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
020package org.apache.isis.core.progmodel.facets.members.describedas.staticmethod;
021
022import java.lang.reflect.Method;
023
024import org.apache.isis.core.commons.lang.MethodExtensions;
025import org.apache.isis.core.commons.lang.StringExtensions;
026import org.apache.isis.core.metamodel.exceptions.MetaModelException;
027import org.apache.isis.core.metamodel.facetapi.Facet;
028import org.apache.isis.core.metamodel.facetapi.FacetHolder;
029import org.apache.isis.core.metamodel.facetapi.FacetUtil;
030import org.apache.isis.core.metamodel.facetapi.FeatureType;
031import org.apache.isis.core.metamodel.facets.describedas.DescribedAsFacet;
032import org.apache.isis.core.metamodel.methodutils.MethodScope;
033import org.apache.isis.core.progmodel.facets.MethodFinderUtils;
034import org.apache.isis.core.progmodel.facets.MethodPrefixBasedFacetFactoryAbstract;
035import org.apache.isis.core.progmodel.facets.MethodPrefixConstants;
036
037/**
038 * Sets up a {@link DescribedAsFacet} if a
039 * {@value MethodPrefixConstants#DESCRIPTION_PREFIX}-prefixed method is present.
040 */
041public class DescribedAsFacetViaDescriptionMethodFacetFactory extends MethodPrefixBasedFacetFactoryAbstract {
042
043    private static final String[] PREFIXES = { MethodPrefixConstants.DESCRIPTION_PREFIX };
044
045    /**
046     * Note that the {@link Facet}s registered are the generic ones from
047     * noa-architecture (where they exist)
048     */
049    public DescribedAsFacetViaDescriptionMethodFacetFactory() {
050        super(FeatureType.MEMBERS, OrphanValidation.VALIDATE, PREFIXES);
051    }
052
053    // ///////////////////////////////////////////////////////
054    // Actions
055    // ///////////////////////////////////////////////////////
056
057    @Override
058    public void process(final ProcessMethodContext processMethodContext) {
059        attachDescribedAsFacetIfDescriptionMethodIsFound(processMethodContext);
060    }
061
062    public static void attachDescribedAsFacetIfDescriptionMethodIsFound(final ProcessMethodContext processMethodContext) {
063
064        final Method method = processMethodContext.getMethod();
065        final String capitalizedName = StringExtensions.asJavaBaseNameStripAccessorPrefixIfRequired(method.getName());
066
067        final Class<?> cls = processMethodContext.getCls();
068        final Method descriptionMethod = MethodFinderUtils.findMethod(cls, MethodScope.CLASS, MethodPrefixConstants.DESCRIPTION_PREFIX + capitalizedName, String.class, new Class[0]);
069        if (descriptionMethod == null) {
070            return;
071        }
072
073        processMethodContext.removeMethod(descriptionMethod);
074        final String description = invokeDescriptionMethod(descriptionMethod);
075
076        final FacetHolder facetedMethod = processMethodContext.getFacetHolder();
077        FacetUtil.addFacet(new DescribedAsFacetViaMethod(description, descriptionMethod, facetedMethod));
078    }
079
080    private static String invokeDescriptionMethod(final Method descriptionMethod) {
081        String description = null;
082        try {
083            description = (String) MethodExtensions.invokeStatic(descriptionMethod);
084        } catch (final ClassCastException ex) {
085            // ignore
086        }
087        if (description == null) {
088            throw new MetaModelException("method " + descriptionMethod + "must return a string");
089        }
090        return description;
091    }
092
093}