001// Copyright 2008, 2010, 2011, 2012 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.internal.transform;
016
017import org.apache.tapestry5.ComponentResources;
018import org.apache.tapestry5.annotations.InjectComponent;
019import org.apache.tapestry5.internal.services.ComponentClassCache;
020import org.apache.tapestry5.ioc.internal.util.InternalUtils;
021import org.apache.tapestry5.ioc.util.UnknownValueException;
022import org.apache.tapestry5.model.MutableComponentModel;
023import org.apache.tapestry5.plastic.*;
024import org.apache.tapestry5.runtime.Component;
025import org.apache.tapestry5.services.transform.ComponentClassTransformWorker2;
026import org.apache.tapestry5.services.transform.TransformationSupport;
027
028/**
029 * Recognizes the {@link org.apache.tapestry5.annotations.InjectComponent} annotation, and converts the field into a
030 * read-only field containing the component. The id of the component may be explicitly stated or will be determined
031 * from the field name.
032 */
033public class InjectComponentWorker implements ComponentClassTransformWorker2
034{
035    private final class InjectedComponentFieldValueConduit extends ReadOnlyComponentFieldConduit
036    {
037        private final ComponentResources resources;
038
039        private final String fieldName, componentId, type;
040
041        private Component embedded;
042
043        private InjectedComponentFieldValueConduit(ComponentResources resources, String fieldName, String type,
044                                                   String componentId)
045        {
046            super(resources, fieldName);
047
048            this.resources = resources;
049            this.fieldName = fieldName;
050            this.componentId = componentId;
051            this.type = type;
052
053            resources.getPageLifecycleCallbackHub().addPageAttachedCallback(new Runnable()
054            {
055                public void run()
056                {
057                    load();
058                }
059            });
060        }
061
062        private void load()
063        {
064            try
065            {
066                embedded = resources.getEmbeddedComponent(componentId);
067            } catch (UnknownValueException ex)
068            {
069                throw new RuntimeException(String.format("Unable to inject component into field %s of class %s: %s",
070                        fieldName, getComponentClassName(), ex.getMessage()), ex);
071            }
072
073            Class fieldType = classCache.forName(type);
074
075            if (!fieldType.isInstance(embedded))
076                throw new RuntimeException(
077                        String
078                                .format(
079                                        "Unable to inject component '%s' into field %s of %s. Class %s is not assignable to a field of type %s.",
080                                        componentId, fieldName, getComponentClassName(),
081                                        embedded.getClass().getName(), fieldType.getName()));
082        }
083
084        private String getComponentClassName()
085        {
086            return resources.getComponentModel().getComponentClassName();
087        }
088
089        public Object get(Object instance, InstanceContext context)
090        {
091            return embedded;
092        }
093    }
094
095    private final ComponentClassCache classCache;
096
097    public InjectComponentWorker(ComponentClassCache classCache)
098    {
099        this.classCache = classCache;
100    }
101
102    public void transform(PlasticClass plasticClass, TransformationSupport support, MutableComponentModel model)
103    {
104        for (PlasticField field : plasticClass.getFieldsWithAnnotation(InjectComponent.class))
105        {
106            InjectComponent annotation = field.getAnnotation(InjectComponent.class);
107
108            field.claim(annotation);
109
110            final String type = field.getTypeName();
111
112            final String componentId = getComponentId(field, annotation);
113
114            final String fieldName = field.getName();
115
116            ComputedValue<FieldConduit<Object>> provider = new ComputedValue<FieldConduit<Object>>()
117            {
118                public FieldConduit<Object> get(InstanceContext context)
119                {
120                    ComponentResources resources = context.get(ComponentResources.class);
121
122                    return new InjectedComponentFieldValueConduit(resources, fieldName, type, componentId);
123                }
124            };
125
126            field.setComputedConduit(provider);
127        }
128
129    }
130
131    private String getComponentId(PlasticField field, InjectComponent annotation)
132    {
133        String id = annotation.value();
134
135        if (InternalUtils.isNonBlank(id))
136            return id;
137
138        return InternalUtils.stripMemberName(field.getName());
139    }
140}