/*
    * 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.ArrayList;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Properties;
  
  import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
  
  /**
   * <p>
   * A Map based Configuration.
   * </p>
   * <p>
   * This implementation of the {@code Configuration} interface is initialized with a {@link java.util.Map}. The methods
   * of the {@code Configuration} interface are implemented on top of the content of this map. The following storage
   * scheme is used:
   * </p>
   * <p>
   * Property keys are directly mapped to map keys, i.e. the {@code getProperty()} method directly performs a
   * {@code get()} on the map. Analogously, {@code setProperty()} or {@code addProperty()} operations write new data into
   * the map. If a value is added to an existing property, a {@link java.util.List} is created, which stores the values of
   * this property.
   * </p>
   * <p>
   * An important use case of this class is to treat a map as a {@code Configuration} allowing access to its data through
   * the richer interface. This can be a bit problematic in some cases because the map may contain values that need not
   * adhere to the default storage scheme used by typical configuration implementations, for example regarding lists. In such
   * cases care must be taken when manipulating the data through the {@code Configuration} interface, for example by calling
   * {@code addProperty()}; results may be different than expected.
   * </p>
   * <p>
   * The handling of list delimiters is a bit different for this configuration implementation: When a property of type
   * String is queried, it is passed to the current {@link org.apache.commons.configuration2.convert.ListDelimiterHandler
   * ListDelimiterHandler} which may generate multiple values. Note that per default a list delimiter handler is set which
   * does not do any list splitting, so this feature is disabled. It can be enabled by setting a properly configured
   * {@code ListDelimiterHandler} implementation, for example a
   * {@link org.apache.commons.configuration2.convert.DefaultListDelimiterHandler DefaultListDelimiterHandler} object.
   * </p>
   * <p>
   * Notice that list splitting is only performed for single string values. If a property has multiple values, the single
   * values are not split even if they contain the list delimiter character.
   * </p>
   * <p>
   * As the underlying {@code Map} is directly used as store of the property values, the thread-safety of this
   * {@code Configuration} implementation depends on the map passed to the constructor.
   * </p>
   * <p>
   * Notes about type safety: For properties with multiple values this implementation creates lists of type {@code Object}
   * and stores them. If a property is assigned another value, the value is added to the list. This can cause problems if
   * the map passed to the constructor already contains lists of other types. This should be avoided, otherwise it cannot
   * be guaranteed that the application might throw {@code ClassCastException} exceptions later.
   * </p>
   *
   * @since 1.1
   */
  public class MapConfiguration extends AbstractConfiguration implements Cloneable {
  
      /**
       * Helper method for converting the type of the {@code Properties} object to a supported map type. As stated by the
       * comment of the constructor, we expect the {@code Properties} object to contain only String key; therefore, it is safe
       * to do this cast.
       *
       * @param props the {@code Properties} to be copied.
       * @return a newly created map with all string keys of the properties.
       */
      @SuppressWarnings("unchecked")
      private static Map<String, Object> toMap(final Properties props) {
          @SuppressWarnings("rawtypes")
          final Map map = props;
          return map;
      }
  
      /** The Map decorated by this configuration. */
      protected Map<String, Object> map;
  
      /** A flag whether trimming of property values should be disabled. */
      private boolean trimmingDisabled;
  
     /**
      * Create a Configuration decorator around the specified Map. The map is used to store the configuration properties, any
      * change will also affect the Map.
      *
      * @param map the map.
      */
     public MapConfiguration(final Map<String, ?> map) {
         this.map = (Map<String, Object>) Objects.requireNonNull(map, "map");
     }
 
     /**
      * Creates a new instance of {@code MapConfiguration} which uses the specified {@code Properties} object as its data
      * store. All changes of this configuration affect the given {@code Properties} object and vice versa. Note that while
      * {@code Properties} actually implements {@code Map<Object, Object>}, we expect it to contain only string keys. Other
      * key types will lead to {@code ClassCastException} exceptions on certain methods.
      *
      * @param props the {@code Properties} object defining the content of this configuration.
      * @since 1.8
      */
     public MapConfiguration(final Properties props) {
         map = toMap(Objects.requireNonNull(props));
     }
 
     @Override
     protected void addPropertyDirect(final String key, final Object value) {
         final Object previousValue = getProperty(key);
 
         if (previousValue == null) {
             map.put(key, value);
         } else if (previousValue instanceof List) {
             // the value is added to the existing list
             // Note: This is problematic. See header comment!
             ((List<Object>) previousValue).add(value);
         } else {
             // the previous value is replaced by a list containing the previous value and the new value
             final List<Object> list = new ArrayList<>();
             list.add(previousValue);
             list.add(value);
 
             map.put(key, list);
         }
     }
 
     @Override
     protected void clearPropertyDirect(final String key) {
         map.remove(key);
     }
 
     /**
      * Returns a copy of this object. The returned configuration will contain the same properties as the original. Event listeners are not cloned.
      *
      * @return the copy.
      * @since 1.3
      */
     @Override
     public Object clone() {
         try {
             final MapConfiguration copy = (MapConfiguration) super.clone();
             copy.map = ConfigurationUtils.clone(map);
             copy.cloneInterpolator(this);
             return copy;
         } catch (final CloneNotSupportedException cex) {
             // cannot happen
             throw new ConfigurationRuntimeException(cex);
         }
     }
 
     @Override
     protected boolean containsKeyInternal(final String key) {
         return map.containsKey(key);
     }
 
     /**
      * Tests whether this configuration contains one or more matches to this value. This operation stops at first match
      * but may be more expensive than the containsKey method.
      *
      * @since 2.11.0
      */
     @Override
     protected boolean containsValueInternal(final Object value) {
         return value != null && map.containsValue(value);
     }
 
     @Override
     protected Iterator<String> getKeysInternal() {
         return map.keySet().iterator();
     }
 
     /**
      * Gets the Map decorated by this configuration.
      *
      * @return the map this configuration is based onto.
      */
     public Map<String, Object> getMap() {
         return map;
     }
 
     @Override
     protected Object getPropertyInternal(final String key) {
         final Object value = map.get(key);
         if (value instanceof String) {
             final Collection<String> list = getListDelimiterHandler().split((String) value, !isTrimmingDisabled());
             return list.size() > 1 ? list : list.iterator().next();
         }
         return value;
     }
 
     @Override
     protected boolean isEmptyInternal() {
         return map.isEmpty();
     }
 
     /**
      * Tests whether the flag whether trimming of property values is disabled.
      *
      * @return <strong>true</strong> if trimming of property values is disabled; <strong>false</strong> otherwise.
      * @since 1.7
      */
     public boolean isTrimmingDisabled() {
         return trimmingDisabled;
     }
 
     /**
      * Sets a flag whether trimming of property values is disabled. This flag is only evaluated if list splitting is
      * enabled. Refer to the header comment for more information about list splitting and trimming.
      *
      * @param trimmingDisabled a flag whether trimming of property values should be disabled.
      * @since 1.7
      */
     public void setTrimmingDisabled(final boolean trimmingDisabled) {
         this.trimmingDisabled = trimmingDisabled;
     }
 
     @Override
     protected int sizeInternal() {
         return map.size();
     }
 
     /**
      * Converts this object to a String suitable for debugging and logging.
      *
      * @since 2.3
      */
     @Override
     public String toString() {
         return getClass().getSimpleName() + " [map=" + map + ", trimmingDisabled=" + trimmingDisabled + "]";
     }
 }