/*
    * 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.jsp.PageContext;
  
  import org.apache.commons.jxpath.DynamicPropertyHandler;
  
  /**
   * Implementation of the {@link DynamicPropertyHandler} interface that provides access to attributes of a {@link PageContext} in all scopes.
   */
  public class PageContextHandler implements DynamicPropertyHandler {
  
      /**
       * Constructs a new instance.
       */
      public PageContextHandler() {
          // empty
      }
  
      /**
       * Returns {@code pageContext.findAttribute(property)}.
       *
       * @param pageContext to search
       * @param property    name
       * @return Object value
       */
      @Override
      public Object getProperty(final Object pageContext, final String property) {
          return ((PageContext) pageContext).findAttribute(property);
      }
  
      @Override
      public String[] getPropertyNames(final Object pageContext) {
          final HashSet<String> set = new HashSet<>();
          Enumeration<String> e = ((PageContext) pageContext).getAttributeNamesInScope(PageContext.PAGE_SCOPE);
          while (e.hasMoreElements()) {
              set.add(e.nextElement());
          }
          e = ((PageContext) pageContext).getAttributeNamesInScope(PageContext.REQUEST_SCOPE);
          while (e.hasMoreElements()) {
              set.add(e.nextElement());
          }
          e = ((PageContext) pageContext).getAttributeNamesInScope(PageContext.SESSION_SCOPE);
          while (e.hasMoreElements()) {
              set.add(e.nextElement());
          }
          e = ((PageContext) pageContext).getAttributeNamesInScope(PageContext.APPLICATION_SCOPE);
          while (e.hasMoreElements()) {
              set.add(e.nextElement());
          }
          return set.toArray(new String[set.size()]);
      }
  
      @Override
      public void setProperty(final Object pageContext, final String property, final Object value) {
          ((PageContext) pageContext).setAttribute(property, value, PageContext.PAGE_SCOPE);
      }
  }