/*
    * 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.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertNotSame;
  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 static org.mockito.Mockito.doThrow;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.when;
  
  import java.io.IOException;
  import java.io.StringWriter;
  import java.util.Collection;
  import java.util.HashSet;
  
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.parsers.ParserConfigurationException;
  import javax.xml.transform.Result;
  import javax.xml.transform.Source;
  import javax.xml.transform.Transformer;
  import javax.xml.transform.TransformerConfigurationException;
  import javax.xml.transform.TransformerException;
  import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;
  
  import org.apache.commons.configuration2.ex.ConfigurationException;
  import org.junit.jupiter.api.Test;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  import org.w3c.dom.Text;
  import org.xml.sax.SAXException;
  
  /**
   * Test class for {@code XMLDocumentHelper}.
   */
  public class TestXMLDocumentHelper {
  
      /** Constant for the name of an element. */
      private static final String ELEMENT = "testElementName";
  
      /** Constant for the name of the test XML file. */
      private static final String TEST_FILE = "testcombine1.xml";
  
      /**
       * Serializes the specified document to a string.
       *
       * @param document the document
       * @return the document serialized to a string
       * @throws ConfigurationException if an error occurs
       */
      private static String documentToString(final Document document) throws ConfigurationException {
          final Transformer transformer = XMLDocumentHelper.createTransformer();
          final StringWriter writer = new StringWriter();
          final Result result = new StreamResult(writer);
          XMLDocumentHelper.transform(transformer, new DOMSource(document.getDocumentElement()), result);
          return writer.toString();
      }
  
      /**
       * Serializes the document wrapped by the given helper to a string.
       *
       * @param helper the document helper
       * @return the document serialized to a string
       * @throws ConfigurationException if an error occurs
       */
      private static String documentToString(final XMLDocumentHelper helper) throws ConfigurationException {
          return documentToString(helper.getDocument());
      }
  
      /**
       * Obtains all text elements contained in the given document.
       *
       * @param document the document
       * @return a collection with all text elements
       */
      private static Collection<Node> findTextElements(final Document document) {
         final Collection<Node> texts = new HashSet<>();
         findTextElementsForNode(document.getDocumentElement(), texts);
         return texts;
     }
 
     /**
      * Recursively obtains all text elements for the given node.
      *
      * @param node the node
      * @param texts the collection with text elements
      */
     private static void findTextElementsForNode(final Node node, final Collection<Node> texts) {
         if (node instanceof Text) {
             texts.add(node);
         }
         final NodeList childNodes = node.getChildNodes();
         for (int i = 0; i < childNodes.getLength(); i++) {
             findTextElementsForNode(childNodes.item(i), texts);
         }
     }
 
     /**
      * Loads a test XML document.
      *
      * @return the test document
      */
     private static Document loadDocument() throws ParserConfigurationException, IOException, SAXException {
         return loadDocument(TEST_FILE);
     }
 
     /**
      * Loads the test document with the given name.
      *
      * @param name the name of the test document
      * @return the parsed document
      */
     private static Document loadDocument(final String name) throws IOException, SAXException, ParserConfigurationException {
         final DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
         return builder.parse(ConfigurationAssert.getTestFile(name));
     }
 
     /**
      * Helper method for testing the element mapping of a copied document.
      *
      * @param file the name of the test file
      */
     private void checkCopyElementMapping(final String file) throws Exception {
         final XMLDocumentHelper helper = XMLDocumentHelper.forSourceDocument(loadDocument(file));
         final XMLDocumentHelper copy = helper.createCopy();
         final Collection<Node> texts = findTextElements(helper.getDocument());
         assertFalse(texts.isEmpty());
         for (final Node n : texts) {
             final Text txtSrc = (Text) n;
             final Text txtCopy = (Text) copy.getElementMapping().get(n);
             assertNotNull(txtCopy, "No matching element for " + n);
             assertEquals(txtSrc.getData(), txtCopy.getData());
         }
     }
 
     /**
      * Tests whether a document can be copied.
      */
     @Test
     void testCopyDocument() throws Exception {
         final XMLDocumentHelper helper = XMLDocumentHelper.forSourceDocument(loadDocument());
         final XMLDocumentHelper copy = helper.createCopy();
         assertNotSame(helper.getDocument(), copy.getDocument());
         final String doc1 = documentToString(helper);
         final String doc2 = documentToString(copy);
         assertEquals(doc1, doc2);
     }
 
     /**
      * Tests the element mapping of a copied document.
      */
     @Test
     void testCopyElementMapping() throws Exception {
         checkCopyElementMapping(TEST_FILE);
     }
 
     /**
      * Tests whether the element is correctly constructed for a more complex document.
      */
     @Test
     void testCopyElementMappingForComplexDocument() throws Exception {
         checkCopyElementMapping("test.xml");
     }
 
     /**
      * Tests whether an exception thrown by a document builder factory is handled correctly.
      */
     @Test
     void testCreateDocumentBuilderFromFactoryException() throws ParserConfigurationException {
         final DocumentBuilderFactory factory = mock(DocumentBuilderFactory.class);
         final ParserConfigurationException pcex = new ParserConfigurationException();
 
         when(factory.newDocumentBuilder()).thenThrow(pcex);
 
         final ConfigurationException cex = assertThrows(ConfigurationException.class, () -> XMLDocumentHelper.createDocumentBuilder(factory));
         assertEquals(pcex, cex.getCause());
     }
 
     /**
      * Tests whether a correct transformer factory can be created.
      */
     @Test
     void testCreateTransformerFactory() {
         assertNotNull(XMLDocumentHelper.createTransformerFactory());
     }
 
     /**
      * Tests whether exceptions while creating transformers are correctly handled.
      */
     @Test
     void testCreateTransformerFactoryException() throws TransformerConfigurationException {
         final TransformerFactory factory = mock(TransformerFactory.class);
         final TransformerConfigurationException cause = new TransformerConfigurationException();
 
         when(factory.newTransformer()).thenThrow(cause);
 
         final ConfigurationException cex = assertThrows(ConfigurationException.class, () -> XMLDocumentHelper.createTransformer(factory));
         assertEquals(cause, cex.getCause());
     }
 
     /**
      * Tests the content of the element mapping for a newly created document.
      */
     @Test
     void testElementMappingForNewDocument() throws ConfigurationException {
         final XMLDocumentHelper helper = XMLDocumentHelper.forNewDocument(ELEMENT);
         assertTrue(helper.getElementMapping().isEmpty());
     }
 
     /**
      * Tests the content of the element mapping for a source document.
      */
     @Test
     void testElementMappingForSourceDocument() throws Exception {
         final Document doc = loadDocument();
         final XMLDocumentHelper helper = XMLDocumentHelper.forSourceDocument(doc);
         assertTrue(helper.getElementMapping().isEmpty());
     }
 
     /**
      * Tests whether an instance can be created wrapping a new document.
      */
     @Test
     void testInitForNewDocument() throws ConfigurationException {
         final XMLDocumentHelper helper = XMLDocumentHelper.forNewDocument(ELEMENT);
         final Document doc = helper.getDocument();
         final Element rootElement = doc.getDocumentElement();
         assertEquals(ELEMENT, rootElement.getNodeName());
         final NodeList childNodes = rootElement.getChildNodes();
         assertEquals(0, childNodes.getLength());
         assertNull(helper.getSourcePublicID());
         assertNull(helper.getSourceSystemID());
     }
 
     /**
      * Tests whether an instance can be created based on a source document.
      */
     @Test
     void testInitForSourceDocument() throws Exception {
         final Document doc = loadDocument();
         final XMLDocumentHelper helper = XMLDocumentHelper.forSourceDocument(doc);
         assertNotSame(doc, helper.getDocument());
         assertEquals(documentToString(doc), documentToString(helper));
     }
 
     /**
      * Tests whether transform() handles a TransformerException.
      */
     @Test
     void testTransformException() throws TransformerException {
         final Transformer transformer = mock(Transformer.class);
         final Source src = mock(Source.class);
         final Result res = mock(Result.class);
         final TransformerException tex = new TransformerException("Test Exception");
 
         doThrow(tex).when(transformer).transform(src, res);
 
         final ConfigurationException cex = assertThrows(ConfigurationException.class, () -> XMLDocumentHelper.transform(transformer, src, res));
         assertEquals(tex, cex.getCause());
     }
 }