from rest_framework import viewsets, permissions, filters
from django_filters.rest_framework import DjangoFilterBackend
from .models import ProcessingBatch
from .serializers import ProcessingBatchListSerializer, ProcessingBatchDetailSerializer, ProcessingBatchWriteSerializer


class ProcessingBatchViewSet(viewsets.ModelViewSet):
    queryset = ProcessingBatch.objects.prefetch_related("qc_results", "shipments", "documents").all()
    permission_classes = [permissions.IsAuthenticated]
    filter_backends = [DjangoFilterBackend, filters.SearchFilter, filters.OrderingFilter]
    filterset_fields = ["status", "grade"]
    search_fields = ["batch_reference"]
    ordering_fields = ["created_at", "harvest_date"]
    ordering = ["-created_at"]

    def get_serializer_class(self):
        if self.action == "list":
            return ProcessingBatchListSerializer
        if self.action in ("create", "update", "partial_update"):
            return ProcessingBatchWriteSerializer
        return ProcessingBatchDetailSerializer

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

    def get_queryset(self):
        user = self.request.user
        qs = super().get_queryset()
        if user.role == "buyer":
            return qs  # Buyers can read all batches per spec
        return qs