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.facetdecorators.help;
021    
022    import org.apache.isis.applib.Identifier;
023    import org.apache.isis.core.metamodel.facetapi.Facet;
024    import org.apache.isis.core.metamodel.facetapi.FacetHolder;
025    import org.apache.isis.core.metamodel.facetapi.IdentifiedHolder;
026    import org.apache.isis.core.metamodel.facetdecorator.FacetDecoratorAbstract;
027    import org.apache.isis.core.metamodel.facets.help.HelpFacet;
028    
029    public class HelpFacetDecoratorUsingHelpManager extends FacetDecoratorAbstract implements HelpFacetDecorator {
030        private final HelpManager helpManager;
031    
032        public HelpFacetDecoratorUsingHelpManager(final HelpManager manager) {
033            helpManager = manager;
034        }
035    
036        @Override
037        public Facet decorate(final Facet facet, final FacetHolder facetHolder) {
038            if (facet.facetType() != HelpFacet.class) {
039                return facet;
040            }
041    
042            if (!(facetHolder instanceof IdentifiedHolder)) {
043                return null;
044            }
045    
046            final IdentifiedHolder identifiedHolder = (IdentifiedHolder) facetHolder;
047            return decorateWithHelpFacet(facet, identifiedHolder);
048        }
049    
050        private Facet decorateWithHelpFacet(final Facet facet, final IdentifiedHolder identifiedHolder) {
051            final Identifier identifier = identifiedHolder.getIdentifier();
052    
053            final String helpText = helpManager.getHelpText(identifier);
054            if (helpText != null) {
055                final HelpFacetLookedUpViaHelpManager decoratingFacet =
056                    new HelpFacetLookedUpViaHelpManager(helpText, facet.getFacetHolder());
057                identifiedHolder.addFacet(decoratingFacet);
058                return decoratingFacet;
059            }
060            return null;
061        }
062    
063        @Override
064        @SuppressWarnings("unchecked")
065        public Class<? extends Facet>[] getFacetTypes() {
066            return new Class[] { HelpFacet.class };
067        }
068    }