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.spec.feature;
  
  import java.util.Optional;
  import java.util.function.Supplier;
  
  import org.apache.causeway.applib.Identifier;
  import org.apache.causeway.commons.functional.Either;
  import org.apache.causeway.core.metamodel.facetapi.FeatureType;
  import org.apache.causeway.core.metamodel.facets.objectvalue.mandatory.MandatoryFacet;
  import org.apache.causeway.core.metamodel.object.ManagedObject;
  import org.apache.causeway.core.metamodel.spec.ObjectSpecification;
  import org.apache.causeway.core.metamodel.spec.Specification;
  
  /**
   * A specification representing a non-{@link FeatureType#OBJECT object}, that
   * therefore has an underlying type (the type of the property, collection)
   *
   * <p>
   * For a property or action parameter, is the type. For a collection is the
   * element type. For an action it is always <tt>null</tt>.
   */
  public interface ObjectFeature extends Specification {
  
      /**
       * Returns the identifier of the member, which must not change. This should
       * be all camel-case with no spaces: so if the member is called 'Return
       * Date' then a suitable id would be 'returnDate'.
       * @implNote for {@link ObjectMember}(s) this is a shortcut for
       * {@link ObjectMember#getFeatureIdentifier()}.getMemberLogicalName()
       * @see Identifier#getMemberLogicalName()
       */
      String getId();
  
      /**
       * Returns the (translated friendly) name for this member - the field or action.
       * If not specified, defaults to the java-source-code name of this member.
       *
       * @apiNote argument is a {@link Supplier}, because the {@link ManagedObject}
       * is only required when the name is provided imperatively and domain-object
       * retrieval might be expensive
       *
       * @see #getFeatureIdentifier()
       */
      String getFriendlyName(Supplier<ManagedObject> domainObjectProvider);
      default String getFriendlyName(final ManagedObject domainObject) {
          return getFriendlyName(()->domainObject);
      }
  
  
      /**
       * Optionally returns the (translated friendly) name for this member -
       * the field or action, based on whether the name is provided statically
       * and not imperatively.
       * <p>
       * If not specified, defaults to the java-source-code name of this member.
       *
       * @see #getFeatureIdentifier()
       */
      Optional<String> getStaticFriendlyName();
  
      /**
       * If not statically (non-imperatively) specified otherwise,
       * the (translated friendly) name inferred from the corresponding domain-object-member (java-source) name.
       * <p>
       * Eg used when rendering a domain-object collection as table,
       * the table's (translated friendly) column names are inferred
       * from the corresponding domain-object-property canonical-name(s).
       * @since 2.0
       */
      String getCanonicalFriendlyName();
  
      /**
       * Either the friendly name's static or canonical form, based on whether the friendly name is resolved
       * statically or imperatively.
       * @see #getStaticFriendlyName()
       * @see #getCanonicalFriendlyName()
       * @since 2.0
       */
      default Either<String, String> getStaticOrCanonicalFriendlyName() {
          var staticFriendlyName = getStaticFriendlyName();
          return staticFriendlyName.isPresent()
                  ? Either.left(staticFriendlyName.get())
                  : Either.right(getCanonicalFriendlyName());
      }
  
      /**
       * Returns a (translated) description of how the member is used - this complements the
       * help text.
       *
       * @apiNote argument is a {@link Supplier}, because the {@link ManagedObject}
       * is only required when the description is provided imperatively and domain-object
       * retrieval might be expensive
       *
       */
      Optional<String> getDescription(final Supplier<ManagedObject> domainObjectProvider);
      default Optional<String> getDescription(final ManagedObject domainObject) {
          return getDescription(()->domainObject);
      }
  
      /**
       * Optionally returns the (translated) description of how the member is used,
       * based on whether the description is provided statically
       * and not imperatively.
       */
      Optional<String> getStaticDescription();
  
      /**
       * If statically (non-imperatively) specified,
       * the (translated friendly) description, otherwise {@code Optional#empty()}.
       * <p>
       * Eg used when rendering a domain-object collection as table,
       * the table's (translated friendly) column descriptions are inferred
       * from the corresponding domain-object-property column-description(s).
       * @return null-able; if empty, no description is available,
       * consequently eg. viewers should not provide any tooltip
       * @since 2.0
       */
      Optional<String> getCanonicalDescription();
  
      /**
       * Optionally either the descriptions's static or canonical form,
       * based on whether a description is present (at all), and if so,
       * resolved either statically or imperatively.
       * @see #getStaticDescription()
       * @see #getCanonicalDescription()
       * @since 2.0
       */
      default Optional<Either<String, String>> getStaticOrCanonicalDescription() {
          var staticDescription = getStaticDescription();
          return staticDescription.isPresent()
                  ? Optional.of(Either.left(staticDescription.get()))
                  : getCanonicalDescription()
                      .map(Either::right);
      }
  
      /**
       * The specification of the associated type.
       * <ul>
       * <li>for a {@link OneToOneAssociation property}, will return the
       * {@link ObjectSpecification} of the type that the <i>getter</i> returns.
       * <li>for a {@link OneToManyAssociation collection} it will be the type of
       * element the collection holds (not the type of collection).
       * <li>for an {@link ObjectAction action} will return {@link ObjectAction#getReturnType()}.
       * <li>for an {@link ObjectActionParameter action parameter}, will return the type of
       * the parameter.
       * </ul>
       * @since 2.0
       */
      ObjectSpecification getElementType();
  
      /**
       * Returns a flag indicating if it can be left unset when the action can be
       * invoked.
       */
      default boolean isOptional() {
          return !MandatoryFacet.isMandatory(this);
      }
  
      String asciiId();
  }
  