text: from __future__ import absolute_import, unicode_literals
  
  from django.core.exceptions import PermissionDenied
  from django.shortcuts import get_object_or_404
  
  from rest_framework import generics
  
  from acls.models import AccessEntry
  from documents.models import Document
  from documents.permissions import PERMISSION_DOCUMENT_VIEW
  from permissions.models import Permission
  from rest_api.filters import MayanObjectPermissionsFilter
  from rest_api.permissions import MayanPermission
  
  from .models import Index, IndexInstanceNode, IndexTemplateNode
  from .permissions import (PERMISSION_DOCUMENT_INDEXING_CREATE,
                            PERMISSION_DOCUMENT_INDEXING_DELETE,
                            PERMISSION_DOCUMENT_INDEXING_EDIT,
                            PERMISSION_DOCUMENT_INDEXING_VIEW)
  from .serializers import (IndexInstanceNodeSerializer, IndexSerializer,
                            IndexTemplateNodeSerializer)
  
  
  class APIIndexListView(generics.ListCreateAPIView):
      serializer_class = IndexSerializer
      queryset = Index.objects.all()
  
      filter_backends = (MayanObjectPermissionsFilter,)
      mayan_object_permissions = {'GET': [PERMISSION_DOCUMENT_INDEXING_VIEW]}
      mayan_view_permissions = {'POST': [PERMISSION_DOCUMENT_INDEXING_CREATE]}
  
      def get(self, *args, **kwargs):
          """Returns a list of all the defined indexes."""
          return super(APIIndexListView, self).get(*args, **kwargs)
  
      def post(self, *args, **kwargs):
          """Create a new index."""
          return super(APIIndexListView, self).post(*args, **kwargs)
  
  
  class APIIndexView(generics.RetrieveUpdateDestroyAPIView):
      serializer_class = IndexSerializer
      queryset = Index.objects.all()
  
      permission_classes = (MayanPermission,)
      mayan_object_permissions = {
          'GET': [PERMISSION_DOCUMENT_INDEXING_VIEW],
          'PUT': [PERMISSION_DOCUMENT_INDEXING_EDIT],
          'PATCH': [PERMISSION_DOCUMENT_INDEXING_EDIT],
          'DELETE': [PERMISSION_DOCUMENT_INDEXING_DELETE]
      }
  
      def delete(self, *args, **kwargs):
          """Delete the selected index."""
          return super(APIIndexView, self).delete(*args, **kwargs)
  
      def get(self, *args, **kwargs):
          """Returns the details of the selected index."""
          return super(APIIndexView, self).get(*args, **kwargs)
  
      def patch(self, *args, **kwargs):
          """Partially edit an index."""
          return super(APIIndexView, self).patch(*args, **kwargs)
  
      def put(self, *args, **kwargs):
          """Edit an index."""
          return super(APIIndexView, self).put(*args, **kwargs)
  
  
  class APIIndexNodeInstanceDocumentListView(generics.ListAPIView):
      """
      Returns a list of all the documents contained by a particular index node instance.
      """
  
      filter_backends = (MayanObjectPermissionsFilter,)
      mayan_object_permissions = {'GET': [PERMISSION_DOCUMENT_VIEW]}
  
      def get_serializer_class(self):
          from documents.serializers import DocumentSerializer
          return DocumentSerializer
  
      def get_queryset(self):
          index_node_instance = get_object_or_404(IndexInstanceNode, pk=self.kwargs['pk'])
          try:
              Permission.objects.check_permissions(self.request.user, [PERMISSION_DOCUMENT_INDEXING_VIEW])
          except PermissionDenied:
              AccessEntry.objects.check_access(PERMISSION_DOCUMENT_INDEXING_VIEW, self.request.user, index_node_instance.index)
  
          return index_node_instance.documents.all()
  
  
  class APIIndexTemplateListView(generics.ListAPIView):
      serializer_class = IndexTemplateNodeSerializer
  
      filter_backends = (MayanObjectPermissionsFilter,)
      mayan_object_permissions = {'GET': [PERMISSION_DOCUMENT_INDEXING_VIEW]}
  
      def get(self, *args, **kwargs):
          """Returns a list of all the template nodes for the selected index."""
          return super(APIIndexTemplateListView, self).get(*args, **kwargs)
  
  
  class APIIndexTemplateView(generics.RetrieveUpdateDestroyAPIView):
      serializer_class = IndexTemplateNodeSerializer
      queryset = IndexTemplateNode.objects.all()
  
      permission_classes = (MayanPermission,)
      mayan_object_permissions = {
          'GET': [PERMISSION_DOCUMENT_INDEXING_VIEW],
          'PUT': [PERMISSION_DOCUMENT_INDEXING_EDIT],
          'PATCH': [PERMISSION_DOCUMENT_INDEXING_EDIT],
          'DELETE': [PERMISSION_DOCUMENT_INDEXING_EDIT]
      }
  
      def delete(self, *args, **kwargs):
          """Delete the selected index template node."""
          return super(APIIndexTemplateView, self).delete(*args, **kwargs)
  
      def get(self, *args, **kwargs):
          """Returns the details of the selected index template node."""
          return super(APIIndexTemplateView, self).get(*args, **kwargs)
  
      def patch(self, *args, **kwargs):
          """Partially edit an index template node."""
          return super(APIIndexTemplateView, self).patch(*args, **kwargs)
  
      def put(self, *args, **kwargs):
          """Edit an index template node."""
          return super(APIIndexTemplateView, self).put(*args, **kwargs)
  
  
  class APIDocumentIndexListView(generics.ListAPIView):
      """
      Returns a list of all the indexes to which a document belongs.
      """
  
      serializer_class = IndexInstanceNodeSerializer
  
      filter_backends = (MayanObjectPermissionsFilter,)
      mayan_object_permissions = {'GET': [PERMISSION_DOCUMENT_INDEXING_VIEW]}
  
      def get_queryset(self):
          document = get_object_or_404(Document, pk=self.kwargs['pk'])
          try:
              Permission.objects.check_permissions(self.request.user, [PERMISSION_DOCUMENT_VIEW])
          except PermissionDenied:
              AccessEntry.objects.check_access(PERMISSION_DOCUMENT_VIEW, self.request.user, document)
  
          return document.node_instances.all()
  