from django.db.models import Count
from django_filters.rest_framework import DjangoFilterBackend
from rest_framework import filters, viewsets
from rest_framework.decorators import action
from rest_framework.response import Response

from commerce.models import (
    Cost,
    Product,
    ProductBinding,
    Sale,
    SaleLine,
    SourceSystem,
    StockSnapshot,
)
from commerce.services import get_product_metrics

from .permissions import CommerceAccessPermission
from .serializers import (
    CostSerializer,
    ProductBindingSerializer,
    ProductMetricsQuerySerializer,
    ProductSerializer,
    SaleSerializer,
    SaleLineSerializer,
    SourceSystemSerializer,
    StockSnapshotSerializer,
)


class SourceSystemViewSet(viewsets.ModelViewSet):
    queryset = SourceSystem.objects.all()
    serializer_class = SourceSystemSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [filters.SearchFilter, filters.OrderingFilter]
    search_fields = ["code", "name"]
    ordering_fields = ["code", "name", "created_at"]
    ordering = ["name"]


class ProductViewSet(viewsets.ModelViewSet):
    queryset = Product.objects.all()
    serializer_class = ProductSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [
        DjangoFilterBackend,
        filters.SearchFilter,
        filters.OrderingFilter,
    ]
    filterset_fields = ["kind", "is_active", "parent"]
    search_fields = ["sku", "name", "barcode", "bindings__external_sku"]
    ordering_fields = ["sku", "name", "created_at", "updated_at"]
    ordering = ["name", "sku"]

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .select_related("parent")
            .prefetch_related("bindings__source")
            .annotate(variants_count=Count("variants", distinct=True))
            .distinct()
        )

    @action(detail=True, methods=["get"])
    def analytics(self, request, pk=None):
        query = ProductMetricsQuerySerializer(data=request.query_params)
        query.is_valid(raise_exception=True)
        product = self.get_object()
        return Response(get_product_metrics(product, **query.validated_data))


class ProductBindingViewSet(viewsets.ModelViewSet):
    queryset = ProductBinding.objects.select_related("product", "source")
    serializer_class = ProductBindingSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [DjangoFilterBackend, filters.SearchFilter]
    filterset_fields = ["product", "source", "is_primary"]
    search_fields = ["external_id", "external_sku", "product__sku", "product__name"]


class SaleViewSet(viewsets.ModelViewSet):
    queryset = Sale.objects.select_related("source", "source_record").prefetch_related(
        "lines__product"
    )
    serializer_class = SaleSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [
        DjangoFilterBackend,
        filters.SearchFilter,
        filters.OrderingFilter,
    ]
    filterset_fields = [
        "source",
        "event_type",
        "channel",
        "status",
        "counts_as_sale",
        "currency",
    ]
    search_fields = ["external_id", "number", "lines__external_sku", "lines__name"]
    ordering_fields = ["occurred_at", "created_at", "updated_at"]
    ordering = ["-occurred_at"]


class SaleLineViewSet(viewsets.ModelViewSet):
    queryset = SaleLine.objects.select_related("sale", "product", "sale__source")
    serializer_class = SaleLineSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [DjangoFilterBackend, filters.SearchFilter]
    filterset_fields = ["sale", "product"]
    search_fields = ["external_id", "external_product_id", "external_sku", "name"]


class CostViewSet(viewsets.ModelViewSet):
    queryset = Cost.objects.select_related("source", "product", "sale_line")
    serializer_class = CostSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [DjangoFilterBackend, filters.OrderingFilter]
    filterset_fields = ["source", "product", "channel", "cost_type", "currency"]
    ordering_fields = ["occurred_at", "amount", "created_at"]
    ordering = ["-occurred_at"]


class StockSnapshotViewSet(viewsets.ModelViewSet):
    queryset = StockSnapshot.objects.select_related("source", "product")
    serializer_class = StockSnapshotSerializer
    permission_classes = [CommerceAccessPermission]
    filter_backends = [DjangoFilterBackend, filters.OrderingFilter]
    filterset_fields = ["source", "product", "warehouse_external_id"]
    ordering_fields = ["captured_at", "quantity", "created_at"]
    ordering = ["-captured_at"]