/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.client5.http.entity.mime;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  
  /**
   * The header of a MIME entity.
   */
  public class Header implements Iterable<MimeField> {
  
      private final List<MimeField> fields;
      private final Map<String, List<MimeField>> fieldMap;
  
      public Header() {
          super();
          this.fields = new LinkedList<>();
          this.fieldMap = new HashMap<>();
      }
  
      public void addField(final MimeField field) {
          if (field == null) {
              return;
          }
          final String key = field.getName().toLowerCase(Locale.ROOT);
          final List<MimeField> values = this.fieldMap.computeIfAbsent(key, k -> new LinkedList<>());
          values.add(field);
          this.fields.add(field);
      }
  
      public List<MimeField> getFields() {
          return new ArrayList<>(this.fields);
      }
  
      public MimeField getField(final String name) {
          if (name == null) {
              return null;
          }
          final String key = name.toLowerCase(Locale.ROOT);
          final List<MimeField> list = this.fieldMap.get(key);
          if (list != null && !list.isEmpty()) {
              return list.get(0);
          }
          return null;
      }
  
      public List<MimeField> getFields(final String name) {
          if (name == null) {
              return null;
          }
          final String key = name.toLowerCase(Locale.ROOT);
          final List<MimeField> list = this.fieldMap.get(key);
          if (list == null || list.isEmpty()) {
              return Collections.emptyList();
          }
          return new ArrayList<>(list);
      }
  
      public int removeFields(final String name) {
          if (name == null) {
              return 0;
          }
          final String key = name.toLowerCase(Locale.ROOT);
          final List<MimeField> removed = fieldMap.remove(key);
          if (removed == null || removed.isEmpty()) {
              return 0;
          }
         this.fields.removeAll(removed);
         return removed.size();
     }
 
     public void setField(final MimeField field) {
         if (field == null) {
             return;
         }
         final String key = field.getName().toLowerCase(Locale.ROOT);
         final List<MimeField> list = fieldMap.get(key);
         if (list == null || list.isEmpty()) {
             addField(field);
             return;
         }
         list.clear();
         list.add(field);
         int firstOccurrence = -1;
         int index = 0;
         for (final Iterator<MimeField> it = this.fields.iterator(); it.hasNext(); index++) {
             final MimeField f = it.next();
             if (f.getName().equalsIgnoreCase(field.getName())) {
                 it.remove();
                 if (firstOccurrence == -1) {
                     firstOccurrence = index;
                 }
             }
         }
         this.fields.add(firstOccurrence, field);
     }
 
     @Override
     public Iterator<MimeField> iterator() {
         return Collections.unmodifiableList(fields).iterator();
     }
 
     @Override
     public String toString() {
         return this.fields.toString();
     }
 
 }