OntologyResponderV2.scala

/*
 * Copyright © 2015-2021 the contributors (see Contributors.md).
 *
 * This file is part of Knora.
 *
 * Knora is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Knora is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with Knora.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.knora.webapi.responders.v2

import java.time.Instant

import akka.http.scaladsl.util.FastFuture
import akka.pattern._
import org.knora.webapi._
import org.knora.webapi.exceptions._
import org.knora.webapi.feature.FeatureFactoryConfig
import org.knora.webapi.messages.IriConversions._
import org.knora.webapi.messages.StringFormatter.{SalsahGuiAttribute, SalsahGuiAttributeDefinition}
import org.knora.webapi.messages.admin.responder.projectsmessages.{
  ProjectGetRequestADM,
  ProjectGetResponseADM,
  ProjectIdentifierADM
}
import org.knora.webapi.messages.admin.responder.usersmessages.UserADM
import org.knora.webapi.messages.store.triplestoremessages._
import org.knora.webapi.messages.util.rdf.{SparqlSelectResult, VariableResultsRow}
import org.knora.webapi.messages.util.{ErrorHandlingMap, KnoraSystemInstances, OntologyUtil, ResponderData}
import org.knora.webapi.messages.v2.responder.SuccessResponseV2
import org.knora.webapi.messages.v2.responder.ontologymessages.Cardinality.{KnoraCardinalityInfo, OwlCardinalityInfo}
import org.knora.webapi.messages.v2.responder.ontologymessages._
import org.knora.webapi.messages.v2.responder.standoffmessages.StandoffDataTypeClasses
import org.knora.webapi.messages.{OntologyConstants, SmartIri}
import org.knora.webapi.responders.Responder.handleUnexpectedMessage
import org.knora.webapi.responders.{IriLocker, Responder}
import org.knora.webapi.util._
import org.knora.webapi.util.cache.CacheUtil

import scala.collection.immutable
import scala.concurrent.Future

/**
  * Responds to requests dealing with ontologies.
  *
  * The API v2 ontology responder reads ontologies from two sources:
  *
  * - The triplestore.
  * - The constant knora-api v2 ontologies that are defined in Scala rather than in the triplestore, [[KnoraBaseToApiV2SimpleTransformationRules]] and [[KnoraBaseToApiV2ComplexTransformationRules]].
  *
  * It maintains an in-memory cache of all ontology data. This cache can be refreshed by sending a [[LoadOntologiesRequestV2]].
  *
  * Read requests to the ontology responder may contain internal or external IRIs as needed. Response messages from the
  * ontology responder will contain internal IRIs and definitions, unless a constant API v2 ontology was requested,
  * in which case the response will be in the requested API v2 schema.
  *
  * In API v2, the ontology responder can also create and update ontologies. Update requests must contain
  * [[ApiV2Complex]] IRIs and definitions.
  *
  * The API v1 ontology responder, which is read-only, delegates most of its work to this responder.
  */
class OntologyResponderV2(responderData: ResponderData) extends Responder(responderData) {

  // The name of the ontology cache.
  private val OntologyCacheName = "ontologyCache"

  // The cache key under which cached ontology data is stored.
  private val OntologyCacheKey = "ontologyCacheData"

  // The global ontology cache lock. This is needed because every ontology update replaces the whole ontology cache
  // (because definitions in one ontology can refer to definitions in another ontology). Without a global lock,
  // concurrent updates (even to different ontologies) could overwrite each other.
  private val ONTOLOGY_CACHE_LOCK_IRI = "http://rdfh.ch/ontologies"

  /**
    * The in-memory cache of ontologies.
    *
    * @param ontologies              a map of ontology IRIs to ontologies.
    * @param subClassOfRelations     a map of subclasses to their base classes.
    * @param superClassOfRelations   a map of base classes to their subclasses.
    * @param subPropertyOfRelations  a map of subproperties to their base proeprties.
    * @param guiAttributeDefinitions a map of salsah-gui:Guielement individuals to their GUI attribute definitions.
    * @param standoffProperties      a set of standoff properties.
    */
  private case class OntologyCacheData(ontologies: Map[SmartIri, ReadOntologyV2],
                                       subClassOfRelations: Map[SmartIri, Seq[SmartIri]],
                                       superClassOfRelations: Map[SmartIri, Set[SmartIri]],
                                       subPropertyOfRelations: Map[SmartIri, Set[SmartIri]],
                                       guiAttributeDefinitions: Map[SmartIri, Set[SalsahGuiAttributeDefinition]],
                                       standoffProperties: Set[SmartIri]) {
    lazy val allPropertyDefs: Map[SmartIri, PropertyInfoContentV2] = ontologies.values
      .flatMap(_.properties.map {
        case (propertyIri, readPropertyInfo) => propertyIri -> readPropertyInfo.entityInfoContent
      })
      .toMap
  }

  /**
    * Receives a message of type [[OntologiesResponderRequestV2]], and returns an appropriate response message.
    */
  def receive(msg: OntologiesResponderRequestV2) = msg match {
    case LoadOntologiesRequestV2(featureFactoryConfig, requestingUser) =>
      loadOntologies(featureFactoryConfig, requestingUser)
    case EntityInfoGetRequestV2(classIris, propertyIris, requestingUser) =>
      getEntityInfoResponseV2(classIris, propertyIris, requestingUser)
    case StandoffEntityInfoGetRequestV2(standoffClassIris, standoffPropertyIris, requestingUser) =>
      getStandoffEntityInfoResponseV2(standoffClassIris, standoffPropertyIris, requestingUser)
    case StandoffClassesWithDataTypeGetRequestV2(requestingUser) =>
      getStandoffStandoffClassesWithDataTypeV2(requestingUser)
    case StandoffAllPropertyEntitiesGetRequestV2(requestingUser) => getAllStandoffPropertyEntitiesV2(requestingUser)
    case CheckSubClassRequestV2(subClassIri, superClassIri, requestingUser) =>
      checkSubClassV2(subClassIri, superClassIri)
    case SubClassesGetRequestV2(resourceClassIri, requestingUser) => getSubClassesV2(resourceClassIri, requestingUser)
    case OntologyKnoraEntityIrisGetRequestV2(namedGraphIri, requestingUser) =>
      getKnoraEntityIrisInNamedGraphV2(namedGraphIri, requestingUser)
    case OntologyEntitiesGetRequestV2(ontologyIri, allLanguages, requestingUser) =>
      getOntologyEntitiesV2(ontologyIri, allLanguages, requestingUser)
    case ClassesGetRequestV2(resourceClassIris, allLanguages, requestingUser) =>
      getClassDefinitionsFromOntologyV2(resourceClassIris, allLanguages, requestingUser)
    case PropertiesGetRequestV2(propertyIris, allLanguages, requestingUser) =>
      getPropertyDefinitionsFromOntologyV2(propertyIris, allLanguages, requestingUser)
    case OntologyMetadataGetByProjectRequestV2(projectIris, requestingUser) =>
      getOntologyMetadataForProjectsV2(projectIris, requestingUser)
    case OntologyMetadataGetByIriRequestV2(ontologyIris, requestingUser) =>
      getOntologyMetadataByIriV2(ontologyIris, requestingUser)
    case createOntologyRequest: CreateOntologyRequestV2 => createOntology(createOntologyRequest)
    case changeOntologyMetadataRequest: ChangeOntologyMetadataRequestV2 =>
      changeOntologyMetadata(changeOntologyMetadataRequest)
    case deleteOntologyCommentRequest: DeleteOntologyCommentRequestV2 =>
      deleteOntologyComment(deleteOntologyCommentRequest)
    case createClassRequest: CreateClassRequestV2 => createClass(createClassRequest)
    case changeClassLabelsOrCommentsRequest: ChangeClassLabelsOrCommentsRequestV2 =>
      changeClassLabelsOrComments(changeClassLabelsOrCommentsRequest)
    case addCardinalitiesToClassRequest: AddCardinalitiesToClassRequestV2 =>
      addCardinalitiesToClass(addCardinalitiesToClassRequest)
    case changeCardinalitiesRequest: ChangeCardinalitiesRequestV2 =>
      changeClassCardinalities(changeCardinalitiesRequest)
    case deleteClassRequest: DeleteClassRequestV2       => deleteClass(deleteClassRequest)
    case createPropertyRequest: CreatePropertyRequestV2 => createProperty(createPropertyRequest)
    case changePropertyLabelsOrCommentsRequest: ChangePropertyLabelsOrCommentsRequestV2 =>
      changePropertyLabelsOrComments(changePropertyLabelsOrCommentsRequest)
    case deletePropertyRequest: DeletePropertyRequestV2 => deleteProperty(deletePropertyRequest)
    case deleteOntologyRequest: DeleteOntologyRequestV2 => deleteOntology(deleteOntologyRequest)
    case other                                          => handleUnexpectedMessage(other, log, this.getClass.getName)
  }

  /**
    * Represents the contents of a named graph representing an ontology.
    *
    * @param ontologyIri       the ontology IRI, which is also the IRI of the named graph.
    * @param constructResponse the triplestore's response to a CONSTRUCT query that gets the contents of the named graph.
    */
  private case class OntologyGraph(ontologyIri: SmartIri, constructResponse: SparqlExtendedConstructResponse)

  /**
    * Loads and caches all ontology information.
    *
    * @param featureFactoryConfig the feature factory configuration.
    * @param requestingUser       the user making the request.
    * @return a [[SuccessResponseV2]].
    */
  private def loadOntologies(featureFactoryConfig: FeatureFactoryConfig,
                             requestingUser: UserADM): Future[SuccessResponseV2] = {
    val loadOntologiesFuture: Future[SuccessResponseV2] = for {
      _ <- Future {
        if (!(requestingUser.id == KnoraSystemInstances.Users.SystemUser.id || requestingUser.permissions.isSystemAdmin)) {
          throw ForbiddenException(s"Only a system administrator can reload ontologies")
        }
      }

      // Get all ontology metadata.
      allOntologyMetadataSparql <- FastFuture.successful(
        org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .getAllOntologyMetadata(triplestore = settings.triplestoreType)
          .toString())
      allOntologyMetadataResponse: SparqlSelectResult <- (storeManager ? SparqlSelectRequest(allOntologyMetadataSparql))
        .mapTo[SparqlSelectResult]
      allOntologyMetadata: Map[SmartIri, OntologyMetadataV2] = buildOntologyMetadata(allOntologyMetadataResponse)

      knoraBaseOntologyMetadata: OntologyMetadataV2 = allOntologyMetadata.getOrElse(
        OntologyConstants.KnoraBase.KnoraBaseOntologyIri.toSmartIri,
        throw InconsistentRepositoryDataException(s"No knora-base ontology found"))
      knoraBaseOntologyVersion: String = knoraBaseOntologyMetadata.ontologyVersion.getOrElse(
        throw InconsistentRepositoryDataException(
          "The knora-base ontology in the repository is not up to date. See the Knora documentation on repository updates."))

      _ = if (knoraBaseOntologyVersion != KnoraBaseVersion) {
        throw InconsistentRepositoryDataException(
          s"The knora-base ontology in the repository has version '$knoraBaseOntologyVersion', but this version of Knora requires '$KnoraBaseVersion'. See the Knora documentation on repository updates.")
      }

      // Get the contents of each named graph containing an ontology.
      ontologyGraphResponseFutures: Iterable[Future[OntologyGraph]] = allOntologyMetadata.keys.map { ontologyIri =>
        val ontologyGraphConstructQuery = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .getOntologyGraph(
            triplestore = settings.triplestoreType,
            ontologyGraph = ontologyIri
          )
          .toString

        (storeManager ? SparqlExtendedConstructRequest(
          sparql = ontologyGraphConstructQuery,
          featureFactoryConfig = featureFactoryConfig
        )).mapTo[SparqlExtendedConstructResponse].map { response =>
          OntologyGraph(ontologyIri = ontologyIri, constructResponse = response)
        }
      }

      ontologyGraphs: Iterable[OntologyGraph] <- Future.sequence(ontologyGraphResponseFutures)

      _ = makeOntologyCache(allOntologyMetadata, ontologyGraphs)
    } yield SuccessResponseV2("Ontologies loaded.")

    loadOntologiesFuture.recover {
      case exception: Throwable =>
        exception match {
          case inconsistentRepositoryDataException: InconsistentRepositoryDataException =>
            log.error(inconsistentRepositoryDataException.message)
            SuccessResponseV2(
              s"An error occurred when loading ontologies: ${inconsistentRepositoryDataException.message}")

          case other => throw other
        }
    }
  }

  /**
    * Given ontology metdata and ontology graphs read from the triplestore, constructs the ontology cache.
    *
    * @param allOntologyMetadata a map of ontology IRIs to ontology metadata.
    * @param ontologyGraphs      a list of ontology graphs.
    */
  private def makeOntologyCache(allOntologyMetadata: Map[SmartIri, OntologyMetadataV2],
                                ontologyGraphs: Iterable[OntologyGraph]): Unit = {
    // Get the IRIs of all the entities in each ontology.

    // A map of ontology IRIs to class IRIs in each ontology.
    val classIrisPerOntology: Map[SmartIri, Set[SmartIri]] = getEntityIrisFromOntologyGraphs(
      ontologyGraphs = ontologyGraphs,
      entityTypes = Set(OntologyConstants.Owl.Class)
    )

    // A map of ontology IRIs to property IRIs in each ontology.
    val propertyIrisPerOntology: Map[SmartIri, Set[SmartIri]] = getEntityIrisFromOntologyGraphs(
      ontologyGraphs = ontologyGraphs,
      entityTypes = Set(
        OntologyConstants.Owl.ObjectProperty,
        OntologyConstants.Owl.DatatypeProperty,
        OntologyConstants.Owl.AnnotationProperty,
        OntologyConstants.Rdf.Property
      )
    )

    // A map of ontology IRIs to named individual IRIs in each ontology.
    val individualIrisPerOntology: Map[SmartIri, Set[SmartIri]] = getEntityIrisFromOntologyGraphs(
      ontologyGraphs = ontologyGraphs,
      entityTypes = Set(OntologyConstants.Owl.NamedIndividual)
    )

    // Construct entity definitions.

    // A map of class IRIs to class definitions.
    val allClassDefs: Map[SmartIri, ClassInfoContentV2] = ontologyGraphs.flatMap { ontologyGraph =>
      constructResponseToClassDefinitions(
        classIris = classIrisPerOntology(ontologyGraph.ontologyIri),
        constructResponse = ontologyGraph.constructResponse
      )
    }.toMap

    // A map of property IRIs to property definitions.
    val allPropertyDefs: Map[SmartIri, PropertyInfoContentV2] = ontologyGraphs.flatMap { ontologyGraph =>
      constructResponseToPropertyDefinitions(
        propertyIris = propertyIrisPerOntology(ontologyGraph.ontologyIri),
        constructResponse = ontologyGraph.constructResponse
      )
    }.toMap

    // A map of OWL named individual IRIs to named individuals.
    val allIndividuals: Map[SmartIri, IndividualInfoContentV2] = ontologyGraphs.flatMap { ontologyGraph =>
      constructResponseToIndividuals(
        individualIris = individualIrisPerOntology(ontologyGraph.ontologyIri),
        constructResponse = ontologyGraph.constructResponse
      )
    }.toMap

    // A map of salsah-gui:Guielement individuals to their GUI attribute definitions.
    val allGuiAttributeDefinitions: Map[SmartIri, Set[SalsahGuiAttributeDefinition]] = makeGuiAttributeDefinitions(
      allIndividuals)

    // Determine relations between entities.

    // A map of class IRIs to their immediate base classes.
    val directSubClassOfRelations: Map[SmartIri, Set[SmartIri]] = allClassDefs.map {
      case (classIri, classDef) => classIri -> classDef.subClassOf
    }

    // A map of property IRIs to their immediate base properties.
    val directSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]] = allPropertyDefs.map {
      case (propertyIri, propertyDef) => propertyIri -> propertyDef.subPropertyOf
    }

    val allClassIris = allClassDefs.keySet
    val allPropertyIris = allPropertyDefs.keySet

    // A map in which each class IRI points to the full sequence of its base classes.
    val allSubClassOfRelations: Map[SmartIri, Seq[SmartIri]] = allClassIris.toSeq.map { classIri =>
      // get the hierarchically ordered base classes.
      val baseClasses: Seq[SmartIri] = OntologyUtil.getAllBaseDefs(classIri, directSubClassOfRelations)
      // prepend the classIri to the sequence of base classes because a class is also a subclass of itself.
      (classIri, classIri +: baseClasses)
    }.toMap

    // A map in which each class IRI points to the full set of its subclasses. A class is also
    // a subclass of itself.
    val allSuperClassOfRelations: Map[SmartIri, Set[SmartIri]] = calculateSuperClassOfRelations(allSubClassOfRelations)

    // Make a map in which each property IRI points to the full set of its base properties. A property is also
    // a subproperty of itself.
    val allSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]] = allPropertyIris.map { propertyIri =>
      (propertyIri, OntologyUtil.getAllBaseDefs(propertyIri, directSubPropertyOfRelations).toSet + propertyIri)
    }.toMap

    // A set of all subproperties of knora-base:resourceProperty.
    val allKnoraResourceProps: Set[SmartIri] = allPropertyIris.filter { prop =>
      val allPropSubPropertyOfRelations = allSubPropertyOfRelations(prop)
      prop == OntologyConstants.KnoraBase.ResourceProperty.toSmartIri ||
      allPropSubPropertyOfRelations.contains(OntologyConstants.KnoraBase.HasValue.toSmartIri) ||
      allPropSubPropertyOfRelations.contains(OntologyConstants.KnoraBase.HasLinkTo.toSmartIri)
    }

    // A set of all subproperties of knora-base:hasLinkTo.
    val allLinkProps: Set[SmartIri] = allPropertyIris.filter(prop =>
      allSubPropertyOfRelations(prop).contains(OntologyConstants.KnoraBase.HasLinkTo.toSmartIri))

    // A set of all subproperties of knora-base:hasLinkToValue.
    val allLinkValueProps: Set[SmartIri] = allPropertyIris.filter(prop =>
      allSubPropertyOfRelations(prop).contains(OntologyConstants.KnoraBase.HasLinkToValue.toSmartIri))

    // A set of all subproperties of knora-base:hasFileValue.
    val allFileValueProps: Set[SmartIri] = allPropertyIris.filter(prop =>
      allSubPropertyOfRelations(prop).contains(OntologyConstants.KnoraBase.HasFileValue.toSmartIri))

    // A map of the cardinalities defined directly on each resource class. Each class IRI points to a map of
    // property IRIs to OwlCardinalityInfo objects.
    val directClassCardinalities: Map[SmartIri, Map[SmartIri, OwlCardinalityInfo]] = allClassDefs.map {
      case (classIri, classDef) =>
        classIri -> classDef.directCardinalities.map {
          case (propertyIri, knoraCardinalityInfo) =>
            propertyIri -> Cardinality.knoraCardinality2OwlCardinality(knoraCardinalityInfo)
        }
    }

    // Allow each class to inherit cardinalities from its base classes.
    val classCardinalitiesWithInheritance: Map[SmartIri, Map[SmartIri, OwlCardinalityInfo]] = allClassIris.map {
      resourceClassIri =>
        val resourceClassCardinalities: Map[SmartIri, OwlCardinalityInfo] = inheritCardinalitiesInLoadedClass(
          classIri = resourceClassIri,
          directSubClassOfRelations = directSubClassOfRelations,
          allSubPropertyOfRelations = allSubPropertyOfRelations,
          directClassCardinalities = directClassCardinalities
        )

        resourceClassIri -> resourceClassCardinalities
    }.toMap

    // Construct a ReadClassInfoV2 for each class.
    val readClassInfos: Map[SmartIri, ReadClassInfoV2] = makeReadClassInfos(
      classDefs = allClassDefs,
      directClassCardinalities = directClassCardinalities,
      classCardinalitiesWithInheritance = classCardinalitiesWithInheritance,
      directSubClassOfRelations = directSubClassOfRelations,
      allSubClassOfRelations = allSubClassOfRelations,
      allSubPropertyOfRelations = allSubPropertyOfRelations,
      allPropertyDefs = allPropertyDefs,
      allKnoraResourceProps = allKnoraResourceProps,
      allLinkProps = allLinkProps,
      allLinkValueProps = allLinkValueProps,
      allFileValueProps = allFileValueProps
    )

    // Construct a ReadPropertyInfoV2 for each property definition.
    val readPropertyInfos: Map[SmartIri, ReadPropertyInfoV2] = makeReadPropertyInfos(
      propertyDefs = allPropertyDefs,
      directSubPropertyOfRelations = directSubPropertyOfRelations,
      allSubPropertyOfRelations = allSubPropertyOfRelations,
      allSubClassOfRelations = allSubClassOfRelations,
      allGuiAttributeDefinitions = allGuiAttributeDefinitions,
      allKnoraResourceProps = allKnoraResourceProps,
      allLinkProps = allLinkProps,
      allLinkValueProps = allLinkValueProps,
      allFileValueProps = allFileValueProps
    )

    // Construct a ReadIndividualV2 for each OWL named individual.
    val readIndividualInfos = makeReadIndividualInfos(allIndividuals)

    // A ReadOntologyV2 for each ontology to be cached.
    val readOntologies: Map[SmartIri, ReadOntologyV2] = allOntologyMetadata.map {
      case (ontologyIri, ontologyMetadata) =>
        ontologyIri -> ReadOntologyV2(
          ontologyMetadata = ontologyMetadata,
          classes = readClassInfos.filter {
            case (classIri, _) => classIri.getOntologyFromEntity == ontologyIri
          },
          properties = readPropertyInfos.filter {
            case (propertyIri, _) => propertyIri.getOntologyFromEntity == ontologyIri
          },
          individuals = readIndividualInfos.filter {
            case (individualIri, _) => individualIri.getOntologyFromEntity == ontologyIri
          },
          isWholeOntology = true
        )
    }

    // A set of the IRIs of all properties used in cardinalities in standoff classes.
    val propertiesUsedInStandoffCardinalities: Set[SmartIri] = readClassInfos.flatMap {
      case (_, readClassInfo) =>
        if (readClassInfo.isStandoffClass) {
          readClassInfo.allCardinalities.keySet
        } else {
          Set.empty[SmartIri]
        }
    }.toSet

    // A set of the IRIs of all properties whose subject class constraint is a standoff class.
    val propertiesWithStandoffTagSubjects: Set[SmartIri] = readPropertyInfos.flatMap {
      case (propertyIri, readPropertyInfo) =>
        readPropertyInfo.entityInfoContent.getPredicateIriObject(
          OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri) match {
          case Some(subjectClassConstraint: SmartIri) =>
            readClassInfos.get(subjectClassConstraint) match {
              case Some(subjectReadClassInfo: ReadClassInfoV2) =>
                if (subjectReadClassInfo.isStandoffClass) {
                  Some(propertyIri)
                } else {
                  None
                }

              case None => None
            }

          case None => None
        }
    }.toSet

    // Construct the ontology cache data.
    val ontologyCacheData: OntologyCacheData = OntologyCacheData(
      ontologies = new ErrorHandlingMap[SmartIri, ReadOntologyV2](readOntologies, { key =>
        s"Ontology not found: $key"
      }),
      subClassOfRelations = new ErrorHandlingMap[SmartIri, Seq[SmartIri]](allSubClassOfRelations, { key =>
        s"Class not found: $key"
      }),
      superClassOfRelations = new ErrorHandlingMap[SmartIri, Set[SmartIri]](allSuperClassOfRelations, { key =>
        s"Class not found: $key"
      }),
      subPropertyOfRelations = new ErrorHandlingMap[SmartIri, Set[SmartIri]](allSubPropertyOfRelations, { key =>
        s"Property not found: $key"
      }),
      guiAttributeDefinitions =
        new ErrorHandlingMap[SmartIri, Set[SalsahGuiAttributeDefinition]](allGuiAttributeDefinitions, { key =>
          s"salsah-gui:Guielement not found: $key"
        }),
      standoffProperties = propertiesUsedInStandoffCardinalities ++ propertiesWithStandoffTagSubjects
    )

    // Check property subject and object class constraints.

    readPropertyInfos.foreach {
      case (propertyIri, readPropertyInfo) =>
        val allSuperPropertyIris: Set[SmartIri] = allSubPropertyOfRelations.getOrElse(propertyIri, Set.empty[SmartIri])

        readPropertyInfo.entityInfoContent.getPredicateIriObject(
          OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri) match {
          case Some(subjectClassConstraint) =>
            // Each property's subject class constraint, if provided, must be a subclass of the subject class constraints of all its base properties.
            checkPropertyConstraint(
              cacheData = ontologyCacheData,
              internalPropertyIri = propertyIri,
              constraintPredicateIri = OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri,
              constraintValueToBeChecked = subjectClassConstraint,
              allSuperPropertyIris = allSuperPropertyIris,
              errorSchema = InternalSchema,
              errorFun = { msg: String =>
                throw InconsistentRepositoryDataException(msg)
              }
            )

            // If the property is defined in a project-specific ontology, its subject class constraint, if provided, must be a Knora resource or standoff class.
            if (!propertyIri.isKnoraBuiltInDefinitionIri) {
              val baseClassesOfSubjectClassConstraint = allSubClassOfRelations(subjectClassConstraint)

              if (!(baseClassesOfSubjectClassConstraint.contains(OntologyConstants.KnoraBase.Resource.toSmartIri) ||
                    baseClassesOfSubjectClassConstraint.contains(OntologyConstants.KnoraBase.StandoffTag.toSmartIri))) {
                throw InconsistentRepositoryDataException(
                  s"Property $propertyIri is defined in a project-specific ontology, but its knora-base:subjectClassConstraint, $subjectClassConstraint, is not a subclass of knora-base:Resource or knora-base:StandoffTag")
              }
            }

          case None => ()
        }

        readPropertyInfo.entityInfoContent.getPredicateIriObject(
          OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri) match {
          case Some(objectClassConstraint) =>
            // Each property's object class constraint, if provided, must be a subclass of the object class constraints of all its base properties.
            checkPropertyConstraint(
              cacheData = ontologyCacheData,
              internalPropertyIri = propertyIri,
              constraintPredicateIri = OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri,
              constraintValueToBeChecked = objectClassConstraint,
              allSuperPropertyIris = allSuperPropertyIris,
              errorSchema = InternalSchema,
              errorFun = { msg: String =>
                throw InconsistentRepositoryDataException(msg)
              }
            )

          case None =>
            // A resource property must have an object class constraint, unless it's knora-base:resourceProperty.
            if (readPropertyInfo.isResourceProp && propertyIri != OntologyConstants.KnoraBase.ResourceProperty.toSmartIri) {
              throw InconsistentRepositoryDataException(
                s"Property $propertyIri has no knora-base:objectClassConstraint")
            }
        }
    }

    // Check references between ontologies.
    checkReferencesBetweenOntologies(ontologyCacheData)

    // Update the cache.
    storeCacheData(ontologyCacheData)
  }

  /**
    * Checks a reference between an ontology entity and another ontology entity to see if the target
    * is in a non-shared ontology in another project.
    *
    * @param ontologyCacheData the ontology cache data.
    * @param sourceEntityIri   the entity whose definition contains the reference.
    * @param targetEntityIri   the entity that's the target of the reference.
    * @param errorFun          a function that throws an exception with the specified message if the reference is invalid.
    */
  private def checkOntologyReferenceInEntity(ontologyCacheData: OntologyCacheData,
                                             sourceEntityIri: SmartIri,
                                             targetEntityIri: SmartIri,
                                             errorFun: String => Nothing): Unit = {
    if (targetEntityIri.isKnoraDefinitionIri) {
      val sourceOntologyIri = sourceEntityIri.getOntologyFromEntity
      val sourceOntologyMetadata = ontologyCacheData.ontologies(sourceOntologyIri).ontologyMetadata

      val targetOntologyIri = targetEntityIri.getOntologyFromEntity
      val targetOntologyMetadata = ontologyCacheData.ontologies(targetOntologyIri).ontologyMetadata

      if (sourceOntologyMetadata.projectIri != targetOntologyMetadata.projectIri) {
        if (!(targetOntologyIri.isKnoraBuiltInDefinitionIri || targetOntologyIri.isKnoraSharedDefinitionIri)) {
          errorFun(
            s"Entity $sourceEntityIri refers to entity $targetEntityIri, which is in a non-shared ontology that belongs to another project")
        }
      }
    }
  }

  /**
    * Checks a property definition to ensure that it doesn't refer to any other non-shared ontologies.
    *
    * @param ontologyCacheData the ontology cache data.
    * @param propertyDef       the property definition.
    * @param errorFun          a function that throws an exception with the specified message if the property definition is invalid.
    */
  private def checkOntologyReferencesInPropertyDef(ontologyCacheData: OntologyCacheData,
                                                   propertyDef: PropertyInfoContentV2,
                                                   errorFun: String => Nothing): Unit = {
    // Ensure that the property isn't a subproperty of any property in a non-shared ontology in another project.

    for (subPropertyOf <- propertyDef.subPropertyOf) {
      checkOntologyReferenceInEntity(
        ontologyCacheData = ontologyCacheData,
        sourceEntityIri = propertyDef.propertyIri,
        targetEntityIri = subPropertyOf,
        errorFun = errorFun
      )
    }

    // Ensure that the property doesn't have subject or object constraints pointing to a non-shared ontology in another project.

    propertyDef.getPredicateIriObject(OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri) match {
      case Some(subjectClassConstraint) =>
        checkOntologyReferenceInEntity(
          ontologyCacheData = ontologyCacheData,
          sourceEntityIri = propertyDef.propertyIri,
          targetEntityIri = subjectClassConstraint,
          errorFun = errorFun
        )

      case None => ()
    }

    propertyDef.getPredicateIriObject(OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri) match {
      case Some(objectClassConstraint) =>
        checkOntologyReferenceInEntity(
          ontologyCacheData = ontologyCacheData,
          sourceEntityIri = propertyDef.propertyIri,
          targetEntityIri = objectClassConstraint,
          errorFun = errorFun
        )

      case None => ()
    }
  }

  /**
    * Checks a class definition to ensure that it doesn't refer to any non-shared ontologies in other projects.
    *
    * @param ontologyCacheData the ontology cache data.
    * @param classDef          the class definition.
    * @param errorFun          a function that throws an exception with the specified message if the property definition is invalid.
    */
  private def checkOntologyReferencesInClassDef(ontologyCacheData: OntologyCacheData,
                                                classDef: ClassInfoContentV2,
                                                errorFun: String => Nothing): Unit = {
    for (subClassOf <- classDef.subClassOf) {
      checkOntologyReferenceInEntity(
        ontologyCacheData = ontologyCacheData,
        sourceEntityIri = classDef.classIri,
        targetEntityIri = subClassOf,
        errorFun = errorFun
      )
    }

    for (cardinalityPropIri <- classDef.directCardinalities.keys) {
      checkOntologyReferenceInEntity(
        ontologyCacheData = ontologyCacheData,
        sourceEntityIri = classDef.classIri,
        targetEntityIri = cardinalityPropIri,
        errorFun = errorFun
      )
    }
  }

  /**
    * Checks references between ontologies to ensure that they do not refer to non-shared ontologies in other projects.
    *
    * @param ontologyCacheData the ontology cache data.
    */
  private def checkReferencesBetweenOntologies(ontologyCacheData: OntologyCacheData): Unit = {
    for (ontology <- ontologyCacheData.ontologies.values) {
      for (propertyInfo <- ontology.properties.values) {
        checkOntologyReferencesInPropertyDef(
          ontologyCacheData = ontologyCacheData,
          propertyDef = propertyInfo.entityInfoContent,
          errorFun = { msg: String =>
            throw InconsistentRepositoryDataException(msg)
          }
        )
      }

      for (classInfo <- ontology.classes.values) {
        checkOntologyReferencesInClassDef(
          ontologyCacheData = ontologyCacheData,
          classDef = classInfo.entityInfoContent,
          errorFun = { msg: String =>
            throw InconsistentRepositoryDataException(msg)
          }
        )
      }
    }
  }

  /**
    * Given a list of ontology graphs, finds the IRIs of all subjects whose `rdf:type` is contained in a given set of types.
    *
    * @param ontologyGraphs a list of ontology graphs.
    * @param entityTypes    the types of entities to be found.
    * @return a map of ontology IRIs to sets of the IRIs of entities with matching types in each ontology.
    */
  private def getEntityIrisFromOntologyGraphs(ontologyGraphs: Iterable[OntologyGraph],
                                              entityTypes: Set[IRI]): Map[SmartIri, Set[SmartIri]] = {
    val entityTypesAsIriLiterals = entityTypes.map(entityType => IriLiteralV2(entityType))

    ontologyGraphs.map { ontologyGraph =>
      val entityIrisInGraph: Set[SmartIri] = ontologyGraph.constructResponse.statements.foldLeft(Set.empty[SmartIri]) {
        case (acc, (subjectIri: IriSubjectV2, subjectStatements: Map[SmartIri, Seq[LiteralV2]])) =>
          val subjectTypeLiterals: Seq[IriLiteralV2] = subjectStatements
            .getOrElse(OntologyConstants.Rdf.Type.toSmartIri,
                       throw InconsistentRepositoryDataException(s"Subject $subjectIri has no rdf:type"))
            .collect {
              case iriLiteral: IriLiteralV2 => iriLiteral
            }

          if (subjectTypeLiterals.exists(entityTypesAsIriLiterals.contains)) {
            acc + subjectIri.value.toSmartIri
          } else {
            acc
          }

        case (acc, _) => acc
      }

      ontologyGraph.ontologyIri -> entityIrisInGraph
    }.toMap
  }

  /**
    * Given the triplestore's response to `getAllOntologyMetadata.scala.txt`, constructs a map of ontology IRIs
    * to ontology metadata for the ontology cache.
    *
    * @param allOntologyMetadataResponse the triplestore's response to the SPARQL query `getAllOntologyMetadata.scala.txt`.
    * @return a map of ontology IRIs to ontology metadata.
    */
  private def buildOntologyMetadata(
      allOntologyMetadataResponse: SparqlSelectResult): Map[SmartIri, OntologyMetadataV2] = {
    allOntologyMetadataResponse.results.bindings.groupBy(_.rowMap("ontologyGraph")).map {
      case (ontologyGraph: IRI, rows: Seq[VariableResultsRow]) =>
        val ontologyIri = rows.head.rowMap("ontologyIri")

        if (ontologyIri != ontologyGraph) {
          throw InconsistentRepositoryDataException(
            s"Ontology $ontologyIri must be stored in named graph $ontologyIri, but it is in $ontologyGraph")
        }

        val ontologySmartIri = ontologyIri.toSmartIri

        if (!ontologySmartIri.isKnoraOntologyIri) {
          throw InconsistentRepositoryDataException(s"Ontology $ontologySmartIri is not a Knora ontology")
        }

        val ontologyMetadataMap: Map[IRI, String] = rows.map { row =>
          val pred =
            row.rowMap.getOrElse("ontologyPred",
                                 throw InconsistentRepositoryDataException(s"Empty predicate in ontology $ontologyIri"))
          val obj = row.rowMap.getOrElse(
            "ontologyObj",
            throw InconsistentRepositoryDataException(s"Empty object for predicate $pred in ontology $ontologyIri"))
          pred -> obj
        }.toMap

        val projectIri: SmartIri = ontologyMetadataMap
          .getOrElse(
            OntologyConstants.KnoraBase.AttachedToProject,
            throw InconsistentRepositoryDataException(s"Ontology $ontologyIri has no knora-base:attachedToProject"))
          .toSmartIri
        val ontologyLabel: String =
          ontologyMetadataMap.getOrElse(OntologyConstants.Rdfs.Label, ontologySmartIri.getOntologyName)
        val lastModificationDate: Option[Instant] = ontologyMetadataMap
          .get(OntologyConstants.KnoraBase.LastModificationDate)
          .map(
            instant =>
              stringFormatter.xsdDateTimeStampToInstant(
                instant,
                throw InconsistentRepositoryDataException(s"Invalid UTC instant: $instant")))
        val ontologyVersion: Option[String] = ontologyMetadataMap.get(OntologyConstants.KnoraBase.OntologyVersion)

        ontologySmartIri -> OntologyMetadataV2(
          ontologyIri = ontologySmartIri,
          projectIri = Some(projectIri),
          label = Some(ontologyLabel),
          lastModificationDate = lastModificationDate,
          ontologyVersion = ontologyVersion
        )
    }
  }

  /**
    * Constructs a map of class IRIs to [[ReadClassInfoV2]] instances, based on class definitions loaded from the
    * triplestore.
    *
    * @param classDefs                         a map of class IRIs to class definitions.
    * @param directClassCardinalities          a map of the cardinalities defined directly on each class. Each resource class
    *                                          IRI points to a map of property IRIs to [[OwlCardinalityInfo]] objects.
    * @param classCardinalitiesWithInheritance a map of the cardinalities defined directly on each class or inherited from
    *                                          base classes. Each class IRI points to a map of property IRIs to
    *                                          [[OwlCardinalityInfo]] objects.
    * @param directSubClassOfRelations         a map of class IRIs to their immediate base classes.
    * @param allSubClassOfRelations            a map of class IRIs to all their base classes.
    * @param allSubPropertyOfRelations         a map of property IRIs to all their base properties.
    * @param allPropertyDefs                   a map of property IRIs to property definitions.
    * @param allKnoraResourceProps             a set of the IRIs of all Knora resource properties.
    * @param allLinkProps                      a set of the IRIs of all link properties.
    * @param allLinkValueProps                 a set of the IRIs of link value properties.
    * @param allFileValueProps                 a set of the IRIs of all file value properties.
    * @return a map of resource class IRIs to their definitions.
    */
  private def makeReadClassInfos(classDefs: Map[SmartIri, ClassInfoContentV2],
                                 directClassCardinalities: Map[SmartIri, Map[SmartIri, OwlCardinalityInfo]],
                                 classCardinalitiesWithInheritance: Map[SmartIri, Map[SmartIri, OwlCardinalityInfo]],
                                 directSubClassOfRelations: Map[SmartIri, Set[SmartIri]],
                                 allSubClassOfRelations: Map[SmartIri, Seq[SmartIri]],
                                 allSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]],
                                 allPropertyDefs: Map[SmartIri, PropertyInfoContentV2],
                                 allKnoraResourceProps: Set[SmartIri],
                                 allLinkProps: Set[SmartIri],
                                 allLinkValueProps: Set[SmartIri],
                                 allFileValueProps: Set[SmartIri]): Map[SmartIri, ReadClassInfoV2] = {
    classDefs.map {
      case (classIri, classDef) =>
        val ontologyIri = classIri.getOntologyFromEntity

        // Get the OWL cardinalities for the class.
        val allOwlCardinalitiesForClass: Map[SmartIri, OwlCardinalityInfo] = classCardinalitiesWithInheritance(classIri)
        val allPropertyIrisForCardinalitiesInClass: Set[SmartIri] = allOwlCardinalitiesForClass.keys.toSet

        // Identify the Knora resource properties, link properties, link value properties, and file value properties in the cardinalities.
        val knoraResourcePropsInClass = allPropertyIrisForCardinalitiesInClass.filter(allKnoraResourceProps)
        val linkPropsInClass = allPropertyIrisForCardinalitiesInClass.filter(allLinkProps)
        val linkValuePropsInClass = allPropertyIrisForCardinalitiesInClass.filter(allLinkValueProps)
        val fileValuePropsInClass = allPropertyIrisForCardinalitiesInClass.filter(allFileValueProps)

        // Make sure there is a link value property for each link property.

        val missingLinkValueProps = linkPropsInClass.map(_.fromLinkPropToLinkValueProp) -- linkValuePropsInClass

        if (missingLinkValueProps.nonEmpty) {
          throw InconsistentRepositoryDataException(
            s"Resource class $classIri has cardinalities for one or more link properties without corresponding link value properties. The missing (or incorrectly defined) property or properties: ${missingLinkValueProps
              .mkString(", ")}")
        }

        // Make sure there is a link property for each link value property.

        val missingLinkProps = linkValuePropsInClass.map(_.fromLinkValuePropToLinkProp) -- linkPropsInClass

        if (missingLinkProps.nonEmpty) {
          throw InconsistentRepositoryDataException(
            s"Resource class $classIri has cardinalities for one or more link value properties without corresponding link properties. The missing (or incorrectly defined) property or properties: ${missingLinkProps
              .mkString(", ")}")
        }

        // Make sure that the cardinality for each link property is the same as the cardinality for the corresponding link value property.
        for (linkProp <- linkPropsInClass) {
          val linkValueProp: SmartIri = linkProp.fromLinkPropToLinkValueProp
          val linkPropCardinality: OwlCardinalityInfo = allOwlCardinalitiesForClass(linkProp)
          val linkValuePropCardinality: OwlCardinalityInfo = allOwlCardinalitiesForClass(linkValueProp)

          if (!linkPropCardinality.equalsWithoutGuiOrder(linkValuePropCardinality)) {
            throw InconsistentRepositoryDataException(
              s"In class $classIri, the cardinality for $linkProp is different from the cardinality for $linkValueProp")
          }
        }

        // The class's direct cardinalities.

        val directCardinalities: Map[SmartIri, KnoraCardinalityInfo] = directClassCardinalities(classIri).map {
          case (propertyIri, owlCardinalityInfo) =>
            propertyIri -> Cardinality.owlCardinality2KnoraCardinality(propertyIri = propertyIri.toString,
                                                                       owlCardinality = owlCardinalityInfo)
        }

        val directCardinalityPropertyIris = directCardinalities.keySet
        val allBaseClasses: Seq[SmartIri] = allSubClassOfRelations(classIri)
        val isKnoraResourceClass = allBaseClasses.contains(OntologyConstants.KnoraBase.Resource.toSmartIri)
        val isStandoffClass = allBaseClasses.contains(OntologyConstants.KnoraBase.StandoffTag.toSmartIri)
        val isValueClass = !(isKnoraResourceClass || isStandoffClass) && allBaseClasses.contains(
          OntologyConstants.KnoraBase.Value.toSmartIri)

        // If the class is defined in project-specific ontology, do the following checks.
        if (!ontologyIri.isKnoraBuiltInDefinitionIri) {
          // It must be either a resource class or a standoff class, but not both.
          if (!(isKnoraResourceClass ^ isStandoffClass)) {
            throw InconsistentRepositoryDataException(
              s"Class $classIri must be a subclass either of knora-base:Resource or of knora-base:StandoffTag (but not both)")
          }

          // All its cardinalities must be on properties that are defined.
          val cardinalitiesOnMissingProps = directCardinalityPropertyIris.filterNot(allPropertyDefs.keySet)

          if (cardinalitiesOnMissingProps.nonEmpty) {
            throw InconsistentRepositoryDataException(
              s"Class $classIri has one or more cardinalities on undefined properties: ${cardinalitiesOnMissingProps
                .mkString(", ")}")
          }

          // It cannot have cardinalities both on property P and on a subproperty of P.

          val maybePropertyAndSubproperty: Option[(SmartIri, SmartIri)] = findPropertyAndSubproperty(
            propertyIris = allPropertyIrisForCardinalitiesInClass,
            subPropertyOfRelations = allSubPropertyOfRelations
          )

          maybePropertyAndSubproperty match {
            case Some((basePropertyIri, propertyIri)) =>
              throw InconsistentRepositoryDataException(
                s"Class $classIri has a cardinality on property $basePropertyIri and on its subproperty $propertyIri")

            case None => ()
          }

          if (isKnoraResourceClass) {
            // If it's a resource class, all its directly defined cardinalities must be on Knora resource properties, not including knora-base:resourceProperty or knora-base:hasValue.

            val cardinalitiesOnInvalidProps = directCardinalityPropertyIris.filterNot(allKnoraResourceProps)

            if (cardinalitiesOnInvalidProps.nonEmpty) {
              throw InconsistentRepositoryDataException(
                s"Resource class $classIri has one or more cardinalities on properties that are not Knora resource properties: ${cardinalitiesOnInvalidProps
                  .mkString(", ")}")
            }

            Set(OntologyConstants.KnoraBase.ResourceProperty, OntologyConstants.KnoraBase.HasValue).foreach {
              invalidProp =>
                if (directCardinalityPropertyIris.contains(invalidProp.toSmartIri)) {
                  throw InconsistentRepositoryDataException(
                    s"Class $classIri has a cardinality on property $invalidProp, which is not allowed")
                }
            }

            // Check for invalid cardinalities on boolean properties.
            checkForInvalidBooleanCardinalities(
              classIri = classIri,
              directCardinalities = directCardinalities,
              allPropertyDefs = allPropertyDefs,
              schemaForErrors = InternalSchema,
              errorFun = { msg: String =>
                throw InconsistentRepositoryDataException(msg)
              }
            )

            // All its base classes with Knora IRIs must also be resource classes.
            for (baseClass <- classDef.subClassOf) {
              if (baseClass.isKnoraDefinitionIri && !allSubClassOfRelations(baseClass).contains(
                    OntologyConstants.KnoraBase.Resource.toSmartIri)) {
                throw InconsistentRepositoryDataException(
                  s"Class $classIri is a subclass of knora-base:Resource, but its base class $baseClass is not")
              }
            }

            // It must have an rdfs:label.
            if (!classDef.predicates.contains(OntologyConstants.Rdfs.Label.toSmartIri)) {
              throw InconsistentRepositoryDataException(s"Class $classIri has no rdfs:label")
            }
          } else {
            // If it's a standoff class, none of its cardinalities must be on Knora resource properties.

            val cardinalitiesOnInvalidProps = directCardinalityPropertyIris.filter(allKnoraResourceProps)

            if (cardinalitiesOnInvalidProps.nonEmpty) {
              throw InconsistentRepositoryDataException(
                s"Standoff class $classIri has one or more cardinalities on properties that are Knora resource properties: ${cardinalitiesOnInvalidProps
                  .mkString(", ")}")
            }

            // All its base classes with Knora IRIs must also be standoff classes.
            for (baseClass <- classDef.subClassOf) {
              if (baseClass.isKnoraDefinitionIri) {
                if (isStandoffClass && !allSubClassOfRelations(baseClass).contains(
                      OntologyConstants.KnoraBase.StandoffTag.toSmartIri)) {
                  throw InconsistentRepositoryDataException(
                    s"Class $classIri is a subclass of knora-base:StandoffTag, but its base class $baseClass is not")
                }
              }
            }
          }
        }

        // Each class must be a subclass of all the classes that are subject class constraints of the properties in its cardinalities.
        checkSubjectClassConstraintsViaCardinalities(
          internalClassDef = classDef,
          allBaseClassIris = allBaseClasses.toSet,
          allClassCardinalityKnoraPropertyDefs = allPropertyDefs.filterKeys(allOwlCardinalitiesForClass.keySet),
          errorSchema = InternalSchema,
          errorFun = { msg: String =>
            throw InconsistentRepositoryDataException(msg)
          }
        )

        val inheritedCardinalities: Map[SmartIri, KnoraCardinalityInfo] = allOwlCardinalitiesForClass
          .filterNot {
            case (propertyIri, _) => directCardinalityPropertyIris.contains(propertyIri)
          }
          .map {
            case (propertyIri, owlCardinalityInfo) =>
              propertyIri -> Cardinality.owlCardinality2KnoraCardinality(propertyIri = propertyIri.toString,
                                                                         owlCardinality = owlCardinalityInfo)
          }

        // Get the class's standoff data type, if any. A standoff class that has a datatype is a subclass of one of the classes
        // in StandoffDataTypeClasses.

        val standoffDataType: Set[SmartIri] = allSubClassOfRelations(classIri).toSet
          .intersect(StandoffDataTypeClasses.getStandoffClassIris.map(_.toSmartIri))

        if (standoffDataType.size > 1) {
          throw InconsistentRepositoryDataException(
            s"Class $classIri is a subclass of more than one standoff datatype: ${standoffDataType.mkString(", ")}")
        }

        // A class can be instantiated if it's in a built-in ontology and marked with knora-base:canBeInstantiated, or if it's
        // a resource class in a project-specific ontology.
        val canBeInstantiated = if (ontologyIri.isKnoraBuiltInDefinitionIri) {
          classDef.predicates
            .get(OntologyConstants.KnoraBase.CanBeInstantiated.toSmartIri)
            .flatMap(_.objects.headOption) match {
            case Some(booleanLiteral: BooleanLiteralV2) => booleanLiteral.value
            case _                                      => false
          }
        } else {
          isKnoraResourceClass
        }

        val readClassInfo = ReadClassInfoV2(
          entityInfoContent = classDef,
          allBaseClasses = allBaseClasses,
          isResourceClass = isKnoraResourceClass,
          isStandoffClass = isStandoffClass,
          isValueClass = isValueClass,
          canBeInstantiated = canBeInstantiated,
          inheritedCardinalities = inheritedCardinalities,
          knoraResourceProperties = knoraResourcePropsInClass,
          linkProperties = linkPropsInClass,
          linkValueProperties = linkValuePropsInClass,
          fileValueProperties = fileValuePropsInClass,
          standoffDataType = standoffDataType.headOption match {
            case Some(dataType: SmartIri) =>
              Some(
                StandoffDataTypeClasses.lookup(
                  dataType.toString,
                  throw InconsistentRepositoryDataException(s"$dataType is not a valid standoff datatype")))

            case None => None
          }
        )

        classIri -> readClassInfo
    }
  }

  /**
    * Checks for invalid cardinalities on boolean properties.
    *
    * @param classIri the class IRI.
    * @param directCardinalities the cardinalities directly defined on the class.
    * @param allPropertyDefs all property definitions.
    */
  def checkForInvalidBooleanCardinalities(classIri: SmartIri,
                                          directCardinalities: Map[SmartIri, KnoraCardinalityInfo],
                                          allPropertyDefs: Map[SmartIri, PropertyInfoContentV2],
                                          schemaForErrors: OntologySchema,
                                          errorFun: String => Nothing): Unit = {
    // A cardinality on a property with a boolean object must be 1 or 0-1.

    val invalidCardinalitiesOnBooleanProps: Set[SmartIri] = directCardinalities.filter {
      case (propertyIri, knoraCardinalityInfo) =>
        val objectClassConstraintIri = OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri

        val propertyObjectClassConstraint: SmartIri = allPropertyDefs(propertyIri).requireIriObject(
          objectClassConstraintIri,
          errorFun(s"Property ${propertyIri
            .toOntologySchema(schemaForErrors)} has no ${objectClassConstraintIri.toOntologySchema(schemaForErrors)}")
        )

        propertyObjectClassConstraint == OntologyConstants.KnoraBase.BooleanValue.toSmartIri &&
        !(knoraCardinalityInfo.cardinality == Cardinality.MustHaveOne || knoraCardinalityInfo.cardinality == Cardinality.MayHaveOne)
    }.keySet

    if (invalidCardinalitiesOnBooleanProps.nonEmpty) {
      errorFun(
        s"Class ${classIri.toOntologySchema(schemaForErrors).toSparql} has one or more invalid cardinalities on boolean properties: ${invalidCardinalitiesOnBooleanProps
          .map(_.toOntologySchema(schemaForErrors).toSparql)
          .mkString(", ")}")
    }
  }

  /**
    * Constructs a map of property IRIs to [[ReadPropertyInfoV2]] instances, based on property definitions loaded from the
    * triplestore.
    *
    * @param propertyDefs                 a map of property IRIs to property definitions.
    * @param directSubPropertyOfRelations a map of property IRIs to their immediate base properties.
    * @param allSubPropertyOfRelations    a map of property IRIs to all their base properties.
    * @param allSubClassOfRelations       a map of class IRIs to all their base classes.
    * @param allGuiAttributeDefinitions   a map of `Guielement` IRIs to sets of [[SalsahGuiAttributeDefinition]].
    * @param allKnoraResourceProps        a set of the IRIs of all Knora resource properties.
    * @param allLinkProps                 a set of the IRIs of all link properties.
    * @param allLinkValueProps            a set of the IRIs of link value properties.
    * @param allFileValueProps            a set of the IRIs of all file value properties.
    * @return a map of property IRIs to [[ReadPropertyInfoV2]] instances.
    */
  private def makeReadPropertyInfos(propertyDefs: Map[SmartIri, PropertyInfoContentV2],
                                    directSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]],
                                    allSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]],
                                    allSubClassOfRelations: Map[SmartIri, Seq[SmartIri]],
                                    allGuiAttributeDefinitions: Map[SmartIri, Set[SalsahGuiAttributeDefinition]],
                                    allKnoraResourceProps: Set[SmartIri],
                                    allLinkProps: Set[SmartIri],
                                    allLinkValueProps: Set[SmartIri],
                                    allFileValueProps: Set[SmartIri]): Map[SmartIri, ReadPropertyInfoV2] = {
    propertyDefs.map {
      case (propertyIri, propertyDef) =>
        val ontologyIri = propertyIri.getOntologyFromEntity

        validateGuiAttributes(
          propertyInfoContent = propertyDef,
          allGuiAttributeDefinitions = allGuiAttributeDefinitions,
          errorFun = { msg: String =>
            throw InconsistentRepositoryDataException(msg)
          }
        )

        val isResourceProp = allKnoraResourceProps.contains(propertyIri)
        val isValueProp =
          allSubPropertyOfRelations(propertyIri).contains(OntologyConstants.KnoraBase.HasValue.toSmartIri)
        val isLinkProp = allLinkProps.contains(propertyIri)
        val isLinkValueProp = allLinkValueProps.contains(propertyIri)
        val isFileValueProp = allFileValueProps.contains(propertyIri)

        // If the property is defined in a project-specific ontology and is a Knora resource property (a subproperty of knora-base:hasValue or knora-base:hasLinkTo), do the following checks.
        if (!propertyIri.isKnoraBuiltInDefinitionIri && isResourceProp) {
          // The property must be a subproperty of knora-base:hasValue or knora-base:hasLinkTo, but not both.
          if (isValueProp && isLinkProp) {
            throw InconsistentRepositoryDataException(
              s"Property $propertyIri cannot be a subproperty of both knora-base:hasValue and knora-base:hasLinkTo")
          }

          // It can't be a subproperty of knora-base:hasFileValue.
          if (isFileValueProp) {
            throw InconsistentRepositoryDataException(
              s"Property $propertyIri cannot be a subproperty of knora-base:hasFileValue")
          }

          // Each of its base properties that has a Knora IRI must also be a Knora resource property.
          for (baseProperty <- propertyDef.subPropertyOf) {
            if (baseProperty.isKnoraDefinitionIri && !allKnoraResourceProps.contains(baseProperty)) {
              throw InconsistentRepositoryDataException(
                s"Property $propertyIri is a subproperty of knora-base:hasValue or knora-base:hasLinkTo, but its base property $baseProperty is not")
            }
          }

          // It must have an rdfs:label.
          if (!propertyDef.predicates.contains(OntologyConstants.Rdfs.Label.toSmartIri)) {
            throw InconsistentRepositoryDataException(s"Property $propertyIri has no rdfs:label")
          }
        }

        // A property is editable if it's in a built-in ontology and marked with knora-base:isEditable,
        // or if it's a resource property in a project-specific ontology.
        val isEditable = if (ontologyIri.isKnoraBuiltInDefinitionIri) {
          propertyDef.predicates
            .get(OntologyConstants.KnoraBase.IsEditable.toSmartIri)
            .flatMap(_.objects.headOption) match {
            case Some(booleanLiteral: BooleanLiteralV2) => booleanLiteral.value
            case _                                      => false
          }
        } else {
          isResourceProp
        }

        val propertyEntityInfo = ReadPropertyInfoV2(
          entityInfoContent = propertyDef,
          isResourceProp = isResourceProp,
          isEditable = isEditable,
          isLinkProp = isLinkProp,
          isLinkValueProp = isLinkValueProp,
          isFileValueProp = isFileValueProp,
          isStandoffInternalReferenceProperty = allSubPropertyOfRelations(propertyIri).contains(
            OntologyConstants.KnoraBase.StandoffTagHasInternalReference.toSmartIri)
        )

        propertyIri -> propertyEntityInfo
    }
  }

  /**
    * Constructs a map of OWL named individual IRIs to [[ReadIndividualInfoV2]] instances.
    *
    * @param individualDefs a map of OWL named individual IRIs to named individuals.
    * @return a map of individual IRIs to [[ReadIndividualInfoV2]] instances.
    */
  private def makeReadIndividualInfos(
      individualDefs: Map[SmartIri, IndividualInfoContentV2]): Map[SmartIri, ReadIndividualInfoV2] = {
    individualDefs.map {
      case (individualIri, individual) =>
        individualIri -> ReadIndividualInfoV2(individual)
    }
  }

  /**
    * Given all the OWL named individuals available, constructs a map of `salsah-gui:Guielement` individuals to
    * their GUI attribute definitions.
    *
    * @param allIndividuals all the OWL named individuals available.
    * @return a map of `salsah-gui:Guielement` individuals to their GUI attribute definitions.
    */
  private def makeGuiAttributeDefinitions(
      allIndividuals: Map[SmartIri, IndividualInfoContentV2]): Map[SmartIri, Set[SalsahGuiAttributeDefinition]] = {
    val guiElementIndividuals: Map[SmartIri, IndividualInfoContentV2] = allIndividuals.filter {
      case (_, individual) => individual.getRdfType.toString == OntologyConstants.SalsahGui.GuiElementClass
    }

    guiElementIndividuals.map {
      case (guiElementIri, guiElementIndividual) =>
        val attributeDefs: Set[SalsahGuiAttributeDefinition] =
          guiElementIndividual.predicates.get(OntologyConstants.SalsahGui.GuiAttributeDefinition.toSmartIri) match {
            case Some(predicateInfo) =>
              predicateInfo.objects.map {
                case StringLiteralV2(attributeDefStr, None) =>
                  stringFormatter.toSalsahGuiAttributeDefinition(
                    attributeDefStr,
                    throw InconsistentRepositoryDataException(
                      s"Invalid salsah-gui:guiAttributeDefinition in $guiElementIri: $attributeDefStr")
                  )

                case other =>
                  throw InconsistentRepositoryDataException(
                    s"Invalid salsah-gui:guiAttributeDefinition in $guiElementIri: $other")
              }.toSet

            case None => Set.empty[SalsahGuiAttributeDefinition]
          }

        guiElementIri -> attributeDefs
    }
  }

  /**
    * Validates the GUI attributes of a resource class property.
    *
    * @param propertyInfoContent        the property definition.
    * @param allGuiAttributeDefinitions the GUI attribute definitions for each GUI element.
    * @param errorFun                   a function that throws an exception. It will be passed the message to be included in the exception.
    */
  private def validateGuiAttributes(propertyInfoContent: PropertyInfoContentV2,
                                    allGuiAttributeDefinitions: Map[SmartIri, Set[SalsahGuiAttributeDefinition]],
                                    errorFun: String => Nothing): Unit = {
    val propertyIri = propertyInfoContent.propertyIri
    val predicates = propertyInfoContent.predicates

    // Find out which salsah-gui:Guielement the property uses, if any.
    val maybeGuiElementPred: Option[PredicateInfoV2] =
      predicates.get(OntologyConstants.SalsahGui.GuiElementProp.toSmartIri)
    val maybeGuiElementIri: Option[SmartIri] = maybeGuiElementPred.map(
      _.requireIriObject(throw InconsistentRepositoryDataException(
        s"Property $propertyIri has an invalid object for ${OntologyConstants.SalsahGui.GuiElementProp}")))

    // Get that Guielement's attribute definitions, if any.
    val guiAttributeDefs: Set[SalsahGuiAttributeDefinition] = maybeGuiElementIri match {
      case Some(guiElementIri) =>
        allGuiAttributeDefinitions.getOrElse(
          guiElementIri,
          errorFun(s"Property $propertyIri has salsah-gui:guiElement $guiElementIri, which doesn't exist"))

      case None => Set.empty[SalsahGuiAttributeDefinition]
    }

    // If the property has the predicate salsah-gui:guiAttribute, syntactically validate the objects of that predicate.
    val guiAttributes: Set[SalsahGuiAttribute] =
      predicates.get(OntologyConstants.SalsahGui.GuiAttribute.toSmartIri) match {
        case Some(guiAttributePred) =>
          val guiElementIri = maybeGuiElementIri.getOrElse(
            errorFun(s"Property $propertyIri has salsah-gui:guiAttribute, but no salsah-gui:guiElement"))

          if (guiAttributeDefs.isEmpty) {
            errorFun(
              s"Property $propertyIri has salsah-gui:guiAttribute, but $guiElementIri has no salsah-gui:guiAttributeDefinition")
          }

          // Syntactically validate each attribute.
          guiAttributePred.objects.map {
            case StringLiteralV2(guiAttributeObj, None) =>
              stringFormatter.toSalsahGuiAttribute(
                s = guiAttributeObj,
                attributeDefs = guiAttributeDefs,
                errorFun =
                  errorFun(s"Property $propertyIri contains an invalid salsah-gui:guiAttribute: $guiAttributeObj")
              )

            case other =>
              errorFun(s"Property $propertyIri contains an invalid salsah-gui:guiAttribute: $other")
          }.toSet

        case None => Set.empty[SalsahGuiAttribute]
      }

    // Check that all required GUI attributes are provided.
    val requiredAttributeNames = guiAttributeDefs.filter(_.isRequired).map(_.attributeName)
    val providedAttributeNames = guiAttributes.map(_.attributeName)
    val missingAttributeNames: Set[String] = requiredAttributeNames -- providedAttributeNames

    if (missingAttributeNames.nonEmpty) {
      errorFun(
        s"Property $propertyIri has one or more missing objects of salsah-gui:guiAttribute: ${missingAttributeNames
          .mkString(", ")}")
    }
  }

  /**
    * Updates the ontology cache.
    *
    * @param cacheData the updated data to be cached.
    */
  private def storeCacheData(cacheData: OntologyCacheData): Unit = {
    CacheUtil.put(cacheName = OntologyCacheName, key = OntologyCacheKey, value = cacheData)
  }

  /**
    * Gets the ontology data from the cache.
    *
    * @return an [[OntologyCacheData]]
    */
  private def getCacheData: Future[OntologyCacheData] = {
    Future {
      CacheUtil.get[OntologyCacheData](cacheName = OntologyCacheName, key = OntologyCacheKey) match {
        case Some(data) => data
        case None =>
          throw ApplicationCacheException(
            s"The Knora API server has not loaded any ontologies, perhaps because of an invalid ontology")
      }
    }
  }

  /**
    * Given a list of resource IRIs and a list of property IRIs (ontology entities), returns an [[EntityInfoGetResponseV2]] describing both resource and property entities.
    *
    * @param classIris      the IRIs of the resource entities to be queried.
    * @param propertyIris   the IRIs of the property entities to be queried.
    * @param requestingUser the user making the request.
    * @return an [[EntityInfoGetResponseV2]].
    */
  private def getEntityInfoResponseV2(classIris: Set[SmartIri] = Set.empty[SmartIri],
                                      propertyIris: Set[SmartIri] = Set.empty[SmartIri],
                                      requestingUser: UserADM): Future[EntityInfoGetResponseV2] = {
    for {
      cacheData <- getCacheData

      // See if any of the requested entities are not Knora entities.

      nonKnoraEntities = (classIris ++ propertyIris).filter(!_.isKnoraEntityIri)

      _ = if (nonKnoraEntities.nonEmpty) {
        throw BadRequestException(s"Some requested entities are not Knora entities: ${nonKnoraEntities.mkString(", ")}")
      }

      // See if any of the requested entities are unavailable in the requested schema.

      classesUnavailableInSchema: Set[SmartIri] = classIris.foldLeft(Set.empty[SmartIri]) {
        case (acc, classIri) =>
          // Is this class IRI hard-coded in the requested schema?
          if (KnoraBaseToApiV2SimpleTransformationRules.externalClassesToAdd.contains(classIri) ||
              KnoraBaseToApiV2ComplexTransformationRules.externalClassesToAdd.contains(classIri)) {
            // Yes, so it's available.
            acc
          } else {
            // No. Is it among the classes removed from the internal ontology in the requested schema?
            classIri.getOntologySchema.get match {
              case apiV2Schema: ApiV2Schema =>
                val internalClassIri = classIri.toOntologySchema(InternalSchema)
                val knoraBaseClassesToRemove = OntologyTransformationRules
                  .getTransformationRules(classIri.getOntologyFromEntity, apiV2Schema)
                  .internalClassesToRemove

                if (knoraBaseClassesToRemove.contains(internalClassIri)) {
                  // Yes. Include it in the set of unavailable classes.
                  acc + classIri
                } else {
                  // No. It's available.
                  acc
                }

              case InternalSchema => acc
            }
          }
      }

      propertiesUnavailableInSchema: Set[SmartIri] = propertyIris.foldLeft(Set.empty[SmartIri]) {
        case (acc, propertyIri) =>
          // Is this property IRI hard-coded in the requested schema?
          if (KnoraBaseToApiV2SimpleTransformationRules.externalPropertiesToAdd.contains(propertyIri) ||
              KnoraBaseToApiV2ComplexTransformationRules.externalPropertiesToAdd.contains(propertyIri)) {
            // Yes, so it's available.
            acc
          } else {
            // No. See if it's available in the requested schema.
            propertyIri.getOntologySchema.get match {
              case apiV2Schema: ApiV2Schema =>
                val internalPropertyIri = propertyIri.toOntologySchema(InternalSchema)

                // If it's a link value property and it's requested in the simple schema, it's unavailable.
                if (apiV2Schema == ApiV2Simple && isLinkValueProp(internalPropertyIri, cacheData)) {
                  acc + propertyIri
                } else {
                  // Is it among the properties removed from the internal ontology in the requested schema?

                  val knoraBasePropertiesToRemove = OntologyTransformationRules
                    .getTransformationRules(propertyIri.getOntologyFromEntity, apiV2Schema)
                    .internalPropertiesToRemove

                  if (knoraBasePropertiesToRemove.contains(internalPropertyIri)) {
                    // Yes. Include it in the set of unavailable properties.
                    acc + propertyIri
                  } else {
                    // No. It's available.
                    acc
                  }
                }

              case InternalSchema => acc
            }
          }
      }

      entitiesUnavailableInSchema = classesUnavailableInSchema ++ propertiesUnavailableInSchema

      _ = if (entitiesUnavailableInSchema.nonEmpty) {
        throw NotFoundException(
          s"Some requested entities were not found: ${entitiesUnavailableInSchema.mkString(", ")}")
      }

      // See if any of the requested entities are hard-coded for knora-api.

      hardCodedExternalClassesAvailable: Map[SmartIri, ReadClassInfoV2] = KnoraBaseToApiV2SimpleTransformationRules.externalClassesToAdd
        .filterKeys(classIris) ++
        KnoraBaseToApiV2ComplexTransformationRules.externalClassesToAdd.filterKeys(classIris)

      hardCodedExternalPropertiesAvailable: Map[SmartIri, ReadPropertyInfoV2] = KnoraBaseToApiV2SimpleTransformationRules.externalPropertiesToAdd
        .filterKeys(propertyIris) ++
        KnoraBaseToApiV2ComplexTransformationRules.externalPropertiesToAdd.filterKeys(propertyIris)

      // Convert the remaining external entity IRIs to internal ones.

      internalToExternalClassIris: Map[SmartIri, SmartIri] = (classIris -- hardCodedExternalClassesAvailable.keySet)
        .map(externalIri => externalIri.toOntologySchema(InternalSchema) -> externalIri)
        .toMap
      internalToExternalPropertyIris: Map[SmartIri, SmartIri] = (propertyIris -- hardCodedExternalPropertiesAvailable.keySet)
        .map(externalIri => externalIri.toOntologySchema(InternalSchema) -> externalIri)
        .toMap

      classIrisForCache = internalToExternalClassIris.keySet
      propertyIrisForCache = internalToExternalPropertyIris.keySet

      // Get the entities that are available in the ontology cache.

      classOntologiesForCache: Iterable[ReadOntologyV2] = cacheData.ontologies
        .filterKeys(classIrisForCache.map(_.getOntologyFromEntity))
        .values
      propertyOntologiesForCache: Iterable[ReadOntologyV2] = cacheData.ontologies
        .filterKeys(propertyIrisForCache.map(_.getOntologyFromEntity))
        .values

      classesAvailableFromCache: Map[SmartIri, ReadClassInfoV2] = classOntologiesForCache.flatMap { ontology =>
        ontology.classes.filterKeys(classIrisForCache)
      }.toMap

      propertiesAvailableFromCache: Map[SmartIri, ReadPropertyInfoV2] = propertyOntologiesForCache.flatMap { ontology =>
        ontology.properties.filterKeys(propertyIrisForCache)
      }.toMap

      allClassesAvailable: Map[SmartIri, ReadClassInfoV2] = classesAvailableFromCache ++ hardCodedExternalClassesAvailable
      allPropertiesAvailable: Map[SmartIri, ReadPropertyInfoV2] = propertiesAvailableFromCache ++ hardCodedExternalPropertiesAvailable

      // See if any entities are missing.

      allExternalClassIrisAvailable: Set[SmartIri] = allClassesAvailable.keySet.map { classIri =>
        if (classIri.getOntologySchema.contains(InternalSchema)) {
          internalToExternalClassIris(classIri)
        } else {
          classIri
        }
      }

      allExternalPropertyIrisAvailable = allPropertiesAvailable.keySet.map { propertyIri =>
        if (propertyIri.getOntologySchema.contains(InternalSchema)) {
          internalToExternalPropertyIris(propertyIri)
        } else {
          propertyIri
        }
      }

      missingClasses = classIris -- allExternalClassIrisAvailable
      missingProperties = propertyIris -- allExternalPropertyIrisAvailable

      missingEntities = missingClasses ++ missingProperties

      _ = if (missingEntities.nonEmpty) {
        throw NotFoundException(s"Some requested entities were not found: ${missingEntities.mkString(", ")}")
      }

      response = EntityInfoGetResponseV2(
        classInfoMap = new ErrorHandlingMap(allClassesAvailable, { key =>
          s"Resource class $key not found"
        }),
        propertyInfoMap = new ErrorHandlingMap(allPropertiesAvailable, { key =>
          s"Property $key not found"
        })
      )
    } yield response
  }

  /**
    * Given a list of standoff class IRIs and a list of property IRIs (ontology entities), returns an [[StandoffEntityInfoGetResponseV2]] describing both resource and property entities.
    *
    * @param standoffClassIris    the IRIs of the resource entities to be queried.
    * @param standoffPropertyIris the IRIs of the property entities to be queried.
    * @param requestingUser       the user making the request.
    * @return a [[StandoffEntityInfoGetResponseV2]].
    */
  private def getStandoffEntityInfoResponseV2(standoffClassIris: Set[SmartIri] = Set.empty[SmartIri],
                                              standoffPropertyIris: Set[SmartIri] = Set.empty[SmartIri],
                                              requestingUser: UserADM): Future[StandoffEntityInfoGetResponseV2] = {
    for {
      cacheData <- getCacheData

      entitiesInWrongSchema = (standoffClassIris ++ standoffPropertyIris).filter(
        _.getOntologySchema.contains(ApiV2Simple))

      _ = if (entitiesInWrongSchema.nonEmpty) {
        throw NotFoundException(
          s"Some requested standoff classes were not found: ${entitiesInWrongSchema.mkString(", ")}")
      }

      classIrisForCache = standoffClassIris.map(_.toOntologySchema(InternalSchema))
      propertyIrisForCache = standoffPropertyIris.map(_.toOntologySchema(InternalSchema))

      classOntologies: Iterable[ReadOntologyV2] = cacheData.ontologies
        .filterKeys(classIrisForCache.map(_.getOntologyFromEntity))
        .values
      propertyOntologies: Iterable[ReadOntologyV2] = cacheData.ontologies
        .filterKeys(propertyIrisForCache.map(_.getOntologyFromEntity))
        .values

      classDefsAvailable: Map[SmartIri, ReadClassInfoV2] = classOntologies.flatMap { ontology =>
        ontology.classes.filter {
          case (classIri, classDef) => classDef.isStandoffClass && standoffClassIris.contains(classIri)
        }
      }.toMap

      propertyDefsAvailable: Map[SmartIri, ReadPropertyInfoV2] = propertyOntologies.flatMap { ontology =>
        ontology.properties.filter {
          case (propertyIri, _) =>
            standoffPropertyIris.contains(propertyIri) && cacheData.standoffProperties.contains(propertyIri)
        }
      }.toMap

      missingClassDefs = classIrisForCache -- classDefsAvailable.keySet
      missingPropertyDefs = propertyIrisForCache -- propertyDefsAvailable.keySet

      _ = if (missingClassDefs.nonEmpty) {
        throw NotFoundException(s"Some requested standoff classes were not found: ${missingClassDefs.mkString(", ")}")
      }

      _ = if (missingPropertyDefs.nonEmpty) {
        throw NotFoundException(
          s"Some requested standoff properties were not found: ${missingPropertyDefs.mkString(", ")}")
      }

      response = StandoffEntityInfoGetResponseV2(
        standoffClassInfoMap = new ErrorHandlingMap(classDefsAvailable, { key =>
          s"Resource class $key not found"
        }),
        standoffPropertyInfoMap = new ErrorHandlingMap(propertyDefsAvailable, { key =>
          s"Property $key not found"
        })
      )
    } yield response
  }

  /**
    * Gets information about all standoff classes that are a subclass of a data type standoff class.
    *
    * @param requestingUser the user making the request.
    * @return a [[StandoffClassesWithDataTypeGetResponseV2]]
    */
  private def getStandoffStandoffClassesWithDataTypeV2(
      requestingUser: UserADM): Future[StandoffClassesWithDataTypeGetResponseV2] = {
    for {
      cacheData <- getCacheData
    } yield
      StandoffClassesWithDataTypeGetResponseV2(
        standoffClassInfoMap = cacheData.ontologies.values.flatMap { ontology =>
          ontology.classes.filter {
            case (_, classDef) => classDef.isStandoffClass && classDef.standoffDataType.isDefined
          }
        }.toMap
      )
  }

  /**
    * Gets all standoff property entities.
    *
    * @param requestingUser the user making the request.
    * @return a [[StandoffAllPropertyEntitiesGetResponseV2]].
    */
  private def getAllStandoffPropertyEntitiesV2(
      requestingUser: UserADM): Future[StandoffAllPropertyEntitiesGetResponseV2] = {
    for {
      cacheData <- getCacheData
    } yield
      StandoffAllPropertyEntitiesGetResponseV2(
        standoffAllPropertiesEntityInfoMap = cacheData.ontologies.values.flatMap { ontology =>
          ontology.properties.filterKeys(cacheData.standoffProperties)
        }.toMap
      )
  }

  /**
    * Checks whether a certain Knora resource or value class is a subclass of another class.
    *
    * @param subClassIri   the IRI of the resource or value class whose subclassOf relations have to be checked.
    * @param superClassIri the IRI of the resource or value class to check for (whether it is a a super class of `subClassIri` or not).
    * @return a [[CheckSubClassResponseV2]].
    */
  private def checkSubClassV2(subClassIri: SmartIri, superClassIri: SmartIri): Future[CheckSubClassResponseV2] = {
    for {
      cacheData <- getCacheData
      response = CheckSubClassResponseV2(
        isSubClass = cacheData.subClassOfRelations.get(subClassIri) match {
          case Some(baseClasses) => baseClasses.contains(superClassIri)
          case None              => throw BadRequestException(s"Class $subClassIri not found")
        }
      )
    } yield response
  }

  /**
    * Gets the IRIs of the subclasses of a class.
    *
    * @param classIri the IRI of the class whose subclasses should be returned.
    * @return a [[SubClassesGetResponseV2]].
    */
  private def getSubClassesV2(classIri: SmartIri, requestingUser: UserADM): Future[SubClassesGetResponseV2] = {
    for {
      cacheData <- getCacheData

      subClassIris = cacheData.superClassOfRelations(classIri).toVector.sorted

      subClasses = subClassIris.map { subClassIri =>
        val classInfo: ReadClassInfoV2 = cacheData.ontologies(subClassIri.getOntologyFromEntity).classes(subClassIri)

        SubClassInfoV2(
          id = subClassIri,
          label = classInfo.entityInfoContent
            .getPredicateStringLiteralObject(
              predicateIri = OntologyConstants.Rdfs.Label.toSmartIri,
              preferredLangs = Some(requestingUser.lang, settings.fallbackLanguage)
            )
            .getOrElse(throw InconsistentRepositoryDataException(s"Resource class $subClassIri has no rdfs:label"))
        )
      }
    } yield
      SubClassesGetResponseV2(
        subClasses = subClasses
      )
  }

  /**
    * Gets the [[OntologyKnoraEntitiesIriInfoV2]] for an ontology.
    *
    * @param ontologyIri    the IRI of the ontology to query
    * @param requestingUser the user making the request.
    * @return an [[OntologyKnoraEntitiesIriInfoV2]].
    */
  private def getKnoraEntityIrisInNamedGraphV2(ontologyIri: SmartIri,
                                               requestingUser: UserADM): Future[OntologyKnoraEntitiesIriInfoV2] = {
    for {
      cacheData <- getCacheData
      ontology = cacheData.ontologies(ontologyIri)
    } yield
      OntologyKnoraEntitiesIriInfoV2(
        ontologyIri = ontologyIri,
        propertyIris = ontology.properties.keySet.filter { propertyIri =>
          isKnoraResourceProperty(propertyIri, cacheData)
        },
        classIris = ontology.classes.filter {
          case (_, classDef) => classDef.isResourceClass
        }.keySet,
        standoffClassIris = ontology.classes.filter {
          case (_, classDef) => classDef.isStandoffClass
        }.keySet,
        standoffPropertyIris = ontology.properties.keySet.filter(cacheData.standoffProperties)
      )
  }

  /**
    * Gets the metadata describing the ontologies that belong to selected projects, or to all projects.
    *
    * @param projectIris    the IRIs of the projects selected, or an empty set if all projects are selected.
    * @param requestingUser the user making the request.
    * @return a [[ReadOntologyMetadataV2]].
    */
  private def getOntologyMetadataForProjectsV2(projectIris: Set[SmartIri],
                                               requestingUser: UserADM): Future[ReadOntologyMetadataV2] = {
    for {
      cacheData <- getCacheData
      returnAllOntologies: Boolean = projectIris.isEmpty

      ontologyMetadata: Set[OntologyMetadataV2] = if (returnAllOntologies) {
        cacheData.ontologies.values.map(_.ontologyMetadata).toSet
      } else {
        cacheData.ontologies.values
          .filter { ontology =>
            projectIris.contains(ontology.ontologyMetadata.projectIri.get)
          }
          .map { ontology =>
            ontology.ontologyMetadata
          }
          .toSet
      }
    } yield
      ReadOntologyMetadataV2(
        ontologies = ontologyMetadata
      )
  }

  /**
    * Gets the metadata describing the specified ontologies, or all ontologies.
    *
    * @param ontologyIris   the IRIs of the ontologies selected, or an empty set if all ontologies are selected.
    * @param requestingUser the user making the request.
    * @return a [[ReadOntologyMetadataV2]].
    */
  private def getOntologyMetadataByIriV2(ontologyIris: Set[SmartIri],
                                         requestingUser: UserADM): Future[ReadOntologyMetadataV2] = {
    for {
      cacheData <- getCacheData
      returnAllOntologies: Boolean = ontologyIris.isEmpty

      ontologyMetadata: Set[OntologyMetadataV2] = if (returnAllOntologies) {
        cacheData.ontologies.values.map(_.ontologyMetadata).toSet
      } else {
        val ontologyIrisForCache = ontologyIris.map(_.toOntologySchema(InternalSchema))
        val missingOntologies = ontologyIrisForCache -- cacheData.ontologies.keySet

        if (missingOntologies.nonEmpty) {
          throw BadRequestException(
            s"One or more requested ontologies were not found: ${missingOntologies.mkString(", ")}")
        }

        cacheData.ontologies
          .filterKeys(ontologyIrisForCache)
          .values
          .map { ontology =>
            ontology.ontologyMetadata
          }
          .toSet
      }
    } yield
      ReadOntologyMetadataV2(
        ontologies = ontologyMetadata
      )
  }

  /**
    * Requests the entities defined in the given ontology.
    *
    * @param ontologyIri    the IRI (internal or external) of the ontology to be queried.
    * @param requestingUser the user making the request.
    * @return a [[ReadOntologyV2]].
    */
  private def getOntologyEntitiesV2(ontologyIri: SmartIri,
                                    allLanguages: Boolean,
                                    requestingUser: UserADM): Future[ReadOntologyV2] = {
    for {
      cacheData <- getCacheData

      _ = if (ontologyIri.getOntologyName == "standoff" && ontologyIri.getOntologySchema.contains(ApiV2Simple)) {
        throw BadRequestException(s"The standoff ontology is not available in the API v2 simple schema")
      }

      ontology = cacheData.ontologies.get(ontologyIri.toOntologySchema(InternalSchema)) match {
        case Some(cachedOntology) => cachedOntology
        case None                 => throw NotFoundException(s"Ontology not found: $ontologyIri")
      }

      // Are we returning data in the user's preferred language, or in all available languages?
      userLang = if (!allLanguages) {
        // Just the user's preferred language.
        Some(requestingUser.lang)
      } else {
        // All available languages.
        None
      }
    } yield
      ontology.copy(
        userLang = userLang
      )
  }

  /**
    * Requests information about OWL classes in a single ontology.
    *
    * @param classIris      the IRIs (internal or external) of the classes to query for.
    * @param requestingUser the user making the request.
    * @return a [[ReadOntologyV2]].
    */
  private def getClassDefinitionsFromOntologyV2(classIris: Set[SmartIri],
                                                allLanguages: Boolean,
                                                requestingUser: UserADM): Future[ReadOntologyV2] = {
    for {
      cacheData <- getCacheData

      ontologyIris = classIris.map(_.getOntologyFromEntity)

      _ = if (ontologyIris.size != 1) {
        throw BadRequestException(s"Only one ontology may be queried per request")
      }

      classInfoResponse: EntityInfoGetResponseV2 <- getEntityInfoResponseV2(classIris = classIris,
                                                                            requestingUser = requestingUser)
      internalOntologyIri = ontologyIris.head.toOntologySchema(InternalSchema)

      // Are we returning data in the user's preferred language, or in all available languages?
      userLang = if (!allLanguages) {
        // Just the user's preferred language.
        Some(requestingUser.lang)
      } else {
        // All available languages.
        None
      }
    } yield
      ReadOntologyV2(
        ontologyMetadata = cacheData.ontologies(internalOntologyIri).ontologyMetadata,
        classes = classInfoResponse.classInfoMap,
        userLang = userLang
      )
  }

  /**
    * Requests information about properties in a single ontology.
    *
    * @param propertyIris   the IRIs (internal or external) of the properties to query for.
    * @param requestingUser the user making the request.
    * @return a [[ReadOntologyV2]].
    */
  private def getPropertyDefinitionsFromOntologyV2(propertyIris: Set[SmartIri],
                                                   allLanguages: Boolean,
                                                   requestingUser: UserADM): Future[ReadOntologyV2] = {
    for {
      cacheData <- getCacheData

      ontologyIris = propertyIris.map(_.getOntologyFromEntity)

      _ = if (ontologyIris.size != 1) {
        throw BadRequestException(s"Only one ontology may be queried per request")
      }

      propertyInfoResponse: EntityInfoGetResponseV2 <- getEntityInfoResponseV2(propertyIris = propertyIris,
                                                                               requestingUser = requestingUser)
      internalOntologyIri = ontologyIris.head.toOntologySchema(InternalSchema)

      // Are we returning data in the user's preferred language, or in all available languages?
      userLang = if (!allLanguages) {
        // Just the user's preferred language.
        Some(requestingUser.lang)
      } else {
        // All available languages.
        None
      }
    } yield
      ReadOntologyV2(
        ontologyMetadata = cacheData.ontologies(internalOntologyIri).ontologyMetadata,
        properties = propertyInfoResponse.propertyInfoMap,
        userLang = userLang
      )
  }

  /**
    * Reads an ontology's metadata.
    *
    * @param internalOntologyIri  the ontology's internal IRI.
    * @param featureFactoryConfig the feature factory configuration.
    * @return an [[OntologyMetadataV2]], or [[None]] if the ontology is not found.
    */
  private def loadOntologyMetadata(internalOntologyIri: SmartIri,
                                   featureFactoryConfig: FeatureFactoryConfig): Future[Option[OntologyMetadataV2]] = {
    for {
      _ <- Future {
        if (!internalOntologyIri.getOntologySchema.contains(InternalSchema)) {
          throw AssertionException(s"Expected an internal ontology IRI: $internalOntologyIri")
        }
      }

      getOntologyInfoSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
        .getOntologyInfo(
          triplestore = settings.triplestoreType,
          ontologyIri = internalOntologyIri
        )
        .toString()

      getOntologyInfoResponse <- (storeManager ? SparqlConstructRequest(
        sparql = getOntologyInfoSparql,
        featureFactoryConfig = featureFactoryConfig
      )).mapTo[SparqlConstructResponse]

      metadata: Option[OntologyMetadataV2] = if (getOntologyInfoResponse.statements.isEmpty) {
        None
      } else {
        getOntologyInfoResponse.statements.get(internalOntologyIri.toString) match {
          case Some(statements: Seq[(IRI, String)]) =>
            val statementMap: Map[IRI, Seq[String]] = statements
              .groupBy {
                case (pred, _) => pred
              }
              .map {
                case (pred, predStatements) =>
                  pred -> predStatements.map {
                    case (_, obj) => obj
                  }
              }

            val projectIris: Seq[String] = statementMap.getOrElse(
              OntologyConstants.KnoraBase.AttachedToProject,
              throw InconsistentRepositoryDataException(
                s"Ontology $internalOntologyIri has no knora-base:attachedToProject")
            )
            val labels: Seq[String] = statementMap.getOrElse(OntologyConstants.Rdfs.Label, Seq.empty[String])
            val comments: Seq[String] = statementMap.getOrElse(OntologyConstants.Rdfs.Comment, Seq.empty[String])
            val lastModDates: Seq[String] =
              statementMap.getOrElse(OntologyConstants.KnoraBase.LastModificationDate, Seq.empty[String])

            val projectIri = if (projectIris.size > 1) {
              throw InconsistentRepositoryDataException(
                s"Ontology $internalOntologyIri has more than one knora-base:attachedToProject")
            } else {
              projectIris.head.toSmartIri
            }

            if (!internalOntologyIri.isKnoraBuiltInDefinitionIri) {
              if (projectIri.toString == OntologyConstants.KnoraAdmin.SystemProject) {
                throw InconsistentRepositoryDataException(
                  s"Ontology $internalOntologyIri cannot be in project ${OntologyConstants.KnoraAdmin.SystemProject}")
              }

              if (internalOntologyIri.isKnoraSharedDefinitionIri && projectIri.toString != OntologyConstants.KnoraAdmin.DefaultSharedOntologiesProject) {
                throw InconsistentRepositoryDataException(
                  s"Shared ontology $internalOntologyIri must be in project ${OntologyConstants.KnoraAdmin.DefaultSharedOntologiesProject}")
              }
            }

            val label: String = if (labels.size > 1) {
              throw InconsistentRepositoryDataException(s"Ontology $internalOntologyIri has more than one rdfs:label")
            } else if (labels.isEmpty) {
              internalOntologyIri.getOntologyName
            } else {
              labels.head
            }

            val comment: Option[String] = if (comments.size > 1) {
              throw InconsistentRepositoryDataException(s"Ontology $internalOntologyIri has more than one rdfs:comment")
            } else comments.headOption

            val lastModificationDate: Option[Instant] = if (lastModDates.size > 1) {
              throw InconsistentRepositoryDataException(
                s"Ontology $internalOntologyIri has more than one ${OntologyConstants.KnoraBase.LastModificationDate}")
            } else if (lastModDates.isEmpty) {
              None
            } else {
              val dateStr = lastModDates.head
              Some(
                stringFormatter.xsdDateTimeStampToInstant(
                  dateStr,
                  throw InconsistentRepositoryDataException(
                    s"Invalid ${OntologyConstants.KnoraBase.LastModificationDate}: $dateStr")))
            }

            Some(
              OntologyMetadataV2(
                ontologyIri = internalOntologyIri,
                projectIri = Some(projectIri),
                label = Some(label),
                comment = comment,
                lastModificationDate = lastModificationDate
              ))

          case None => None
        }
      }
    } yield metadata
  }

  /**
    * Creates a new, empty ontology.
    *
    * @param createOntologyRequest the request message.
    * @return a [[SuccessResponseV2]].
    */
  private def createOntology(createOntologyRequest: CreateOntologyRequestV2): Future[ReadOntologyMetadataV2] = {
    def makeTaskFuture(internalOntologyIri: SmartIri): Future[ReadOntologyMetadataV2] = {
      for {
        cacheData <- getCacheData

        // Make sure the ontology doesn't already exist.
        existingOntologyMetadata: Option[OntologyMetadataV2] <- loadOntologyMetadata(
          internalOntologyIri = internalOntologyIri,
          featureFactoryConfig = createOntologyRequest.featureFactoryConfig
        )

        _ = if (existingOntologyMetadata.nonEmpty) {
          throw BadRequestException(
            s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} cannot be created, because it already exists")
        }

        // If this is a shared ontology, make sure it's in the default shared ontologies project.
        _ = if (createOntologyRequest.isShared && createOntologyRequest.projectIri.toString != OntologyConstants.KnoraAdmin.DefaultSharedOntologiesProject) {
          throw BadRequestException(
            s"Shared ontologies must be created in project <${OntologyConstants.KnoraAdmin.DefaultSharedOntologiesProject}>")
        }

        // If it's in the default shared ontologies project, make sure it's a shared ontology.
        _ = if (createOntologyRequest.projectIri.toString == OntologyConstants.KnoraAdmin.DefaultSharedOntologiesProject && !createOntologyRequest.isShared) {
          throw BadRequestException(
            s"Ontologies created in project <${OntologyConstants.KnoraAdmin.DefaultSharedOntologiesProject}> must be shared")
        }

        // Create the ontology.

        currentTime: Instant = Instant.now

        createOntologySparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .createOntology(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            projectIri = createOntologyRequest.projectIri,
            isShared = createOntologyRequest.isShared,
            ontologyLabel = createOntologyRequest.label,
            ontologyComment = createOntologyRequest.comment,
            currentTime = currentTime
          )
          .toString

        _ <- (storeManager ? SparqlUpdateRequest(createOntologySparql)).mapTo[SparqlUpdateResponse]

        // Check that the update was successful. To do this, we have to undo the SPARQL-escaping of the input.

        unescapedNewMetadata = OntologyMetadataV2(
          ontologyIri = internalOntologyIri,
          projectIri = Some(createOntologyRequest.projectIri),
          label = Some(createOntologyRequest.label),
          comment = createOntologyRequest.comment,
          lastModificationDate = Some(currentTime)
        ).unescape

        maybeLoadedOntologyMetadata: Option[OntologyMetadataV2] <- loadOntologyMetadata(
          internalOntologyIri = internalOntologyIri,
          featureFactoryConfig = createOntologyRequest.featureFactoryConfig
        )

        _ = maybeLoadedOntologyMetadata match {
          case Some(loadedOntologyMetadata) =>
            if (loadedOntologyMetadata != unescapedNewMetadata) {
              throw UpdateNotPerformedException()
            }

          case None => throw UpdateNotPerformedException()
        }

        // Update the ontology cache with the unescaped metadata.

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> ReadOntologyV2(
              ontologyMetadata = unescapedNewMetadata))
          ))

      } yield ReadOntologyMetadataV2(ontologies = Set(unescapedNewMetadata))
    }

    for {
      requestingUser <- FastFuture.successful(createOntologyRequest.requestingUser)
      projectIri = createOntologyRequest.projectIri

      // check if the requesting user is allowed to create an ontology
      _ = if (!(requestingUser.permissions.isProjectAdmin(projectIri.toString) || requestingUser.permissions.isSystemAdmin)) {
        // println(s"requestingUser: $requestingUser")
        // println(s"requestingUser.permissionData.isProjectAdmin(<${projectIri.toString}>): ${requestingUser.permissionData.isProjectAdmin(projectIri.toString)}")
        throw ForbiddenException(
          s"A new ontology in the project ${createOntologyRequest.projectIri} can only be created by an admin of that project, or by a system admin.")
      }

      // Get project info for the shortcode.
      projectInfo: ProjectGetResponseADM <- (responderManager ? ProjectGetRequestADM(
        identifier = ProjectIdentifierADM(maybeIri = Some(projectIri.toString)),
        featureFactoryConfig = createOntologyRequest.featureFactoryConfig,
        requestingUser = requestingUser
      )).mapTo[ProjectGetResponseADM]

      // Check that the ontology name is valid.
      validOntologyName = stringFormatter.validateProjectSpecificOntologyName(
        createOntologyRequest.ontologyName,
        throw BadRequestException(s"Invalid project-specific ontology name: ${createOntologyRequest.ontologyName}"))

      // Make the internal ontology IRI.
      internalOntologyIri = stringFormatter.makeProjectSpecificInternalOntologyIri(validOntologyName,
                                                                                   createOntologyRequest.isShared,
                                                                                   projectInfo.project.shortcode)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = createOntologyRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () => makeTaskFuture(internalOntologyIri)
      )
    } yield taskResult
  }

  /**
    * Changes ontology metadata.
    *
    * @param changeOntologyMetadataRequest the request to change the metadata.
    * @return a [[ReadOntologyMetadataV2]] containing the new metadata.
    */
  def changeOntologyMetadata(
      changeOntologyMetadataRequest: ChangeOntologyMetadataRequestV2): Future[ReadOntologyMetadataV2] = {
    def makeTaskFuture(internalOntologyIri: SmartIri): Future[ReadOntologyMetadataV2] = {
      for {
        cacheData <- getCacheData

        // Check that the user has permission to update the ontology.
        projectIri <- checkPermissionsForOntologyUpdate(
          internalOntologyIri = internalOntologyIri,
          requestingUser = changeOntologyMetadataRequest.requestingUser
        )

        // Check that the ontology exists and has not been updated by another user since the client last read its metadata.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = changeOntologyMetadataRequest.lastModificationDate,
          featureFactoryConfig = changeOntologyMetadataRequest.featureFactoryConfig
        )

        // get the metadata of the ontology.
        oldMetadata: OntologyMetadataV2 = cacheData.ontologies(internalOntologyIri).ontologyMetadata
        // Was there a comment in the ontology metadata?
        ontologyHasComment: Boolean = oldMetadata.comment.nonEmpty

        // Update the metadata.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .changeOntologyMetadata(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            newLabel = changeOntologyMetadataRequest.label,
            hasOldComment = ontologyHasComment,
            deleteOldComment = ontologyHasComment && changeOntologyMetadataRequest.comment.nonEmpty,
            newComment = changeOntologyMetadataRequest.comment,
            lastModificationDate = changeOntologyMetadataRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the update was successful. To do this, we have to undo the SPARQL-escaping of the input.

        // Is there any new label given?
        label = if (changeOntologyMetadataRequest.label.isEmpty) {
          // No. Consider the old label for checking the update.
          oldMetadata.label
        } else {
          // Yes. Consider the new label for checking the update.
          changeOntologyMetadataRequest.label
        }

        // Is there any new comment given?
        comment = if (changeOntologyMetadataRequest.comment.isEmpty) {
          // No. Consider the old comment for checking the update.
          oldMetadata.comment
        } else {
          // Yes. Consider the new comment for checking the update.
          changeOntologyMetadataRequest.comment
        }

        unescapedNewMetadata = OntologyMetadataV2(
          ontologyIri = internalOntologyIri,
          projectIri = Some(projectIri),
          label = label,
          comment = comment,
          lastModificationDate = Some(currentTime)
        ).unescape

        maybeLoadedOntologyMetadata: Option[OntologyMetadataV2] <- loadOntologyMetadata(
          internalOntologyIri = internalOntologyIri,
          featureFactoryConfig = changeOntologyMetadataRequest.featureFactoryConfig
        )

        _ = maybeLoadedOntologyMetadata match {
          case Some(loadedOntologyMetadata) =>
            if (loadedOntologyMetadata != unescapedNewMetadata) {
              throw UpdateNotPerformedException()
            }

          case None => throw UpdateNotPerformedException()
        }

        // Update the ontology cache with the unescaped metadata.

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> cacheData
              .ontologies(internalOntologyIri)
              .copy(ontologyMetadata = unescapedNewMetadata))
          ))

      } yield ReadOntologyMetadataV2(ontologies = Set(unescapedNewMetadata))
    }

    for {
      _ <- checkExternalOntologyIriForUpdate(changeOntologyMetadataRequest.ontologyIri)
      internalOntologyIri = changeOntologyMetadataRequest.ontologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = changeOntologyMetadataRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () => makeTaskFuture(internalOntologyIri = internalOntologyIri)
      )
    } yield taskResult
  }

  def deleteOntologyComment(
      deleteOntologyCommentRequestV2: DeleteOntologyCommentRequestV2): Future[ReadOntologyMetadataV2] = {
    def makeTaskFuture(internalOntologyIri: SmartIri): Future[ReadOntologyMetadataV2] = {
      for {
        cacheData <- getCacheData

        // Check that the user has permission to update the ontology.
        projectIri <- checkPermissionsForOntologyUpdate(
          internalOntologyIri = internalOntologyIri,
          requestingUser = deleteOntologyCommentRequestV2.requestingUser
        )

        // Check that the ontology exists and has not been updated by another user since the client last read its metadata.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = deleteOntologyCommentRequestV2.lastModificationDate,
          featureFactoryConfig = deleteOntologyCommentRequestV2.featureFactoryConfig
        )

        // get the metadata of the ontology.
        oldMetadata: OntologyMetadataV2 = cacheData.ontologies(internalOntologyIri).ontologyMetadata
        // Was there a comment in the ontology metadata?
        ontologyHasComment: Boolean = oldMetadata.comment.nonEmpty

        // Update the metadata.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .changeOntologyMetadata(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            newLabel = None,
            hasOldComment = ontologyHasComment,
            deleteOldComment = true,
            newComment = None,
            lastModificationDate = deleteOntologyCommentRequestV2.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the update was successful.

        unescapedNewMetadata = OntologyMetadataV2(
          ontologyIri = internalOntologyIri,
          projectIri = Some(projectIri),
          label = oldMetadata.label,
          comment = None,
          lastModificationDate = Some(currentTime)
        ).unescape

        maybeLoadedOntologyMetadata: Option[OntologyMetadataV2] <- loadOntologyMetadata(
          internalOntologyIri = internalOntologyIri,
          featureFactoryConfig = deleteOntologyCommentRequestV2.featureFactoryConfig
        )

        _ = maybeLoadedOntologyMetadata match {
          case Some(loadedOntologyMetadata) =>
            if (loadedOntologyMetadata != unescapedNewMetadata) {
              throw UpdateNotPerformedException()
            }

          case None => throw UpdateNotPerformedException()
        }

        // Update the ontology cache with the unescaped metadata.

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> cacheData
              .ontologies(internalOntologyIri)
              .copy(ontologyMetadata = unescapedNewMetadata))
          ))

      } yield ReadOntologyMetadataV2(ontologies = Set(unescapedNewMetadata))
    }

    for {
      _ <- checkExternalOntologyIriForUpdate(deleteOntologyCommentRequestV2.ontologyIri)
      internalOntologyIri = deleteOntologyCommentRequestV2.ontologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = deleteOntologyCommentRequestV2.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () => makeTaskFuture(internalOntologyIri = internalOntologyIri)
      )
    } yield taskResult
  }

  /**
    * Creates a class in an existing ontology.
    *
    * @param createClassRequest the request to create the class.
    * @return a [[ReadOntologyV2]] in the internal schema, the containing the definition of the new class.
    */
  private def createClass(createClassRequest: CreateClassRequestV2): Future[ReadOntologyV2] = {
    def makeTaskFuture(internalClassIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyV2] = {
      for {
        cacheData <- getCacheData
        internalClassDef: ClassInfoContentV2 = createClassRequest.classInfoContent.toOntologySchema(InternalSchema)

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = createClassRequest.lastModificationDate,
          featureFactoryConfig = createClassRequest.featureFactoryConfig
        )

        // Check that the class's rdf:type is owl:Class.

        rdfType: SmartIri = internalClassDef.requireIriObject(OntologyConstants.Rdf.Type.toSmartIri,
                                                              throw BadRequestException(s"No rdf:type specified"))

        _ = if (rdfType != OntologyConstants.Owl.Class.toSmartIri) {
          throw BadRequestException(s"Invalid rdf:type for property: $rdfType")
        }

        ontology = cacheData.ontologies(internalOntologyIri)

        // Check that the class doesn't exist yet.
        _ = if (ontology.classes.contains(internalClassIri)) {
          throw BadRequestException(s"Class ${createClassRequest.classInfoContent.classIri} already exists")
        }

        // Check that the class's IRI isn't already used for something else.
        _ = if (ontology.properties.contains(internalClassIri) || ontology.individuals.contains(internalClassIri)) {
          throw BadRequestException(s"IRI ${createClassRequest.classInfoContent.classIri} is already used")
        }

        // Check that the base classes that have Knora IRIs are defined as Knora resource classes.

        missingBaseClasses = internalClassDef.subClassOf
          .filter(_.isKnoraInternalEntityIri)
          .filter(baseClassIri => !isKnoraInternalResourceClass(baseClassIri, cacheData))

        _ = if (missingBaseClasses.nonEmpty) {
          throw BadRequestException(
            s"One or more specified base classes are invalid: ${missingBaseClasses.mkString(", ")}")
        }

        // Check for rdfs:subClassOf cycles.

        allBaseClassIrisWithoutSelf: Set[SmartIri] = internalClassDef.subClassOf.flatMap { baseClassIri =>
          cacheData.subClassOfRelations.getOrElse(baseClassIri, Set.empty[SmartIri]).toSet
        }

        _ = if (allBaseClassIrisWithoutSelf.contains(internalClassIri)) {
          throw BadRequestException(
            s"Class ${createClassRequest.classInfoContent.classIri} would have a cyclical rdfs:subClassOf")
        }

        // Check that the class is a subclass of knora-base:Resource.

        allBaseClassIris: Seq[SmartIri] = internalClassIri +: allBaseClassIrisWithoutSelf.toSeq

        _ = if (!allBaseClassIris.contains(OntologyConstants.KnoraBase.Resource.toSmartIri)) {
          throw BadRequestException(
            s"Class ${createClassRequest.classInfoContent.classIri} would not be a subclass of knora-api:Resource")
        }

        // Check that the cardinalities are valid, and add any inherited cardinalities.
        (internalClassDefWithLinkValueProps, cardinalitiesForClassWithInheritance) = checkCardinalitiesBeforeAdding(
          internalClassDef = internalClassDef,
          allBaseClassIris = allBaseClassIris.toSet,
          cacheData = cacheData
        )

        // Check that the class definition doesn't refer to any non-shared ontologies in other projects.
        _ = checkOntologyReferencesInClassDef(
          ontologyCacheData = cacheData,
          classDef = internalClassDefWithLinkValueProps,
          errorFun = { msg: String =>
            throw BadRequestException(msg)
          }
        )

        // Prepare to update the ontology cache, undoing the SPARQL-escaping of the input.

        propertyIrisOfAllCardinalitiesForClass = cardinalitiesForClassWithInheritance.keySet

        inheritedCardinalities: Map[SmartIri, KnoraCardinalityInfo] = cardinalitiesForClassWithInheritance.filterNot {
          case (propertyIri, _) => internalClassDefWithLinkValueProps.directCardinalities.contains(propertyIri)
        }

        unescapedClassDefWithLinkValueProps = internalClassDefWithLinkValueProps.unescape

        readClassInfo = ReadClassInfoV2(
          entityInfoContent = unescapedClassDefWithLinkValueProps,
          allBaseClasses = allBaseClassIris,
          isResourceClass = true,
          canBeInstantiated = true,
          inheritedCardinalities = inheritedCardinalities,
          knoraResourceProperties = propertyIrisOfAllCardinalitiesForClass.filter(propertyIri =>
            isKnoraResourceProperty(propertyIri, cacheData)),
          linkProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isLinkProp(propertyIri, cacheData)),
          linkValueProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isLinkValueProp(propertyIri, cacheData)),
          fileValueProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isFileValueProp(propertyIri, cacheData))
        )

        // Add the SPARQL-escaped class to the triplestore.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .createClass(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            classDef = internalClassDefWithLinkValueProps,
            lastModificationDate = createClassRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = createClassRequest.featureFactoryConfig
        )

        // Check that the data that was saved corresponds to the data that was submitted.

        loadedClassDef <- loadClassDefinition(
          classIri = internalClassIri,
          featureFactoryConfig = createClassRequest.featureFactoryConfig
        )

        _ = if (loadedClassDef != unescapedClassDefWithLinkValueProps) {
          throw InconsistentRepositoryDataException(
            s"Attempted to save class definition $unescapedClassDefWithLinkValueProps, but $loadedClassDef was saved")
        }

        // Update the cache.

        updatedSubClassOfRelations = cacheData.subClassOfRelations + (internalClassIri -> allBaseClassIris)
        updatedSuperClassOfRelations = calculateSuperClassOfRelations(updatedSubClassOfRelations)

        updatedOntology = ontology.copy(
          ontologyMetadata = ontology.ontologyMetadata.copy(
            lastModificationDate = Some(currentTime)
          ),
          classes = ontology.classes + (internalClassIri -> readClassInfo)
        )

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology),
            subClassOfRelations = updatedSubClassOfRelations,
            superClassOfRelations = updatedSuperClassOfRelations
          ))

        // Read the data back from the cache.

        response <- getClassDefinitionsFromOntologyV2(
          classIris = Set(internalClassIri),
          allLanguages = true,
          requestingUser = createClassRequest.requestingUser
        )
      } yield response
    }

    for {
      requestingUser <- FastFuture.successful(createClassRequest.requestingUser)

      externalClassIri = createClassRequest.classInfoContent.classIri
      externalOntologyIri = externalClassIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalClassIri,
        requestingUser = requestingUser
      )

      internalClassIri = externalClassIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = createClassRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalClassIri = internalClassIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Before creating a new class or adding cardinalities to an existing class, checks the validity of the
    * cardinalities directly defined on the class. Adds link value properties for the corresponding
    * link properties.
    *
    * @param internalClassDef        the internal definition of the class.
    * @param allBaseClassIris        the IRIs of all the class's base classes, including the class itself.
    * @param cacheData               the ontology cache.
    * @param existingLinkPropsToKeep the link properties that are already defined on the class and that
    *                                will be kept after the update.
    * @return the updated class definition, and the cardinalities resulting from inheritance.
    */
  private def checkCardinalitiesBeforeAdding(
      internalClassDef: ClassInfoContentV2,
      allBaseClassIris: Set[SmartIri],
      cacheData: OntologyCacheData,
      existingLinkPropsToKeep: Set[SmartIri] = Set.empty): (ClassInfoContentV2, Map[SmartIri, KnoraCardinalityInfo]) = {
    // If the class has cardinalities, check that the properties are already defined as Knora properties.

    val propertyDefsForDirectCardinalities: Set[ReadPropertyInfoV2] = internalClassDef.directCardinalities.keySet.map {
      propertyIri =>
        if (!isKnoraResourceProperty(propertyIri, cacheData) || propertyIri.toString == OntologyConstants.KnoraBase.ResourceProperty || propertyIri.toString == OntologyConstants.KnoraBase.HasValue) {
          throw NotFoundException(s"Invalid property for cardinality: <${propertyIri.toOntologySchema(ApiV2Complex)}>")
        }

        cacheData.ontologies(propertyIri.getOntologyFromEntity).properties(propertyIri)
    }

    val existingLinkValuePropsToKeep = existingLinkPropsToKeep.map(_.fromLinkPropToLinkValueProp)
    val newLinkPropsInClass: Set[SmartIri] = propertyDefsForDirectCardinalities
      .filter(_.isLinkProp)
      .map(_.entityInfoContent.propertyIri) -- existingLinkValuePropsToKeep
    val newLinkValuePropsInClass: Set[SmartIri] = propertyDefsForDirectCardinalities
      .filter(_.isLinkValueProp)
      .map(_.entityInfoContent.propertyIri) -- existingLinkValuePropsToKeep

    // Don't allow link value prop cardinalities to be included in the request.

    if (newLinkValuePropsInClass.nonEmpty) {
      throw BadRequestException(s"In class ${internalClassDef.classIri.toOntologySchema(ApiV2Complex)}, cardinalities have been submitted for one or more link value properties: ${newLinkValuePropsInClass
        .map(_.toOntologySchema(ApiV2Complex))
        .mkString(", ")}. Just submit the link properties, and the link value properties will be included automatically.")
    }

    // Add a link value prop cardinality for each new link prop cardinality.

    val linkValuePropCardinalitiesToAdd: Map[SmartIri, KnoraCardinalityInfo] = newLinkPropsInClass.map { linkPropIri =>
      val linkValuePropIri = linkPropIri.fromLinkPropToLinkValueProp

      // Ensure that the link value prop exists.
      cacheData
        .ontologies(linkValuePropIri.getOntologyFromEntity)
        .properties
        .getOrElse(linkValuePropIri, throw NotFoundException(s"Link value property <$linkValuePropIri> not found"))

      linkValuePropIri -> internalClassDef.directCardinalities(linkPropIri)
    }.toMap

    val classDefWithAddedLinkValueProps = internalClassDef.copy(
      directCardinalities = internalClassDef.directCardinalities ++ linkValuePropCardinalitiesToAdd
    )

    // Get the cardinalities that the class can inherit.

    val cardinalitiesAvailableToInherit: Map[SmartIri, KnoraCardinalityInfo] =
      classDefWithAddedLinkValueProps.subClassOf.flatMap { baseClassIri =>
        cacheData.ontologies(baseClassIri.getOntologyFromEntity).classes(baseClassIri).allCardinalities
      }.toMap

    // Check that the cardinalities directly defined on the class are compatible with any inheritable
    // cardinalities, and let directly-defined cardinalities override cardinalities in base classes.

    val thisClassKnoraCardinalities = classDefWithAddedLinkValueProps.directCardinalities.map {
      case (propertyIri, knoraCardinality) =>
        propertyIri -> Cardinality.knoraCardinality2OwlCardinality(knoraCardinality)
    }

    val inheritableKnoraCardinalities = cardinalitiesAvailableToInherit.map {
      case (propertyIri, knoraCardinality) =>
        propertyIri -> Cardinality.knoraCardinality2OwlCardinality(knoraCardinality)
    }

    val cardinalitiesForClassWithInheritance: Map[SmartIri, KnoraCardinalityInfo] = overrideCardinalities(
      classIri = internalClassDef.classIri,
      thisClassCardinalities = thisClassKnoraCardinalities,
      inheritableCardinalities = inheritableKnoraCardinalities,
      allSubPropertyOfRelations = cacheData.subPropertyOfRelations,
      errorSchema = ApiV2Complex, { msg: String =>
        throw BadRequestException(msg)
      }
    ).map {
      case (propertyIri, owlCardinalityInfo) =>
        propertyIri -> Cardinality.owlCardinality2KnoraCardinality(propertyIri = propertyIri.toString,
                                                                   owlCardinality = owlCardinalityInfo)
    }

    // Check that the class is a subclass of all the classes that are subject class constraints of the Knora resource properties in its cardinalities.

    val knoraResourcePropertyIrisInCardinalities = cardinalitiesForClassWithInheritance.keySet.filter { propertyIri =>
      isKnoraResourceProperty(
        propertyIri = propertyIri,
        cacheData = cacheData
      )
    }

    val allClassCardinalityKnoraPropertyDefs: Map[SmartIri, PropertyInfoContentV2] =
      knoraResourcePropertyIrisInCardinalities.map { propertyIri =>
        propertyIri -> cacheData.ontologies(propertyIri.getOntologyFromEntity).properties(propertyIri).entityInfoContent
      }.toMap

    checkSubjectClassConstraintsViaCardinalities(
      internalClassDef = classDefWithAddedLinkValueProps,
      allBaseClassIris = allBaseClassIris,
      allClassCardinalityKnoraPropertyDefs = allClassCardinalityKnoraPropertyDefs,
      errorSchema = ApiV2Complex,
      errorFun = { msg: String =>
        throw BadRequestException(msg)
      }
    )

    // It cannot have cardinalities both on property P and on a subproperty of P.

    val maybePropertyAndSubproperty: Option[(SmartIri, SmartIri)] = findPropertyAndSubproperty(
      propertyIris = cardinalitiesForClassWithInheritance.keySet,
      subPropertyOfRelations = cacheData.subPropertyOfRelations
    )

    maybePropertyAndSubproperty match {
      case Some((basePropertyIri, propertyIri)) =>
        throw BadRequestException(
          s"Class <${classDefWithAddedLinkValueProps.classIri.toOntologySchema(ApiV2Complex)}> has a cardinality on property <${basePropertyIri
            .toOntologySchema(ApiV2Complex)}> and on its subproperty <${propertyIri.toOntologySchema(ApiV2Complex)}>")

      case None => ()
    }

    // Check for invalid cardinalities on boolean properties.
    checkForInvalidBooleanCardinalities(
      classIri = internalClassDef.classIri,
      directCardinalities = internalClassDef.directCardinalities,
      allPropertyDefs = cacheData.allPropertyDefs,
      schemaForErrors = ApiV2Complex,
      errorFun = { msg: String =>
        throw BadRequestException(msg)
      }
    )

    (classDefWithAddedLinkValueProps, cardinalitiesForClassWithInheritance)
  }

  /**
    * Given a set of property IRIs, determines whether the set contains a property P and a subproperty of P.
    *
    * @param propertyIris           the set of property IRIs.
    * @param subPropertyOfRelations all the subproperty relations in the triplestore.
    * @return a property and its subproperty, if found.
    */
  private def findPropertyAndSubproperty(
      propertyIris: Set[SmartIri],
      subPropertyOfRelations: Map[SmartIri, Set[SmartIri]]): Option[(SmartIri, SmartIri)] = {
    propertyIris.flatMap { propertyIri =>
      val maybeBasePropertyIri: Option[SmartIri] = (propertyIris - propertyIri).find { otherPropertyIri =>
        subPropertyOfRelations.get(propertyIri).exists { baseProperties: Set[SmartIri] =>
          baseProperties.contains(otherPropertyIri)
        }
      }

      maybeBasePropertyIri.map { basePropertyIri =>
        (basePropertyIri, propertyIri)
      }
    }.headOption
  }

  /**
    * Checks that a class is a subclass of all the classes that are subject class constraints of the Knora resource properties in its cardinalities.
    *
    * @param internalClassDef                     the class definition.
    * @param allBaseClassIris                     the IRIs of all the class's base classes.
    * @param allClassCardinalityKnoraPropertyDefs the definitions of all the Knora resource properties on which the class has cardinalities (whether directly defined
    *                                             or inherited).
    * @param errorSchema                          the ontology schema to be used in error messages.
    * @param errorFun                             a function that throws an exception. It will be called with an error message argument if the cardinalities are invalid.
    */
  private def checkSubjectClassConstraintsViaCardinalities(
      internalClassDef: ClassInfoContentV2,
      allBaseClassIris: Set[SmartIri],
      allClassCardinalityKnoraPropertyDefs: Map[SmartIri, PropertyInfoContentV2],
      errorSchema: OntologySchema,
      errorFun: String => Nothing): Unit = {
    allClassCardinalityKnoraPropertyDefs.foreach {
      case (propertyIri, propertyDef) =>
        propertyDef.predicates.get(OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri) match {
          case Some(subjectClassConstraintPred) =>
            val subjectClassConstraint = subjectClassConstraintPred.requireIriObject(
              throw InconsistentRepositoryDataException(
                s"Property $propertyIri has an invalid object for ${OntologyConstants.KnoraBase.SubjectClassConstraint}"))

            if (!allBaseClassIris.contains(subjectClassConstraint)) {
              val hasOrWouldInherit = if (internalClassDef.directCardinalities.contains(propertyIri)) {
                "has"
              } else {
                "would inherit"
              }

              errorFun(s"Class ${internalClassDef.classIri.toOntologySchema(errorSchema)} $hasOrWouldInherit a cardinality for property ${propertyIri
                .toOntologySchema(errorSchema)}, but is not a subclass of that property's ${OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri
                .toOntologySchema(errorSchema)}, ${subjectClassConstraint.toOntologySchema(errorSchema)}")
            }

          case None => ()
        }
    }
  }

  /**
    * Adds cardinalities to an existing class definition.
    *
    * @param addCardinalitiesRequest the request to add the cardinalities.
    * @return a [[ReadOntologyV2]] in the internal schema, containing the new class definition.
    */
  private def addCardinalitiesToClass(
      addCardinalitiesRequest: AddCardinalitiesToClassRequestV2): Future[ReadOntologyV2] = {
    def makeTaskFuture(internalClassIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyV2] = {
      for {
        cacheData <- getCacheData
        internalClassDef: ClassInfoContentV2 = addCardinalitiesRequest.classInfoContent.toOntologySchema(InternalSchema)

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = addCardinalitiesRequest.lastModificationDate,
          featureFactoryConfig = addCardinalitiesRequest.featureFactoryConfig
        )

        // Check that the class's rdf:type is owl:Class.

        rdfType: SmartIri = internalClassDef.requireIriObject(OntologyConstants.Rdf.Type.toSmartIri,
                                                              throw BadRequestException(s"No rdf:type specified"))

        _ = if (rdfType != OntologyConstants.Owl.Class.toSmartIri) {
          throw BadRequestException(s"Invalid rdf:type for property: $rdfType")
        }

        // Check that cardinalities were submitted.

        _ = if (internalClassDef.directCardinalities.isEmpty) {
          throw BadRequestException("No cardinalities specified")
        }

        // Check that the class exists, that it's a Knora resource class, and that the submitted cardinalities aren't for properties that already have cardinalities
        // directly defined on the class.

        ontology = cacheData.ontologies(internalOntologyIri)

        existingReadClassInfo: ReadClassInfoV2 = ontology.classes.getOrElse(
          internalClassIri,
          throw BadRequestException(s"Class ${addCardinalitiesRequest.classInfoContent.classIri} does not exist"))

        existingClassDef: ClassInfoContentV2 = existingReadClassInfo.entityInfoContent

        redundantCardinalities = existingClassDef.directCardinalities.keySet
          .intersect(internalClassDef.directCardinalities.keySet)

        _ = if (redundantCardinalities.nonEmpty) {
          throw BadRequestException(
            s"The cardinalities of ${addCardinalitiesRequest.classInfoContent.classIri} already include the following property or properties: ${redundantCardinalities
              .mkString(", ")}")
        }

        // Check that the class isn't used in data, and that it has no subclasses.

        _ <- isEntityUsed(
          entityIri = internalClassIri,
          errorFun = throw BadRequestException(
            s"Cardinalities cannot be added to class ${addCardinalitiesRequest.classInfoContent.classIri}, because it is used in data or has a subclass"),
          ignoreKnoraConstraints = true // It's OK if a property refers to the class via knora-base:subjectClassConstraint or knora-base:objectClassConstraint.
        )

        // Make an updated class definition.

        newInternalClassDef = existingClassDef.copy(
          directCardinalities = existingClassDef.directCardinalities ++ internalClassDef.directCardinalities
        )

        // Check that the new cardinalities are valid, and add any inherited cardinalities.

        allBaseClassIrisWithoutInternal: Seq[SmartIri] = newInternalClassDef.subClassOf.toSeq.flatMap { baseClassIri =>
          cacheData.subClassOfRelations.getOrElse(baseClassIri, Seq.empty[SmartIri])
        }

        allBaseClassIris: Seq[SmartIri] = internalClassIri +: allBaseClassIrisWithoutInternal

        (newInternalClassDefWithLinkValueProps, cardinalitiesForClassWithInheritance) = checkCardinalitiesBeforeAdding(
          internalClassDef = newInternalClassDef,
          allBaseClassIris = allBaseClassIris.toSet,
          cacheData = cacheData,
          existingLinkPropsToKeep = existingReadClassInfo.linkProperties
        )

        // Check that the class definition doesn't refer to any non-shared ontologies in other projects.
        _ = checkOntologyReferencesInClassDef(
          ontologyCacheData = cacheData,
          classDef = newInternalClassDefWithLinkValueProps,
          errorFun = { msg: String =>
            throw BadRequestException(msg)
          }
        )

        // Prepare to update the ontology cache. (No need to deal with SPARQL-escaping here, because there
        // isn't any text to escape in cardinalities.)

        propertyIrisOfAllCardinalitiesForClass = cardinalitiesForClassWithInheritance.keySet

        inheritedCardinalities: Map[SmartIri, KnoraCardinalityInfo] = cardinalitiesForClassWithInheritance.filterNot {
          case (propertyIri, _) => newInternalClassDefWithLinkValueProps.directCardinalities.contains(propertyIri)
        }

        readClassInfo = ReadClassInfoV2(
          entityInfoContent = newInternalClassDefWithLinkValueProps,
          allBaseClasses = allBaseClassIris,
          isResourceClass = true,
          canBeInstantiated = true,
          inheritedCardinalities = inheritedCardinalities,
          knoraResourceProperties = propertyIrisOfAllCardinalitiesForClass.filter(propertyIri =>
            isKnoraResourceProperty(propertyIri, cacheData)),
          linkProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isLinkProp(propertyIri, cacheData)),
          linkValueProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isLinkValueProp(propertyIri, cacheData)),
          fileValueProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isFileValueProp(propertyIri, cacheData))
        )

        // Add the cardinalities to the class definition in the triplestore.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .addCardinalitiesToClass(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            classIri = internalClassIri,
            cardinalitiesToAdd = newInternalClassDefWithLinkValueProps.directCardinalities,
            lastModificationDate = addCardinalitiesRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = addCardinalitiesRequest.featureFactoryConfig
        )

        // Check that the data that was saved corresponds to the data that was submitted.

        loadedClassDef <- loadClassDefinition(
          classIri = internalClassIri,
          featureFactoryConfig = addCardinalitiesRequest.featureFactoryConfig
        )

        _ = if (loadedClassDef != newInternalClassDefWithLinkValueProps) {
          throw InconsistentRepositoryDataException(
            s"Attempted to save class definition $newInternalClassDefWithLinkValueProps, but $loadedClassDef was saved")
        }

        // Update the cache.

        updatedOntology = ontology.copy(
          ontologyMetadata = ontology.ontologyMetadata.copy(
            lastModificationDate = Some(currentTime)
          ),
          classes = ontology.classes + (internalClassIri -> readClassInfo)
        )

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology)
          ))

        // Read the data back from the cache.

        response <- getClassDefinitionsFromOntologyV2(
          classIris = Set(internalClassIri),
          allLanguages = true,
          requestingUser = addCardinalitiesRequest.requestingUser
        )
      } yield response
    }

    for {
      requestingUser <- FastFuture.successful(addCardinalitiesRequest.requestingUser)

      externalClassIri = addCardinalitiesRequest.classInfoContent.classIri
      externalOntologyIri = externalClassIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalClassIri,
        requestingUser = requestingUser
      )

      internalClassIri = externalClassIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = addCardinalitiesRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalClassIri = internalClassIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Replaces a class's cardinalities with new ones.
    *
    * @param changeCardinalitiesRequest the request to add the cardinalities.
    * @return a [[ReadOntologyV2]] in the internal schema, containing the new class definition.
    */
  private def changeClassCardinalities(
      changeCardinalitiesRequest: ChangeCardinalitiesRequestV2): Future[ReadOntologyV2] = {
    def makeTaskFuture(internalClassIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyV2] = {
      for {
        cacheData <- getCacheData
        internalClassDef: ClassInfoContentV2 = changeCardinalitiesRequest.classInfoContent.toOntologySchema(
          InternalSchema)

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = changeCardinalitiesRequest.lastModificationDate,
          featureFactoryConfig = changeCardinalitiesRequest.featureFactoryConfig
        )

        // Check that the class's rdf:type is owl:Class.

        rdfType: SmartIri = internalClassDef.requireIriObject(OntologyConstants.Rdf.Type.toSmartIri,
                                                              throw BadRequestException(s"No rdf:type specified"))

        _ = if (rdfType != OntologyConstants.Owl.Class.toSmartIri) {
          throw BadRequestException(s"Invalid rdf:type for property: $rdfType")
        }

        // Check that the class exists.

        ontology = cacheData.ontologies(internalOntologyIri)

        existingClassDef: ClassInfoContentV2 = ontology.classes
          .getOrElse(
            internalClassIri,
            throw BadRequestException(s"Class ${changeCardinalitiesRequest.classInfoContent.classIri} does not exist"))
          .entityInfoContent

        // Check that the class isn't used in data, and that it has no subclasses.

        _ <- isEntityUsed(
          entityIri = internalClassIri,
          errorFun = throw BadRequestException(
            s"The cardinalities of class ${changeCardinalitiesRequest.classInfoContent.classIri} cannot be changed, because it is used in data or has a subclass"),
          ignoreKnoraConstraints = true // It's OK if a property refers to the class via knora-base:subjectClassConstraint or knora-base:objectClassConstraint.
        )

        // Make an updated class definition.

        newInternalClassDef = existingClassDef.copy(
          directCardinalities = internalClassDef.directCardinalities
        )

        // Check that the new cardinalities are valid, and add any inherited cardinalities.

        allBaseClassIrisWithoutInternal: Seq[SmartIri] = newInternalClassDef.subClassOf.toSeq.flatMap { baseClassIri =>
          cacheData.subClassOfRelations.getOrElse(baseClassIri, Seq.empty[SmartIri])
        }

        allBaseClassIris: Seq[SmartIri] = internalClassIri +: allBaseClassIrisWithoutInternal

        (newInternalClassDefWithLinkValueProps, cardinalitiesForClassWithInheritance) = checkCardinalitiesBeforeAdding(
          internalClassDef = newInternalClassDef,
          allBaseClassIris = allBaseClassIris.toSet,
          cacheData = cacheData
        )

        // Check that the class definition doesn't refer to any non-shared ontologies in other projects.
        _ = checkOntologyReferencesInClassDef(
          ontologyCacheData = cacheData,
          classDef = newInternalClassDefWithLinkValueProps,
          errorFun = { msg: String =>
            throw BadRequestException(msg)
          }
        )

        // Prepare to update the ontology cache. (No need to deal with SPARQL-escaping here, because there
        // isn't any text to escape in cardinalities.)

        propertyIrisOfAllCardinalitiesForClass = cardinalitiesForClassWithInheritance.keySet

        inheritedCardinalities: Map[SmartIri, KnoraCardinalityInfo] = cardinalitiesForClassWithInheritance.filterNot {
          case (propertyIri, _) => newInternalClassDefWithLinkValueProps.directCardinalities.contains(propertyIri)
        }

        readClassInfo = ReadClassInfoV2(
          entityInfoContent = newInternalClassDefWithLinkValueProps,
          allBaseClasses = allBaseClassIris,
          isResourceClass = true,
          canBeInstantiated = true,
          inheritedCardinalities = inheritedCardinalities,
          knoraResourceProperties = propertyIrisOfAllCardinalitiesForClass.filter(propertyIri =>
            isKnoraResourceProperty(propertyIri, cacheData)),
          linkProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isLinkProp(propertyIri, cacheData)),
          linkValueProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isLinkValueProp(propertyIri, cacheData)),
          fileValueProperties =
            propertyIrisOfAllCardinalitiesForClass.filter(propertyIri => isFileValueProp(propertyIri, cacheData))
        )

        // Add the cardinalities to the class definition in the triplestore.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .replaceClassCardinalities(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            classIri = internalClassIri,
            newCardinalities = newInternalClassDefWithLinkValueProps.directCardinalities,
            lastModificationDate = changeCardinalitiesRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = changeCardinalitiesRequest.featureFactoryConfig
        )

        // Check that the data that was saved corresponds to the data that was submitted.

        loadedClassDef <- loadClassDefinition(
          classIri = internalClassIri,
          featureFactoryConfig = changeCardinalitiesRequest.featureFactoryConfig
        )

        _ = if (loadedClassDef != newInternalClassDefWithLinkValueProps) {
          throw InconsistentRepositoryDataException(
            s"Attempted to save class definition $newInternalClassDefWithLinkValueProps, but $loadedClassDef was saved")
        }

        // Update the cache.

        updatedOntology = ontology.copy(
          ontologyMetadata = ontology.ontologyMetadata.copy(
            lastModificationDate = Some(currentTime)
          ),
          classes = ontology.classes + (internalClassIri -> readClassInfo)
        )

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology)
          ))

        // Read the data back from the cache.

        response <- getClassDefinitionsFromOntologyV2(
          classIris = Set(internalClassIri),
          allLanguages = true,
          requestingUser = changeCardinalitiesRequest.requestingUser
        )
      } yield response
    }

    for {
      requestingUser <- FastFuture.successful(changeCardinalitiesRequest.requestingUser)

      externalClassIri = changeCardinalitiesRequest.classInfoContent.classIri
      externalOntologyIri = externalClassIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalClassIri,
        requestingUser = requestingUser
      )

      internalClassIri = externalClassIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = changeCardinalitiesRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalClassIri = internalClassIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Deletes a class.
    *
    * @param deleteClassRequest the request to delete the class.
    * @return a [[SuccessResponseV2]].
    */
  private def deleteClass(deleteClassRequest: DeleteClassRequestV2): Future[ReadOntologyMetadataV2] = {
    def makeTaskFuture(internalClassIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyMetadataV2] = {
      for {
        cacheData <- getCacheData

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = deleteClassRequest.lastModificationDate,
          featureFactoryConfig = deleteClassRequest.featureFactoryConfig
        )

        // Check that the class exists.

        ontology = cacheData.ontologies(internalOntologyIri)

        _ = if (!ontology.classes.contains(internalClassIri)) {
          throw BadRequestException(s"Class ${deleteClassRequest.classIri} does not exist")
        }

        // Check that the class isn't used in data or ontologies.

        _ <- isEntityUsed(
          entityIri = internalClassIri,
          errorFun = throw BadRequestException(
            s"Class ${deleteClassRequest.classIri} cannot be deleted, because it is used in data or ontologies")
        )

        // Delete the class from the triplestore.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .deleteClass(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            classIri = internalClassIri,
            lastModificationDate = deleteClassRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = deleteClassRequest.featureFactoryConfig
        )

        // Update the cache.

        updatedOntology = ontology.copy(
          ontologyMetadata = ontology.ontologyMetadata.copy(
            lastModificationDate = Some(currentTime)
          ),
          classes = ontology.classes - internalClassIri
        )

        updatedSubClassOfRelations = (cacheData.subClassOfRelations - internalClassIri).map {
          case (subClass, baseClasses) => subClass -> (baseClasses.toSet - internalClassIri).toSeq
        }

        updatedSuperClassOfRelations = calculateSuperClassOfRelations(updatedSubClassOfRelations)

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology),
            subClassOfRelations = updatedSubClassOfRelations,
            superClassOfRelations = updatedSuperClassOfRelations
          ))
      } yield ReadOntologyMetadataV2(Set(updatedOntology.ontologyMetadata))
    }

    for {
      requestingUser <- FastFuture.successful(deleteClassRequest.requestingUser)

      externalClassIri = deleteClassRequest.classIri
      externalOntologyIri = externalClassIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalClassIri,
        requestingUser = requestingUser
      )

      internalClassIri = externalClassIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = deleteClassRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalClassIri = internalClassIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Deletes a property. If the property is a link property, the corresponding link value property is also deleted.
    *
    * @param deletePropertyRequest the request to delete the property.
    * @return a [[ReadOntologyMetadataV2]].
    */
  private def deleteProperty(deletePropertyRequest: DeletePropertyRequestV2): Future[ReadOntologyMetadataV2] = {
    def makeTaskFuture(internalPropertyIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyMetadataV2] = {
      for {
        cacheData <- getCacheData

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = deletePropertyRequest.lastModificationDate,
          featureFactoryConfig = deletePropertyRequest.featureFactoryConfig
        )

        // Check that the property exists.

        ontology = cacheData.ontologies(internalOntologyIri)
        propertyDef: ReadPropertyInfoV2 = ontology.properties.getOrElse(
          internalPropertyIri,
          throw BadRequestException(s"Property ${deletePropertyRequest.propertyIri} does not exist"))

        _ = if (propertyDef.isLinkValueProp) {
          throw BadRequestException(
            s"A link value property cannot be deleted directly; delete the corresponding link property instead")
        }

        maybeInternalLinkValuePropertyIri: Option[SmartIri] = if (propertyDef.isLinkProp) {
          Some(internalPropertyIri.fromLinkPropToLinkValueProp)
        } else {
          None
        }

        // Check that the property isn't used in data or ontologies.

        _ <- isEntityUsed(
          entityIri = internalPropertyIri,
          errorFun = throw BadRequestException(
            s"Property ${deletePropertyRequest.propertyIri} cannot be deleted, because it is used in data or ontologies")
        )

        _ <- maybeInternalLinkValuePropertyIri match {
          case Some(internalLinkValuePropertyIri) =>
            isEntityUsed(
              entityIri = internalLinkValuePropertyIri,
              errorFun = throw BadRequestException(
                s"Property ${deletePropertyRequest.propertyIri} cannot be deleted, because the corresponding link value property, ${internalLinkValuePropertyIri
                  .toOntologySchema(ApiV2Complex)}, is used in data or ontologies")
            )

          case None => FastFuture.successful(())
        }

        // Delete the property from the triplestore.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .deleteProperty(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            propertyIri = internalPropertyIri,
            maybeLinkValuePropertyIri = maybeInternalLinkValuePropertyIri,
            lastModificationDate = deletePropertyRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = deletePropertyRequest.featureFactoryConfig
        )

        // Update the cache.

        propertiesToRemoveFromCache = Set(internalPropertyIri) ++ maybeInternalLinkValuePropertyIri

        updatedOntology = ontology.copy(
          ontologyMetadata = ontology.ontologyMetadata.copy(
            lastModificationDate = Some(currentTime)
          ),
          properties = ontology.properties -- propertiesToRemoveFromCache
        )

        updatedSubPropertyOfRelations = (cacheData.subPropertyOfRelations -- propertiesToRemoveFromCache).map {
          case (subProperty, baseProperties) => subProperty -> (baseProperties -- propertiesToRemoveFromCache)
        }

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology),
            subPropertyOfRelations = updatedSubPropertyOfRelations
          ))
      } yield ReadOntologyMetadataV2(Set(updatedOntology.ontologyMetadata))
    }

    for {
      requestingUser <- FastFuture.successful(deletePropertyRequest.requestingUser)

      externalPropertyIri = deletePropertyRequest.propertyIri
      externalOntologyIri = externalPropertyIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalPropertyIri,
        requestingUser = requestingUser
      )

      internalPropertyIri = externalPropertyIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = deletePropertyRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalPropertyIri = internalPropertyIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  def deleteOntology(deleteOntologyRequest: DeleteOntologyRequestV2): Future[SuccessResponseV2] = {
    def makeTaskFuture(internalOntologyIri: SmartIri): Future[SuccessResponseV2] = {
      for {
        cacheData <- getCacheData

        // Check that the user has permission to update the ontology.
        _ <- checkPermissionsForOntologyUpdate(
          internalOntologyIri = internalOntologyIri,
          requestingUser = deleteOntologyRequest.requestingUser
        )

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = deleteOntologyRequest.lastModificationDate,
          featureFactoryConfig = deleteOntologyRequest.featureFactoryConfig
        )

        // Check that none of the entities in the ontology are used in data or in other ontologies.

        ontology = cacheData.ontologies(internalOntologyIri)

        isOntologyUsedSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .isOntologyUsed(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            classIris = ontology.classes.keySet,
            propertyIris = ontology.properties.keySet
          )
          .toString()

        isOntologyUsedResponse: SparqlSelectResult <- (storeManager ? SparqlSelectRequest(isOntologyUsedSparql))
          .mapTo[SparqlSelectResult]

        _ = if (isOntologyUsedResponse.results.bindings.nonEmpty) {
          val subjects: Seq[String] = isOntologyUsedResponse.results.bindings
            .map { row =>
              row.rowMap("s")
            }
            .map(s => "<" + s + ">")
            .toVector
            .sorted

          throw BadRequestException(
            s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} cannot be deleted, because of subjects that refer to it: ${subjects
              .mkString(", ")}")
        }

        // Delete everything in the ontology's named graph.

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .deleteOntology(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology has been deleted.

        maybeOntologyMetadata <- loadOntologyMetadata(
          internalOntologyIri = internalOntologyIri,
          featureFactoryConfig = deleteOntologyRequest.featureFactoryConfig
        )

        _ = if (maybeOntologyMetadata.nonEmpty) {
          throw UpdateNotPerformedException(
            s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} was not deleted. Please report this as a possible bug.")
        }

        // Remove the ontology from the cache.

        updatedSubClassOfRelations = cacheData.subClassOfRelations
          .filterNot {
            case (subClass, _) => subClass.getOntologyFromEntity == internalOntologyIri
          }
          .map {
            case (subClass, baseClasses) =>
              subClass -> baseClasses.filterNot(_.getOntologyFromEntity == internalOntologyIri)
          }

        updatedSuperClassOfRelations = calculateSuperClassOfRelations(updatedSubClassOfRelations)

        updatedSubPropertyOfRelations = cacheData.subPropertyOfRelations
          .filterNot {
            case (subProperty, _) => subProperty.getOntologyFromEntity == internalOntologyIri
          }
          .map {
            case (subProperty, baseProperties) =>
              subProperty -> baseProperties.filterNot(_.getOntologyFromEntity == internalOntologyIri)
          }

        updatedStandoffProperties = cacheData.standoffProperties.filterNot(
          _.getOntologyFromEntity == internalOntologyIri)

        updatedCacheData = cacheData.copy(
          ontologies = cacheData.ontologies - internalOntologyIri,
          subClassOfRelations = updatedSubClassOfRelations,
          superClassOfRelations = updatedSuperClassOfRelations,
          subPropertyOfRelations = updatedSubPropertyOfRelations,
          standoffProperties = updatedStandoffProperties
        )

        _ = storeCacheData(updatedCacheData)
      } yield SuccessResponseV2(s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} has been deleted")
    }

    for {
      _ <- checkExternalOntologyIriForUpdate(deleteOntologyRequest.ontologyIri)
      internalOntologyIri = deleteOntologyRequest.ontologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = deleteOntologyRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Creates a property in an existing ontology.
    *
    * @param createPropertyRequest the request to create the property.
    * @return a [[ReadOntologyV2]] in the internal schema, the containing the definition of the new property.
    */
  private def createProperty(createPropertyRequest: CreatePropertyRequestV2): Future[ReadOntologyV2] = {
    def makeTaskFuture(internalPropertyIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyV2] = {
      for {
        cacheData <- getCacheData
        internalPropertyDef = createPropertyRequest.propertyInfoContent.toOntologySchema(InternalSchema)

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = createPropertyRequest.lastModificationDate,
          featureFactoryConfig = createPropertyRequest.featureFactoryConfig
        )

        // Check that the property's rdf:type is owl:ObjectProperty.

        rdfType: SmartIri = internalPropertyDef.requireIriObject(OntologyConstants.Rdf.Type.toSmartIri,
                                                                 throw BadRequestException(s"No rdf:type specified"))

        _ = if (rdfType != OntologyConstants.Owl.ObjectProperty.toSmartIri) {
          throw BadRequestException(s"Invalid rdf:type for property: $rdfType")
        }

        // Check that the property doesn't exist yet.

        ontology = cacheData.ontologies(internalOntologyIri)

        _ = if (ontology.properties.contains(internalPropertyIri)) {
          throw BadRequestException(s"Property ${createPropertyRequest.propertyInfoContent.propertyIri} already exists")
        }

        // Check that the property's IRI isn't already used for something else.
        _ = if (ontology.classes.contains(internalPropertyIri) || ontology.individuals.contains(internalPropertyIri)) {
          throw BadRequestException(s"IRI ${createPropertyRequest.propertyInfoContent.propertyIri} is already used")
        }

        // Check that the base properties that have Knora IRIs are defined as Knora resource properties.

        knoraSuperProperties = internalPropertyDef.subPropertyOf.filter(_.isKnoraInternalEntityIri)
        invalidSuperProperties = knoraSuperProperties.filterNot(baseProperty =>
          isKnoraResourceProperty(baseProperty, cacheData) && baseProperty.toString != OntologyConstants.KnoraBase.ResourceProperty)

        _ = if (invalidSuperProperties.nonEmpty) {
          throw BadRequestException(
            s"One or more specified base properties are invalid: ${invalidSuperProperties.mkString(", ")}")
        }

        // Check for rdfs:subPropertyOf cycles.

        allKnoraSuperPropertyIrisWithoutSelf: Set[SmartIri] = knoraSuperProperties.flatMap { superPropertyIri =>
          cacheData.subPropertyOfRelations.getOrElse(superPropertyIri, Set.empty[SmartIri])
        }

        _ = if (allKnoraSuperPropertyIrisWithoutSelf.contains(internalPropertyIri)) {
          throw BadRequestException(
            s"Property ${createPropertyRequest.propertyInfoContent.propertyIri} would have a cyclical rdfs:subPropertyOf")
        }

        // Check the property is a subproperty of knora-base:hasValue or knora-base:hasLinkTo, but not both.

        allKnoraSuperPropertyIris: Set[SmartIri] = allKnoraSuperPropertyIrisWithoutSelf + internalPropertyIri

        isValueProp = allKnoraSuperPropertyIris.contains(OntologyConstants.KnoraBase.HasValue.toSmartIri)
        isLinkProp = allKnoraSuperPropertyIris.contains(OntologyConstants.KnoraBase.HasLinkTo.toSmartIri)
        isLinkValueProp = allKnoraSuperPropertyIris.contains(OntologyConstants.KnoraBase.HasLinkToValue.toSmartIri)
        isFileValueProp = allKnoraSuperPropertyIris.contains(OntologyConstants.KnoraBase.HasFileValue.toSmartIri)

        _ = if (!(isValueProp || isLinkProp)) {
          throw BadRequestException(
            s"Property ${createPropertyRequest.propertyInfoContent.propertyIri} would not be a subproperty of knora-api:hasValue or knora-api:hasLinkTo")
        }

        _ = if (isValueProp && isLinkProp) {
          throw BadRequestException(
            s"Property ${createPropertyRequest.propertyInfoContent.propertyIri} would be a subproperty of both knora-api:hasValue and knora-api:hasLinkTo")
        }

        // Don't allow new file value properties to be created.

        _ = if (isFileValueProp) {
          throw BadRequestException("New file value properties cannot be created")
        }

        // Don't allow new link value properties to be created directly, because we do that automatically when creating a link property.

        _ = if (isLinkValueProp) {
          throw BadRequestException(
            "New link value properties cannot be created directly. Create a link property instead.")
        }

        // Check the property's salsah-gui:guiElement and salsah-gui:guiAttribute.
        _ = validateGuiAttributes(
          propertyInfoContent = internalPropertyDef,
          allGuiAttributeDefinitions = cacheData.guiAttributeDefinitions,
          errorFun = { msg: String =>
            throw BadRequestException(msg)
          }
        )

        // If we're creating a link property, make the definition of the corresponding link value property.
        maybeLinkValuePropertyDef: Option[PropertyInfoContentV2] = if (isLinkProp) {
          val linkValuePropertyDef = linkPropertyDefToLinkValuePropertyDef(internalPropertyDef)

          if (ontology.properties.contains(linkValuePropertyDef.propertyIri)) {
            throw BadRequestException(s"Link value property ${linkValuePropertyDef.propertyIri} already exists")
          }

          Some(linkValuePropertyDef)
        } else {
          None
        }

        // Check that the subject class constraint, if provided, designates a Knora resource class that exists.

        maybeSubjectClassConstraintPred: Option[PredicateInfoV2] = internalPropertyDef.predicates.get(
          OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri)
        maybeSubjectClassConstraint = maybeSubjectClassConstraintPred.map(
          _.requireIriObject(throw BadRequestException("Invalid knora-api:subjectType")))

        _ = maybeSubjectClassConstraint.foreach { subjectClassConstraint =>
          if (!isKnoraInternalResourceClass(subjectClassConstraint, cacheData)) {
            throw BadRequestException(
              s"Invalid subject class constraint: ${subjectClassConstraint.toOntologySchema(ApiV2Complex)}")
          }
        }

        // Check that the object class constraint designates an appropriate class that exists.

        objectClassConstraint: SmartIri = internalPropertyDef.requireIriObject(
          OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri,
          throw BadRequestException(s"No knora-api:objectType specified"))

        // If this is a value property, ensure its object class constraint is not LinkValue or a file value class.
        _ = if (!isLinkProp) {
          if (objectClassConstraint.toString == OntologyConstants.KnoraBase.LinkValue ||
              OntologyConstants.KnoraBase.FileValueClasses.contains(objectClassConstraint.toString)) {
            throw BadRequestException(
              s"Invalid object class constraint for value property: ${objectClassConstraint.toOntologySchema(ApiV2Complex)}")
          }
        }

        // Check that the subject class, if provided, is a subclass of the subject classes of the base properties.

        _ = maybeSubjectClassConstraint match {
          case Some(subjectClassConstraint) =>
            checkPropertyConstraint(
              cacheData = cacheData,
              internalPropertyIri = internalPropertyIri,
              constraintPredicateIri = OntologyConstants.KnoraBase.SubjectClassConstraint.toSmartIri,
              constraintValueToBeChecked = subjectClassConstraint,
              allSuperPropertyIris = allKnoraSuperPropertyIris,
              errorSchema = ApiV2Complex,
              errorFun = { msg: String =>
                throw BadRequestException(msg)
              }
            )

          case None => ()
        }

        // Check that the object class is a subclass of the object classes of the base properties.

        _ = checkPropertyConstraint(
          cacheData = cacheData,
          internalPropertyIri = internalPropertyIri,
          constraintPredicateIri = OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri,
          constraintValueToBeChecked = objectClassConstraint,
          allSuperPropertyIris = allKnoraSuperPropertyIris,
          errorSchema = ApiV2Complex,
          errorFun = { msg: String =>
            throw BadRequestException(msg)
          }
        )

        // Check that the property definition doesn't refer to any non-shared ontologies in other projects.
        _ = checkOntologyReferencesInPropertyDef(
          ontologyCacheData = cacheData,
          propertyDef = internalPropertyDef,
          errorFun = { msg: String =>
            throw BadRequestException(msg)
          }
        )

        // Add the property (and the link value property if needed) to the triplestore.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .createProperty(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            propertyDef = internalPropertyDef,
            maybeLinkValuePropertyDef = maybeLinkValuePropertyDef,
            lastModificationDate = createPropertyRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = createPropertyRequest.featureFactoryConfig
        )

        // Check that the data that was saved corresponds to the data that was submitted. To make this comparison,
        // we have to undo the SPARQL-escaping of the input.

        loadedPropertyDef <- loadPropertyDefinition(
          propertyIri = internalPropertyIri,
          featureFactoryConfig = createPropertyRequest.featureFactoryConfig
        )

        unescapedInputPropertyDef = internalPropertyDef.unescape

        _ = if (loadedPropertyDef != unescapedInputPropertyDef) {
          throw InconsistentRepositoryDataException(
            s"Attempted to save property definition $unescapedInputPropertyDef, but $loadedPropertyDef was saved")
        }

        maybeLoadedLinkValuePropertyDefFuture: Option[Future[PropertyInfoContentV2]] = maybeLinkValuePropertyDef.map {
          linkValuePropertyDef =>
            loadPropertyDefinition(
              propertyIri = linkValuePropertyDef.propertyIri,
              featureFactoryConfig = createPropertyRequest.featureFactoryConfig
            )
        }

        maybeLoadedLinkValuePropertyDef: Option[PropertyInfoContentV2] <- ActorUtil.optionFuture2FutureOption(
          maybeLoadedLinkValuePropertyDefFuture)
        maybeUnescapedNewLinkValuePropertyDef = maybeLinkValuePropertyDef.map(_.unescape)

        _ = (maybeLoadedLinkValuePropertyDef, maybeUnescapedNewLinkValuePropertyDef) match {
          case (Some(loadedLinkValuePropertyDef), Some(unescapedNewLinkPropertyDef)) =>
            if (loadedLinkValuePropertyDef != unescapedNewLinkPropertyDef) {
              throw InconsistentRepositoryDataException(
                s"Attempted to save link value property definition $unescapedNewLinkPropertyDef, but $loadedLinkValuePropertyDef was saved")
            }

          case _ => ()
        }

        // Update the ontology cache, using the unescaped definition(s).

        readPropertyInfo = ReadPropertyInfoV2(
          entityInfoContent = unescapedInputPropertyDef,
          isEditable = true,
          isResourceProp = true,
          isLinkProp = isLinkProp
        )

        maybeLinkValuePropertyCacheEntry: Option[(SmartIri, ReadPropertyInfoV2)] = maybeUnescapedNewLinkValuePropertyDef
          .map { unescapedNewLinkPropertyDef =>
            unescapedNewLinkPropertyDef.propertyIri -> ReadPropertyInfoV2(
              entityInfoContent = unescapedNewLinkPropertyDef,
              isResourceProp = true,
              isLinkValueProp = true
            )
          }

        updatedOntologyMetadata = ontology.ontologyMetadata.copy(
          lastModificationDate = Some(currentTime)
        )

        updatedOntology = ontology.copy(
          ontologyMetadata = updatedOntologyMetadata,
          properties = ontology.properties ++ maybeLinkValuePropertyCacheEntry + (internalPropertyIri -> readPropertyInfo)
        )

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology),
            subPropertyOfRelations = cacheData.subPropertyOfRelations + (internalPropertyIri -> allKnoraSuperPropertyIris)
          ))

        // Read the data back from the cache.

        response <- getPropertyDefinitionsFromOntologyV2(
          propertyIris = Set(internalPropertyIri),
          allLanguages = true,
          requestingUser = createPropertyRequest.requestingUser
        )
      } yield response
    }

    for {
      requestingUser <- FastFuture.successful(createPropertyRequest.requestingUser)

      externalPropertyIri = createPropertyRequest.propertyInfoContent.propertyIri
      externalOntologyIri = externalPropertyIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalPropertyIri,
        requestingUser = requestingUser
      )

      internalPropertyIri = externalPropertyIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = createPropertyRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalPropertyIri = internalPropertyIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Changes the values of `rdfs:label` or `rdfs:comment` in a property definition.
    *
    * @param changePropertyLabelsOrCommentsRequest the request to change the property's labels or comments.
    * @return a [[ReadOntologyV2]] containing the modified property definition.
    */
  private def changePropertyLabelsOrComments(
      changePropertyLabelsOrCommentsRequest: ChangePropertyLabelsOrCommentsRequestV2): Future[ReadOntologyV2] = {
    def makeTaskFuture(internalPropertyIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyV2] = {
      for {
        cacheData <- getCacheData

        ontology = cacheData.ontologies(internalOntologyIri)

        currentReadPropertyInfo: ReadPropertyInfoV2 = ontology.properties.getOrElse(
          internalPropertyIri,
          throw NotFoundException(s"Property ${changePropertyLabelsOrCommentsRequest.propertyIri} not found"))

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = changePropertyLabelsOrCommentsRequest.lastModificationDate,
          featureFactoryConfig = changePropertyLabelsOrCommentsRequest.featureFactoryConfig
        )

        // If this is a link property, also change the labels/comments of the corresponding link value property.

        maybeCurrentLinkValueReadPropertyInfo: Option[ReadPropertyInfoV2] = if (currentReadPropertyInfo.isLinkProp) {
          val linkValuePropertyIri = internalPropertyIri.fromLinkPropToLinkValueProp
          Some(
            ontology.properties.getOrElse(
              linkValuePropertyIri,
              throw InconsistentRepositoryDataException(s"Link value property $linkValuePropertyIri not found")))
        } else {
          None
        }

        // Do the update.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .changePropertyLabelsOrComments(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            propertyIri = internalPropertyIri,
            maybeLinkValuePropertyIri = maybeCurrentLinkValueReadPropertyInfo.map(_.entityInfoContent.propertyIri),
            predicateToUpdate = changePropertyLabelsOrCommentsRequest.predicateToUpdate,
            newObjects = changePropertyLabelsOrCommentsRequest.newObjects,
            lastModificationDate = changePropertyLabelsOrCommentsRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = changePropertyLabelsOrCommentsRequest.featureFactoryConfig
        )

        // Check that the data that was saved corresponds to the data that was submitted. To make this comparison,
        // we have to undo the SPARQL-escaping of the input.

        loadedPropertyDef <- loadPropertyDefinition(
          propertyIri = internalPropertyIri,
          featureFactoryConfig = changePropertyLabelsOrCommentsRequest.featureFactoryConfig
        )

        unescapedNewLabelOrCommentPredicate: PredicateInfoV2 = PredicateInfoV2(
          predicateIri = changePropertyLabelsOrCommentsRequest.predicateToUpdate,
          objects = changePropertyLabelsOrCommentsRequest.newObjects
        ).unescape

        unescapedNewPropertyDef: PropertyInfoContentV2 = currentReadPropertyInfo.entityInfoContent.copy(
          predicates = currentReadPropertyInfo.entityInfoContent.predicates + (changePropertyLabelsOrCommentsRequest.predicateToUpdate -> unescapedNewLabelOrCommentPredicate)
        )

        _ = if (loadedPropertyDef != unescapedNewPropertyDef) {
          throw InconsistentRepositoryDataException(
            s"Attempted to save property definition $unescapedNewPropertyDef, but $loadedPropertyDef was saved")
        }

        maybeLoadedLinkValuePropertyDefFuture: Option[Future[PropertyInfoContentV2]] = maybeCurrentLinkValueReadPropertyInfo
          .map { linkValueReadPropertyInfo =>
            loadPropertyDefinition(
              propertyIri = linkValueReadPropertyInfo.entityInfoContent.propertyIri,
              featureFactoryConfig = changePropertyLabelsOrCommentsRequest.featureFactoryConfig
            )
          }

        maybeLoadedLinkValuePropertyDef: Option[PropertyInfoContentV2] <- ActorUtil.optionFuture2FutureOption(
          maybeLoadedLinkValuePropertyDefFuture)

        maybeUnescapedNewLinkValuePropertyDef: Option[PropertyInfoContentV2] = maybeLoadedLinkValuePropertyDef.map {
          loadedLinkValuePropertyDef =>
            val unescapedNewLinkPropertyDef = maybeCurrentLinkValueReadPropertyInfo.get.entityInfoContent.copy(
              predicates = maybeCurrentLinkValueReadPropertyInfo.get.entityInfoContent.predicates + (changePropertyLabelsOrCommentsRequest.predicateToUpdate -> unescapedNewLabelOrCommentPredicate)
            )

            if (loadedLinkValuePropertyDef != unescapedNewLinkPropertyDef) {
              throw InconsistentRepositoryDataException(
                s"Attempted to save link value property definition $unescapedNewLinkPropertyDef, but $loadedLinkValuePropertyDef was saved")
            }

            unescapedNewLinkPropertyDef
        }

        // Update the ontology cache, using the unescaped definition(s).

        newReadPropertyInfo = ReadPropertyInfoV2(
          entityInfoContent = unescapedNewPropertyDef,
          isEditable = true,
          isResourceProp = true,
          isLinkProp = currentReadPropertyInfo.isLinkProp
        )

        maybeLinkValuePropertyCacheEntry: Option[(SmartIri, ReadPropertyInfoV2)] = maybeUnescapedNewLinkValuePropertyDef
          .map { unescapedNewLinkPropertyDef =>
            unescapedNewLinkPropertyDef.propertyIri -> ReadPropertyInfoV2(
              entityInfoContent = unescapedNewLinkPropertyDef,
              isResourceProp = true,
              isLinkValueProp = true
            )
          }

        updatedOntologyMetadata = ontology.ontologyMetadata.copy(
          lastModificationDate = Some(currentTime)
        )

        updatedOntology = ontology.copy(
          ontologyMetadata = updatedOntologyMetadata,
          properties = ontology.properties ++ maybeLinkValuePropertyCacheEntry + (internalPropertyIri -> newReadPropertyInfo)
        )

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology)
          ))

        // Read the data back from the cache.

        response <- getPropertyDefinitionsFromOntologyV2(propertyIris = Set(internalPropertyIri),
                                                         allLanguages = true,
                                                         requestingUser =
                                                           changePropertyLabelsOrCommentsRequest.requestingUser)
      } yield response
    }

    for {
      requestingUser <- FastFuture.successful(changePropertyLabelsOrCommentsRequest.requestingUser)

      externalPropertyIri = changePropertyLabelsOrCommentsRequest.propertyIri
      externalOntologyIri = externalPropertyIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalPropertyIri,
        requestingUser = requestingUser
      )

      internalPropertyIri = externalPropertyIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = changePropertyLabelsOrCommentsRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalPropertyIri = internalPropertyIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Changes the values of `rdfs:label` or `rdfs:comment` in a class definition.
    *
    * @param changeClassLabelsOrCommentsRequest the request to change the class's labels or comments.
    * @return a [[ReadOntologyV2]] containing the modified class definition.
    */
  private def changeClassLabelsOrComments(
      changeClassLabelsOrCommentsRequest: ChangeClassLabelsOrCommentsRequestV2): Future[ReadOntologyV2] = {
    def makeTaskFuture(internalClassIri: SmartIri, internalOntologyIri: SmartIri): Future[ReadOntologyV2] = {
      for {
        cacheData <- getCacheData

        ontology = cacheData.ontologies(internalOntologyIri)
        currentReadClassInfo: ReadClassInfoV2 = ontology.classes.getOrElse(
          internalClassIri,
          throw NotFoundException(s"Class ${changeClassLabelsOrCommentsRequest.classIri} not found"))

        // Check that the ontology exists and has not been updated by another user since the client last read it.
        _ <- checkOntologyLastModificationDateBeforeUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = changeClassLabelsOrCommentsRequest.lastModificationDate,
          featureFactoryConfig = changeClassLabelsOrCommentsRequest.featureFactoryConfig
        )

        // Do the update.

        currentTime: Instant = Instant.now

        updateSparql = org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .changeClassLabelsOrComments(
            triplestore = settings.triplestoreType,
            ontologyNamedGraphIri = internalOntologyIri,
            ontologyIri = internalOntologyIri,
            classIri = internalClassIri,
            predicateToUpdate = changeClassLabelsOrCommentsRequest.predicateToUpdate,
            newObjects = changeClassLabelsOrCommentsRequest.newObjects,
            lastModificationDate = changeClassLabelsOrCommentsRequest.lastModificationDate,
            currentTime = currentTime
          )
          .toString()

        _ <- (storeManager ? SparqlUpdateRequest(updateSparql)).mapTo[SparqlUpdateResponse]

        // Check that the ontology's last modification date was updated.

        _ <- checkOntologyLastModificationDateAfterUpdate(
          internalOntologyIri = internalOntologyIri,
          expectedLastModificationDate = currentTime,
          featureFactoryConfig = changeClassLabelsOrCommentsRequest.featureFactoryConfig
        )

        // Check that the data that was saved corresponds to the data that was submitted. To make this comparison,
        // we have to undo the SPARQL-escaping of the input.

        loadedClassDef: ClassInfoContentV2 <- loadClassDefinition(
          classIri = internalClassIri,
          featureFactoryConfig = changeClassLabelsOrCommentsRequest.featureFactoryConfig
        )

        unescapedNewLabelOrCommentPredicate = PredicateInfoV2(
          predicateIri = changeClassLabelsOrCommentsRequest.predicateToUpdate,
          objects = changeClassLabelsOrCommentsRequest.newObjects
        ).unescape

        unescapedNewClassDef: ClassInfoContentV2 = currentReadClassInfo.entityInfoContent.copy(
          predicates = currentReadClassInfo.entityInfoContent.predicates + (changeClassLabelsOrCommentsRequest.predicateToUpdate -> unescapedNewLabelOrCommentPredicate)
        )

        _ = if (loadedClassDef != unescapedNewClassDef) {
          throw InconsistentRepositoryDataException(
            s"Attempted to save class definition $unescapedNewClassDef, but $loadedClassDef was saved")
        }

        // Update the ontology cache, using the unescaped definition(s).

        newReadClassInfo = currentReadClassInfo.copy(
          entityInfoContent = unescapedNewClassDef
        )

        updatedOntology = ontology.copy(
          ontologyMetadata = ontology.ontologyMetadata.copy(
            lastModificationDate = Some(currentTime)
          ),
          classes = ontology.classes + (internalClassIri -> newReadClassInfo)
        )

        _ = storeCacheData(
          cacheData.copy(
            ontologies = cacheData.ontologies + (internalOntologyIri -> updatedOntology)
          ))

        // Read the data back from the cache.

        response <- getClassDefinitionsFromOntologyV2(
          classIris = Set(internalClassIri),
          allLanguages = true,
          requestingUser = changeClassLabelsOrCommentsRequest.requestingUser
        )
      } yield response
    }

    for {
      requestingUser <- FastFuture.successful(changeClassLabelsOrCommentsRequest.requestingUser)

      externalClassIri = changeClassLabelsOrCommentsRequest.classIri
      externalOntologyIri = externalClassIri.getOntologyFromEntity

      _ <- checkOntologyAndEntityIrisForUpdate(
        externalOntologyIri = externalOntologyIri,
        externalEntityIri = externalClassIri,
        requestingUser = requestingUser
      )

      internalClassIri = externalClassIri.toOntologySchema(InternalSchema)
      internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema)

      // Do the remaining pre-update checks and the update while holding a global ontology cache lock.
      taskResult <- IriLocker.runWithIriLock(
        apiRequestID = changeClassLabelsOrCommentsRequest.apiRequestID,
        iri = ONTOLOGY_CACHE_LOCK_IRI,
        task = () =>
          makeTaskFuture(
            internalClassIri = internalClassIri,
            internalOntologyIri = internalOntologyIri
        )
      )
    } yield taskResult
  }

  /**
    * Before an update of an ontology entity, checks that the entity's external IRI, and that of its ontology,
    * are valid, and checks that the user has permission to update the ontology.
    *
    * @param externalOntologyIri the external IRI of the ontology.
    * @param externalEntityIri   the external IRI of the entity.
    * @param requestingUser      the user making the request.
    */
  private def checkOntologyAndEntityIrisForUpdate(externalOntologyIri: SmartIri,
                                                  externalEntityIri: SmartIri,
                                                  requestingUser: UserADM): Future[Unit] = {
    for {
      _ <- checkExternalOntologyIriForUpdate(externalOntologyIri)
      _ <- checkExternalEntityIriForUpdate(externalEntityIri = externalEntityIri)
      _ <- checkPermissionsForOntologyUpdate(
        internalOntologyIri = externalOntologyIri.toOntologySchema(InternalSchema),
        requestingUser = requestingUser
      )
    } yield ()
  }

  /**
    * Loads a property definition from the triplestore and converts it to a [[PropertyInfoContentV2]].
    *
    * @param propertyIri the IRI of the property to be loaded.
    * @param featureFactoryConfig the feature factory configuration.
    * @return a [[PropertyInfoContentV2]] representing the property definition.
    */
  private def loadPropertyDefinition(propertyIri: SmartIri,
                                     featureFactoryConfig: FeatureFactoryConfig): Future[PropertyInfoContentV2] = {
    for {
      sparql <- Future(
        org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .getPropertyDefinition(
            triplestore = settings.triplestoreType,
            propertyIri = propertyIri
          )
          .toString())

      constructResponse <- (storeManager ? SparqlExtendedConstructRequest(
        sparql = sparql,
        featureFactoryConfig = featureFactoryConfig
      )).mapTo[SparqlExtendedConstructResponse]
    } yield
      constructResponseToPropertyDefinition(
        propertyIri = propertyIri,
        constructResponse = constructResponse
      )
  }

  /**
    * Given a map of predicate IRIs to predicate objects describing an entity, returns a map of smart IRIs to [[PredicateInfoV2]]
    * objects that can be used to construct an [[EntityInfoContentV2]].
    *
    * @param entityDefMap a map of predicate IRIs to predicate objects.
    * @return a map of smart IRIs to [[PredicateInfoV2]] objects.
    */
  private def getEntityPredicatesFromConstructResponse(
      entityDefMap: Map[SmartIri, Seq[LiteralV2]]): Map[SmartIri, PredicateInfoV2] = {
    entityDefMap.map {
      case (predicateIri: SmartIri, predObjs: Seq[LiteralV2]) =>
        val predicateInfo = PredicateInfoV2(
          predicateIri = predicateIri,
          objects = predObjs.map {
            case IriLiteralV2(iriStr) =>
              // We use xsd:dateTime in the triplestore (because it is supported in SPARQL), but we return
              // the more restrictive xsd:dateTimeStamp in the API.
              if (iriStr == OntologyConstants.Xsd.DateTime) {
                SmartIriLiteralV2(OntologyConstants.Xsd.DateTimeStamp.toSmartIri)
              } else {
                SmartIriLiteralV2(iriStr.toSmartIri)
              }

            case ontoLiteral: OntologyLiteralV2 => ontoLiteral

            case other =>
              throw InconsistentRepositoryDataException(s"Predicate $predicateIri has an invalid object: $other")
          }
        )

        predicateIri -> predicateInfo
    }
  }

  /**
    * Extracts property definitions from a SPARQL CONSTRUCT response.
    *
    * @param propertyIris      the IRIs of the properties to be read.
    * @param constructResponse the SPARQL construct response to be read.
    * @return a map of property IRIs to property definitions.
    */
  private def constructResponseToPropertyDefinitions(
      propertyIris: Set[SmartIri],
      constructResponse: SparqlExtendedConstructResponse): Map[SmartIri, PropertyInfoContentV2] = {
    propertyIris.map { propertyIri =>
      propertyIri -> constructResponseToPropertyDefinition(
        propertyIri = propertyIri,
        constructResponse = constructResponse
      )
    }.toMap
  }

  /**
    * Converts a SPARQL CONSTRUCT response to a [[PropertyInfoContentV2]].
    *
    * @param propertyIri       the IRI of the property to be read.
    * @param constructResponse the SPARQL CONSTRUCT response to be read.
    * @return a [[PropertyInfoContentV2]] representing a property definition.
    */
  private def constructResponseToPropertyDefinition(
      propertyIri: SmartIri,
      constructResponse: SparqlExtendedConstructResponse): PropertyInfoContentV2 = {
    // All properties defined in the triplestore must be in Knora ontologies.

    val ontologyIri = propertyIri.getOntologyFromEntity

    if (!ontologyIri.isKnoraOntologyIri) {
      throw InconsistentRepositoryDataException(s"Property $propertyIri is not in a Knora ontology")
    }

    val statements = constructResponse.statements

    // Get the statements whose subject is the property.
    val propertyDefMap: Map[SmartIri, Seq[LiteralV2]] = statements(IriSubjectV2(propertyIri.toString))

    val subPropertyOf: Set[SmartIri] = propertyDefMap.get(OntologyConstants.Rdfs.SubPropertyOf.toSmartIri) match {
      case Some(baseProperties) =>
        baseProperties.map {
          case iriLiteral: IriLiteralV2 => iriLiteral.value.toSmartIri
          case other                    => throw InconsistentRepositoryDataException(s"Unexpected object for rdfs:subPropertyOf: $other")
        }.toSet

      case None => Set.empty[SmartIri]
    }

    val otherPreds: Map[SmartIri, PredicateInfoV2] = getEntityPredicatesFromConstructResponse(
      propertyDefMap - OntologyConstants.Rdfs.SubPropertyOf.toSmartIri)

    // salsah-gui:guiOrder isn't allowed here.
    if (otherPreds.contains(OntologyConstants.SalsahGui.GuiOrder.toSmartIri)) {
      throw InconsistentRepositoryDataException(s"Property $propertyIri contains salsah-gui:guiOrder")
    }

    val propertyDef = PropertyInfoContentV2(
      propertyIri = propertyIri,
      subPropertyOf = subPropertyOf,
      predicates = otherPreds,
      ontologySchema = propertyIri.getOntologySchema.get
    )

    if (!propertyIri.isKnoraBuiltInDefinitionIri && propertyDef.getRdfTypes.contains(
          OntologyConstants.Owl.TransitiveProperty.toSmartIri)) {
      throw InconsistentRepositoryDataException(
        s"Project-specific property $propertyIri cannot be an owl:TransitiveProperty")
    }

    propertyDef
  }

  /**
    * Reads OWL named individuals from a SPARQL CONSTRUCT response.
    *
    * @param individualIris    the IRIs of the named individuals to be read.
    * @param constructResponse the SPARQL CONSTRUCT response.
    * @return a map of individual IRIs to named individuals.
    */
  private def constructResponseToIndividuals(
      individualIris: Set[SmartIri],
      constructResponse: SparqlExtendedConstructResponse): Map[SmartIri, IndividualInfoContentV2] = {
    individualIris.map { individualIri =>
      individualIri -> constructResponseToIndividual(
        individualIri = individualIri,
        constructResponse = constructResponse
      )
    }.toMap
  }

  /**
    * Reads an OWL named individual from a SPARQL CONSTRUCT response.
    *
    * @param individualIri     the IRI of the individual to be read.
    * @param constructResponse the SPARQL CONSTRUCT response.
    * @return an [[IndividualInfoContentV2]] representing the named individual.
    */
  private def constructResponseToIndividual(
      individualIri: SmartIri,
      constructResponse: SparqlExtendedConstructResponse): IndividualInfoContentV2 = {
    val statements = constructResponse.statements

    // Get the statements whose subject is the individual.
    val individualMap: Map[SmartIri, Seq[LiteralV2]] = statements(IriSubjectV2(individualIri.toString))

    val predicates: Map[SmartIri, PredicateInfoV2] = getEntityPredicatesFromConstructResponse(individualMap)

    IndividualInfoContentV2(
      individualIri = individualIri,
      predicates = predicates,
      ontologySchema = individualIri.getOntologySchema.get
    )
  }

  /**
    * Loads a class definition from the triplestore and converts it to a [[ClassInfoContentV2]].
    *
    * @param classIri the IRI of the class to be loaded.
    * @param featureFactoryConfig the feature factory configuration.
    * @return a [[ClassInfoContentV2]] representing the class definition.
    */
  private def loadClassDefinition(classIri: SmartIri,
                                  featureFactoryConfig: FeatureFactoryConfig): Future[ClassInfoContentV2] = {
    for {
      sparql <- Future(
        org.knora.webapi.messages.twirl.queries.sparql.v2.txt
          .getClassDefinition(
            triplestore = settings.triplestoreType,
            classIri = classIri
          )
          .toString())

      constructResponse <- (storeManager ? SparqlExtendedConstructRequest(
        sparql = sparql,
        featureFactoryConfig = featureFactoryConfig
      )).mapTo[SparqlExtendedConstructResponse]
    } yield
      constructResponseToClassDefinition(
        classIri = classIri,
        constructResponse = constructResponse
      )
  }

  /**
    * Extracts class definitions from a SPARQL CONSTRUCT response.
    *
    * @param classIris         the IRIs of the classes to be read.
    * @param constructResponse the SPARQL CONSTRUCT response to be read.
    * @return a map of class IRIs to class definitions.
    */
  private def constructResponseToClassDefinitions(
      classIris: Set[SmartIri],
      constructResponse: SparqlExtendedConstructResponse): Map[SmartIri, ClassInfoContentV2] = {
    classIris.map { classIri =>
      classIri -> constructResponseToClassDefinition(
        classIri = classIri,
        constructResponse = constructResponse
      )
    }.toMap
  }

  /**
    * Converts a SPARQL CONSTRUCT response to a [[ClassInfoContentV2]].
    *
    * @param classIri          the IRI of the class to be read.
    * @param constructResponse the SPARQL CONSTRUCT response to be read.
    * @return a [[ClassInfoContentV2]] representing a class definition.
    */
  private def constructResponseToClassDefinition(
      classIri: SmartIri,
      constructResponse: SparqlExtendedConstructResponse): ClassInfoContentV2 = {
    // All classes defined in the triplestore must be in Knora ontologies.

    val ontologyIri = classIri.getOntologyFromEntity

    if (!ontologyIri.isKnoraOntologyIri) {
      throw InconsistentRepositoryDataException(s"Class $classIri is not in a Knora ontology")
    }

    val statements = constructResponse.statements

    // Get the statements whose subject is the class.
    val classDefMap: Map[SmartIri, Seq[LiteralV2]] = statements(IriSubjectV2(classIri.toString))

    // Get the IRIs of the class's base classes.

    val subClassOfObjects: Seq[LiteralV2] =
      classDefMap.getOrElse(OntologyConstants.Rdfs.SubClassOf.toSmartIri, Seq.empty[LiteralV2])

    val subClassOf: Set[SmartIri] = subClassOfObjects.collect {
      case iriLiteral: IriLiteralV2 => iriLiteral.value.toSmartIri
    }.toSet

    // Get the blank nodes representing cardinalities.

    val restrictionBlankNodeIDs: Set[BlankNodeLiteralV2] = subClassOfObjects.collect {
      case blankNodeLiteral: BlankNodeLiteralV2 => blankNodeLiteral
    }.toSet

    val directCardinalities: Map[SmartIri, KnoraCardinalityInfo] = restrictionBlankNodeIDs.map { blankNodeID =>
      val blankNode: Map[SmartIri, Seq[LiteralV2]] = statements.getOrElse(
        BlankNodeSubjectV2(blankNodeID.value),
        throw InconsistentRepositoryDataException(
          s"Blank node '${blankNodeID.value}' not found in construct query result")
      )

      val blankNodeTypeObjs: Seq[LiteralV2] = blankNode.getOrElse(
        OntologyConstants.Rdf.Type.toSmartIri,
        throw InconsistentRepositoryDataException(s"Blank node '${blankNodeID.value}' has no rdf:type"))

      blankNodeTypeObjs match {
        case Seq(IriLiteralV2(OntologyConstants.Owl.Restriction)) => ()
        case _ =>
          throw InconsistentRepositoryDataException(s"Blank node '${blankNodeID.value}' is not an owl:Restriction")
      }

      val onPropertyObjs: Seq[LiteralV2] = blankNode.getOrElse(
        OntologyConstants.Owl.OnProperty.toSmartIri,
        throw InconsistentRepositoryDataException(s"Blank node '${blankNodeID.value}' has no owl:onProperty"))

      val propertyIri: SmartIri = onPropertyObjs match {
        case Seq(propertyIri: IriLiteralV2) => propertyIri.value.toSmartIri
        case other                          => throw InconsistentRepositoryDataException(s"Invalid object for owl:onProperty: $other")
      }

      val owlCardinalityPreds: Set[SmartIri] = blankNode.keySet.filter { predicate =>
        OntologyConstants.Owl.cardinalityOWLRestrictions(predicate.toString)
      }

      if (owlCardinalityPreds.size != 1) {
        throw InconsistentRepositoryDataException(
          s"Expected one cardinality predicate in blank node '${blankNodeID.value}', got ${owlCardinalityPreds.size}")
      }

      val owlCardinalityIri = owlCardinalityPreds.head

      val owlCardinalityValue: Int = blankNode(owlCardinalityIri) match {
        case Seq(IntLiteralV2(intVal)) => intVal
        case other =>
          throw InconsistentRepositoryDataException(
            s"Expected one integer object for predicate $owlCardinalityIri in blank node '${blankNodeID.value}', got $other")
      }

      val guiOrder: Option[Int] = blankNode.get(OntologyConstants.SalsahGui.GuiOrder.toSmartIri) match {
        case Some(Seq(IntLiteralV2(intVal))) => Some(intVal)
        case None                            => None
        case other =>
          throw InconsistentRepositoryDataException(
            s"Expected one integer object for predicate ${OntologyConstants.SalsahGui.GuiOrder} in blank node '${blankNodeID.value}', got $other")
      }

      // salsah-gui:guiElement and salsah-gui:guiAttribute aren't allowed here.

      if (blankNode.contains(OntologyConstants.SalsahGui.GuiElementProp.toSmartIri)) {
        throw InconsistentRepositoryDataException(
          s"Class $classIri contains salsah-gui:guiElement in an owl:Restriction")
      }

      if (blankNode.contains(OntologyConstants.SalsahGui.GuiAttribute.toSmartIri)) {
        throw InconsistentRepositoryDataException(
          s"Class $classIri contains salsah-gui:guiAttribute in an owl:Restriction")
      }

      propertyIri -> Cardinality.owlCardinality2KnoraCardinality(
        propertyIri = propertyIri.toString,
        owlCardinality = Cardinality.OwlCardinalityInfo(
          owlCardinalityIri = owlCardinalityIri.toString,
          owlCardinalityValue = owlCardinalityValue,
          guiOrder = guiOrder
        )
      )
    }.toMap

    // Get any other predicates of the class.

    val otherPreds: Map[SmartIri, PredicateInfoV2] = getEntityPredicatesFromConstructResponse(
      classDefMap - OntologyConstants.Rdfs.SubClassOf.toSmartIri)

    ClassInfoContentV2(
      classIri = classIri,
      subClassOf = subClassOf,
      predicates = otherPreds,
      directCardinalities = directCardinalities,
      ontologySchema = classIri.getOntologySchema.get
    )
  }

  /**
    * Checks that a property's `knora-base:subjectClassConstraint` or `knora-base:objectClassConstraint` is compatible with (i.e. a subclass of)
    * the ones in all its base properties.
    *
    * @param internalPropertyIri        the internal IRI of the property to be checked.
    * @param constraintPredicateIri     the internal IRI of the constraint, i.e. `knora-base:subjectClassConstraint` or `knora-base:objectClassConstraint`.
    * @param constraintValueToBeChecked the constraint value to be checked.
    * @param allSuperPropertyIris       the IRIs of all the base properties of the property, including indirect base properties and the property itself.
    * @param errorSchema                the ontology schema to be used for error messages.
    * @param errorFun                   a function that throws an exception. It will be called with an error message argument if the property constraint is invalid.
    */
  private def checkPropertyConstraint(cacheData: OntologyCacheData,
                                      internalPropertyIri: SmartIri,
                                      constraintPredicateIri: SmartIri,
                                      constraintValueToBeChecked: SmartIri,
                                      allSuperPropertyIris: Set[SmartIri],
                                      errorSchema: OntologySchema,
                                      errorFun: String => Nothing): Unit = {
    // The property constraint value must be a Knora class, or one of a limited set of classes defined in OWL.
    val superClassesOfConstraintValueToBeChecked: Set[SmartIri] =
      if (OntologyConstants.Owl.ClassesThatCanBeKnoraClassConstraints.contains(constraintValueToBeChecked.toString)) {
        Set(constraintValueToBeChecked)
      } else {
        cacheData.subClassOfRelations
          .getOrElse(
            constraintValueToBeChecked,
            errorFun(
              s"Property ${internalPropertyIri.toOntologySchema(errorSchema)} cannot have a ${constraintPredicateIri
                .toOntologySchema(errorSchema)} of " +
                s"${constraintValueToBeChecked.toOntologySchema(errorSchema)}")
          )
          .toSet
      }

    // Get the definitions of all the Knora superproperties of the property.
    val superPropertyInfos: Set[ReadPropertyInfoV2] = (allSuperPropertyIris - internalPropertyIri).collect {
      case superPropertyIri if superPropertyIri.isKnoraDefinitionIri =>
        cacheData
          .ontologies(superPropertyIri.getOntologyFromEntity)
          .properties
          .getOrElse(
            superPropertyIri,
            errorFun(
              s"Property ${internalPropertyIri.toOntologySchema(errorSchema)} is a subproperty of $superPropertyIri, which is undefined")
          )
    }

    // For each superproperty definition, get the value of the specified constraint in that definition, if any. Here we
    // make a map of superproperty IRIs to superproperty constraint values.
    val superPropertyConstraintValues: Map[SmartIri, SmartIri] = superPropertyInfos.flatMap { superPropertyInfo =>
      superPropertyInfo.entityInfoContent.predicates
        .get(constraintPredicateIri)
        .map(_.requireIriObject(throw InconsistentRepositoryDataException(
          s"Property ${superPropertyInfo.entityInfoContent.propertyIri} has an invalid object for $constraintPredicateIri")))
        .map { superPropertyConstraintValue =>
          superPropertyInfo.entityInfoContent.propertyIri -> superPropertyConstraintValue
        }
    }.toMap

    // Check that the constraint value to be checked is a subclass of the constraint value in every superproperty.

    superPropertyConstraintValues.foreach {
      case (superPropertyIri, superPropertyConstraintValue) =>
        if (!superClassesOfConstraintValueToBeChecked.contains(superPropertyConstraintValue)) {
          errorFun(
            s"Property ${internalPropertyIri.toOntologySchema(errorSchema)} cannot have a ${constraintPredicateIri
              .toOntologySchema(errorSchema)} of " +
              s"${constraintValueToBeChecked.toOntologySchema(errorSchema)}, because that is not a subclass of " +
              s"${superPropertyConstraintValue.toOntologySchema(errorSchema)}, which is the ${constraintPredicateIri
                .toOntologySchema(errorSchema)} of " +
              s"a base property, ${superPropertyIri.toOntologySchema(errorSchema)}")
        }
    }
  }

  /**
    * Checks the last modification date of an ontology before an update.
    *
    * @param internalOntologyIri          the internal IRI of the ontology.
    * @param expectedLastModificationDate the last modification date that should now be attached to the ontology.
    * @param featureFactoryConfig the feature factory configuration.
    * @return a failed Future if the expected last modification date is not found.
    */
  private def checkOntologyLastModificationDateBeforeUpdate(
      internalOntologyIri: SmartIri,
      expectedLastModificationDate: Instant,
      featureFactoryConfig: FeatureFactoryConfig): Future[Unit] = {
    checkOntologyLastModificationDate(
      internalOntologyIri = internalOntologyIri,
      expectedLastModificationDate = expectedLastModificationDate,
      featureFactoryConfig = featureFactoryConfig,
      errorFun = throw EditConflictException(
        s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} has been modified by another user, please reload it and try again.")
    )
  }

  /**
    * Checks the last modification date of an ontology after an update.
    *
    * @param internalOntologyIri          the internal IRI of the ontology.
    * @param expectedLastModificationDate the last modification date that should now be attached to the ontology.
    * @param featureFactoryConfig the feature factory configuration.
    * @return a failed Future if the expected last modification date is not found.
    */
  private def checkOntologyLastModificationDateAfterUpdate(internalOntologyIri: SmartIri,
                                                           expectedLastModificationDate: Instant,
                                                           featureFactoryConfig: FeatureFactoryConfig): Future[Unit] = {
    checkOntologyLastModificationDate(
      internalOntologyIri = internalOntologyIri,
      expectedLastModificationDate = expectedLastModificationDate,
      featureFactoryConfig = featureFactoryConfig,
      errorFun = throw UpdateNotPerformedException(
        s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} was not updated. Please report this as a possible bug.")
    )
  }

  /**
    * Checks the last modification date of an ontology.
    *
    * @param internalOntologyIri          the internal IRI of the ontology.
    * @param expectedLastModificationDate the last modification date that the ontology is expected to have.
    * @param featureFactoryConfig the feature factory configuration.
    * @param errorFun                     a function that throws an exception. It will be called if the expected last modification date is not found.
    * @return a failed Future if the expected last modification date is not found.
    */
  private def checkOntologyLastModificationDate(internalOntologyIri: SmartIri,
                                                expectedLastModificationDate: Instant,
                                                featureFactoryConfig: FeatureFactoryConfig,
                                                errorFun: => Nothing): Future[Unit] = {
    for {
      existingOntologyMetadata: Option[OntologyMetadataV2] <- loadOntologyMetadata(
        internalOntologyIri = internalOntologyIri,
        featureFactoryConfig = featureFactoryConfig
      )

      _ = existingOntologyMetadata match {
        case Some(metadata) =>
          metadata.lastModificationDate match {
            case Some(lastModificationDate) =>
              if (lastModificationDate != expectedLastModificationDate) {
                errorFun
              }

            case None =>
              throw InconsistentRepositoryDataException(
                s"Ontology $internalOntologyIri has no ${OntologyConstants.KnoraBase.LastModificationDate}")
          }

        case None =>
          throw NotFoundException(
            s"Ontology $internalOntologyIri (corresponding to ${internalOntologyIri.toOntologySchema(ApiV2Complex)}) not found")
      }
    } yield ()
  }

  /**
    * Checks whether the user has permission to update an ontology.
    *
    * @param internalOntologyIri the internal IRI of the ontology.
    * @param requestingUser      the user making the request.
    * @return the project IRI.
    */
  private def checkPermissionsForOntologyUpdate(internalOntologyIri: SmartIri,
                                                requestingUser: UserADM): Future[SmartIri] = {
    for {
      cacheData <- getCacheData

      projectIri = cacheData.ontologies
        .getOrElse(
          internalOntologyIri,
          throw NotFoundException(s"Ontology ${internalOntologyIri.toOntologySchema(ApiV2Complex)} not found")
        )
        .ontologyMetadata
        .projectIri
        .get

      _ = if (!requestingUser.permissions.isProjectAdmin(projectIri.toString) && !requestingUser.permissions.isSystemAdmin) {
        // not a project or system admin
        throw ForbiddenException("Ontologies can be modified only by a project or system admin.")
      }

    } yield projectIri
  }

  /**
    * Checks whether an ontology IRI is valid for an update.
    *
    * @param externalOntologyIri the external IRI of the ontology.
    * @return a failed Future if the IRI is not valid for an update.
    */
  private def checkExternalOntologyIriForUpdate(externalOntologyIri: SmartIri): Future[Unit] = {
    if (!externalOntologyIri.isKnoraOntologyIri) {
      FastFuture.failed(throw BadRequestException(s"Invalid ontology IRI for request: $externalOntologyIri}"))
    } else if (!externalOntologyIri.getOntologySchema.contains(ApiV2Complex)) {
      FastFuture.failed(throw BadRequestException(s"Invalid ontology schema for request: $externalOntologyIri"))
    } else if (externalOntologyIri.isKnoraBuiltInDefinitionIri) {
      FastFuture.failed(
        throw BadRequestException(s"Ontology $externalOntologyIri cannot be modified via the Knora API"))
    } else {
      FastFuture.successful(())
    }
  }

  /**
    * Checks whether an entity IRI is valid for an update.
    *
    * @param externalEntityIri the external IRI of the entity.
    * @return a failed Future if the entity IRI is not valid for an update, or is not from the specified ontology.
    */
  private def checkExternalEntityIriForUpdate(externalEntityIri: SmartIri): Future[Unit] = {
    if (!externalEntityIri.isKnoraApiV2EntityIri) {
      FastFuture.failed(throw BadRequestException(s"Invalid entity IRI for request: $externalEntityIri"))
    } else if (!externalEntityIri.getOntologySchema.contains(ApiV2Complex)) {
      FastFuture.failed(throw BadRequestException(s"Invalid ontology schema for request: $externalEntityIri"))
    } else {
      FastFuture.successful(())
    }
  }

  /**
    * Given the definition of a link property, returns the definition of the corresponding link value property.
    *
    * @param internalPropertyDef the definition of the the link property, in the internal schema.
    * @return the definition of the corresponding link value property.
    */
  private def linkPropertyDefToLinkValuePropertyDef(
      internalPropertyDef: PropertyInfoContentV2): PropertyInfoContentV2 = {
    val linkValuePropIri = internalPropertyDef.propertyIri.fromLinkPropToLinkValueProp

    val newPredicates
      : Map[SmartIri, PredicateInfoV2] = (internalPropertyDef.predicates - OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri) +
      (OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri -> PredicateInfoV2(
        predicateIri = OntologyConstants.KnoraBase.ObjectClassConstraint.toSmartIri,
        objects = Seq(SmartIriLiteralV2(OntologyConstants.KnoraBase.LinkValue.toSmartIri))
      ))

    internalPropertyDef.copy(
      propertyIri = linkValuePropIri,
      predicates = newPredicates,
      subPropertyOf = Set(OntologyConstants.KnoraBase.HasLinkToValue.toSmartIri)
    )
  }

  /**
    * Given the cardinalities directly defined on a given class, and the cardinalities that it could inherit (directly
    * or indirectly) from its base classes, combines the two, filtering out the base class cardinalities ones that are overridden
    * by cardinalities defined directly on the given class. Checks that if a directly defined cardinality overrides an inheritable one,
    * the directly defined one is at least as restrictive as the inheritable one.
    *
    * @param classIri                  the class IRI.
    * @param thisClassCardinalities    the cardinalities directly defined on a given resource class.
    * @param inheritableCardinalities  the cardinalities that the given resource class could inherit from its base classes.
    * @param allSubPropertyOfRelations a map in which each property IRI points to the full set of its base properties.
    * @param errorSchema               the ontology schema to be used in error messages.
    * @param errorFun                  a function that throws an exception. It will be called with an error message argument if the cardinalities are invalid.
    * @return a map in which each key is the IRI of a property that has a cardinality in the resource class (or that it inherits
    *         from its base classes), and each value is the cardinality on the property.
    */
  private def overrideCardinalities(classIri: SmartIri,
                                    thisClassCardinalities: Map[SmartIri, OwlCardinalityInfo],
                                    inheritableCardinalities: Map[SmartIri, OwlCardinalityInfo],
                                    allSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]],
                                    errorSchema: OntologySchema,
                                    errorFun: String => Nothing): Map[SmartIri, OwlCardinalityInfo] = {
    // A map of directly defined properties to the base class properties they can override.
    val overrides: Map[SmartIri, Set[SmartIri]] = thisClassCardinalities.map {
      case (thisClassProp, thisClassCardinality) =>
        // For each directly defined cardinality, get its base properties, if available.
        // If the class has a cardinality for a non-Knora property like rdfs:label (which can happen only
        // if it's a built-in class), we won't have any information about the base properties of that property.
        val basePropsOfThisClassProp: Set[SmartIri] =
          allSubPropertyOfRelations.getOrElse(thisClassProp, Set.empty[SmartIri])

        val overridedBaseProps: Set[SmartIri] = inheritableCardinalities.foldLeft(Set.empty[SmartIri]) {
          case (acc, (baseClassProp, baseClassCardinality)) =>
            // Can the directly defined cardinality override the inheritable one?
            if (thisClassProp == baseClassProp || basePropsOfThisClassProp.contains(baseClassProp)) {
              // Yes. Is the directly defined one at least as restrictive as the inheritable one?

              val thisClassKnoraCardinality: KnoraCardinalityInfo = Cardinality.owlCardinality2KnoraCardinality(
                propertyIri = thisClassProp.toString,
                owlCardinality = thisClassCardinality
              )

              val inheritableKnoraCardinality: KnoraCardinalityInfo = Cardinality.owlCardinality2KnoraCardinality(
                propertyIri = baseClassProp.toString,
                owlCardinality = baseClassCardinality
              )

              if (!Cardinality.isCompatible(directCardinality = thisClassKnoraCardinality.cardinality,
                                            inheritableCardinality = inheritableKnoraCardinality.cardinality)) {
                // No. Throw an exception.
                errorFun(
                  s"In class <${classIri.toOntologySchema(errorSchema)}>, the directly defined cardinality $thisClassKnoraCardinality on ${thisClassProp.toOntologySchema(
                    errorSchema)} is not compatible with the inherited cardinality $inheritableKnoraCardinality on ${baseClassProp
                    .toOntologySchema(errorSchema)}, because it is less restrictive")
              } else {
                // Yes. Filter out the inheritable one, because the directly defined one overrides it.
                acc + baseClassProp
              }
            } else {
              // No. Let the class inherit the inheritable cardinality.
              acc
            }
        }

        thisClassProp -> overridedBaseProps
    }

    // A map of base class properties to the directly defined properties that can override them.
    val reverseOverrides: Map[SmartIri, Set[SmartIri]] = overrides
      .map {
        // Unpack the sets to make an association list.
        case (thisClassProp: SmartIri, baseClassProps: Set[SmartIri]) =>
          baseClassProps.map { baseClassProp =>
            thisClassProp -> baseClassProp
          }
      }
      .flatten
      .map {
        // Reverse the direction of the association list.
        case (thisClassProp: SmartIri, baseClassProp: SmartIri) =>
          baseClassProp -> thisClassProp
      }
      .groupBy {
        // Group by base class prop to make a map.
        case (baseClassProp: SmartIri, _) => baseClassProp
      }
      .map {
        // Make sets of directly defined props.
        case (baseClassProp: SmartIri, thisClassProps: immutable.Iterable[(SmartIri, SmartIri)]) =>
          baseClassProp -> thisClassProps.map {
            case (_, thisClassProp) => thisClassProp
          }.toSet
      }

    // Are there any base class properties that are overridden by more than one directly defined property,
    // and do any of those base properties have cardinalities that could cause conflicts between the cardinalities
    // on the directly defined cardinalities?
    reverseOverrides.foreach {
      case (baseClassProp, thisClassProps) =>
        if (thisClassProps.size > 1) {
          val overriddenCardinality: KnoraCardinalityInfo = Cardinality.owlCardinality2KnoraCardinality(
            propertyIri = baseClassProp.toString,
            owlCardinality = inheritableCardinalities(baseClassProp)
          )

          if (overriddenCardinality.cardinality == Cardinality.MustHaveOne || overriddenCardinality.cardinality == Cardinality.MayHaveOne) {
            errorFun(
              s"In class <${classIri.toOntologySchema(errorSchema)}>, there is more than one cardinality that would override the inherited cardinality $overriddenCardinality on <${baseClassProp
                .toOntologySchema(errorSchema)}>")
          }
        }
    }

    thisClassCardinalities ++ inheritableCardinalities.filterNot {
      case (basePropIri, _) => reverseOverrides.contains(basePropIri)
    }
  }

  /**
    * Given all the `rdfs:subClassOf` relations between classes, calculates all the inverse relations.
    *
    * @param allSubClassOfRelations all the `rdfs:subClassOf` relations between classes.
    * @return a map of IRIs of resource classes to sets of the IRIs of their subclasses.
    */
  private def calculateSuperClassOfRelations(
      allSubClassOfRelations: Map[SmartIri, Seq[SmartIri]]): Map[SmartIri, Set[SmartIri]] = {
    allSubClassOfRelations.toVector
      .flatMap {
        case (subClass: SmartIri, baseClasses: Seq[SmartIri]) =>
          baseClasses.map { baseClass =>
            baseClass -> subClass
          }
      }
      .groupBy(_._1)
      .map {
        case (baseClass: SmartIri, baseClassAndSubClasses: Vector[(SmartIri, SmartIri)]) =>
          baseClass -> baseClassAndSubClasses.map(_._2).toSet
      }
  }

  /**
    * Given a class loaded from the triplestore, recursively adds its inherited cardinalities to the cardinalities it defines
    * directly. A cardinality for a subproperty in a subclass overrides a cardinality for a base property in
    * a base class.
    *
    * @param classIri                  the IRI of the class whose properties are to be computed.
    * @param directSubClassOfRelations a map of the direct `rdfs:subClassOf` relations defined on each class.
    * @param allSubPropertyOfRelations a map in which each property IRI points to the full set of its base properties.
    * @param directClassCardinalities  a map of the cardinalities defined directly on each class.
    * @return a map in which each key is the IRI of a property that has a cardinality in the class (or that it inherits
    *         from its base classes), and each value is the cardinality on the property.
    */
  private def inheritCardinalitiesInLoadedClass(
      classIri: SmartIri,
      directSubClassOfRelations: Map[SmartIri, Set[SmartIri]],
      allSubPropertyOfRelations: Map[SmartIri, Set[SmartIri]],
      directClassCardinalities: Map[SmartIri, Map[SmartIri, OwlCardinalityInfo]]): Map[SmartIri, OwlCardinalityInfo] = {
    // Recursively get properties that are available to inherit from base classes. If we have no information about
    // a class, that could mean that it isn't a subclass of knora-base:Resource (e.g. it's something like
    // foaf:Person), in which case we assume that it has no base classes.
    val cardinalitiesAvailableToInherit: Map[SmartIri, OwlCardinalityInfo] = directSubClassOfRelations
      .getOrElse(classIri, Set.empty[SmartIri])
      .foldLeft(Map.empty[SmartIri, OwlCardinalityInfo]) {
        case (acc, baseClass) =>
          acc ++ inheritCardinalitiesInLoadedClass(
            classIri = baseClass,
            directSubClassOfRelations = directSubClassOfRelations,
            allSubPropertyOfRelations = allSubPropertyOfRelations,
            directClassCardinalities = directClassCardinalities
          )
      }

    // Get the properties that have cardinalities defined directly on this class. Again, if we have no information
    // about a class, we assume that it has no cardinalities.
    val thisClassCardinalities: Map[SmartIri, OwlCardinalityInfo] =
      directClassCardinalities.getOrElse(classIri, Map.empty[SmartIri, OwlCardinalityInfo])

    // Combine the cardinalities defined directly on this class with the ones that are available to inherit.
    overrideCardinalities(
      classIri = classIri,
      thisClassCardinalities = thisClassCardinalities,
      inheritableCardinalities = cardinalitiesAvailableToInherit,
      allSubPropertyOfRelations = allSubPropertyOfRelations,
      errorSchema = InternalSchema, { msg: String =>
        throw InconsistentRepositoryDataException(msg)
      }
    )
  }

  /**
    * Checks whether a class IRI refers to a Knora internal resource class.
    *
    * @param classIri the class IRI.
    * @return `true` if the class IRI refers to a Knora resource class, or `false` if the class
    *         does not exist or is not a Knora internal resource class.
    */
  private def isKnoraInternalResourceClass(classIri: SmartIri, cacheData: OntologyCacheData): Boolean = {
    classIri.isKnoraInternalEntityIri &&
    cacheData.ontologies(classIri.getOntologyFromEntity).classes.get(classIri).exists(_.isResourceClass)
  }

  /**
    * Checks whether a property is a subproperty of `knora-base:resourceProperty`.
    *
    * @param propertyIri the property IRI.
    * @param cacheData   the ontology cache.
    * @return `true` if the property is a subproperty of `knora-base:resourceProperty`.
    */
  private def isKnoraResourceProperty(propertyIri: SmartIri, cacheData: OntologyCacheData): Boolean = {
    propertyIri.isKnoraEntityIri &&
    cacheData.ontologies(propertyIri.getOntologyFromEntity).properties.get(propertyIri).exists(_.isResourceProp)
  }

  /**
    * Checks whether a property is a subproperty of `knora-base:hasLinkTo`.
    *
    * @param propertyIri the property IRI.
    * @param cacheData   the ontology cache.
    * @return `true` if the property is a subproperty of `knora-base:hasLinkTo`.
    */
  private def isLinkProp(propertyIri: SmartIri, cacheData: OntologyCacheData): Boolean = {
    propertyIri.isKnoraEntityIri &&
    cacheData.ontologies(propertyIri.getOntologyFromEntity).properties.get(propertyIri).exists(_.isLinkProp)
  }

  /**
    * Checks whether a property is a subproperty of `knora-base:hasLinkToValue`.
    *
    * @param propertyIri the property IRI.
    * @param cacheData   the ontology cache.
    * @return `true` if the property is a subproperty of `knora-base:hasLinkToValue`.
    */
  private def isLinkValueProp(propertyIri: SmartIri, cacheData: OntologyCacheData): Boolean = {
    propertyIri.isKnoraEntityIri &&
    cacheData.ontologies(propertyIri.getOntologyFromEntity).properties.get(propertyIri).exists(_.isLinkValueProp)
  }

  /**
    * Checks whether a property is a subproperty of `knora-base:hasFileValue`.
    *
    * @param propertyIri the property IRI.
    * @param cacheData   the ontology cache.
    * @return `true` if the property is a subproperty of `knora-base:hasFileValue`.
    */
  private def isFileValueProp(propertyIri: SmartIri, cacheData: OntologyCacheData): Boolean = {
    propertyIri.isKnoraEntityIri &&
    cacheData.ontologies(propertyIri.getOntologyFromEntity).properties.get(propertyIri).exists(_.isFileValueProp)
  }
}