/*
    * 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.maven.doxia.siterenderer;
  
  import java.io.File;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  
  import org.htmlunit.BrowserVersion;
  import org.htmlunit.CollectingAlertHandler;
  import org.htmlunit.WebClient;
  import org.htmlunit.html.DomElement;
  import org.htmlunit.html.DomNodeList;
  import org.htmlunit.html.HtmlAnchor;
  import org.htmlunit.html.HtmlElement;
  import org.htmlunit.html.HtmlHeading1;
  import org.htmlunit.html.HtmlMain;
  import org.htmlunit.html.HtmlPage;
  import org.htmlunit.html.HtmlSection;
  
  import static org.codehaus.plexus.testing.PlexusExtension.getTestFile;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  /**
   * Verify client side rendering of Mermaid diagrams.
   */
  public class MermaidVerifier extends AbstractVerifier {
  
      private final String externalJsScript;
  
      public MermaidVerifier(String externalJsScript) {
          this.externalJsScript = externalJsScript;
      }
  
      /**
       * Verifies a HtmlPage.
       *
       * @param file the file to verify.
       *
       * @throws Exception if something goes wrong.
       */
      public void verify(String file) throws Exception {
          File jsTest = getTestFile(file);
          assertNotNull(jsTest);
          assertTrue(jsTest.exists());
  
          // HtmlUnit
          try (WebClient webClient = new WebClient(BrowserVersion.CHROME)) {
              webClient.getOptions().setCssEnabled(false);
              // the JS for Mermaid is too complex for HtmlUnit, so disable it and just verify the presence of the script
              // element
              webClient.getOptions().setJavaScriptEnabled(false);
  
              final List<String> collectedAlerts = new ArrayList<>(4);
              webClient.setAlertHandler(new CollectingAlertHandler(collectedAlerts));
  
              HtmlPage page = (HtmlPage) webClient.getPage(jsTest.toURI().toURL());
              assertNotNull(page);
  
              HtmlElement element = page.getHtmlElementById("contentBox");
              assertNotNull(element);
              HtmlMain main = (HtmlMain) element;
              assertNotNull(main);
  
              Iterator<HtmlElement> elementIterator =
                      main.getHtmlElementDescendants().iterator();
  
              // ----------------------------------------------------------------------
              //
              // ----------------------------------------------------------------------
  
              HtmlSection section = (HtmlSection) elementIterator.next();
              assertNotNull(section);
  
              HtmlAnchor anchor = (HtmlAnchor) elementIterator.next();
              assertNotNull(anchor);
              assertEquals("Example_Mermaid_diagram", anchor.getAttribute("id"));
              HtmlHeading1 h1 = (HtmlHeading1) elementIterator.next();
              assertNotNull(h1);
              assertEquals("Example Mermaid diagram", h1.asNormalizedText().trim());
 
             DomNodeList<DomElement> scripts = page.getElementsByTagName("script");
             assertEquals(2, scripts.getLength());
 
             // first one is the external Mermaid script,
             String scriptSrc = scripts.get(0).getAttribute("src");
             assertTrue(scriptSrc.contains("mermaid"));
 
             if (externalJsScript != null) {
                 assertEquals(externalJsScript, scripts.get(0).asXml());
             } else {
                 // check if file exists in site
                 File scriptFile = new File(jsTest.getParentFile(), scriptSrc).getCanonicalFile();
                 assertTrue(scriptFile.exists(), "Couldn't find referenced Mermaid file: " + scriptFile);
             }
 
             // second one is the inline script to call the Mermaid API
             scripts.get(1).asNormalizedText().trim().contains("mermaid.initialize");
 
             // code element should have been removed
             DomNodeList<DomElement> codes = page.getElementsByTagName("code");
             assertEquals(0, codes.getLength(), "code element should have been removed");
 
             // pre must carry the correct class attribute
             DomNodeList<DomElement> pres = page.getElementsByTagName("pre");
             assertEquals(1, pres.getLength(), "there should be exactly one pre element");
             assertEquals("mermaid", pres.get(0).getAttribute("class"));
         }
     }
 }