001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one
003     *  or more contributor license agreements.  See the NOTICE file
004     *  distributed with this work for additional information
005     *  regarding copyright ownership.  The ASF licenses this file
006     *  to you under the Apache License, Version 2.0 (the
007     *  "License"); you may not use this file except in compliance
008     *  with the License.  You may obtain a copy of the License at
009     *
010     *        http://www.apache.org/licenses/LICENSE-2.0
011     *
012     *  Unless required by applicable law or agreed to in writing,
013     *  software distributed under the License is distributed on an
014     *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     *  KIND, either express or implied.  See the License for the
016     *  specific language governing permissions and limitations
017     *  under the License.
018     */
019    
020    package org.apache.isis.core.progmodel.facets.param.defaults.fromtype;
021    
022    import org.apache.isis.core.metamodel.facetapi.FacetUtil;
023    import org.apache.isis.core.metamodel.facetapi.FeatureType;
024    import org.apache.isis.core.metamodel.facets.AnnotationBasedFacetFactoryAbstract;
025    import org.apache.isis.core.metamodel.facets.actions.defaults.ActionDefaultsFacet;
026    import org.apache.isis.core.metamodel.spec.ObjectSpecification;
027    import org.apache.isis.core.progmodel.facets.object.defaults.DefaultedFacet;
028    
029    public class ParameterDefaultDerivedFromTypeFacetFactory extends AnnotationBasedFacetFactoryAbstract {
030    
031        public ParameterDefaultDerivedFromTypeFacetFactory() {
032            super(FeatureType.PARAMETERS_ONLY);
033        }
034    
035        /**
036         * If there is a {@link DefaultedFacet} on any of the action's parameter types, then installs a
037         * {@link ActionDefaultsFacet} for the action.
038         */
039        @Override
040        public void processParams(final ProcessParameterContext processParameterContext) {
041            // don't overwrite any defaults already picked up
042            if (processParameterContext.getFacetHolder().getFacet(ActionDefaultsFacet.class) != null) {
043                return;
044            }
045    
046            // try to infer defaults from any of the parameter's underlying types
047            final Class<?>[] parameterTypes = processParameterContext.getMethod().getParameterTypes();
048            final DefaultedFacet[] parameterTypeDefaultedFacets = new DefaultedFacet[parameterTypes.length];
049            boolean hasAtLeastOneDefault = false;
050            for (int i = 0; i < parameterTypes.length; i++) {
051                final Class<?> paramType = parameterTypes[i];
052                parameterTypeDefaultedFacets[i] = getDefaultedFacet(paramType);
053                hasAtLeastOneDefault = hasAtLeastOneDefault | (parameterTypeDefaultedFacets[i] != null);
054            }
055            if (hasAtLeastOneDefault) {
056                FacetUtil.addFacet(new ActionParameterDefaultFacetDerivedFromTypeFacets(parameterTypeDefaultedFacets,
057                    processParameterContext.getFacetHolder()));
058            }
059        }
060    
061        private DefaultedFacet getDefaultedFacet(final Class<?> paramType) {
062            final ObjectSpecification paramTypeSpec = getSpecificationLookup().loadSpecification(paramType);
063            return paramTypeSpec.getFacet(DefaultedFacet.class);
064        }
065    
066    }