/*
    * 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.tree;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotSame;
  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.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.junit.jupiter.api.Test;
  
  /**
   * Test class for {@code ImmutableNode}
   */
  public class TestImmutableNode {
  
      /** Constant for a test node name. */
      private static final String NAME = "testNode";
  
      /** Constant for an attribute key. */
      private static final String ATTR = "attr";
  
      /** Constant for an attribute value. */
      private static final String ATTR_VALUE = "attrValue";
  
      /** Constant for a test node value. */
      private static final Integer VALUE = 42;
  
      /**
       * Checks whether a node has the expected attributes.
       *
       * @param node the node to be checked
       * @param expAttrs the expected attributes
       */
      private static void checkAttributes(final ImmutableNode node, final Map<String, ?> expAttrs) {
          assertEquals(expAttrs, node.getAttributes());
      }
  
      /**
       * Helper method for testing whether a node contains all the attributes in the specified map.
       *
       * @param node the node to be checked
       * @param attributes the map with expected attributes
       */
      private static void checkAttributesContained(final ImmutableNode node, final Map<String, Object> attributes) {
          for (final Map.Entry<String, Object> e : attributes.entrySet()) {
              assertEquals(e.getValue(), node.getAttributes().get(e.getKey()));
          }
      }
  
      /**
       * Checks whether a node has exactly the specified children.
       *
       * @param parent the parent node to be checked
       * @param children the expected children
       */
      private static void checkChildNodes(final ImmutableNode parent, final ImmutableNode... children) {
          checkChildNodes(parent, Arrays.asList(children));
      }
  
      /**
       * Checks whether a node has the expected children.
       *
       * @param node the node to be checked
       * @param expChildren the collection with the expected children
       */
      private static void checkChildNodes(final ImmutableNode node, final List<ImmutableNode> expChildren) {
          assertEquals(expChildren, node.getChildren());
      }
  
      /**
       * Checks whether an updated node has the expected basic properties.
       *
       * @param org the original node
       * @param updated the updated node
       */
      private static void checkUpdatedNode(final ImmutableNode org, final ImmutableNode updated) {
         assertNotSame(org, updated);
         assertEquals(NAME, updated.getNodeName());
         assertEquals(VALUE, updated.getValue());
     }
 
     /**
      * Sets up a builder with default settings.
      *
      * @return the default builder
      */
     private static ImmutableNode.Builder setUpBuilder() {
         final ImmutableNode.Builder builder = new ImmutableNode.Builder();
         builder.name(NAME).value(VALUE);
         return builder;
     }
 
     /** A counter for generating unique child node names. */
     private int childCounter;
 
     /**
      * Helper method for testing a setAttributes() operation which has no effect.
      *
      * @param attributes the map with attributes
      */
     private void checkSetAttributesNoOp(final Map<String, Object> attributes) {
         final ImmutableNode node = createDefaultNode(VALUE);
         assertSame(node, node.setAttributes(attributes));
     }
 
     /**
      * Creates a default child node with a unique name.
      *
      * @return the new child node
      */
     private ImmutableNode createChild() {
         final int idx = childCounter++;
         return new ImmutableNode.Builder().name("Child" + idx).value("childValue" + idx).create();
     }
 
     /**
      * Creates a default node instance which can be used by tests for updating properties.
      *
      * @param value the value of the node
      * @return the default node instance
      */
     private ImmutableNode createDefaultNode(final Object value) {
         return createDefaultNode(NAME, value);
     }
 
     /**
      * Creates a default node instance with a variable name and value that can be used by tests for updating properties.
      *
      * @param name the name of the node
      * @param value the value of the node
      * @return the default node instance
      */
     private ImmutableNode createDefaultNode(final String name, final Object value) {
         final ImmutableNode.Builder builder = new ImmutableNode.Builder(1);
         return builder.name(name).addChild(createChild()).addAttribute("testAttr", "anotherTest").value(value).create();
     }
 
     /**
      * Tests whether addAttributes() handles null input.
      */
     @Test
     void testAddAttributesNull() {
         final ImmutableNode.Builder builder = setUpBuilder();
         builder.addAttributes(null);
         final ImmutableNode node = builder.create();
         assertTrue(node.getAttributes().isEmpty());
     }
 
     /**
      * Tests whether a child node can be added.
      */
     @Test
     void testAddChild() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child2 = new ImmutableNode.Builder().name("child2").create();
         final ImmutableNode node2 = node.addChild(child2);
         checkUpdatedNode(node, node2);
         checkChildNodes(node2, node.getChildren().get(0), child2);
     }
 
     /**
      * Tests whether a new null child node is rejected.
      */
     @Test
     void testAddChildNull() {
         final ImmutableNode node = createDefaultNode(VALUE);
         assertThrows(IllegalArgumentException.class, () -> node.addChild(null));
     }
 
     /**
      * Tests whether addChildren() can deal with null input.
      */
     @Test
     void testAddChildrenNull() {
         final ImmutableNode.Builder builder = setUpBuilder();
         builder.addChildren(null);
         final ImmutableNode node = builder.create();
         assertTrue(node.getChildren().isEmpty());
     }
 
     /**
      * Tests whether null entries in a collection with new child nodes are ignored.
      */
     @Test
     void testAddChildrenNullElement() {
         final ImmutableNode.Builder builder = setUpBuilder();
         final List<ImmutableNode> children = Arrays.asList(createChild(), null, createChild());
         builder.addChildren(children);
         final ImmutableNode node = builder.create();
         checkChildNodes(node, children.get(0), children.get(2));
     }
 
     /**
      * Tests that a node's attributes cannot be directly manipulated.
      */
     @Test
     void testAttributesImmutable() {
         final ImmutableNode node = setUpBuilder().create();
         final Map<String, Object> attributes = node.getAttributes();
         assertThrows(UnsupportedOperationException.class, () -> attributes.put("test", VALUE));
     }
 
     /**
      * Tests that a node's children cannot be manipulated.
      */
     @Test
     void testChildrenImmutable() {
         final ImmutableNode node = setUpBuilder().create();
         final List<ImmutableNode> children = node.getChildren();
         assertThrows(UnsupportedOperationException.class, () -> children.add(null));
     }
 
     /**
      * Tests getting named children.
      */
     @Test
     void testGetChildrenByMissingName() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child2 = new ImmutableNode.Builder().name("child2").create();
         final ImmutableNode node2 = node.addChild(child2);
         checkUpdatedNode(node, node2);
         assertTrue(node2.getChildren("NotFound").isEmpty());
     }
 
     /**
      * Tests getting named children.
      */
     @Test
     void testGetChildrenByName() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child2 = new ImmutableNode.Builder().name("child2").create();
         final ImmutableNode node2 = node.addChild(child2);
         checkUpdatedNode(node, node2);
         assertEquals("child2", node2.getChildren("child2").get(0).getNodeName());
         assertEquals(child2, node2.getChildren("child2").get(0));
     }
 
     /**
      * Tests getting named children.
      */
     @Test
     void testGetChildrenByNullName() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child2 = new ImmutableNode.Builder().name("child2").create();
         final ImmutableNode node2 = node.addChild(child2);
         checkUpdatedNode(node, node2);
         assertTrue(node2.getChildren(null).isEmpty());
     }
 
     /**
      * Tests whether multiple child nodes can be added to a builder.
      */
     @Test
     void testNodeWithAddMultipleChildren() {
         final int childCount = 4;
         final List<ImmutableNode> childNodes = new ArrayList<>(childCount);
         for (int i = 0; i < childCount; i++) {
             final ImmutableNode.Builder childBuilder = new ImmutableNode.Builder();
             final ImmutableNode child = childBuilder.name(NAME + i).value(i).create();
             childNodes.add(child);
         }
         final ImmutableNode.Builder builder = setUpBuilder();
         final ImmutableNode node = builder.addChildren(childNodes).create();
         checkChildNodes(node, childNodes);
     }
 
     /**
      * Tests whether a node with attributes can be created.
      */
     @Test
     void testNodeWithAttributes() {
         final ImmutableNode.Builder builder = setUpBuilder();
         final int attrCount = 4;
         final Map<String, Object> attrs = new HashMap<>();
         for (int i = 0; i < attrCount; i++) {
             final String attrName = NAME + i;
             attrs.put(attrName, i);
             builder.addAttribute(attrName, i);
         }
         final ImmutableNode node = builder.create();
         checkAttributes(node, attrs);
     }
 
     /**
      * Tests that the map of attributes cannot be changed by a later manipulation of the builder.
      */
     @Test
     void testNodeWithAttributesManipulateLater() {
         final ImmutableNode.Builder builder = setUpBuilder();
         builder.addAttribute(ATTR, ATTR_VALUE);
         final ImmutableNode node = builder.create();
         builder.addAttribute("attr2", "a2");
         assertEquals(1, node.getAttributes().size());
         assertEquals(ATTR_VALUE, node.getAttributes().get(ATTR));
     }
 
     /**
      * Tests whether child nodes can be added.
      */
     @Test
     void testNodeWithChildren() {
         final int childCount = 8;
         final List<ImmutableNode> childNodes = new ArrayList<>(childCount);
         final ImmutableNode.Builder builder = new ImmutableNode.Builder(childCount);
         for (int i = 0; i < childCount; i++) {
             final ImmutableNode.Builder childBuilder = new ImmutableNode.Builder();
             final ImmutableNode child = childBuilder.name(NAME + i).value(i).create();
             builder.addChild(child);
             childNodes.add(child);
         }
         final ImmutableNode node = builder.name(NAME).create();
         checkChildNodes(node, childNodes);
     }
 
     /**
      * Tests that the list of children cannot be changed by a later manipulation of the builder.
      */
     @Test
     void testNodeWithChildrenManipulateLater() {
         final ImmutableNode.Builder builder = setUpBuilder();
         final ImmutableNode child = new ImmutableNode.Builder().name("Child").create();
         final ImmutableNode node = builder.addChild(child).create();
         builder.addChild(new ImmutableNode.Builder().name("AnotherChild").create());
         checkChildNodes(node, Collections.singletonList(child));
     }
 
     /**
      * Tests whether multiple attributes can be added in a single operation.
      */
     @Test
     void testNodeWithMultipleAttributes() {
         final ImmutableNode.Builder builder = setUpBuilder();
         final int attrCount = 4;
         final Map<String, Object> attrs = new HashMap<>();
         for (int i = 0; i < attrCount; i++) {
             final String attrName = NAME + i;
             attrs.put(attrName, i);
         }
         final ImmutableNode node = builder.addAttributes(attrs).create();
         checkAttributes(node, attrs);
     }
 
     /**
      * Tests whether the builder ignores a null child node.
      */
     @Test
     void testNodeWithNullChild() {
         final ImmutableNode.Builder builder = setUpBuilder();
         builder.addChild(null);
         final ImmutableNode node = builder.create();
         checkChildNodes(node);
     }
 
     /**
      * Tests whether an existing attribute can be removed.
      */
     @Test
     void testRemoveAttributeExisting() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final String attrName = node.getAttributes().keySet().iterator().next();
         final ImmutableNode node2 = node.removeAttribute(attrName);
         checkUpdatedNode(node, node2);
         assertSame(node.getChildren(), node2.getChildren());
         assertTrue(node2.getAttributes().isEmpty());
     }
 
     /**
      * Tests removeAttribute() if the attribute does not exist.
      */
     @Test
     void testRemoveAttributeNotExisting() {
         final ImmutableNode node = createDefaultNode(VALUE);
         assertSame(node, node.removeAttribute(ATTR));
     }
 
     /**
      * Tests whether a child node can be removed.
      */
     @Test
     void testRemoveChildExisting() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child = node.getChildren().get(0);
         final ImmutableNode node2 = node.removeChild(child);
         checkUpdatedNode(node, node2);
         checkChildNodes(node2);
     }
 
     /**
      * Tests whether the correct child node is removed if there are multiple.
      */
     @Test
     void testRemoveChildMultiple() {
         final ImmutableNode childRemove = createChild();
         final ImmutableNode node = createDefaultNode(VALUE).addChild(createChild()).addChild(childRemove).addChild(createChild());
         final ImmutableNode node2 = node.removeChild(childRemove);
         checkChildNodes(node2, node.getChildren().get(0), node.getChildren().get(1), node.getChildren().get(3));
     }
 
     /**
      * Tests whether the behavior of removeChildNode() if the node in question is not found.
      */
     @Test
     void testRemoveChildNodeNotExisting() {
         final ImmutableNode node = createDefaultNode(VALUE);
         assertSame(node, node.removeChild(null));
     }
 
     /**
      * Tests whether a child node can be replaced by another one.
      */
     @Test
     void testReplaceChildExisting() {
         final ImmutableNode childRemove = createChild();
         final ImmutableNode childReplace = createChild();
         final ImmutableNode node = createDefaultNode(VALUE).addChild(childRemove);
         final ImmutableNode node2 = node.replaceChild(childRemove, childReplace);
         checkUpdatedNode(node, node2);
         checkChildNodes(node2, node.getChildren().get(0), childReplace);
     }
 
     /**
      * Tests replaceChild() if the child node cannot be found.
      */
     @Test
     void testReplaceChildNotExisting() {
         final ImmutableNode node = createDefaultNode(VALUE);
         assertSame(node, node.replaceChild(createChild(), createChild()));
     }
 
     /**
      * Tries to replace a child node by null.
      */
     @Test
     void testReplaceChildNull() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child = createChild();
         assertThrows(IllegalArgumentException.class, () -> node.replaceChild(child, null));
     }
 
     /**
      * Tests whether all children can be replaced at once.
      */
     @Test
     void testReplaceChildren() {
         final int childCount = 8;
         final List<ImmutableNode> newChildren = new ArrayList<>(childCount);
         for (int i = 0; i < childCount; i++) {
             newChildren.add(createChild());
         }
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode node2 = node.replaceChildren(newChildren);
         checkUpdatedNode(node, node2);
         checkChildNodes(node2, newChildren);
     }
 
     /**
      * Tests whether a node's children can be replaced by a null collection.
      */
     @Test
     void testReplaceChildrenNullCollection() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode node2 = node.replaceChildren(null);
         checkUpdatedNode(node, node2);
         checkChildNodes(node2);
     }
 
     /**
      * Tests whether attribute values can be set.
      */
     @Test
     void testSetAttribute() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode node2 = node.setAttribute("attr", ATTR_VALUE);
         checkUpdatedNode(node, node2);
         assertSame(node.getChildren(), node2.getChildren());
         final Map<String, Object> newAttrs = new HashMap<>(node.getAttributes());
         newAttrs.put(ATTR, ATTR_VALUE);
         checkAttributes(node2, newAttrs);
     }
 
     /**
      * Tests whether an attribute can be overridden.
      */
     @Test
     void testSetAttributeOverride() {
         final ImmutableNode.Builder builder = setUpBuilder();
         final String attr2 = ATTR + "_other";
         final Map<String, Object> attrs = new HashMap<>();
         attrs.put(ATTR, ATTR_VALUE);
         attrs.put(attr2, "someValue");
         final ImmutableNode node = builder.addAttributes(attrs).create();
         final ImmutableNode node2 = node.setAttribute(attr2, VALUE);
         attrs.put(attr2, VALUE);
         checkAttributes(node2, attrs);
     }
 
     /**
      * Tests whether multiple attributes can be set.
      */
     @Test
     void testSetAttributes() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final Map<String, Object> attributes = new HashMap<>();
         attributes.put("newAttribute1", "value1");
         attributes.put("newAttribute2", "value2");
         final ImmutableNode node2 = node.setAttributes(attributes);
         assertEquals(attributes.size() + node.getAttributes().size(), node2.getAttributes().size());
         checkAttributesContained(node2, attributes);
         checkAttributesContained(node2, node.getAttributes());
     }
 
     /**
      * Tests setAttributes() if an empty map is passed in.
      */
     @Test
     void testSetAttributesEmpty() {
         checkSetAttributesNoOp(new HashMap<>());
     }
 
     /**
      * Tests setAttributes() for null input.
      */
     @Test
     void testSetAttributesNull() {
         checkSetAttributesNoOp(null);
     }
 
     /**
      * Tests whether the name of a node can be changed for a new instance.
      */
     @Test
     void testSetName() {
         final ImmutableNode node = createDefaultNode("anotherName", VALUE);
         final ImmutableNode node2 = node.setName(NAME);
         checkUpdatedNode(node, node2);
         assertSame(node.getChildren(), node2.getChildren());
         assertSame(node.getAttributes(), node2.getAttributes());
     }
 
     /**
      * Tests whether a new node with a changed value can be created.
      */
     @Test
     void testSetValue() {
         final ImmutableNode node = createDefaultNode("test");
         final ImmutableNode node2 = node.setValue(VALUE);
         checkUpdatedNode(node, node2);
         assertSame(node.getChildren(), node2.getChildren());
         assertSame(node.getAttributes(), node2.getAttributes());
     }
 
     /**
      * Tests whether a node with basic properties can be created.
      */
     @Test
     void testSimpleProperties() {
         final ImmutableNode node = setUpBuilder().create();
         assertEquals(NAME, node.getNodeName());
         assertTrue(node.getChildren().isEmpty());
         assertTrue(node.getAttributes().isEmpty());
     }
 
     /**
      * Tests streaming children.
      */
     @Test
     void testStream() {
         final ImmutableNode node = createDefaultNode(VALUE);
         final ImmutableNode child2 = new ImmutableNode.Builder().name("child2").create();
         final ImmutableNode node2 = node.addChild(child2);
         checkUpdatedNode(node, node2);
         assertEquals(1, node.stream().count());
         assertEquals(0, child2.stream().count());
         assertEquals(2, node2.stream().count());
         assertEquals(1, node.stream().count());
     }
 
 }