from django.db.models import ProtectedError
from rest_framework import status
from rest_framework.exceptions import PermissionDenied
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.viewsets import ModelViewSet

from .models import Brand
from .serializers import BrandSerializer


class BrandViewSet(ModelViewSet):
    """
    品牌视图集：所有已认证用户可读，仅管理员可写
    """
    serializer_class = BrandSerializer
    permission_classes = [IsAuthenticated]

    def get_queryset(self):
        queryset = Brand.objects.all()
        search = self.request.query_params.get('search')
        if search:
            queryset = queryset.filter(name__icontains=search)
        return queryset

    def _check_admin(self, action_verb):
        if self.request.user.role != 'admin':
            raise PermissionDenied(f"只有管理员可以{action_verb}品牌")

    def perform_create(self, serializer):
        self._check_admin("创建")
        serializer.save()

    def perform_update(self, serializer):
        self._check_admin("修改")
        serializer.save()

    def destroy(self, request, *args, **kwargs):
        if request.user.role != 'admin':
            raise PermissionDenied("只有管理员可以删除品牌")
        instance = self.get_object()
        try:
            instance.delete()
        except ProtectedError:
            return Response(
                {"detail": "该品牌下存在材料，无法删除"},
                status=status.HTTP_400_BAD_REQUEST,
            )
        return Response(status=status.HTTP_204_NO_CONTENT)