// Copyright 2007, 2008, 2009 The Apache Software Foundation

 //

 // Licensed 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.tapestry5.internal.transform;

 import org.apache.tapestry5.Asset;

 import org.apache.tapestry5.ComponentResources;

 import org.apache.tapestry5.annotations.SetupRender;

 import org.apache.tapestry5.internal.services.ComponentResourcesOperation;

 import org.apache.tapestry5.ioc.Resource;

 import org.apache.tapestry5.ioc.internal.util.CollectionFactory;

 import org.apache.tapestry5.ioc.services.SymbolSource;

 import org.apache.tapestry5.model.MutableComponentModel;

 import org.apache.tapestry5.services.AssetSource;

 import org.apache.tapestry5.services.ClassTransformation;

 import org.apache.tapestry5.services.ComponentClassTransformWorker;

 import org.apache.tapestry5.services.TransformConstants;

 import java.util.List;

 import java.util.Locale;

 /**

  * Base class for workers that automatically inlcude assets in the page (via methods on {@link

  * org.apache.tapestry5.RenderSupport}).

  */

 public abstract class AbstractIncludeAssetWorker implements ComponentClassTransformWorker

 {

     private final AssetSource assetSource;

     private final SymbolSource symbolSource;

     public AbstractIncludeAssetWorker(AssetSource assetSource, SymbolSource symbolSource)

     {

         this.assetSource = assetSource;

         this.symbolSource = symbolSource;

     }

     /**

      * Expands symbols in the path, then adds an operation into the setup render phase of the component. Ultimately,

      * {@link #handleAsset(org.apache.tapestry5.Asset)} will be invoked for each asset (dervied from assetPaths).

      *

      * @param transformation transformation process for component

      * @param model          component model for component

      * @param assetPaths     raw paths to be converted to assets

      */

     protected final void addOperationForAssetPaths(ClassTransformation transformation,

                                                    MutableComponentModel model, String[] assetPaths)

     {

         final Resource baseResource = model.getBaseResource();

         final List<String> paths = CollectionFactory.newList();

         for (String value : assetPaths)

         {

             String expanded = symbolSource.expandSymbols(value);

             paths.add(expanded);

         }

         ComponentResourcesOperation op = new ComponentResourcesOperation()

         {

             // Remember that ONE instances of this op will be injected into EVERY instance

             // of the component ... that means that we can't do any aggresive caching

             // inside the operation (the operation must be threadsafe).

             public void perform(ComponentResources resources)

             {

                 Locale locale = resources.getLocale();

                 for (String assetPath : paths)

                 {

                     Asset asset = assetSource.getAsset(baseResource, assetPath, locale);

                     handleAsset(asset);

                 }

             }

         };

         String opFieldName = transformation.addInjectedField(ComponentResourcesOperation.class, "operation", op);

         String resourcesName = transformation.getResourcesFieldName();

         String body = String.format("%s.perform(%s);", opFieldName, resourcesName);

         // This is what I like about this approach; the injected body is tiny.  The downside is that

         // the object that gets injected is hard to test, hard enough that we'll just concentrate on

         // the integration test, thank you.

         transformation.extendMethod(TransformConstants.SETUP_RENDER_SIGNATURE, body);

         model.addRenderPhase(SetupRender.class);

     }

     /**

      * Invoked, from the component's setup render phase, for each asset. This method must be threadsafe.  Most

      * implementation pass the asset to a particular method of {@link org.apache.tapestry5.RenderSupport}.

      *

      * @param asset to be processed

      */

     protected abstract void handleAsset(Asset asset);

 }