content: /**
   * (The MIT License)
   *
   * Copyright (c) 2008 - 2012:
   *
   * * {Aaron Patterson}[http://tenderlovemaking.com]
   * * {Mike Dalessio}[http://mike.daless.io]
   * * {Charles Nutter}[http://blog.headius.com]
   * * {Sergio Arbeo}[http://www.serabe.com]
   * * {Patrick Mahoney}[http://polycrystal.org]
   * * {Yoko Harada}[http://yokolet.blogspot.com]
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * 'Software'), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   * 
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
   * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
   * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package nokogiri.internals;
  
  import static nokogiri.internals.NokogiriHelpers.getNokogiriClass;
  import static nokogiri.internals.NokogiriHelpers.isNamespace;
  import static nokogiri.internals.NokogiriHelpers.stringOrNil;
  import nokogiri.HtmlDocument;
  import nokogiri.NokogiriService;
  import nokogiri.XmlDocument;
  
  import org.apache.xerces.parsers.DOMParser;
  import org.apache.xerces.xni.Augmentations;
  import org.apache.xerces.xni.QName;
  import org.apache.xerces.xni.XMLAttributes;
  import org.apache.xerces.xni.XNIException;
  import org.apache.xerces.xni.parser.XMLDocumentFilter;
  import org.apache.xerces.xni.parser.XMLParserConfiguration;
  import org.cyberneko.html.HTMLConfiguration;
  import org.cyberneko.html.filters.DefaultFilter;
  import org.jruby.Ruby;
  import org.jruby.RubyClass;
  import org.jruby.runtime.ThreadContext;
  import org.jruby.runtime.builtin.IRubyObject;
  import org.w3c.dom.Document;
  import org.w3c.dom.NamedNodeMap;
  import org.w3c.dom.NodeList;
  
  /**
   * Parser for HtmlDocument. This class actually parses HtmlDocument using NekoHtml.
   * 
   * @author sergio
   * @author Patrick Mahoney <pat@polycrystal.org>
   * @author Yoko Harada <yokolet@gmail.com>
   */
  public class HtmlDomParserContext extends XmlDomParserContext {
  
      public HtmlDomParserContext(Ruby runtime, IRubyObject options) {
          super(runtime, options);
      }
      
      public HtmlDomParserContext(Ruby runtime, IRubyObject encoding, IRubyObject options) {
          super(runtime, encoding, options);
      }
  
      @Override
      protected void initErrorHandler() {
          if (options.strict) {
              errorHandler = new NokogiriStrictErrorHandler(options.noError, options.noWarning);
          } else {
              errorHandler = new NokogiriNonStrictErrorHandler4NekoHtml(options.noError, options.noWarning);
          }
      }
  
      @Override
      protected void initParser(Ruby runtime) {
          XMLParserConfiguration config = new HTMLConfiguration();
          XMLDocumentFilter removeNSAttrsFilter = new RemoveNSAttrsFilter();
          XMLDocumentFilter elementValidityCheckFilter = new ElementValidityCheckFilter(errorHandler);
          //XMLDocumentFilter[] filters = { removeNSAttrsFilter,  elementValidityCheckFilter};
          XMLDocumentFilter[] filters = { elementValidityCheckFilter};
  
          config.setErrorHandler(this.errorHandler);
          parser = new DOMParser(config);
  
          // see http://nekohtml.sourceforge.net/settings.html for details
          setProperty("http://cyberneko.org/html/properties/default-encoding", java_encoding);
          setProperty("http://cyberneko.org/html/properties/names/elems", "lower");
          setProperty("http://cyberneko.org/html/properties/names/attrs", "lower");
          setProperty("http://cyberneko.org/html/properties/filters", filters);
          setFeature("http://cyberneko.org/html/features/report-errors", true);
          setFeature("http://xml.org/sax/features/namespaces", false);
          setFeature("http://cyberneko.org/html/features/insert-doctype", true);
      }
  
      /**
       * Enable NekoHTML feature for balancing tags in a document fragment.
       * 
       * This method is used in XmlNode#in_context method.
       */
      public void enableDocumentFragment() {
          setFeature("http://cyberneko.org/html/features/balance-tags/document-fragment", true);
      }
  
      @Override
      protected XmlDocument getNewEmptyDocument(ThreadContext context) {
          IRubyObject[] args = new IRubyObject[0];
          return (XmlDocument) XmlDocument.rbNew(context, getNokogiriClass(context.getRuntime(), "Nokogiri::HTML::Document"), args);
      }
  
      @Override
      protected XmlDocument wrapDocument(ThreadContext context,
                                         RubyClass klazz,
                                         Document document) {
          HtmlDocument htmlDocument = (HtmlDocument) NokogiriService.HTML_DOCUMENT_ALLOCATOR.allocate(context.getRuntime(), klazz);
          htmlDocument.setDocumentNode(context, document);
          if (ruby_encoding.isNil()) {
              // ruby_encoding might have detected by HtmlDocument::EncodingReader
              if (detected_encoding != null && !detected_encoding.isNil()) {
                  ruby_encoding = detected_encoding;
              } else {
                  // no encoding given & no encoding detected, then try to get it
                  String charset = tryGetCharsetFromHtml5MetaTag(document);
                  ruby_encoding = stringOrNil(context.getRuntime(), charset);
              }
          }
          htmlDocument.setEncoding(ruby_encoding);
          htmlDocument.setParsedEncoding(java_encoding);
          return htmlDocument;
      }
      
      // NekoHtml doesn't understand HTML5 meta tag format. This fails to detect charset
      // from an HTML5 style meta tag. Luckily, the meta tag and charset exists in DOM tree
      // so, this method attempts to find the charset.
      private String tryGetCharsetFromHtml5MetaTag(Document document) {
          if (!"html".equalsIgnoreCase(document.getDocumentElement().getNodeName())) return null;
          NodeList list = document.getDocumentElement().getChildNodes();
          for (int i = 0; i < list.getLength(); i++) {
              if ("head".equalsIgnoreCase(list.item(i).getNodeName())) {
                  NodeList headers = list.item(i).getChildNodes();
                  for (int j = 0; j < headers.getLength(); j++) {
                      if ("meta".equalsIgnoreCase(headers.item(j).getNodeName())) {
                          NamedNodeMap nodeMap = headers.item(j).getAttributes();
                          for (int k = 0; k < nodeMap.getLength(); k++) {
                              if ("charset".equalsIgnoreCase(nodeMap.item(k).getNodeName())) {
                                  return nodeMap.item(k).getNodeValue();
                              }
                          }
                      }
                  }
              }
          }
          return null;
      }
  
      /**
       * Filter to strip out attributes that pertain to XML namespaces.
       */
      public static class RemoveNSAttrsFilter extends DefaultFilter {
          @Override
          public void startElement(QName element, XMLAttributes attrs,
                                   Augmentations augs) throws XNIException {
              int i;
              for (i = 0; i < attrs.getLength(); ++i) {
                  if (isNamespace(attrs.getQName(i))) {
                      attrs.removeAttributeAt(i);
                      --i;
                  }
              }
  
              element.uri = null;
              super.startElement(element, attrs, augs);
          }
      }
      
      public static class ElementValidityCheckFilter extends DefaultFilter {
          private NokogiriErrorHandler errorHandler;
          
          private ElementValidityCheckFilter(NokogiriErrorHandler errorHandler) {
              this.errorHandler = errorHandler;
          }
          
          // element names from xhtml1-strict.dtd
          private static String[][] element_names = {
                  {"a", "abbr", "acronym", "address", "area"},
                  {"b", "base", "basefont", "bdo", "big", "blockquote", "body", "br", "button"},
                  {"caption", "cite", "code", "col", "colgroup"},
                  {"dd", "del", "dfn", "div", "dl", "dt"},
                  {"em"},
                  {"fieldset", "font", "form", "frame", "frameset"},
                  {}, // g
                  {"h1", "h2", "h3", "h4", "h5", "h6", "head", "hr", "html"},
                  {"i", "iframe", "img", "input", "ins"},
                  {}, // j
                  {"kbd"},
                  {"label", "legend", "li", "link"},
                  {"map", "meta"},
                  {"noframes", "noscript"},
                  {"object", "ol", "optgroup", "option"},
                  {"p", "param", "pre"},
                  {"q"},
                  {}, // r
                  {"s", "samp", "script", "select", "small", "span", "strike", "strong", "style", "sub", "sup"},
                  {"table", "tbody", "td", "textarea", "tfoot", "th", "thead", "title", "tr", "tt"},
                  {"u", "ul"},
                  {"var"},
                  {}, // w
                  {}, // x
                  {}, // y
                  {}  // z
          };
          
          private boolean isValid(String testee) {
              char[] c = testee.toCharArray();
              int index = new Integer(c[0]) - 97;
              if (index > 25) return false;
              for (int i=0; i<element_names[index].length; i++) {
                  if (testee.equals(element_names[index][i])) {
                      return true;
                  }
              }
              return false;
          }
          
          @Override
          public void startElement(QName name, XMLAttributes attrs, Augmentations augs) throws XNIException {
              if (!isValid(name.rawname)) {
                  errorHandler.getErrors().add(new Exception("Tag " + name.rawname + " invalid"));
              }
              super.startElement(name, attrs, augs);
          }
      }
  }
  