import logging

from django.apps import apps
from django.core.exceptions import ObjectDoesNotExist
from django.db import OperationalError, ProgrammingError
from netbox.plugins import get_plugin_config

from .rack_width import effective_width_positions

logger = logging.getLogger(__name__)

TOPOLOGY_RACK_ELEVATION_VIEW = "plugins:netbox_topology_views:rack_elevation"


def is_topology_rack_elevation_request(request):
    resolver_match = getattr(request, "resolver_match", None)
    return getattr(resolver_match, "view_name", None) == TOPOLOGY_RACK_ELEVATION_VIEW


def topology_rack_width_enabled(request):
    """Return whether the optional Topology Views rack integration applies."""
    return bool(
        is_topology_rack_elevation_request(request)
        and get_plugin_config("netbox_utilities", "topology_views_rack_width_enabled")
        and apps.is_installed("netbox_topology_views")
    )


def serialize_topology_placement(placement):
    return serialize_topology_width(
        placement.device,
        placement.width,
        placement.horizontal_position,
        source="stored",
    )


def serialize_topology_width(device, width, horizontal_position, *, source):
    width = int(width)
    horizontal_position = int(horizontal_position)
    return {
        "device_id": device.pk,
        "url": device.get_absolute_url(),
        "width": width,
        "horizontal_position": horizontal_position,
        "left_percent": round((horizontal_position - 1) / width * 100, 8),
        "width_percent": round(100 / width, 8),
        "width_source": source,
    }


def get_topology_rack_width_data(request):
    """Return permitted partial-width devices shown by Topology Views."""
    if not topology_rack_width_enabled(request):
        return None

    data = {"devices": [], "status": "ready", "schema_version": 3, "complete": False}
    if not request.GET:
        return data

    from dcim.models import Device, Rack

    try:
        racks = Rack.objects.restrict(request.user, "view")
        selected_racks = request.GET.getlist("rack_id")
        if selected_racks:
            racks = racks.filter(pk__in=selected_racks)
        else:
            selected_sites = request.GET.getlist("site_id")
            selected_locations = request.GET.getlist("location_id")
            if selected_sites:
                racks = racks.filter(site_id__in=selected_sites)
            if selected_locations:
                racks = racks.filter(location_id__in=selected_locations)

        devices = list(
            Device.objects.restrict(request.user, "view")
            .filter(
                rack_id__in=racks.values("pk"),
                position__gt=0,
                device_type__u_height__gt=0,
            )
            .select_related("device_type", "netbox_utilities_rack_placement")
            .order_by("rack_id", "face", "position", "pk")
        )
        widths = effective_width_positions(devices)
        data["devices"] = [
            serialize_topology_width(device, width, position, source=source)
            for device in devices
            for width, position, source in (widths[device.pk],)
            if width > 1
        ]
        data["complete"] = True
        return data
    except (
        AttributeError,
        ObjectDoesNotExist,
        OperationalError,
        ProgrammingError,
        TypeError,
        ValueError,
    ):
        # Keep NetBox usable while plugin migrations are being installed.
        logger.warning(
            "Could not load partial rack widths for NetBox Topology Views path %s; using its native rack layout",
            request.get_full_path(),
            exc_info=True,
        )
        data["status"] = "native-fallback"
        return data