/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.myfaces.resource;
  
  import java.io.InputStream;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.Iterator;
  import java.util.Set;
  import javax.faces.application.ResourceHandler;
  import javax.faces.application.ResourceVisitOption;
  
  import javax.faces.context.FacesContext;
  import org.apache.myfaces.shared.resource.ExternalContextResourceLoaderIterator;
  import org.apache.myfaces.shared.resource.ResourceLoader;
  import org.apache.myfaces.shared.resource.ResourceMeta;
  import org.apache.myfaces.shared.resource.ResourceMetaImpl;
  import org.apache.myfaces.shared.util.WebConfigParamUtils;
  import org.apache.myfaces.util.SkipMatchIterator;
  
  /**
   * A resource loader implementation which loads resources from the webapp root.
   * It uses the methods on ExternalContext for handle resources.
   * 
   */
  public class RootExternalContextResourceLoader extends ResourceLoader
  {
      private static final String CONTRACTS = "contracts";
      
      private static final String RESOURCES = "resources";
      
      private String contractsDirectory = null;
      
      private String resourcesDirectory = null;
  
      public RootExternalContextResourceLoader()
      {
          super("");
          FacesContext facesContext = FacesContext.getCurrentInstance();
          contractsDirectory = WebConfigParamUtils.getStringInitParameter(facesContext.getExternalContext(), 
                  ResourceHandler.WEBAPP_CONTRACTS_DIRECTORY_PARAM_NAME, CONTRACTS);
          contractsDirectory = contractsDirectory.startsWith("/") ? contractsDirectory : '/'+contractsDirectory;
          
          resourcesDirectory = WebConfigParamUtils.getStringInitParameter(facesContext.getExternalContext(), 
              ResourceHandler.WEBAPP_RESOURCES_DIRECTORY_PARAM_NAME, RESOURCES);
          resourcesDirectory = resourcesDirectory.startsWith("/") ? resourcesDirectory : '/'+resourcesDirectory;
      }
  
      protected Set<String> getResourcePaths(String path)
      {
          String correctedPath = path.startsWith("/") ? path : '/' + path;
  
          return FacesContext.getCurrentInstance().getExternalContext().getResourcePaths(correctedPath);
      }
  
      @Override
      public String getResourceVersion(String path)
      {
          return null;
      }
  
      @Override
      public String getLibraryVersion(String path)
      {
          return null;
      }
  
      //@Override
      public URL getResourceURL(String resourceId)
      {
          try
          {
              String correctedResourceId = resourceId.startsWith("/") ? resourceId : "/"+resourceId;
  
              return FacesContext.getCurrentInstance().getExternalContext().getResource(
                  correctedResourceId);
  
          }
          catch (MalformedURLException e)
          {
              return null;
          }
      }
     
     @Override
     public URL getResourceURL(ResourceMeta resourceMeta)
     {
         if (resourceMeta.getLocalePrefix() != null)
         {
             // the webapp root folder cannot be localized, 
             // but if the resource lives in /contracts/[contract-name] it can be.
             return null;
         }
         return getResourceURL(resourceMeta.getResourceIdentifier());
     }
 
     @Override
     public InputStream getResourceInputStream(ResourceMeta resourceMeta)
     {
         String resourceId = resourceMeta.getResourceIdentifier();
         String correctedResourceId = resourceId.startsWith("/") ? resourceId : "/"+resourceId;
 
         return FacesContext.getCurrentInstance().getExternalContext().getResourceAsStream(correctedResourceId);
     }
 
     @Override
     public ResourceMeta createResourceMeta(String prefix, String libraryName, String libraryVersion,
                                            String resourceName, String resourceVersion)
     {
         return new ResourceMetaImpl(prefix, libraryName, libraryVersion, resourceName, resourceVersion);
     }
 
     @Override
     public boolean libraryExists(String libraryName)
     {
         //No library can be created in root resolver
         return false;
     }
     
     @Override
     public Iterator<String> iterator(FacesContext facesContext, 
             String path, int maxDepth, ResourceVisitOption... options)
     {
         String basePath = path;
         
         if (getPrefix() != null)
         {
             basePath = getPrefix() + '/' + (path.startsWith("/") ? path.substring(1) : path);
         }
         
         return new RootExternalContextResourceLoaderIterator(
                 new ExternalContextResourceLoaderIterator(facesContext, basePath, maxDepth, options), 
                     this.contractsDirectory, this.resourcesDirectory);
     }
     
     private static class RootExternalContextResourceLoaderIterator extends SkipMatchIterator<String>
     {
         private String contractsDirectory;
         private String resourcesDirectory;
         
         public RootExternalContextResourceLoaderIterator(Iterator delegate, String contractsDirectory, 
                 String resourcesDirectory)
         {
             super(delegate);
             this.contractsDirectory = contractsDirectory;
             this.resourcesDirectory = resourcesDirectory;
         }
 
         @Override
         protected boolean match(String instance)
         {
             return instance.startsWith(contractsDirectory) || instance.startsWith(resourcesDirectory);
         }
     }
 }