/*
    * 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.builder.combined;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.commons.beanutils.DynaBean;
  import org.apache.commons.beanutils.DynaClass;
  import org.apache.commons.beanutils.DynaProperty;
  import org.apache.commons.configuration2.beanutils.BeanHelper;
  
  /**
   * <p>
   * An implementation of the {@code DynaBean} interfaces which wraps multiple other beans.
   * </p>
   * <p>
   * An instance of this class is constructed with a collection of beans to be wrapped. When reading or writing a property
   * the wrapped bean which defines this property is determined, and the operation is executed on this bean.
   * </p>
   * <p>
   * The wrapped beans should have disjunct properties. Otherwise, it is undefined which bean property is read or written.
   * </p>
   *
   * @since 2.0
   */
  final class MultiWrapDynaBean implements DynaBean {
  
      /**
       * Creates a {@code DynaBean} object for the given bean.
       *
       * @param bean the bean
       * @return the {@code DynaBean} for this bean
       */
      private static DynaBean createDynaBean(final Object bean) {
          if (bean instanceof DynaBean) {
              return (DynaBean) bean;
          }
          return BeanHelper.createWrapDynaBean(bean);
      }
  
      /** Stores the class of this DynaBean. */
      private final DynaClass dynaClass;
  
      /** A map which associates property names with their defining beans. */
      private final Map<String, DynaBean> propsToBeans;
  
      /**
       * Creates a new instance of {@code MultiWrapDynaBean} and initializes it with the given collections of beans to be
       * wrapped.
       *
       * @param beans the wrapped beans
       */
      public MultiWrapDynaBean(final Collection<?> beans) {
          propsToBeans = new HashMap<>();
          final Collection<DynaClass> beanClasses = new ArrayList<>(beans.size());
  
          beans.forEach(bean -> {
              final DynaBean dynaBean = createDynaBean(bean);
              final DynaClass beanClass = dynaBean.getDynaClass();
              for (final DynaProperty prop : beanClass.getDynaProperties()) {
                  // ensure an order of properties
                  propsToBeans.putIfAbsent(prop.getName(), dynaBean);
              }
              beanClasses.add(beanClass);
          });
  
          dynaClass = new MultiWrapDynaClass(beanClasses);
      }
  
      /**
       * {@inheritDoc} This operation is not supported by the {@code WrapDynaBean} objects used internally by this class.
       * Therefore, just an exception is thrown.
       */
      @Override
      public boolean contains(final String name, final String key) {
          throw new UnsupportedOperationException("contains() operation not supported.");
      }
  
      /**
       * Returns the bean instance to which the given property belongs. If no such bean is found, an arbitrary bean is
       * returned. (This causes the operation on this bean to fail with a meaningful error message.)
       *
      * @param property the property name
      * @return the bean defining this property
      */
     private DynaBean fetchBean(final String property) {
         DynaBean dynaBean = propsToBeans.get(property);
         if (dynaBean == null) {
             dynaBean = propsToBeans.values().iterator().next();
         }
         return dynaBean;
     }
 
     @Override
     public Object get(final String name) {
         return fetchBean(name).get(name);
     }
 
     @Override
     public Object get(final String name, final int index) {
         return fetchBean(name).get(name, index);
     }
 
     @Override
     public Object get(final String name, final String key) {
         return fetchBean(name).get(name, key);
     }
 
     /**
      * {@inheritDoc} This implementation returns an instance of {@code MultiWrapDynaClass}.
      */
     @Override
     public DynaClass getDynaClass() {
         return dynaClass;
     }
 
     /**
      * {@inheritDoc} This operation is not supported by the {@code WrapDynaBean} objects used internally by this class.
      * Therefore, just an exception is thrown.
      */
     @Override
     public void remove(final String name, final String key) {
         throw new UnsupportedOperationException("remove() operation not supported.");
     }
 
     @Override
     public void set(final String name, final int index, final Object value) {
         fetchBean(name).set(name, index, value);
     }
 
     @Override
     public void set(final String name, final Object value) {
         fetchBean(name).set(name, value);
     }
 
     @Override
     public void set(final String name, final String key, final Object value) {
         fetchBean(name).set(name, key, value);
     }
 }