content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you under the Apache License, Version 2.0 (the
   *  "License"); you may not use this file except in compliance
   *  with the License.  You may obtain a copy of the License at
   *
   *        http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing,
   *  software distributed under the License is distributed on an
   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *  KIND, either express or implied.  See the License for the
   *  specific language governing permissions and limitations
   *  under the License.
   */
  package org.apache.causeway.core.metamodel.interactions.managed;
  
  import java.util.Optional;
  
  import org.jspecify.annotations.Nullable;
  
  import org.apache.causeway.applib.Identifier;
  import org.apache.causeway.commons.internal.exceptions._Exceptions;
  import org.apache.causeway.core.metamodel.facetapi.Facet;
  import org.apache.causeway.core.metamodel.spec.ObjectSpecification;
  import org.apache.causeway.core.metamodel.spec.feature.ObjectFeature;
  
  sealed public interface ManagedFeature
  permits ManagedMember, ManagedParameter {
  
      Identifier getIdentifier();
  
      /**
       * @return The feature's translated friendly name, as rendered with the UI.
       */
      String getFriendlyName();
  
      /**
       * @return Optionally the feature's translated description, as rendered with the UI (eg. tooltips).
       */
      Optional<String> getDescription();
  
      /**
       * @return The specification of the feature's underlying type.
       * For actions this is the specification of the action's return type.
       */
      ObjectSpecification getElementType();
  
      /**
       * @return The feature's underlying type.
       * For actions this is the action's return type.
       */
      default Class<?> getElementClass() {
          return getElementType().getCorrespondingClass();
      }
  
      ObjectFeature getMetaModel();
  
      /**
       * @param facetType
       * @return Optionally the feature's facet of the specified {@code facetType}
       * (as per the type it reports from {@link Facet#facetType()}), based on existence.
       */
      default <T extends Facet> Optional<T> getFacet(final @Nullable Class<T> facetType) {
          return facetType!=null
                  ? Optional.ofNullable(getMetaModel().getFacet(facetType))
                  : Optional.empty();
      }
  
      /**
       * @param facetType
       * @return Whether there exists a facet for this feature, that is of the
       * specified {@code facetType} (as per the type it reports from {@link Facet#facetType()}).
       */
      default <T extends Facet> boolean hasFacet(final @Nullable Class<T> facetType) {
          return facetType!=null
                  ? getMetaModel().getFacet(facetType)!=null
                  : false;
      }
  
      default <T extends Facet> T getFacetElseFail(final @Nullable Class<T> facetType) {
          return getFacet(facetType)
                  .orElseThrow(()->_Exceptions
                          .noSuchElement("Feature %s has no such facet %s",
                                  getIdentifier(),
                                  facetType.getName()));
      }
  
  }
  