/*

  * 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.fileupload.util;

 import java.io.Serializable;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.Iterator;

 import java.util.LinkedHashMap;

 import java.util.List;

 import java.util.Locale;

 import java.util.Map;

 import org.apache.commons.fileupload.FileItemHeaders;

 /**

  * Default implementation of the {@link FileItemHeaders} interface.

  *

  * @since 1.2.1

  */

 public class FileItemHeadersImpl implements FileItemHeaders, Serializable {

     /**

      * Serial version UID, being used, if serialized.

      */

     private static final long serialVersionUID = -4455695752627032559L;

     /**

      * Map of <code>String</code> keys to a <code>List</code> of

      * <code>String</code> instances.

      */

     private final Map<String, List<String>> headerNameToValueListMap = new LinkedHashMap<String, List<String>>();

     /**

      * {@inheritDoc}

      */

     public String getHeader(String name) {

         String nameLower = name.toLowerCase(Locale.ENGLISH);

         List<String> headerValueList = headerNameToValueListMap.get(nameLower);

         if (null == headerValueList) {

             return null;

         }

         return headerValueList.get(0);

     }

     /**

      * {@inheritDoc}

      */

     public Iterator<String> getHeaderNames() {

         return headerNameToValueListMap.keySet().iterator();

     }

     /**

      * {@inheritDoc}

      */

     public Iterator<String> getHeaders(String name) {

         String nameLower = name.toLowerCase(Locale.ENGLISH);

         List<String> headerValueList = headerNameToValueListMap.get(nameLower);

         if (null == headerValueList) {

             headerValueList = Collections.emptyList();

         }

         return headerValueList.iterator();

     }

     /**

      * Method to add header values to this instance.

      *

      * @param name name of this header

      * @param value value of this header

      */

     public synchronized void addHeader(String name, String value) {

         String nameLower = name.toLowerCase(Locale.ENGLISH);

         List<String> headerValueList = headerNameToValueListMap.get(nameLower);

         if (null == headerValueList) {

             headerValueList = new ArrayList<String>();

             headerNameToValueListMap.put(nameLower, headerValueList);

         }

         headerValueList.add(value);

     }

 }