from django.db import models
from django.contrib.gis.db import models as geo_models
from django.db.models import Q
from django.core.validators import MaxValueValidator
from django.utils import timezone
from django.contrib.auth.models import Group
from django.contrib.contenttypes.fields import GenericRelation
from django.core.exceptions import ValidationError
from django.urls import reverse
from django.utils import timezone
from django.core.exceptions import PermissionDenied
from django.core.validators import RegexValidator

from djadhere.utils import get_active_filter, is_overlapping
from adhesions.models import Adhesion
from banking.models import Payment


class IPPrefix(models.Model):
    prefix = models.CharField(max_length=128)

    def __str__(self):
        return self.prefix


class IPResourceManager(models.Manager):
    def get_queryset(self):
        qs = super().get_queryset()
        # On rajoute une super annotation « in_use » pour savoir si l’IP est dispo ou non :-)
        query = Q(resource=models.OuterRef('pk')) & get_active_filter()
        qs = qs.annotate(
                    in_use_by_service=models.Exists(
                        ServiceAllocation.objects.filter(query)
                    ),
                    in_use_by_antenna=models.Exists(
                        AntennaAllocation.objects.filter(query)
                    ),
                    in_use=models.ExpressionWrapper(
                        models.F('in_use_by_service') + models.F('in_use_by_antenna'),
                        output_field=models.BooleanField()
                    )
        )
        return qs


class IPResource(models.Model):
    CATEGORIES = (
        (0, 'IP Public'),
        (1, 'IP Antenne'),
    )

    ip = models.GenericIPAddressField(verbose_name='IP', primary_key=True)
    prefixes = models.ManyToManyField(IPPrefix, verbose_name='préfixes')
    reserved = models.BooleanField(default=False, verbose_name='réservée')
    category = models.IntegerField(choices=CATEGORIES, verbose_name='catégorie')
    notes = models.TextField(blank=True, default='')

    objects = IPResourceManager()

    @property
    def allocations(self):
        if self.category == 0:
            return self.service_allocations
        if self.category == 1:
            return self.antenna_allocations

    class Meta:
        ordering = ['ip']
        verbose_name = 'IP'
        verbose_name_plural = 'IP'

    def __str__(self):
        return str(self.ip)


class ServiceType(models.Model):
    name = models.CharField(max_length=64, verbose_name='Nom', unique=True)

    class Meta:
        ordering = ['name']
        verbose_name = 'type de service'
        verbose_name_plural = 'types de service'

    def __str__(self):
        return self.name


class Service(models.Model):
    adhesion = models.ForeignKey(Adhesion, verbose_name='Adhérent', related_name='services')
    service_type = models.ForeignKey(ServiceType, related_name='services',
                                     verbose_name='Type de service')
    label = models.CharField(blank=True, default='', max_length=128)
    notes = models.TextField(blank=True, default='')
    active = models.BooleanField(default=True, verbose_name='actif')
    created = models.DateTimeField(auto_now_add=True)
    contributions = GenericRelation(Payment,
                                   content_type_field='reason_type',
                                   object_id_field='reason_id',
                                   related_query_name='service')

    @property
    def contribution(self):
        try:
            return self.contributions.exclude(period=0).get(get_active_filter())
        except Payment.DoesNotExist:
            return None
        # MultipleObjectsReturned non catché volontairement, cf remarque adhesions.Adhesion.contribution

    def clean(self):
        super().clean()
        # Vérification de l’unicité par type de service du label
        if self.label != '' and Service.objects.exclude(pk=self.pk).filter(service_type=self.service_type, label=self.label):
            raise ValidationError("Un service du même type existe déjà avec ce label.")

    def __str__(self):
        s = str(self.service_type)
        if self.label:
            s += ' ' + self.label
        return s


class Antenna(models.Model):
    position = geo_models.PointField(null=True)
    mac = models.CharField(
            blank=True,
            default='',
            max_length=17,
            validators=[
                RegexValidator(r'^([0-9a-fA-F]{2}([:-]?|$)){6}$'),
            ])
    notes = models.TextField(blank=True)

    class Meta:
        verbose_name = 'antenne'

    def __str__(self):
        return 'Antenne %d' % self.pk


class Route(models.Model):
    name = models.CharField(max_length=64)

    def __str__(self):
        return self.name


class Allocation(models.Model):
    start = models.DateTimeField(verbose_name='Début de la période d’allocation', default=timezone.now)
    end = models.DateTimeField(null=True, blank=True, verbose_name='Fin de la période d’allocation')
    notes = models.TextField(blank=True, default='')

    @property
    def active(self):
        now = timezone.now()
        return self.start <= now and (self.end is None or self.end >= now)

    def clean(self):
        super().clean()
        # Vérification de la cohérence des champs start et end
        if self.end and self.start > self.end:
            raise ValidationError("La date de début de l’allocation doit être antérieur "
                                  "à la date de fin de l’allocation.")
        if self.resource_id:
            if self.resource.reserved:
                raise ValidationError("L’IP sélectionnée est réservée")
            # Vérification de l’abscence de chevauchement de la période d’allocation
            allocations = type(self).objects.filter(resource__pk=self.resource.pk)
            if is_overlapping(self, allocations):
                raise ValidationError("La période d’allocation de cette ressource chevauche "
                                        "avec une période d’allocation précédente.")

    class Meta:
        abstract = True
        ordering = ['-start']

    def __str__(self):
        return str(self.resource)


class ServiceAllocation(Allocation):
    resource = models.ForeignKey(IPResource, verbose_name='Ressource', related_name='service_allocations',
                        related_query_name='service_allocation', limit_choices_to={'category': 0})
    service = models.ForeignKey(Service, related_name='allocations', related_query_name='allocation')
    route = models.ForeignKey(Route, verbose_name='Route', related_name='services', related_query_name='allocation')

    class Meta:
        verbose_name = 'allocation'
        verbose_name_plural = 'allocations'


class AntennaAllocation(Allocation):
    resource = models.ForeignKey(IPResource, verbose_name='Ressource', related_name='antenna_allocations',
                        related_query_name='antenna_allocation', limit_choices_to={'category': 1})
    antenna = models.ForeignKey(Antenna, related_name='allocations', related_query_name='allocation')

    class Meta:
        verbose_name = 'allocation'
        verbose_name_plural = 'allocations'