from collections import OrderedDict

from django.conf import settings
from django.db.models import Count, F
from django.http import HttpResponse, HttpResponseForbidden
from django.shortcuts import get_object_or_404
from drf_yasg import openapi
from drf_yasg.openapi import Parameter
from drf_yasg.utils import swagger_auto_schema
from rest_framework.decorators import action
from rest_framework.mixins import ListModelMixin
from rest_framework.response import Response
from rest_framework.viewsets import GenericViewSet, ViewSet

from circuits.models import Circuit
from dcim import filters
from dcim.models import (Cable, ConsolePort, ConsolePortTemplate, ConsoleServerPort, ConsoleServerPortTemplate, Device,
                         DeviceBay, DeviceBayTemplate, DeviceRole, DeviceType, FrontPort, FrontPortTemplate, Interface,
                         InterfaceTemplate, InventoryItem, Manufacturer, Platform, PowerFeed, PowerOutlet,
                         PowerOutletTemplate, PowerPanel, PowerPort, PowerPortTemplate, Rack, RackGroup,
                         RackReservation, RackRole, RearPort, RearPortTemplate, Region, Site, VirtualChassis)
from extras.api.serializers import RenderedGraphSerializer
from extras.api.views import CustomFieldModelViewSet
from extras.models import Graph
from ipam.models import Prefix, VLAN
from utilities.api import (IsAuthenticatedOrLoginNotRequired, ModelViewSet, ServiceUnavailable,
                           get_serializer_for_model)
from utilities.utils import get_subquery
from virtualization.models import VirtualMachine
from . import serializers
from .exceptions import MissingFilterException


# Mixins

class CableTraceMixin(object):

    @action(detail=True, url_path='trace')
    def trace(self, request, pk):
        """
        Trace a complete cable path and return each segment as a three-tuple of (termination, cable, termination).
        """
        obj = get_object_or_404(self.queryset.model, pk=pk)

        # Initialize the path array
        path = []

        for near_end, cable, far_end in obj.trace()[0]:

            # Serialize each object
            serializer_a = get_serializer_for_model(near_end, prefix='Nested')
            x = serializer_a(near_end, context={
                'request': request
            }).data
            if cable is not None:
                y = serializers.TracedCableSerializer(cable, context={
                    'request': request
                }).data
            else:
                y = None
            if far_end is not None:
                serializer_b = get_serializer_for_model(far_end, prefix='Nested')
                z = serializer_b(far_end, context={
                    'request': request
                }).data
            else:
                z = None

            path.append((x, y, z))

        return Response(path)


#
# Regions
#

class RegionViewSet(ModelViewSet):
    queryset = Region.objects.annotate(
        site_count=Count('sites')
    )
    serializer_class = serializers.RegionSerializer
    filterset_class = filters.RegionFilterSet


#
# Sites
#

class SiteViewSet(CustomFieldModelViewSet):
    queryset = Site.objects.prefetch_related(
        'region', 'tenant', 'tags'
    ).annotate(
        device_count=get_subquery(Device, 'site'),
        rack_count=get_subquery(Rack, 'site'),
        prefix_count=get_subquery(Prefix, 'site'),
        vlan_count=get_subquery(VLAN, 'site'),
        circuit_count=get_subquery(Circuit, 'terminations__site'),
        virtualmachine_count=get_subquery(VirtualMachine, 'cluster__site'),
    )
    serializer_class = serializers.SiteSerializer
    filterset_class = filters.SiteFilterSet

    @action(detail=True)
    def graphs(self, request, pk):
        """
        A convenience method for rendering graphs for a particular site.
        """
        site = get_object_or_404(Site, pk=pk)
        queryset = Graph.objects.filter(type__model='site')
        serializer = RenderedGraphSerializer(queryset, many=True, context={
            'graphed_object': site
        })
        return Response(serializer.data)


#
# Rack groups
#

class RackGroupViewSet(ModelViewSet):
    queryset = RackGroup.objects.prefetch_related('site').annotate(
        rack_count=Count('racks')
    )
    serializer_class = serializers.RackGroupSerializer
    filterset_class = filters.RackGroupFilterSet


#
# Rack roles
#

class RackRoleViewSet(ModelViewSet):
    queryset = RackRole.objects.annotate(
        rack_count=Count('racks')
    )
    serializer_class = serializers.RackRoleSerializer
    filterset_class = filters.RackRoleFilterSet


#
# Racks
#

class RackViewSet(CustomFieldModelViewSet):
    queryset = Rack.objects.prefetch_related(
        'site', 'group__site', 'role', 'tenant', 'tags'
    ).annotate(
        device_count=get_subquery(Device, 'rack'),
        powerfeed_count=get_subquery(PowerFeed, 'rack')
    )
    serializer_class = serializers.RackSerializer
    filterset_class = filters.RackFilterSet

    @swagger_auto_schema(
        responses={
            200: serializers.RackUnitSerializer(many=True)
        },
        query_serializer=serializers.RackElevationDetailFilterSerializer
    )
    @action(detail=True)
    def elevation(self, request, pk=None):
        """
        Rack elevation representing the list of rack units. Also supports rendering the elevation as an SVG.
        """
        rack = get_object_or_404(Rack, pk=pk)
        serializer = serializers.RackElevationDetailFilterSerializer(data=request.GET)
        if not serializer.is_valid():
            return Response(serializer.errors, 400)
        data = serializer.validated_data

        if data['render'] == 'svg':
            # Render and return the elevation as an SVG drawing with the correct content type
            drawing = rack.get_elevation_svg(
                face=data['face'],
                unit_width=data['unit_width'],
                unit_height=data['unit_height'],
                legend_width=data['legend_width'],
                include_images=data['include_images'],
                base_url=request.build_absolute_uri('/')
            )
            return HttpResponse(drawing.tostring(), content_type='image/svg+xml')

        else:
            # Return a JSON representation of the rack units in the elevation
            elevation = rack.get_rack_units(
                face=data['face'],
                exclude=data['exclude'],
                expand_devices=data['expand_devices']
            )

            # Enable filtering rack units by ID
            q = data['q']
            if q:
                elevation = [u for u in elevation if q in str(u['id']) or q in str(u['name'])]

            page = self.paginate_queryset(elevation)
            if page is not None:
                rack_units = serializers.RackUnitSerializer(page, many=True, context={
                    'request': request
                })
                return self.get_paginated_response(rack_units.data)


#
# Rack reservations
#

class RackReservationViewSet(ModelViewSet):
    queryset = RackReservation.objects.prefetch_related('rack', 'user', 'tenant')
    serializer_class = serializers.RackReservationSerializer
    filterset_class = filters.RackReservationFilterSet

    # Assign user from request
    def perform_create(self, serializer):
        serializer.save(user=self.request.user)


#
# Manufacturers
#

class ManufacturerViewSet(ModelViewSet):
    queryset = Manufacturer.objects.annotate(
        devicetype_count=get_subquery(DeviceType, 'manufacturer'),
        inventoryitem_count=get_subquery(InventoryItem, 'manufacturer'),
        platform_count=get_subquery(Platform, 'manufacturer')
    )
    serializer_class = serializers.ManufacturerSerializer
    filterset_class = filters.ManufacturerFilterSet


#
# Device types
#

class DeviceTypeViewSet(CustomFieldModelViewSet):
    queryset = DeviceType.objects.prefetch_related('manufacturer').prefetch_related('tags').annotate(
        device_count=Count('instances')
    )
    serializer_class = serializers.DeviceTypeSerializer
    filterset_class = filters.DeviceTypeFilterSet


#
# Device type components
#

class ConsolePortTemplateViewSet(ModelViewSet):
    queryset = ConsolePortTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.ConsolePortTemplateSerializer
    filterset_class = filters.ConsolePortTemplateFilterSet


class ConsoleServerPortTemplateViewSet(ModelViewSet):
    queryset = ConsoleServerPortTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.ConsoleServerPortTemplateSerializer
    filterset_class = filters.ConsoleServerPortTemplateFilterSet


class PowerPortTemplateViewSet(ModelViewSet):
    queryset = PowerPortTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.PowerPortTemplateSerializer
    filterset_class = filters.PowerPortTemplateFilterSet


class PowerOutletTemplateViewSet(ModelViewSet):
    queryset = PowerOutletTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.PowerOutletTemplateSerializer
    filterset_class = filters.PowerOutletTemplateFilterSet


class InterfaceTemplateViewSet(ModelViewSet):
    queryset = InterfaceTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.InterfaceTemplateSerializer
    filterset_class = filters.InterfaceTemplateFilterSet


class FrontPortTemplateViewSet(ModelViewSet):
    queryset = FrontPortTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.FrontPortTemplateSerializer
    filterset_class = filters.FrontPortTemplateFilterSet


class RearPortTemplateViewSet(ModelViewSet):
    queryset = RearPortTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.RearPortTemplateSerializer
    filterset_class = filters.RearPortTemplateFilterSet


class DeviceBayTemplateViewSet(ModelViewSet):
    queryset = DeviceBayTemplate.objects.prefetch_related('device_type__manufacturer')
    serializer_class = serializers.DeviceBayTemplateSerializer
    filterset_class = filters.DeviceBayTemplateFilterSet


#
# Device roles
#

class DeviceRoleViewSet(ModelViewSet):
    queryset = DeviceRole.objects.all()
    #     annotate(
    #     device_count=Count('devices'),
    #     virtualmachine_count=Count('virtual_machines')
    # )
    serializer_class = serializers.DeviceRoleSerializer
    filterset_class = filters.DeviceRoleFilterSet


#
# Platforms
#

class PlatformViewSet(ModelViewSet):
    queryset = Platform.objects.annotate(
        device_count=get_subquery(Device, 'platform'),
        virtualmachine_count=get_subquery(VirtualMachine, 'platform')
    )
    serializer_class = serializers.PlatformSerializer
    filterset_class = filters.PlatformFilterSet


#
# Devices
#

class DeviceViewSet(CustomFieldModelViewSet):
    queryset = Device.objects.prefetch_related(
        'device_type__manufacturer', 'device_role', 'tenant', 'platform', 'site', 'rack', 'parent_bay',
        'virtual_chassis__master', 'primary_ip4__nat_outside', 'primary_ip6__nat_outside', 'tags',
    )
    filterset_class = filters.DeviceFilterSet

    def get_serializer_class(self):
        """
        Select the specific serializer based on the request context.

        If the `brief` query param equates to True, return the NestedDeviceSerializer

        If the `exclude` query param includes `config_context` as a value, return the DeviceSerializer

        Else, return the DeviceWithConfigContextSerializer
        """

        request = self.get_serializer_context()['request']
        if request.query_params.get('brief', False):
            return serializers.NestedDeviceSerializer

        elif 'config_context' in request.query_params.get('exclude', []):
            return serializers.DeviceSerializer

        return serializers.DeviceWithConfigContextSerializer

    @action(detail=True)
    def graphs(self, request, pk):
        """
        A convenience method for rendering graphs for a particular Device.
        """
        device = get_object_or_404(Device, pk=pk)
        queryset = Graph.objects.filter(type__model='device')
        serializer = RenderedGraphSerializer(queryset, many=True, context={
            'graphed_object': device
        })

        return Response(serializer.data)

    @swagger_auto_schema(
        manual_parameters=[
            Parameter(
                name='method',
                in_='query',
                required=True,
                type=openapi.TYPE_STRING
            )
        ],
        responses={
            '200': serializers.DeviceNAPALMSerializer
        }
    )
    @action(detail=True, url_path='napalm')
    def napalm(self, request, pk):
        """
        Execute a NAPALM method on a Device
        """
        device = get_object_or_404(Device, pk=pk)
        if not device.primary_ip:
            raise ServiceUnavailable("This device does not have a primary IP address configured.")
        if device.platform is None:
            raise ServiceUnavailable("No platform is configured for this device.")
        if not device.platform.napalm_driver:
            raise ServiceUnavailable("No NAPALM driver is configured for this device's platform ().".format(
                device.platform
            ))

        # Check that NAPALM is installed
        try:
            import napalm
            from napalm.base.exceptions import ModuleImportError
        except ImportError:
            raise ServiceUnavailable("NAPALM is not installed. Please see the documentation for instructions.")

        # Validate the configured driver
        try:
            driver = napalm.get_network_driver(device.platform.napalm_driver)
        except ModuleImportError:
            raise ServiceUnavailable("NAPALM driver for platform {} not found: {}.".format(
                device.platform, device.platform.napalm_driver
            ))

        # Verify user permission
        if not request.user.has_perm('dcim.napalm_read'):
            return HttpResponseForbidden()

        # Connect to the device
        napalm_methods = request.GET.getlist('method')
        response = OrderedDict([(m, None) for m in napalm_methods])
        ip_address = str(device.primary_ip.address.ip)
        username = settings.NAPALM_USERNAME
        password = settings.NAPALM_PASSWORD
        optional_args = settings.NAPALM_ARGS.copy()
        if device.platform.napalm_args is not None:
            optional_args.update(device.platform.napalm_args)

        # Update NAPALM parameters according to the request headers
        for header in request.headers:
            if header[:9].lower() != 'x-napalm-':
                continue

            key = header[9:]
            if key.lower() == 'username':
                username = request.headers[header]
            elif key.lower() == 'password':
                password = request.headers[header]
            elif key:
                optional_args[key.lower()] = request.headers[header]

        d = driver(
            hostname=ip_address,
            username=username,
            password=password,
            timeout=settings.NAPALM_TIMEOUT,
            optional_args=optional_args
        )
        try:
            d.open()
        except Exception as e:
            raise ServiceUnavailable("Error connecting to the device at {}: {}".format(ip_address, e))

        # Validate and execute each specified NAPALM method
        for method in napalm_methods:
            if not hasattr(driver, method):
                response[method] = {
                    'error': 'Unknown NAPALM method'
                }
                continue
            if not method.startswith('get_'):
                response[method] = {
                    'error': 'Only get_* NAPALM methods are supported'
                }
                continue
            try:
                response[method] = getattr(d, method)()
            except NotImplementedError:
                response[method] = {
                    'error': 'Method {} not implemented for NAPALM driver {}'.format(method, driver)
                }
            except Exception as e:
                response[method] = {
                    'error': 'Method {} failed: {}'.format(method, e)
                }
        d.close()

        return Response(response)


#
# Device components
#

class ConsolePortViewSet(CableTraceMixin, ModelViewSet):
    queryset = ConsolePort.objects.prefetch_related('device', 'connected_endpoint__device', 'cable', 'tags')
    serializer_class = serializers.ConsolePortSerializer
    filterset_class = filters.ConsolePortFilterSet


class ConsoleServerPortViewSet(CableTraceMixin, ModelViewSet):
    queryset = ConsoleServerPort.objects.prefetch_related('device', 'connected_endpoint__device', 'cable', 'tags')
    serializer_class = serializers.ConsoleServerPortSerializer
    filterset_class = filters.ConsoleServerPortFilterSet


class PowerPortViewSet(CableTraceMixin, ModelViewSet):
    queryset = PowerPort.objects.prefetch_related(
        'device', '_connected_poweroutlet__device', '_connected_powerfeed', 'cable', 'tags'
    )
    serializer_class = serializers.PowerPortSerializer
    filterset_class = filters.PowerPortFilterSet


class PowerOutletViewSet(CableTraceMixin, ModelViewSet):
    queryset = PowerOutlet.objects.prefetch_related('device', 'connected_endpoint__device', 'cable', 'tags')
    serializer_class = serializers.PowerOutletSerializer
    filterset_class = filters.PowerOutletFilterSet


class InterfaceViewSet(CableTraceMixin, ModelViewSet):
    queryset = Interface.objects.prefetch_related(
        'device', '_connected_interface', '_connected_circuittermination', 'cable', 'ip_addresses', 'tags'
    ).filter(
        device__isnull=False
    )
    serializer_class = serializers.InterfaceSerializer
    filterset_class = filters.InterfaceFilterSet

    @action(detail=True)
    def graphs(self, request, pk):
        """
        A convenience method for rendering graphs for a particular interface.
        """
        interface = get_object_or_404(Interface, pk=pk)
        queryset = Graph.objects.filter(type__model='interface')
        serializer = RenderedGraphSerializer(queryset, many=True, context={
            'graphed_object': interface
        })
        return Response(serializer.data)


class FrontPortViewSet(CableTraceMixin, ModelViewSet):
    queryset = FrontPort.objects.prefetch_related('device__device_type__manufacturer', 'rear_port', 'cable', 'tags')
    serializer_class = serializers.FrontPortSerializer
    filterset_class = filters.FrontPortFilterSet


class RearPortViewSet(CableTraceMixin, ModelViewSet):
    queryset = RearPort.objects.prefetch_related('device__device_type__manufacturer', 'cable', 'tags')
    serializer_class = serializers.RearPortSerializer
    filterset_class = filters.RearPortFilterSet


class DeviceBayViewSet(ModelViewSet):
    queryset = DeviceBay.objects.prefetch_related('installed_device').prefetch_related('tags')
    serializer_class = serializers.DeviceBaySerializer
    filterset_class = filters.DeviceBayFilterSet


class InventoryItemViewSet(ModelViewSet):
    queryset = InventoryItem.objects.prefetch_related('device', 'manufacturer').prefetch_related('tags')
    serializer_class = serializers.InventoryItemSerializer
    filterset_class = filters.InventoryItemFilterSet


#
# Connections
#

class ConsoleConnectionViewSet(ListModelMixin, GenericViewSet):
    queryset = ConsolePort.objects.prefetch_related(
        'device', 'connected_endpoint__device'
    ).filter(
        connected_endpoint__isnull=False
    )
    serializer_class = serializers.ConsolePortSerializer
    filterset_class = filters.ConsoleConnectionFilterSet


class PowerConnectionViewSet(ListModelMixin, GenericViewSet):
    queryset = PowerPort.objects.prefetch_related(
        'device', 'connected_endpoint__device'
    ).filter(
        _connected_poweroutlet__isnull=False
    )
    serializer_class = serializers.PowerPortSerializer
    filterset_class = filters.PowerConnectionFilterSet


class InterfaceConnectionViewSet(ListModelMixin, GenericViewSet):
    queryset = Interface.objects.prefetch_related(
        'device', '_connected_interface__device'
    ).filter(
        # Avoid duplicate connections by only selecting the lower PK in a connected pair
        _connected_interface__isnull=False,
        pk__lt=F('_connected_interface')
    )
    serializer_class = serializers.InterfaceConnectionSerializer
    filterset_class = filters.InterfaceConnectionFilterSet


#
# Cables
#

class CableViewSet(ModelViewSet):
    queryset = Cable.objects.prefetch_related(
        'termination_a', 'termination_b'
    )
    serializer_class = serializers.CableSerializer
    filterset_class = filters.CableFilterSet


#
# Virtual chassis
#

class VirtualChassisViewSet(ModelViewSet):
    queryset = VirtualChassis.objects.prefetch_related('tags').annotate(
        member_count=Count('members')
    )
    serializer_class = serializers.VirtualChassisSerializer
    filterset_class = filters.VirtualChassisFilterSet


#
# Power panels
#

class PowerPanelViewSet(ModelViewSet):
    queryset = PowerPanel.objects.prefetch_related(
        'site', 'rack_group'
    ).annotate(
        powerfeed_count=Count('powerfeeds')
    )
    serializer_class = serializers.PowerPanelSerializer
    filterset_class = filters.PowerPanelFilterSet


#
# Power feeds
#

class PowerFeedViewSet(CustomFieldModelViewSet):
    queryset = PowerFeed.objects.prefetch_related('power_panel', 'rack', 'tags')
    serializer_class = serializers.PowerFeedSerializer
    filterset_class = filters.PowerFeedFilterSet


#
# Miscellaneous
#

class ConnectedDeviceViewSet(ViewSet):
    """
    This endpoint allows a user to determine what device (if any) is connected to a given peer device and peer
    interface. This is useful in a situation where a device boots with no configuration, but can detect its neighbors
    via a protocol such as LLDP. Two query parameters must be included in the request:

    * `peer_device`: The name of the peer device
    * `peer_interface`: The name of the peer interface
    """
    permission_classes = [IsAuthenticatedOrLoginNotRequired]
    _device_param = Parameter(
        name='peer_device',
        in_='query',
        description='The name of the peer device',
        required=True,
        type=openapi.TYPE_STRING
    )
    _interface_param = Parameter(
        name='peer_interface',
        in_='query',
        description='The name of the peer interface',
        required=True,
        type=openapi.TYPE_STRING
    )

    def get_view_name(self):
        return "Connected Device Locator"

    @swagger_auto_schema(
        manual_parameters=[_device_param, _interface_param],
        responses={
            '200': serializers.DeviceSerializer
        }
    )
    def list(self, request):

        peer_device_name = request.query_params.get(self._device_param.name)
        peer_interface_name = request.query_params.get(self._interface_param.name)

        if not peer_device_name or not peer_interface_name:
            raise MissingFilterException(detail='Request must include "peer_device" and "peer_interface" filters.')

        # Determine local interface from peer interface's connection
        peer_interface = get_object_or_404(Interface, device__name=peer_device_name, name=peer_interface_name)
        local_interface = peer_interface._connected_interface

        if local_interface is None:
            return Response()

        return Response(serializers.DeviceSerializer(local_interface.device, context={
            'request': request
        }).data)