/*
    * 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 static org.apache.commons.configuration2.tree.NodeStructureHelper.ROOT_AUTHORS_TREE;
  import static org.apache.commons.configuration2.tree.NodeStructureHelper.ROOT_PERSONAE_TREE;
  import static org.apache.commons.configuration2.tree.NodeStructureHelper.nodeForKey;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertSame;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.junit.jupiter.api.Test;
  
  /**
   * A base test class for {@code NodeHandler} implementations for immutable nodes. Concrete sub classes have to implement
   * a method which creates a new handler object for a given nodes structure.
   */
  public abstract class AbstractImmutableNodeHandlerTest {
      /**
       * A dummy NodeMatcher implementation that will simply accept all passed in nodes.
       */
      private static final class DummyNodeMatcher implements NodeMatcher<Object> {
          @Override
          public <T> boolean matches(final T node, final NodeHandler<T> handler, final Object criterion) {
              return true;
          }
      }
  
      /**
       * Creates a new {@code NodeHandler} object for the specified nodes structure.
       *
       * @param root the root of the nodes structure
       * @return the handler object
       */
      protected abstract NodeHandler<ImmutableNode> createHandler(ImmutableNode root);
  
      /**
       * Tests whether the correct parent for the root node is returned.
       */
      @Test
      public void testGetParentForRoot() {
          final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
          assertNull(handler.getParent(ROOT_AUTHORS_TREE));
      }
  
      /**
       * Tries to query the parent node for a node which does not belong to the managed tree.
       */
      @Test
      public void testGetParentInvalidNode() {
          final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
          final ImmutableNode node = new ImmutableNode.Builder().name("unknown").create();
          assertThrows(IllegalArgumentException.class, () -> handler.getParent(node));
      }
  
      /**
       * Tests whether the correct parent nodes are returned. All nodes in the tree are checked.
       */
      @Test
      public void testGetParentNode() {
          final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
          for (int authorIdx = 0; authorIdx < NodeStructureHelper.authorsLength(); authorIdx++) {
              final ImmutableNode authorNode = nodeForKey(handler.getRootNode(), NodeStructureHelper.author(authorIdx));
              assertSame(handler.getRootNode(), handler.getParent(authorNode), "Wrong parent for " + NodeStructureHelper.author(authorIdx));
              for (int workIdx = 0; workIdx < NodeStructureHelper.worksLength(authorIdx); workIdx++) {
                  final String workKey = NodeStructureHelper.appendPath(NodeStructureHelper.author(authorIdx), NodeStructureHelper.work(authorIdx, workIdx));
                  final ImmutableNode workNode = nodeForKey(handler.getRootNode(), workKey);
                  assertSame(authorNode, handler.getParent(workNode), "Wrong parent for " + workKey);
                  for (int personaIdx = 0; personaIdx < NodeStructureHelper.personaeLength(authorIdx, workIdx); personaIdx++) {
                      final String personKey = NodeStructureHelper.appendPath(workKey, NodeStructureHelper.persona(authorIdx, workIdx, personaIdx));
                      final ImmutableNode personNode = nodeForKey(handler.getRootNode(), personKey);
                      assertSame(workNode, handler.getParent(personNode), "Wrong parent for " + personKey);
                  }
              }
          }
      }
  
      /**
      * Tests whether a node's attributes can be queried.
      */
     @Test
     public void testNodeHandlerGetAttributes() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = nodeForKey(handler, "Puck");
         assertEquals(node.getAttributes().keySet(), handler.getAttributes(node));
     }
 
     /**
      * Tests that the keys of attributes cannot be modified.
      */
     @Test
     public void testNodeHandlerGetAttributesImmutable() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = nodeForKey(handler, "Puck");
         final Set<String> attributes = handler.getAttributes(node);
         assertThrows(UnsupportedOperationException.class, () -> attributes.add("test"));
     }
 
     /**
      * Tests whether the value of an attribute can be queried.
      */
     @Test
     public void testNodeHandlerGetAttributeValue() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = nodeForKey(handler, "Prospero");
         assertEquals("Shakespeare", handler.getAttributeValue(node, NodeStructureHelper.ATTR_AUTHOR));
     }
 
     /**
      * Tests whether a child at a given index can be accessed.
      */
     @Test
     public void testNodeHandlerGetChildAtIndex() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode node = nodeForKey(handler, NodeStructureHelper.author(0));
         assertSame(node.getChildren().get(1), handler.getChild(node, 1));
     }
 
     /**
      * Tests whether the children of a node can be queried.
      */
     @Test
     public void testNodeHandlerGetChildren() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode node = nodeForKey(handler, NodeStructureHelper.author(0));
         assertSame(node.getChildren(), handler.getChildren(node));
     }
 
     /**
      * Tests whether all children of a specific name can be queried.
      */
     @Test
     public void testNodeHandlerGetChildrenByName() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final String name = "Achilles";
         final Set<ImmutableNode> children = new HashSet<>(handler.getChildren(ROOT_PERSONAE_TREE, name));
         assertEquals(3, children.size());
         for (final ImmutableNode c : children) {
             assertEquals(name, c.getNodeName());
         }
     }
 
     /**
      * Tests whether the collection of children cannot be modified.
      */
     @Test
     public void testNodeHandlerGetChildrenByNameImmutable() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final List<ImmutableNode> children = handler.getChildren(ROOT_PERSONAE_TREE, "Ajax");
         assertThrows(UnsupportedOperationException.class, () -> children.add(null));
     }
 
     /**
      * Tests whether the number of all children can be queried.
      */
     @Test
     public void testNodeHandlerGetChildrenCountAll() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode node = nodeForKey(handler, NodeStructureHelper.author(0));
         assertEquals(NodeStructureHelper.worksLength(0), handler.getChildrenCount(node, null));
     }
 
     /**
      * Tests whether the number of all children with a given name can be queried.
      */
     @Test
     public void testNodeHandlerGetChildrenCountSpecific() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         assertEquals(3, handler.getChildrenCount(ROOT_PERSONAE_TREE, "Achilles"));
     }
 
     /**
      * Tests a filter operation on child nodes.
      */
     @Test
     public void testNodeHandlerGetMatchingChildren() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode target = NodeStructureHelper.nodeForKey(ROOT_AUTHORS_TREE, NodeStructureHelper.author(1));
         final Set<String> encounteredAuthors = new HashSet<>();
 
         final NodeMatcher<ImmutableNode> matcher = new NodeMatcher<ImmutableNode>() {
             @Override
             public <T> boolean matches(final T node, final NodeHandler<T> paramHandler, final ImmutableNode criterion) {
                 encounteredAuthors.add(paramHandler.nodeName(node));
                 return node == target;
             }
         };
 
         final List<ImmutableNode> result = handler.getMatchingChildren(handler.getRootNode(), matcher, target);
         assertEquals(1, result.size());
         assertSame(target, result.get(0));
 
         final Set<String> expectedAuthors = new HashSet<>();
         for (int i = 0; i < NodeStructureHelper.authorsLength(); i++) {
             expectedAuthors.add(NodeStructureHelper.author(i));
         }
         assertEquals(expectedAuthors, encounteredAuthors);
     }
 
     /**
      * Tests whether filtered nodes can be counted.
      */
     @Test
     public void testNodeHandlerGetMatchingChildrenCount() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         assertEquals(NodeStructureHelper.authorsLength(), handler.getMatchingChildrenCount(handler.getRootNode(), new DummyNodeMatcher(), this));
     }
 
     /**
      * Tests that the list returned by getMatchingChildren() cannot be modified.
      */
     @Test
     public void testNodeHandlerGetMatchingChildrenImmutable() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final List<ImmutableNode> result = handler.getMatchingChildren(handler.getRootNode(), new DummyNodeMatcher(), this);
         assertThrows(UnsupportedOperationException.class, result::clear);
     }
 
     /**
      * Tests a negative check whether a node has attributes.
      */
     @Test
     public void testNodeHandlerHasAttributesFalse() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         assertFalse(handler.hasAttributes(ROOT_PERSONAE_TREE));
     }
 
     /**
      * Tests a positive check whether a node has attributes.
      */
     @Test
     public void testNodeHandlerHasAttributesTrue() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = nodeForKey(handler, "Puck");
         assertTrue(handler.hasAttributes(node));
     }
 
     /**
      * Tests whether the index of a given child can be queried.
      */
     @Test
     public void testNodeHandlerIndexOfChild() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final String key = "Simmons/Hyperion";
         final ImmutableNode parent = nodeForKey(handler, key);
         final ImmutableNode child = nodeForKey(handler, key + "/Weintraub");
         assertEquals(3, handler.indexOfChild(parent, child));
     }
 
     /**
      * Tests the indexOfChild() method for an unknown child node.
      */
     @Test
     public void testNodeHandlerIndexOfUnknownChild() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode parent = nodeForKey(handler, "Homer/Ilias");
         final ImmutableNode child = nodeForKey(handler, "Shakespeare/Troilus and Cressida/Achilles");
         assertEquals(-1, handler.indexOfChild(parent, child));
     }
 
     /**
      * Tests whether a node with attributes is defined.
      */
     @Test
     public void testNodeHandlerIsDefinedAttributes() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = new ImmutableNode.Builder().addAttribute(NodeStructureHelper.ATTR_AUTHOR, NodeStructureHelper.author(0)).create();
         assertTrue(handler.isDefined(node));
     }
 
     /**
      * Tests whether a node with children is defined.
      */
     @Test
     public void testNodeHandlerIsDefinedChildren() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode node = nodeForKey(handler, NodeStructureHelper.author(2));
         assertTrue(handler.isDefined(node));
     }
 
     /**
      * Tests whether an undefined node is correctly detected.
      */
     @Test
     public void testNodeHandlerIsDefinedFalse() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = new ImmutableNode.Builder().name(NodeStructureHelper.author(1)).create();
         assertFalse(handler.isDefined(node));
     }
 
     /**
      * Tests whether a node with a value is defined.
      */
     @Test
     public void testNodeHandlerIsDefinedValue() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_PERSONAE_TREE);
         final ImmutableNode node = new ImmutableNode.Builder().value(42).create();
         assertTrue(handler.isDefined(node));
     }
 
     /**
      * Tests whether the name of a node can be queried.
      */
     @Test
     public void testNodeHandlerName() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         final ImmutableNode author = nodeForKey(handler, NodeStructureHelper.author(0));
         assertEquals(NodeStructureHelper.author(0), handler.nodeName(author));
     }
 
     /**
      * Tests whether the value of a node can be queried.
      */
     @Test
     public void testNodeHandlerValue() {
         final NodeHandler<ImmutableNode> handler = createHandler(ROOT_AUTHORS_TREE);
         ImmutableNode work = nodeForKey(handler, "Shakespeare/The Tempest");
         final int year = 1611;
         work = work.setValue(year);
         assertEquals(year, handler.getValue(work));
     }
 }