// Copyright 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.services;

 import org.apache.tapestry5.SymbolConstants;

 import org.apache.tapestry5.ioc.Resource;

 import org.apache.tapestry5.ioc.annotations.Inject;

 import org.apache.tapestry5.ioc.annotations.Symbol;

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

 import org.apache.tapestry5.services.AssetFactory;

 import org.apache.tapestry5.services.ClasspathAssetAliasManager;

 import org.apache.tapestry5.services.ContextProvider;

 import org.apache.tapestry5.services.Response;

 import javax.servlet.http.HttpServletResponse;

 import java.io.IOException;

 public class AssetResourceLocatorImpl implements AssetResourceLocator

 {

     private final ClasspathAssetAliasManager aliasManager;

     private final ResourceCache resourceCache;

     private final AssetFactory contextAssetFactory;

     private final Response response;

     private final String applicationAssetPrefix;

     public AssetResourceLocatorImpl(ClasspathAssetAliasManager aliasManager,

                                     ResourceCache resourceCache,

                                     @Inject @Symbol(SymbolConstants.APPLICATION_VERSION)

                                     String applicationVersion,

                                     @ContextProvider

                                     AssetFactory contextAssetFactory,

                                     Response response)

     {

         this.aliasManager = aliasManager;

         this.resourceCache = resourceCache;

         this.contextAssetFactory = contextAssetFactory;

         this.response = response;

         applicationAssetPrefix = RequestConstants.ASSET_PATH_PREFIX + RequestConstants.CONTEXT_FOLDER + applicationVersion + "/";

     }

     public Resource findResourceForPath(String path) throws IOException

     {

         if (path.startsWith(applicationAssetPrefix))

             return findContextResource(path.substring(applicationAssetPrefix.length()));

         String resourcePath = aliasManager.toResourcePath(path);

         Resource resource = new ClasspathResource(resourcePath);

         if (!resourceCache.requiresDigest(resource)) return resource;

         String file = resource.getFile();

         // Somehow this code got real ugly, but it's all about preventing NPEs when a resource

         // that should have a digest doesn't.

         boolean valid = false;

         Resource result = resource;

         int lastdotx = file.lastIndexOf('.');

         if (lastdotx > 0)

         {

             int prevdotx = file.lastIndexOf('.', lastdotx - 1);

             if (prevdotx > 0)

             {

                 String requestDigest = file.substring(prevdotx + 1, lastdotx);

                 // Strip the digest out of the file name.

                 String realFile = file.substring(0, prevdotx) + file.substring(lastdotx);

                 result = resource.forFile(realFile);

                 String actualDigest = resourceCache.getDigest(result);

                 valid = requestDigest.equals(actualDigest);

             }

         }

         if (valid) return result;

         // TODO: Perhaps we should send an exception here, so that the caller can decide

         // to send the error. I'm not happy with this.

         response.sendError(HttpServletResponse.SC_FORBIDDEN,

                            ServicesMessages.wrongAssetDigest(result));

         return null;

     }

     private Resource findContextResource(String contextPath)

     {

         return contextAssetFactory.getRootResource().forFile(contextPath);

     }

 }