/*
    * 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;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertInstanceOf;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  import org.apache.commons.configuration2.convert.DefaultListDelimiterHandler;
  import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
  import org.apache.commons.configuration2.tree.DefaultConfigurationKey;
  import org.apache.commons.configuration2.tree.DefaultExpressionEngine;
  import org.apache.commons.configuration2.tree.ImmutableNode;
  import org.apache.commons.configuration2.tree.NodeStructureHelper;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  /**
   * Test class for {@code BaseHierarchicalConfiguration}.
   */
  public class TestHierarchicalConfiguration {
  
      /** Constant for a changed name. */
      private static final String NEW_NAME = "alteredName";
  
      /**
       * Creates a {@code DefaultConfigurationKey} object.
       *
       * @return the new key object
       */
      private static DefaultConfigurationKey createConfigurationKey() {
          return new DefaultConfigurationKey(DefaultExpressionEngine.INSTANCE);
      }
  
      /** The configuration to be tested. */
      private BaseHierarchicalConfiguration config;
  
      /**
       * Tests access to sub configurations as children of a defined node.
       *
       * @param withUpdates the updates flag
       * @param expectedName the expected table name when reading a property
       */
      private void checkChildConfigurationsAtWithUpdates(final boolean withUpdates, final String expectedName) {
          final String key = "tables.table(0)";
          final List<HierarchicalConfiguration<ImmutableNode>> children = withUpdates ? config.childConfigurationsAt(key, true)
              : config.childConfigurationsAt(key);
          assertEquals(2, children.size());
          final HierarchicalConfiguration<ImmutableNode> sub = children.get(0);
          sub.setProperty(null, NEW_NAME);
          assertEquals(expectedName, config.getString(key + ".name"));
      }
  
      /**
       * Checks configurationAt() if the passed in key selects an attribute.
       *
       * @param withUpdates the updates flag
       */
      private void checkConfigurationAtAttributeNode(final boolean withUpdates) {
          final String key = "tables.table(0)[@type]";
          config.addProperty(key, "system");
          assertThrows(ConfigurationRuntimeException.class, () -> config.configurationAt(key, withUpdates));
      }
  
      /**
       * Helper method for checking a configurationsAt() method. It is also tested whether the configuration is connected to
       * its parent.
       *
       * @param withUpdates the updates flag
       * @param expName the expected name in the parent configuration
       */
      private void checkConfigurationsAtWithUpdate(final boolean withUpdates, final String expName) {
          final String key = "tables.table(1).fields.field";
          final List<HierarchicalConfiguration<ImmutableNode>> lstFlds = withUpdates ? config.configurationsAt(key, true) : config.configurationsAt(key);
          checkSubConfigurations(lstFlds);
          lstFlds.get(0).setProperty("name", NEW_NAME);
          assertEquals(expName, config.getString("tables.table(1).fields.field(0).name"));
      }
  
     /**
      * Checks the content of the passed in configuration object. Used by some tests that copy a configuration.
      *
      * @param c the configuration to check
      */
     private void checkContent(final Configuration c) {
         for (int i = 0; i < NodeStructureHelper.tablesLength(); i++) {
             assertEquals(NodeStructureHelper.table(i), c.getString("tables.table(" + i + ").name"));
             for (int j = 0; j < NodeStructureHelper.fieldsLength(i); j++) {
                 assertEquals(NodeStructureHelper.field(i, j), c.getString("tables.table(" + i + ").fields.field(" + j + ").name"));
             }
         }
     }
 
     /**
      * Helper method for checking a list of sub configurations pointing to the single fields of the table configuration.
      *
      * @param lstFlds the list with sub configurations
      */
     private void checkSubConfigurations(final List<? extends ImmutableConfiguration> lstFlds) {
         assertEquals(NodeStructureHelper.fieldsLength(1), lstFlds.size());
         for (int i = 0; i < NodeStructureHelper.fieldsLength(1); i++) {
             final ImmutableConfiguration sub = lstFlds.get(i);
             assertEquals(NodeStructureHelper.field(1, i), sub.getString("name"), "Wrong field at position " + i);
         }
     }
 
     @BeforeEach
     public void setUp() throws Exception {
         final ImmutableNode root = new ImmutableNode.Builder(1).addChild(NodeStructureHelper.ROOT_TABLES_TREE).create();
         config = new BaseHierarchicalConfiguration();
         config.getNodeModel().setRootNode(root);
     }
 
     /**
      * Tests the result of childConfigurationsAt() if the key does not point to an existing node.
      */
     @Test
     void testChildConfigurationsAtNotFound() {
         assertTrue(config.childConfigurationsAt("not.existing.key").isEmpty());
     }
 
     /**
      * Tests the result of childConfigurationsAt() if the key selects multiple nodes.
      */
     @Test
     void testChildConfigurationsAtNoUniqueKey() {
         assertTrue(config.childConfigurationsAt("tables.table").isEmpty());
     }
 
     /**
      * Tests whether sub configurations for the children of a given node can be queried if no updates are propagated.
      */
     @Test
     void testChildConfigurationsAtNoUpdates() {
         checkChildConfigurationsAtWithUpdates(false, NodeStructureHelper.table(0));
     }
 
     /**
      * Tests whether sub configurations for the children of a given node can be queried that support updates.
      */
     @Test
     void testChildConfigurationsAtWithUpdates() {
         checkChildConfigurationsAtWithUpdates(true, NEW_NAME);
     }
 
     @Test
     void testClone() {
         final Configuration copy = (Configuration) config.clone();
         assertInstanceOf(BaseHierarchicalConfiguration.class, copy);
         config.setProperty("tables.table(0).name", "changed table name");
         checkContent(copy);
     }
 
     /**
      * Tests configurationAt() if the passed in key selects an attribute result.
      */
     @Test
     void testConfigurationAtAttributeNode() {
         checkConfigurationAtAttributeNode(false);
     }
 
     /**
      * Tests configurationAt() if the passed in key selects an attribute result and the updates flag is set.
      */
     @Test
     void testConfigurationAtAttributeNodeWithUpdates() {
         checkConfigurationAtAttributeNode(true);
     }
 
     /**
      * Tests whether a {@code SubnodeConfiguration} can be cleared and its root node can be removed from its parent
      * configuration.
      */
     @Test
     void testConfigurationAtClearAndDetach() {
         config.addProperty("test.sub.test", "success");
         config.addProperty("test.other", "check");
         final HierarchicalConfiguration<ImmutableNode> sub = config.configurationAt("test.sub", true);
         sub.clear();
         assertTrue(sub.isEmpty());
         assertNull(config.getString("test.sub.test"));
         sub.setProperty("test", "failure!");
         assertNull(config.getString("test.sub.test"));
     }
 
     /**
      * Tests the configurationAt() method if the passed in key selects multiple nodes. This should cause an exception.
      */
     @Test
     void testConfigurationAtMultipleNodes() {
         assertThrows(ConfigurationRuntimeException.class, () -> config.configurationAt("tables.table.name"));
     }
 
     /**
      * Tests configurationAt() if the passed in key selects multiple nodes and the update flag is set.
      */
     @Test
     void testConfigurationAtMultipleNodesWithUpdates() {
         assertThrows(ConfigurationRuntimeException.class, () -> config.configurationAt("tables.table.name", true));
     }
 
     /**
      * Tests whether a configuration obtained via configurationAt() contains the expected properties.
      */
     @Test
     void testConfigurationAtReadAccess() {
         final HierarchicalConfiguration<ImmutableNode> subConfig = config.configurationAt("tables.table(1)");
         assertEquals(NodeStructureHelper.table(1), subConfig.getString("name"));
         final List<Object> lstFlds = subConfig.getList("fields.field.name");
 
         final List<String> expected = new ArrayList<>();
         for (int i = 0; i < NodeStructureHelper.fieldsLength(1); i++) {
             expected.add(NodeStructureHelper.field(1, i));
         }
         assertEquals(expected, lstFlds);
     }
 
     /**
      * Tests the configurationAt() method if the passed in key does not exist.
      */
     @Test
     void testConfigurationAtUnknownSubTree() {
         assertThrows(ConfigurationRuntimeException.class, () -> config.configurationAt("non.existing.key"));
     }
 
     /**
      * Tests configurationAt() for a non existing key if the update flag is set.
      */
     @Test
     void testConfigurationAtUnknownSubTreeWithUpdates() {
         assertThrows(ConfigurationRuntimeException.class, () -> config.configurationAt("non.existing.key", true));
     }
 
     /**
      * Tests an update operation on a parent configuration if the sub configuration is connected.
      */
     @Test
     void testConfigurationAtUpdateParentConnected() {
         final HierarchicalConfiguration<ImmutableNode> subConfig = config.configurationAt("tables.table(1)", true);
         config.setProperty("tables.table(1).fields.field(2).name", "testField");
         assertEquals("testField", subConfig.getString("fields.field(2).name"));
     }
 
     /**
      * Tests an update operation on a parent configuration if the sub configuration is independent.
      */
     @Test
     void testConfigurationAtUpdateParentIndependent() {
         final HierarchicalConfiguration<ImmutableNode> subConfig = config.configurationAt("tables.table(1)");
         config.setProperty("tables.table(1).fields.field(2).name", "testField");
         assertEquals(NodeStructureHelper.field(1, 2), subConfig.getString("fields.field(2).name"));
     }
 
     /**
      * Tests an update operation on a sub configuration which is connected to its parent.
      */
     @Test
     void testConfigurationAtUpdateSubConfigConnected() {
         final HierarchicalConfiguration<ImmutableNode> subConfig = config.configurationAt("tables.table(1)", true);
         subConfig.setProperty("name", "testTable");
         assertEquals("testTable", config.getString("tables.table(1).name"));
     }
 
     /**
      * Tests an update operation on a sub configuration which is independent on its parent.
      */
     @Test
     void testConfigurationAtUpdateSubConfigIndependent() {
         final HierarchicalConfiguration<ImmutableNode> subConfig = config.configurationAt("tables.table(1)");
         subConfig.setProperty("name", "testTable");
         assertEquals("testTable", subConfig.getString("name"));
         assertEquals(NodeStructureHelper.table(1), config.getString("tables.table(1).name"));
     }
 
     /**
      * Tests whether a connected configuration is correctly initialized with properties of its parent.
      */
     @Test
     void testConfigurationAtWithUpdateInitialized() {
         final String key = "tables.table";
         config.setListDelimiterHandler(new DefaultListDelimiterHandler(';'));
         config.setThrowExceptionOnMissing(true);
         final List<HierarchicalConfiguration<ImmutableNode>> subs = config.configurationsAt(key, true);
         final BaseHierarchicalConfiguration sub = (BaseHierarchicalConfiguration) subs.get(0);
         assertEquals(config.getListDelimiterHandler(), sub.getListDelimiterHandler());
         assertTrue(sub.isThrowExceptionOnMissing());
     }
 
     /**
      * Tests configurationsAt() if an attribute key is passed in.
      */
     @Test
     void testConfigurationsAtAttributeKey() {
         final String attrKey = "tables.table(0)[@type]";
         config.addProperty(attrKey, "user");
         assertTrue(config.configurationsAt(attrKey).isEmpty());
     }
 
     /**
      * Tests the configurationsAt() method when the passed in key does not select any sub nodes.
      */
     @Test
     void testConfigurationsAtEmpty() {
         assertTrue(config.configurationsAt("unknown.key").isEmpty());
     }
 
     /**
      * Tests the configurationsAt() method if the sub configurations are not connected.
      */
     @Test
     void testConfigurationsAtNoUpdate() {
         checkConfigurationsAtWithUpdate(false, NodeStructureHelper.field(1, 0));
     }
 
     /**
      * Tests configurationsAt() if the sub configurations are connected.
      */
     @Test
     void testConfigurationsAtWithUpdates() {
         checkConfigurationsAtWithUpdate(true, NEW_NAME);
     }
 
     /**
      * Tests whether immutable configurations for the children of a given node can be queried.
      */
     @Test
     void testImmutableChildConfigurationsAt() {
         final List<ImmutableHierarchicalConfiguration> children = config.immutableChildConfigurationsAt("tables.table(0)");
         assertEquals(2, children.size());
         final ImmutableHierarchicalConfiguration c1 = children.get(0);
         assertEquals("name", c1.getRootElementName());
         assertEquals(NodeStructureHelper.table(0), c1.getString(null));
         final ImmutableHierarchicalConfiguration c2 = children.get(1);
         assertEquals("fields", c2.getRootElementName());
         assertEquals(NodeStructureHelper.field(0, 0), c2.getString("field(0).name"));
     }
 
     /**
      * Tests whether an immutable configuration for a sub tree can be obtained.
      */
     @Test
     void testImmutableConfigurationAt() {
         final ImmutableHierarchicalConfiguration subConfig = config.immutableConfigurationAt("tables.table(1)");
         assertEquals(NodeStructureHelper.table(1), subConfig.getString("name"));
         final List<Object> lstFlds = subConfig.getList("fields.field.name");
 
         final List<String> expected = new ArrayList<>();
         for (int i = 0; i < NodeStructureHelper.fieldsLength(1); i++) {
             expected.add(NodeStructureHelper.field(1, i));
         }
         assertEquals(expected, lstFlds);
     }
 
     /**
      * Tests whether the support updates flag is taken into account when creating an immutable sub configuration.
      */
     @Test
     void testImmutableConfigurationAtSupportUpdates() {
         final String newTableName = NodeStructureHelper.table(1) + "_other";
         final ImmutableHierarchicalConfiguration subConfig = config.immutableConfigurationAt("tables.table(1)", true);
         config.addProperty("tables.table(-1).name", newTableName);
         config.clearTree("tables.table(1)");
         assertEquals(newTableName, subConfig.getString("name"));
     }
 
     /**
      * Tests whether a list of immutable sub configurations can be queried.
      */
     @Test
     void testImmutableConfigurationsAt() {
         final List<ImmutableHierarchicalConfiguration> lstFlds = config.immutableConfigurationsAt("tables.table(1).fields.field");
         checkSubConfigurations(lstFlds);
     }
 
     /**
      * Tests the copy constructor.
      */
     @Test
     void testInitCopy() {
         final BaseHierarchicalConfiguration copy = new BaseHierarchicalConfiguration(config);
         checkContent(copy);
     }
 
     /**
      * Tests the copy constructor when a null reference is passed.
      */
     @Test
     void testInitCopyNull() {
         final BaseHierarchicalConfiguration copy = new BaseHierarchicalConfiguration((HierarchicalConfiguration<ImmutableNode>) null);
         assertTrue(copy.isEmpty());
     }
 
     /**
      * Tests whether the nodes of a copied configuration are independent from the source configuration.
      */
     @Test
     void testInitCopyUpdate() {
         final BaseHierarchicalConfiguration copy = new BaseHierarchicalConfiguration(config);
         config.setProperty("tables.table(0).name", "NewTable");
         checkContent(copy);
     }
 
     /**
      * Tests obtaining a configuration with all variables substituted.
      */
     @Test
     void testInterpolatedConfiguration() {
         config.setListDelimiterHandler(new DefaultListDelimiterHandler(','));
         final BaseHierarchicalConfiguration c = (BaseHierarchicalConfiguration) InterpolationTestHelper.testInterpolatedConfiguration(config);
 
         // tests whether the hierarchical structure has been maintained
         checkContent(c);
     }
 
     /**
      * Tests whether interpolation works on an empty configuration.
      */
     @Test
     void testInterpolatedConfigurationEmpty() {
         config = new BaseHierarchicalConfiguration();
         assertTrue(config.interpolatedConfiguration().isEmpty());
     }
 
     /**
      * Tests interpolation with a subset.
      */
     @Test
     void testInterpolationSubset() {
         InterpolationTestHelper.testInterpolationSubset(config);
     }
 
     /**
      * Tests whether interpolation with a subset configuration works over multiple layers.
      */
     @Test
     void testInterpolationSubsetMultipleLayers() {
         config.clear();
         config.addProperty("var", "value");
         config.addProperty("prop2.prop[@attr]", "${var}");
         final Configuration sub1 = config.subset("prop2");
         final Configuration sub2 = sub1.subset("prop");
         assertEquals("value", sub2.getString("[@attr]"));
     }
 
     @Test
     void testSubset() {
         // test the subset on the first table
         Configuration subset = config.subset("tables.table(0)");
         assertEquals(NodeStructureHelper.table(0), subset.getProperty("name"));
 
         Object prop = subset.getProperty("fields.field.name");
         Collection<?> collection = assertInstanceOf(Collection.class, prop);
         assertEquals(5, collection.size());
 
         for (int i = 0; i < NodeStructureHelper.fieldsLength(0); i++) {
             final DefaultConfigurationKey key = createConfigurationKey();
             key.append("fields").append("field").appendIndex(i);
             key.append("name");
             assertEquals(NodeStructureHelper.field(0, i), subset.getProperty(key.toString()));
         }
 
         // test the subset on the second table
         assertTrue(config.subset("tables.table(2)").isEmpty());
 
         // test the subset on the fields
         subset = config.subset("tables.table.fields.field");
         prop = subset.getProperty("name");
         collection = assertInstanceOf(Collection.class, prop);
         int expectedFieldCount = 0;
         for (int i = 0; i < NodeStructureHelper.tablesLength(); i++) {
             expectedFieldCount += NodeStructureHelper.fieldsLength(i);
         }
         assertEquals(expectedFieldCount, collection.size());
 
         assertEquals(NodeStructureHelper.field(0, 0), subset.getProperty("name(0)"));
 
         // test the subset on the field names
         subset = config.subset("tables.table.fields.field.name");
         assertTrue(subset.isEmpty());
     }
 
     /**
      * Tests subset() if the passed in key selects an attribute.
      */
     @Test
     void testSubsetAttributeResult() {
         final String key = "tables.table(0)[@type]";
         config.addProperty(key, "system");
         final BaseHierarchicalConfiguration subset = (BaseHierarchicalConfiguration) config.subset(key);
         assertTrue(subset.getModel().getNodeHandler().getRootNode().getChildren().isEmpty());
         assertEquals("system", subset.getString("[@type]"));
     }
 
     /**
      * Tests the subset() method if the specified key selects multiple keys. The resulting root node should have a value
      * only if exactly one of the selected nodes has a value. Related to CONFIGURATION-295.
      */
     @Test
     void testSubsetMultipleNodesWithValues() {
         config.setProperty("tables.table(0).fields", "My fields");
         Configuration subset = config.subset("tables.table.fields");
         assertEquals("My fields", subset.getString(""));
         config.setProperty("tables.table(1).fields", "My other fields");
         subset = config.subset("tables.table.fields");
         assertNull(subset.getString(""));
     }
 
     /**
      * Tests the subset() method if the specified node has a value. This value must be available in the subset, too. Related
      * to CONFIGURATION-295.
      */
     @Test
     void testSubsetNodeWithValue() {
         config.setProperty("tables.table(0).fields", "My fields");
         final Configuration subset = config.subset("tables.table(0).fields");
         assertEquals(NodeStructureHelper.field(0, 0), subset.getString("field(0).name"));
         assertEquals("My fields", subset.getString(""));
     }
 }