.network_address in parentRange.getNetwork():
				usableNet = candidateNet

		# check if there are still networks left in range
		if not usableNet:
			# search for free network
			nets = list(parentRange.getNetwork().subnets())
			for subRange in parentRange.inetnum_set.all():
				newNet = None
				for net in nets:
					if subRange.getNetwork().network_address in net:
						newNet = net
				if not newNet:
					# critical error, we want a 500 here
					raise ValueError("Subnet not in range")

				nets.remove(newNet)
				nets.extend(newNet.address_exclude(subRange.getNetwork()))

			nets = sorted(nets)
			for net in nets:
				if net.prefixlen <= prefixLen:
					usableNet = net
					break

		if not usableNet:
			raise ValidationError("No space left in given range")

		ret["network"] = "%s/%s" % (usableNet.network_address, prefixLen)
		ret["success"] = True
	except ValidationError as e:
		ret["errorMsg"] = e.message

	return JsonResponse(ret)


@login_required
def getSubnet(request):

	ret = {
		"success": False,
		"errorMsg": None,
		"network": None,
	}

	try:
		netName = request.GET.get('net', None)
		mnts = request.user.maintainer_set.all()
		nets = InetNum.objects.filter(Q(mnt_by__in=mnts) | Q(mnt_lower__in=mnts)).distinct()
		net = nets.get(handle=netName)

		ret["success"] = True
		ret["network"] = net.prefix()
	except InetNum.DoesNotExist:
		ret["errorMsg"] = "Chosen network does not exist"

	return JsonResponse(ret)


@login_required
def checkDomain(request):
	ret = {
		"success": False,
		"errorMsg": None,
		"domain": None,
		"result": None,
	}

	try:
		domainName = Domain.fixName(request.GET.get('domain', ''))
		domain = Domain.objects.get(name=domainName)
		if not domain.canEdit(request.user):
			raise Domain.DoesNotExist()

		ret["success"] = True
		ret["domain"] = domain.name
		# FIXME: change this if we ever have more than one...
		ret["result"] = helperCheckDomain(domain.name, TLD_NAMESERVERS[0], domain.nameservers.all())
	except Domain.DoesNotExist:
		ret["errorMsg"] = "Domain does not exist"

	return JsonResponse(ret)


@login_required
def checkRzone(request):
	ret = {
		"success": False,
		"errorMsg": None,
		"domain": None,
		"result": None,
	}

	try:
		rzonePk = ReverseZone.fixName(request.GET.get('rzone', ''))
		rzone = ReverseZone.objects.get(pk=rzonePk)
		if not rzone.canEdit(request.user):
			raise ReverseZone.DoesNotExist()

		ret["success"] = True
		# FIXME: change this if we ever have more than one...
		ret["result"] = helperCheckDomain(rzone.name, TLD_NAMESERVERS[0], rzone.nameservers.all())
	except Domain.DoesNotExist:
		ret["errorMsg"] = "ReverseZone does not exist"

	return JsonResponse(ret)