/*
    * 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.commons.vfs2.util;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.URL;
  import java.util.Enumeration;
  import java.util.Locale;
  import java.util.Properties;
  import java.util.ResourceBundle;
  
  /**
   * A specialization of a resource bundle.
   *
   * @since 2.0
   */
  public class CombinedResources extends ResourceBundle {
  
      // locale.getLanguage()
      // locale.getCountry()
      // locale.getVariant()
  
      private final String resourceName;
      private volatile boolean inited;
      private final Properties properties = new Properties();
  
      /**
       * Constructs a new instance.
       *
       * @param resourceName A resource name.
       */
      public CombinedResources(final String resourceName) {
          this.resourceName = resourceName;
          init();
      }
  
      @Override
      public Enumeration<String> getKeys() {
          return new Enumeration<String>() {
              @Override
              public boolean hasMoreElements() {
                  return properties.keys().hasMoreElements();
              }
  
              @Override
              public String nextElement() {
                  // We know that our properties will only ever contain Strings
                  return (String) properties.keys().nextElement();
              }
  
          };
      }
  
      /**
       * Gets the resource name.
       *
       * @return the resource name.
       */
      public String getResourceName() {
          return resourceName;
      }
  
      @Override
      protected Object handleGetObject(final String key) {
          return properties.get(key);
      }
  
      /**
       * Initializes this instance.
       */
      protected void init() {
          if (inited) {
              return;
          }
          loadResources(getResourceName());
          loadResources(Locale.getDefault());
          loadResources(getLocale());
          inited = true;
      }
  
      /**
       * Loads resources.
       *
       * @param locale a Locale.
      */
     protected void loadResources(final Locale locale) {
         if (locale == null) {
             return;
         }
         final String[] parts = {locale.getLanguage(), locale.getCountry(), locale.getVariant()};
         final StringBuilder sb = new StringBuilder();
         for (int i = 0; i < 3; i++) {
             sb.append(getResourceName());
             for (int j = 0; j < i; j++) {
                 sb.append('_').append(parts[j]);
             }
             if (!parts[i].isEmpty()) {
                 sb.append('_').append(parts[i]);
                 loadResources(sb.toString());
             }
             sb.setLength(0);
         }
     }
 
     /**
      * Loads a resource.
      *
      * @param resourceName the resource to load.
      */
     protected void loadResources(String resourceName) {
         ClassLoader loader = getClass().getClassLoader();
         if (loader == null) {
             loader = ClassLoader.getSystemClassLoader();
         }
         if (loader != null) {
             resourceName = resourceName.replace('.', '/') + ".properties";
             try {
                 final Enumeration<URL> resources = loader.getResources(resourceName);
                 while (resources.hasMoreElements()) {
                     final URL resource = resources.nextElement();
                     try (InputStream inputStream = resource.openConnection().getInputStream()) {
                         properties.load(inputStream);
                     } catch (final IOException ignored) {
                         // Ignore
                     }
                 }
             } catch (final IOException ignored) {
                 // Ignore
             }
         }
     }
 }