from django.db import transaction
from rest_framework import generics, status
from rest_framework.exceptions import NotFound
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView

from apps.billing.permissions import HasActiveFeature
from apps.bizapps.models import Appointment, Customer, LedgerEntry, Product, StockMovement

from .serializers import (
    AdjustStockSerializer,
    AppointmentSerializer,
    CustomerSerializer,
    LedgerEntrySerializer,
    ProductSerializer,
    StockMovementSerializer,
)

# همه‌ی این ریزاپ‌ها با جم فعال می‌شوند (یا دوره‌ی آزمایشی) — `feature_key`
# روی هر ویو مشخص می‌کند HasActiveFeature باید چه چیزی را چک کند.
# permission_classes اینجا Base است تا زیرکلاس‌ها فراموش نکنند.


class _UserScopedListCreateView(generics.ListCreateAPIView):
    permission_classes = [IsAuthenticated, HasActiveFeature]

    def get_queryset(self):
        return self.model.objects.filter(user=self.request.user)

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


class _UserScopedDetailView(generics.RetrieveUpdateDestroyAPIView):
    permission_classes = [IsAuthenticated, HasActiveFeature]

    def get_queryset(self):
        return self.model.objects.filter(user=self.request.user)


class CustomerListCreateView(_UserScopedListCreateView):
    model = Customer
    serializer_class = CustomerSerializer
    feature_key = "customers"


class CustomerDetailView(_UserScopedDetailView):
    model = Customer
    serializer_class = CustomerSerializer
    feature_key = "customers"


class LedgerEntryListCreateView(_UserScopedListCreateView):
    model = LedgerEntry
    serializer_class = LedgerEntrySerializer
    feature_key = "ledger"


class LedgerEntryDetailView(_UserScopedDetailView):
    model = LedgerEntry
    serializer_class = LedgerEntrySerializer
    feature_key = "ledger"


class ProductListCreateView(_UserScopedListCreateView):
    model = Product
    serializer_class = ProductSerializer
    feature_key = "inventory"


class ProductDetailView(_UserScopedDetailView):
    model = Product
    serializer_class = ProductSerializer
    feature_key = "inventory"


class ProductAdjustStockView(APIView):
    """تعدیل اتمیک موجودی (+/-) + یک ردیف تاریخچه — به‌جای این‌که کلاینت
    مستقیم quantity جدید را PATCH کند (که هیچ تاریخچه‌ای نمی‌سازد و اگر دو
    درخواست هم‌زمان بیایند می‌تواند یکی را گم کند)."""

    permission_classes = [IsAuthenticated, HasActiveFeature]
    feature_key = "inventory"

    @transaction.atomic
    def post(self, request, pk):
        try:
            product = Product.objects.select_for_update().get(pk=pk, user=request.user)
        except Product.DoesNotExist:
            raise NotFound("کالا یافت نشد.")

        serializer = AdjustStockSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        delta = serializer.validated_data["delta"]

        product.quantity += delta
        product.save(update_fields=["quantity", "updated_at"])
        StockMovement.objects.create(
            product=product,
            delta=delta,
            quantity_after=product.quantity,
            note=serializer.validated_data.get("note", ""),
        )
        return Response(ProductSerializer(product).data, status=status.HTTP_200_OK)


class ProductMovementsView(generics.ListAPIView):
    """تاریخچه‌ی تغییرات موجودی یک کالا — جدیدترین اول."""

    serializer_class = StockMovementSerializer
    permission_classes = [IsAuthenticated, HasActiveFeature]
    feature_key = "inventory"

    def get_queryset(self):
        return StockMovement.objects.filter(
            product_id=self.kwargs["pk"], product__user=self.request.user
        )


class AppointmentListCreateView(_UserScopedListCreateView):
    model = Appointment
    serializer_class = AppointmentSerializer
    feature_key = "booking"


class AppointmentDetailView(_UserScopedDetailView):
    model = Appointment
    serializer_class = AppointmentSerializer
    feature_key = "booking"