from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.mixins import PermissionRequiredMixin
from django.core.paginator import Paginator
from django.db.models import Q
from django.views.generic import TemplateView
from dcim.models import Location, Region, Site, SiteGroup
from ipam.models import Prefix
import netaddr

from .forms import NetworkOverviewFilterForm


def _descendant_ids(obj):
    """Return an object's ID plus nested-tree descendants across NetBox versions."""
    try:
        return list(obj.get_descendants(include_self=True).values_list("pk", flat=True))
    except (AttributeError, TypeError):
        ids = list(obj.get_descendants().values_list("pk", flat=True))
        return [obj.pk, *ids]


def _scope_query(model, ids):
    content_type = ContentType.objects.get_for_model(model)
    return Q(scope_type=content_type, scope_id__in=ids)


def apply_overview_filters(queryset, data):
    if q := data.get("q"):
        search = Q(description__icontains=q) | Q(comments__icontains=q)
        try:
            search |= Q(prefix__net_contains_or_equals=str(netaddr.IPNetwork(q)))
        except (netaddr.AddrFormatError, ValueError):
            pass
        queryset = queryset.filter(search)
    if tenant := data.get("tenant"):
        queryset = queryset.filter(tenant=tenant)
    if group := data.get("tenant_group"):
        queryset = queryset.filter(tenant__group_id__in=_descendant_ids(group))
    if location := data.get("location"):
        queryset = queryset.filter(_scope_query(Location, _descendant_ids(location)))
    if site := data.get("site"):
        location_ids = Location.objects.filter(site=site).values_list("pk", flat=True)
        queryset = queryset.filter(
            _scope_query(Site, [site.pk]) | _scope_query(Location, location_ids)
        )
    if site_group := data.get("site_group"):
        site_ids = Site.objects.filter(group_id__in=_descendant_ids(site_group)).values_list(
            "pk", flat=True
        )
        location_ids = Location.objects.filter(site_id__in=site_ids).values_list("pk", flat=True)
        queryset = queryset.filter(
            _scope_query(SiteGroup, _descendant_ids(site_group))
            | _scope_query(Site, site_ids)
            | _scope_query(Location, location_ids)
        )
    if region := data.get("organization"):
        region_ids = _descendant_ids(region)
        site_ids = Site.objects.filter(region_id__in=region_ids).values_list("pk", flat=True)
        location_ids = Location.objects.filter(site_id__in=site_ids).values_list("pk", flat=True)
        queryset = queryset.filter(
            _scope_query(Region, region_ids)
            | _scope_query(Site, site_ids)
            | _scope_query(Location, location_ids)
        )
    return queryset


class NetworkOverviewView(PermissionRequiredMixin, TemplateView):
    template_name = "netbox_better_ips/network_overview.html"
    permission_required = "ipam.view_prefix"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        form = NetworkOverviewFilterForm(self.request.GET or None)
        prefixes = Prefix.objects.restrict(self.request.user, "view").select_related(
            "vrf", "tenant", "scope_type"
        )
        if form.is_valid():
            prefixes = apply_overview_filters(prefixes, form.cleaned_data)
        prefixes = prefixes.order_by("prefix", "vrf")
        paginator = Paginator(prefixes, 50)
        context.update(
            {
                "filter_form": form,
                "page_obj": paginator.get_page(self.request.GET.get("page")),
                "total_count": prefixes.count(),
            }
        )
        return context