/*

  * 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.spi.impl;

 import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.net.URL;

 import java.net.URLConnection;

 import java.util.Collections;

 import java.util.Enumeration;

 import java.util.LinkedHashSet;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Map;

 import java.util.ServiceLoader;

 import java.util.Set;

 import javax.faces.context.ExternalContext;

 import org.apache.myfaces.shared.util.ClassUtils;

 import org.apache.myfaces.spi.ServiceProviderFinder;

 /**

  * 

  * @author Leonardo Uribe

  * @since 2.0.3

  *

  */

 public class DefaultServiceProviderFinder extends ServiceProviderFinder

 {

     private static final String META_INF_SERVICES = "META-INF/services/";

     private Map<String, List<String>> knownServicesMap = null;

     protected Set<URL> getURLs(String spiClass)

     {

         // Use LinkedHashSet to preserve iteration order

         Enumeration<URL> profiles = null;

         try

         {

             profiles = ClassUtils.getContextClassLoader().getResources(

                     META_INF_SERVICES + spiClass);

         }

         catch (IOException e)

         {

             return null;

         }

         if (null != profiles && profiles.hasMoreElements())

         {

             Set<URL> urls = new LinkedHashSet<URL>();

             while (profiles.hasMoreElements())

             {

                 URL url = profiles.nextElement();

                 urls.add(url);

             }

             return urls;

         }

         return Collections.emptySet();

     }

     @Override

     public List<String> getServiceProviderList(String spiClass)

     {

         if (knownServicesMap != null)

         {

             List<String> result = knownServicesMap.get(spiClass);

             if (result != null)

             {

                 return result;

             }

         }

         Set<URL> urls = getURLs(spiClass);

         if (!urls.isEmpty())

         {

             List<String> results = new LinkedList<String>();

             for (URL url : urls)

             {

                 InputStream is = null;

                 try

                 {

                     try

                     {

                         is = openStreamWithoutCache(url);

                         if (is != null)

                         {

                             // This code is needed by EBCDIC and other

                             // strange systems.  It's a fix for bugs

                             // reported in xerces

                             BufferedReader rd;

                             try

                             {

                                 rd = new BufferedReader(new InputStreamReader(is,

                                         "UTF-8"));

                             }

                             catch (java.io.UnsupportedEncodingException e)

                             {

                                 rd = new BufferedReader(new InputStreamReader(is));

                             }

                             try

                             {

                                 String serviceImplName;

                                 while ((serviceImplName = rd.readLine()) != null)

                                 {

                                     int idx = serviceImplName.indexOf('#');

                                     if (idx >= 0)

                                     {

                                         serviceImplName = serviceImplName

                                                 .substring(0, idx);

                                     }

                                     serviceImplName = serviceImplName.trim();

                                     if (serviceImplName.length() != 0)

                                     {

                                         results.add(serviceImplName);

                                     }

                                 }

                             }

                             finally

                             {

                                 if (rd != null)

                                 {

                                     rd.close();

                                 }

                             }

                         }

                     }

                     finally

                     {

                         if (is != null)

                         {

                             is.close();

                         }

                     }

                 }

                 catch (IOException e)

                 {

                     // ignore

                 }

             }

             return results;

         }

         return Collections.emptyList();

     }

     private InputStream openStreamWithoutCache(URL url) throws IOException

     {

         URLConnection connection = url.openConnection();

         connection.setUseCaches(false);

         return connection.getInputStream();

     }

     @Override

     public <S> ServiceLoader<S> load(Class<S> spiClass)

     {

         return ServiceLoader.load(spiClass);

     }

     @Override

     public void initKnownServiceProviderMapInfo(ExternalContext ectx, Map<String, List<String>> map)

     {

         knownServicesMap = map;

     }

 }