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.viewer.graphql.model.domain.rich.query;
  
  import graphql.schema.DataFetchingEnvironment;
  import graphql.schema.GraphQLOutputType;
  
  import static graphql.schema.GraphQLFieldDefinition.newFieldDefinition;
  
  import org.apache.causeway.core.metamodel.object.ManagedObject;
  import org.apache.causeway.core.metamodel.spec.feature.ObjectAssociation;
  import org.apache.causeway.viewer.graphql.model.context.Context;
  import org.apache.causeway.viewer.graphql.model.domain.Element;
  import org.apache.causeway.viewer.graphql.model.domain.common.interactors.MemberInteractor;
  import org.apache.causeway.viewer.graphql.model.fetcher.BookmarkedPojo;
  
  public abstract class RichAssociationGet<T extends ObjectAssociation> extends Element {
  
      final MemberInteractor<T> memberInteractor;
  
      public RichAssociationGet(
              final MemberInteractor<T> memberInteractor,
              final Context context) {
          super(context);
          this.memberInteractor = memberInteractor;
  
          GraphQLOutputType type = outputTypeFor(memberInteractor);
          if (type != null) {
              var fieldBuilder = newFieldDefinition()
                      .name("get")
                      .type(type);
              setField(fieldBuilder.build());
          } else {
              setField(null);
          }
      }
  
      abstract GraphQLOutputType outputTypeFor(MemberInteractor<T> holder);
  
      @Override
      protected Object fetchData(final DataFetchingEnvironment environment) {
  
          // TODO: introduce evaluator
          var sourcePojo = BookmarkedPojo.sourceFrom(environment);
  
          var sourcePojoClass = sourcePojo.getClass();
          var objectSpecification = context.specificationLoader.loadSpecification(sourcePojoClass);
          if (objectSpecification == null) {
              // not expected
              return null;
          }
  
          var association = memberInteractor.getObjectMember();
          var managedObject = ManagedObject.adaptSingular(objectSpecification, sourcePojo);
          var resultManagedObject = association.get(managedObject);
  
          return resultManagedObject != null
                  ? resultManagedObject.getPojo()
                  : null;
      }
  
  }
  