/*
    * 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.beanutils2;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  
  /**
   * <p>
   * A base class for decorators providing {@code Map} behavior on {@link DynaBean}s.
   * </p>
   *
   * <p>
   * The motivation for this implementation is to provide access to {@link DynaBean} properties in technologies that are unaware of BeanUtils and
   * {@link DynaBean}s - such as the expression languages of JSTL and JSF.
   * </p>
   *
   * <p>
   * This rather technical base class implements the methods of the {@code Map} interface on top of a {@code DynaBean}. It was introduced to handle generic
   * parameters in a meaningful way without breaking backwards compatibility of the 1.x {@code DynaBeanMapDecorator} class: A map wrapping a {@code DynaBean}
   * should be of type {@code Map<String, Object>}. However, when using these generic parameters in {@code DynaBeanMapDecorator} this would be an incompatible
   * change (as method signatures would have to be adapted). To solve this problem, this generic base class is added which allows specifying the key type as
   * parameter. This makes it easy to have a new subclass using the correct generic parameters while {@code DynaBeanMapDecorator} could still remain with
   * compatible parameters.
   * </p>
   *
   * @param <K> the type of the keys in the decorated map
   * @since 1.9.0
   */
  public abstract class BaseDynaBeanMapDecorator<K> implements Map<K, Object> {
  
      /**
       * Map.Entry implementation.
       */
      private static final class MapEntry<K> implements Map.Entry<K, Object> {
  
          private final K key;
          private final Object value;
  
          MapEntry(final K key, final Object value) {
              this.key = key;
              this.value = value;
          }
  
          @Override
          public boolean equals(final Object obj) {
              if (this == obj) {
                  return true;
              }
              if (!(obj instanceof Map.Entry)) {
                  return false;
              }
              final Map.Entry<?, ?> other = (Map.Entry<?, ?>) obj;
              return Objects.equals(key, other.getKey()) && Objects.equals(value, other.getValue());
          }
  
          @Override
          public K getKey() {
              return key;
          }
  
          @Override
          public Object getValue() {
              return value;
          }
  
          @Override
          public int hashCode() {
              return Objects.hash(key, value);
          }
  
          @Override
          public Object setValue(final Object value) {
              throw new UnsupportedOperationException();
          }
      }
  
      private final DynaBean dynaBean;
      private final boolean readOnly;
 
     private transient Set<K> keySet;
 
     /**
      * Constructs a read only Map for the specified {@link DynaBean}.
      *
      * @param dynaBean The dyna bean being decorated
      * @throws IllegalArgumentException if the {@link DynaBean} is null.
      */
     public BaseDynaBeanMapDecorator(final DynaBean dynaBean) {
         this(dynaBean, true);
     }
 
     /**
      * Constructs a Map for the specified {@link DynaBean}.
      *
      * @param dynaBean The dyna bean being decorated
      * @param readOnly {@code true} if the Map is read only otherwise {@code false}
      * @throws IllegalArgumentException if the {@link DynaBean} is null.
      */
     public BaseDynaBeanMapDecorator(final DynaBean dynaBean, final boolean readOnly) {
         this.dynaBean = Objects.requireNonNull(dynaBean, "dynaBean");
         this.readOnly = readOnly;
     }
 
     /**
      * clear() operation is not supported.
      *
      * @throws UnsupportedOperationException This operation is not yet supported
      */
     @Override
     public void clear() {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Indicate whether the {@link DynaBean} contains a specified value for one (or more) of its properties.
      *
      * @param key The {@link DynaBean}'s property name
      * @return {@code true} if one of the {@link DynaBean}'s properties contains a specified value.
      */
     @Override
     public boolean containsKey(final Object key) {
         final DynaClass dynaClass = getDynaBean().getDynaClass();
         final DynaProperty dynaProperty = dynaClass.getDynaProperty(toString(key));
         return dynaProperty != null;
     }
 
     /**
      * Indicates whether the decorated {@link DynaBean} contains a specified value.
      *
      * @param value The value to check for.
      * @return {@code true} if one of the {@link DynaBean}'s properties contains the specified value, otherwise {@code false}.
      */
     @Override
     public boolean containsValue(final Object value) {
         final DynaProperty[] properties = getDynaProperties();
         for (final DynaProperty property : properties) {
             final String key = property.getName();
             final Object prop = getDynaBean().get(key);
             if (value == null) {
                 if (prop == null) {
                     return true;
                 }
             } else if (value.equals(prop)) {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Converts the name of a property to the key type of this decorator.
      *
      * @param propertyName the name of a property
      * @return the converted key to be used in the decorated map
      */
     protected abstract K convertKey(String propertyName);
 
     /**
      * <p>
      * Returns the Set of the property/value mappings in the decorated {@link DynaBean}.
      * </p>
      *
      * <p>
      * Each element in the Set is a {@code Map.Entry} type.
      * </p>
      *
      * @return An unmodifiable set of the DynaBean property name/value pairs
      */
     @Override
     public Set<Map.Entry<K, Object>> entrySet() {
         final DynaProperty[] properties = getDynaProperties();
         final Set<Map.Entry<K, Object>> set = new HashSet<>(properties.length);
         for (final DynaProperty property : properties) {
             final K key = convertKey(property.getName());
             final Object value = getDynaBean().get(property.getName());
             set.add(new MapEntry<>(key, value));
         }
         return Collections.unmodifiableSet(set);
     }
 
     /**
      * Gets the value for the specified key from the decorated {@link DynaBean}.
      *
      * @param key The {@link DynaBean}'s property name
      * @return The value for the specified property.
      */
     @Override
     public Object get(final Object key) {
         return getDynaBean().get(toString(key));
     }
 
     /**
      * Provide access to the underlying {@link DynaBean} this Map decorates.
      *
      * @return the decorated {@link DynaBean}.
      */
     public DynaBean getDynaBean() {
         return dynaBean;
     }
 
     /**
      * Convenience method to retrieve the {@link DynaProperty}s for this {@link DynaClass}.
      *
      * @return The an array of the {@link DynaProperty}s.
      */
     private DynaProperty[] getDynaProperties() {
         return getDynaBean().getDynaClass().getDynaProperties();
     }
 
     /**
      * Indicate whether the decorated {@link DynaBean} has any properties.
      *
      * @return {@code true} if the {@link DynaBean} has no properties, otherwise {@code false}.
      */
     @Override
     public boolean isEmpty() {
         return getDynaProperties().length == 0;
     }
 
     /**
      * Indicate whether the Map is read only.
      *
      * @return {@code true} if the Map is read only, otherwise {@code false}.
      */
     public boolean isReadOnly() {
         return readOnly;
     }
 
     /**
      * <p>
      * Returns the Set of the property names in the decorated {@link DynaBean}.
      * </p>
      *
      * <p>
      * <strong>N.B.</strong>For {@link DynaBean}s whose associated {@link DynaClass} is a {@link MutableDynaClass} a new Set is created every time, otherwise
      * the Set is created only once and cached.
      * </p>
      *
      * @return An unmodifiable set of the {@link DynaBean}s property names.
      */
     @Override
     public Set<K> keySet() {
         if (keySet != null) {
             return keySet;
         }
 
         // Create a Set of the keys
         final DynaProperty[] properties = getDynaProperties();
         Set<K> set = new HashSet<>(properties.length);
         for (final DynaProperty property : properties) {
             set.add(convertKey(property.getName()));
         }
         set = Collections.unmodifiableSet(set);
 
         // Cache the keySet if Not a MutableDynaClass
         final DynaClass dynaClass = getDynaBean().getDynaClass();
         if (!(dynaClass instanceof MutableDynaClass)) {
             keySet = set;
         }
 
         return set;
 
     }
 
     /**
      * Puts the value for the specified property in the decorated {@link DynaBean}.
      *
      * @param key   The {@link DynaBean}'s property name
      * @param value The value for the specified property.
      * @return The previous property's value.
      * @throws UnsupportedOperationException if {@code isReadOnly()} is true.
      */
     @Override
     public Object put(final K key, final Object value) {
         if (isReadOnly()) {
             throw new UnsupportedOperationException("Map is read only");
         }
         final String property = toString(key);
         final Object previous = getDynaBean().get(property);
         getDynaBean().set(property, value);
         return previous;
     }
 
     /**
      * Copy the contents of a Map to the decorated {@link DynaBean}.
      *
      * @param map The Map of values to copy.
      * @throws UnsupportedOperationException if {@code isReadOnly()} is true.
      */
     @Override
     public void putAll(final Map<? extends K, ? extends Object> map) {
         if (isReadOnly()) {
             throw new UnsupportedOperationException("Map is read only");
         }
         map.forEach(this::put);
     }
 
     /**
      * remove() operation is not supported.
      *
      * @param key The {@link DynaBean}'s property name
      * @return the value removed
      * @throws UnsupportedOperationException This operation is not yet supported
      */
     @Override
     public Object remove(final Object key) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Returns the number properties in the decorated {@link DynaBean}.
      *
      * @return The number of properties.
      */
     @Override
     public int size() {
         return getDynaProperties().length;
     }
 
     /**
      * Convenience method to convert an Object to a String.
      *
      * @param obj The Object to convert
      * @return String representation of the object
      */
     private String toString(final Object obj) {
         return Objects.toString(obj, null);
     }
 
     /**
      * Returns the set of property values in the decorated {@link DynaBean}.
      *
      * @return Unmodifiable collection of values.
      */
     @Override
     public Collection<Object> values() {
         final DynaProperty[] properties = getDynaProperties();
         final List<Object> values = new ArrayList<>(properties.length);
         for (final DynaProperty property : properties) {
             final String key = property.getName();
             final Object value = getDynaBean().get(key);
             values.add(value);
         }
         return Collections.unmodifiableList(values);
     }
 
 }