/*
    * 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.configuration2.tree;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Set;
  import java.util.stream.Collectors;
  
  /**
   * <p>
   * An abstract base class for a {@link NodeHandler} implementation for {@link ImmutableNode} objects.
   * </p>
   * <p>
   * This class already implements all methods which need no other information than the passed in node object.
   * Functionality which requires additional state (for example querying the root node or a parent node) has to be added by
   * concrete sub classes.
   * </p>
   *
   * @since 2.0
   */
  abstract class AbstractImmutableNodeHandler implements NodeHandler<ImmutableNode> {
      /**
       * Checks if the passed in node is defined. Result is <strong>true</strong> if the node contains any data.
       *
       * @param node the node in question
       * @return <strong>true</strong> if the node is defined, <strong>false</strong> otherwise
       */
      static boolean checkIfNodeDefined(final ImmutableNode node) {
          return node.getValue() != null || !node.getChildren().isEmpty() || !node.getAttributes().isEmpty();
      }
  
      @Override
      public Set<String> getAttributes(final ImmutableNode node) {
          return node.getAttributes().keySet();
      }
  
      @Override
      public Object getAttributeValue(final ImmutableNode node, final String name) {
          return node.getAttributes().get(name);
      }
  
      @Override
      public ImmutableNode getChild(final ImmutableNode node, final int index) {
          return node.getChildren().get(index);
      }
  
      @Override
      public List<ImmutableNode> getChildren(final ImmutableNode node) {
          return node.getChildren();
      }
  
      /**
       * {@inheritDoc} This implementation returns an immutable list with all child nodes that have the specified name.
       */
      @Override
      public List<ImmutableNode> getChildren(final ImmutableNode node, final String name) {
          return getMatchingChildren(node, NodeNameMatchers.EQUALS, name);
      }
  
      @Override
      public int getChildrenCount(final ImmutableNode node, final String name) {
          if (name == null) {
              return node.getChildren().size();
          }
          return getMatchingChildrenCount(node, NodeNameMatchers.EQUALS, name);
      }
  
      /**
       * {@inheritDoc} This implementation returns an immutable list with all child nodes accepted by the specified matcher.
       */
      @Override
      public <C> List<ImmutableNode> getMatchingChildren(final ImmutableNode node, final NodeMatcher<C> matcher, final C criterion) {
          return Collections.unmodifiableList(node.stream().filter(c -> matcher.matches(c, this, criterion)).collect(Collectors.toList()));
      }
  
      @Override
      public <C> int getMatchingChildrenCount(final ImmutableNode node, final NodeMatcher<C> matcher, final C criterion) {
          return getMatchingChildren(node, matcher, criterion).size();
      }
  
      @Override
      public Object getValue(final ImmutableNode node) {
          return node.getValue();
      }
 
     @Override
     public boolean hasAttributes(final ImmutableNode node) {
         return !node.getAttributes().isEmpty();
     }
 
     @Override
     public int indexOfChild(final ImmutableNode parent, final ImmutableNode child) {
         return parent.getChildren().indexOf(child);
     }
 
     /**
      * {@inheritDoc} This implementation assumes that a node is defined if it has a value or has children or has attributes.
      */
     @Override
     public boolean isDefined(final ImmutableNode node) {
         return checkIfNodeDefined(node);
     }
 
     @Override
     public String nodeName(final ImmutableNode node) {
         return node.getNodeName();
     }
 }