# This file is part of dnmgmt, a number resource management system
# Licensed under GNU General Public License v3 or later
# Written by Sebastian Lohff (seba@someserver.de)

from django.db import models
from django.db.models import Q
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 __init__(self, *args, **kwargs):
    #    super(WhoisObject, self).__init__(*args, **kwargs)

    #    if getattr(self, "handle"):
    #        field = self._meta.get_field("handle")
    #        if HandleValidatorWithSuffix not in map(type, field.validators):
    #            print(self.handle, "NOOOOT")
    #            field.validators.append(HandleValidatorWithSuffix(self.handleSuffix))
    #        else:
    #            print(self.handle, list(map(type, field.validators)))

    def getPK(self):
        return self.handle

    def __str__(self):
        return self.handle

    def getAppName(self):
        return "whoisdb"

    def getClassName(self):
        return self._meta.object_name

    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("Delete reason checking is not implemented for this model")

    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", verbose_name="Administrative Contact")

    rir = models.BooleanField(default=False)
    lir = models.BooleanField(default=False)

    # autoInclude = models.BooleanField(default=True)

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

    def getNoDeleteReasons(self):
        reasons = []

        # FIXME: Tempfix for circular dependency problem
        import domains.models

        mntables = [Contact, ASBlock, ASNumber, InetNum, domains.models.Domain, domains.models.Nameserver]
        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

    def canEdit(self, user):
        return user in self.auth.all()


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

    mnt_by = models.ManyToManyField(Maintainer, help_text="You can select multiple maintainers here")

    def canEdit(self, user):
        if not hasattr(user, "maintainer_set"):
            return False

        mnts = user.maintainer_set.all()
        objmnts = self.mnt_by.all()
        if hasattr(self, "mnt_lower"):
            objmnts |= self.mnt_lower.all()

        for objmnt in objmnts:
            if objmnt in mnts:
                return True
        return False

    @classmethod
    def getMntQueryset(clazz, mnts, instance, attr=None):
        mntQ = Q(mnt_by__in=mnts)
        if hasattr(clazz, "mnt_lower"):
            mntQ |= Q(mnt_lower__in=mnts)

        qs = clazz.objects.filter(mntQ)
        if attr and instance and instance.pk:
            if type(instance._meta.get_field(attr)) == models.ManyToManyField:
                qs |= getattr(instance, attr).all()
            elif getattr(instance, attr) is not None:
                qs |= clazz.objects.filter(pk=getattr(instance, attr).pk)

        return qs.distinct()


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, default=TYPE_PERSON)

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

    def getNoDeleteReasons(self):
        reasons = []

        contactables = [Maintainer, ASBlock, ASNumber, InetNum]
        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)
    name = models.CharField(max_length=32)
    asBegin = models.PositiveIntegerField()
    asEnd = models.PositiveIntegerField()
    description = models.CharField(max_length=64, blank=True)
    admin_c = models.ManyToManyField("Contact")

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

    def contains(self, block):
        return self.asBegin <= block.asBegin <= self.asEnd and self.asBegin <= block.asEnd <= self.asEnd

    def getResource(self):
        return "%s - %s" % (self.asBegin, self.asEnd)

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

    def getNoDeleteReasons(self):
        reasons = []

        if self.asblock_set.count() > 0:
            reasons.append("The AS block is referenced by the following other blocks: %s" % (", ".join(map(lambda _x: _x.handle, self.asblock_set.all()))))

        if self.asnumber_set.count() > 0:
            reasons.append("The AS block is referenced by the following as numbers: %s" % (", ".join(map(lambda _x: _x.handle, self.asnumber_set.all()))))

        return reasons


class ASNumber(MntdObject):
    handleSuffix = "AS"

    number = models.PositiveIntegerField(unique=True, db_index=True)
    volatile = models.BooleanField(default=False, help_text="Check if this AS is not going to be online 24/7 (for example on a laptop)")
    asblock = models.ForeignKey(ASBlock, models.CASCADE)
    name = models.CharField(max_length=32)
    description = models.CharField(max_length=64, blank=True)
    admin_c = models.ManyToManyField("Contact")

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

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

    def getNoDeleteReasons(self):
        reasons = []

        return reasons

    def getResource(self):
        return str(self.number)


class InetNum(MntdObject):
    class Meta:
        unique_together = (
            ("address", "netmask"),
        )

    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)
    origin_as = models.ManyToManyField(ASNumber, blank=True)
    admin_c = models.ManyToManyField("Contact")

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

    def getResource(self):
        return self.prefix()

    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("whoisdb:handle-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