from rest_framework import permissions, viewsets

from .models import Document
from .serializers import DocumentDetailSerializer, DocumentListSerializer, DocumentUploadSerializer


class IsOwnerOrPublic(permissions.BasePermission):
    """Allow access if user is owner or the document is public."""

    def has_object_permission(self, request, view, obj: Document) -> bool:
        if request.method in permissions.SAFE_METHODS:
            return obj.is_public or obj.owner == request.user
        return obj.owner == request.user


class DocumentViewSet(viewsets.ModelViewSet):
    """CRUD for documents with owner-scoping."""
    permission_classes = [permissions.IsAuthenticated, IsOwnerOrPublic]

    def get_serializer_class(self):
        if self.action == "create":
            return DocumentUploadSerializer
        if self.action in ("retrieve", "update", "partial_update"):
            return DocumentDetailSerializer
        return DocumentListSerializer

    def get_queryset(self):
        user = self.request.user
        qs = Document.objects.select_related("owner")
        if self.action == "list":
            return qs.filter(owner=user) | qs.filter(is_public=True)
        return qs

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