/*
    * 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
    *
    *     https://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.configuration2;
  
  import java.util.AbstractMap;
  import java.util.AbstractSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  
  /**
   * <p>
   * The {@code ConfigurationMap} wraps a configuration-collection {@link org.apache.commons.configuration2.Configuration}
   * instance to provide a {@code Map} interface.
   * </p>
   *
   * <p>
   * <em>Note:</em> This implementation is incomplete.
   * </p>
   *
   * @since 1.0
   */
  public class ConfigurationMap extends AbstractMap<Object, Object> {
      /**
       * Sets of entries in the map.
       */
      static class ConfigurationSet extends AbstractSet<Map.Entry<Object, Object>> {
          /**
           * Iterator over the entries in the ConfigurationMap.
           */
          private final class ConfigurationSetIterator implements Iterator<Map.Entry<Object, Object>> {
              /** An iterator over the keys in the configuration. */
              private final Iterator<String> keys;
  
              private ConfigurationSetIterator() {
                  keys = configuration.getKeys();
              }
  
              @Override
              public boolean hasNext() {
                  return keys.hasNext();
              }
  
              @Override
              public Map.Entry<Object, Object> next() {
                  return new Entry(keys.next());
              }
  
              @Override
              public void remove() {
                  keys.remove();
              }
          }
  
          /**
           * A Map entry in the ConfigurationMap.
           */
          private final class Entry implements Map.Entry<Object, Object> {
              /** The key of the map entry. */
              private final Object key;
  
              private Entry(final Object key) {
                  this.key = key;
              }
  
              @Override
              public Object getKey() {
                  return key;
              }
  
              @Override
              public Object getValue() {
                  return configuration.getProperty((String) key);
              }
  
              @Override
              public Object setValue(final Object value) {
                  final Object old = getValue();
                  configuration.setProperty((String) key, value);
                  return old;
              }
          }
  
         /** The configuration mapped to this entry set. */
         private final Configuration configuration;
 
         ConfigurationSet(final Configuration configuration) {
             this.configuration = configuration;
         }
 
         /**
          * @see java.util.Collection#iterator()
          */
         @Override
         public Iterator<Map.Entry<Object, Object>> iterator() {
             return new ConfigurationSetIterator();
         }
 
         /**
          * @see java.util.Collection#size()
          */
         @Override
         public int size() {
             // Ouch. Now _that_ one is expensive...
             int count = 0;
             for (final Iterator<String> iterator = configuration.getKeys(); iterator.hasNext();) {
                 iterator.next();
                 count++;
             }
             return count;
         }
     }
 
     /**
      * The {@code Configuration} wrapped by this class.
      */
     private final Configuration configuration;
 
     /**
      * Creates a new instance of a {@code ConfigurationMap} that wraps the specified {@code Configuration} instance.
      *
      * @param configuration {@code Configuration} instance.
      */
     public ConfigurationMap(final Configuration configuration) {
         this.configuration = Objects.requireNonNull(configuration, "configuration");
     }
 
     /**
      * Returns a set with the entries contained in this configuration-based map.
      *
      * @return a set with the contained entries
      * @see Map#entrySet()
      */
     @Override
     public Set<Map.Entry<Object, Object>> entrySet() {
         return new ConfigurationSet(configuration);
     }
 
     /**
      * Gets the value of the specified key. The key is converted to a string and then passed to the underlying
      * configuration.
      *
      * @param key the key
      * @return the value of this key
      * @see Map#get(Object)
      */
     @Override
     public Object get(final Object key) {
         return configuration.getProperty(String.valueOf(key));
     }
 
     /**
      * Gets the wrapped {@code Configuration} object.
      *
      * @return the wrapped configuration
      * @since 1.2
      */
     public Configuration getConfiguration() {
         return configuration;
     }
 
     /**
      * Stores the value for the specified key. The value is stored in the underlying configuration.
      *
      * @param key the key (will be converted to a string)
      * @param value the value
      * @return the old value of this key or <strong>null</strong> if it is new
      * @see Map#put(Object, Object)
      */
     @Override
     public Object put(final Object key, final Object value) {
         final String strKey = String.valueOf(key);
         final Object old = configuration.getProperty(strKey);
         configuration.setProperty(strKey, value);
         return old;
     }
 }