/*
    * 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.context.servlet;
  
  import java.util.ArrayList;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import javax.servlet.http.HttpServletRequest;
  
  import org.apache.myfaces.util.AbstractAttributeMap;
  
  /**
   * HttpServletRequest header values (multi-value headers) as Map of String[].
   * 
   * @author Anton Koinov (latest modification by $Author$)
   * @version $Revision$ $Date$
   */
  public final class RequestHeaderValuesMap extends AbstractAttributeMap<String[]>
  {
      private final HttpServletRequest _httpServletRequest;
      private final Map<String, String[]> _valueCache = new HashMap<String, String[]>();
  
      RequestHeaderValuesMap(final HttpServletRequest httpServletRequest)
      {
          _httpServletRequest = httpServletRequest;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      protected String[] getAttribute(final String key)
      {
          String[] ret = _valueCache.get(key);
          if (ret == null)
          {
              ret = toArray(_httpServletRequest.getHeaders(key));
              _valueCache.put(key, ret);
          }
  
          return ret;
      }
  
      @Override
      protected void setAttribute(final String key, final String[] value)
      {
          throw new UnsupportedOperationException("Cannot set HttpServletRequest HeaderValues");
      }
  
      @Override
      protected void removeAttribute(final String key)
      {
          throw new UnsupportedOperationException("Cannot remove HttpServletRequest HeaderValues");
      }
  
      @Override
      @SuppressWarnings("unchecked")
      protected Enumeration<String> getAttributeNames()
      {
          return _httpServletRequest.getHeaderNames();
      }
  
      private String[] toArray(Enumeration<String> e)
      {
          List<String> ret = new ArrayList<String>();
  
          while (e.hasMoreElements())
          {
              ret.add(e.nextElement());
          }
  
          return ret.toArray(new String[ret.size()]);
      }
  }