/*
    * 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.jxpath.servlet;
  
  import java.util.Enumeration;
  import java.util.HashSet;
  
  import javax.servlet.ServletContext;
  
  import org.apache.commons.jxpath.DynamicPropertyHandler;
  
  /**
   * Implementation of the {@link DynamicPropertyHandler} interface that provides access to attributes of a {@link ServletContext}.
   */
  public class ServletContextHandler implements DynamicPropertyHandler {
  
      private static final int DEFAULT_PROPERTY_COUNT = 16;
  
      /**
       * Constructs a new instance.
       */
      public ServletContextHandler() {
          // empty
      }
  
      /**
       * Collect the property names from bean, storing in set.
       *
       * @param set  destination
       * @param bean to read
       */
      protected void collectPropertyNames(final HashSet<String> set, Object bean) {
          if (bean instanceof HttpSessionAndServletContext) {
              bean = ((HttpSessionAndServletContext) bean).getServletContext();
          }
          final Enumeration<String> e = ((ServletContext) bean).getAttributeNames();
          while (e.hasMoreElements()) {
              set.add(e.nextElement());
          }
      }
  
      @Override
      public Object getProperty(final Object context, final String property) {
          return ((ServletContext) context).getAttribute(property);
      }
  
      @Override
      public String[] getPropertyNames(final Object context) {
          final HashSet<String> set = new HashSet<>(DEFAULT_PROPERTY_COUNT);
          collectPropertyNames(set, context);
          return set.toArray(new String[set.size()]);
      }
  
      @Override
      public void setProperty(final Object context, final String property, final Object value) {
          ((ServletContext) context).setAttribute(property, value);
      }
  }