/*
    * Copyright (c) 2002-2025 Gargoyle Software Inc.
    *
    * Licensed 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.htmlunit.html.xpath;
  
  import java.util.Map;
  
  import org.htmlunit.html.DomAttr;
  import org.htmlunit.html.DomElement;
  import org.htmlunit.html.DomNode;
  import org.htmlunit.xml.XmlPage;
  import org.htmlunit.xpath.xml.utils.PrefixResolverDefault;
  import org.w3c.dom.Node;
  
  /**
   * Custom {@link PrefixResolverDefault} extension.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   */
  public final class HtmlUnitPrefixResolver extends PrefixResolverDefault {
  
      /**
       * Creates a new instance.
       * @param xpathExpressionContext the context from which XPath expression prefixes will be resolved
       */
      public HtmlUnitPrefixResolver(final Node xpathExpressionContext) {
          super(xpathExpressionContext);
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public String getNamespaceForPrefix(final String prefix, final Node namespaceContext) {
          String namespace = super.getNamespaceForPrefix(prefix, namespaceContext);
          if (namespace == null) {
              if (namespaceContext instanceof XmlPage) {
                  final DomElement documentElement = ((XmlPage) namespaceContext).getDocumentElement();
                  if (documentElement != null) {
                      namespace = getNamespace(documentElement, prefix);
                  }
              }
              else if (namespaceContext instanceof DomElement) {
                  namespace = getNamespace((DomElement) namespaceContext, prefix);
              }
          }
          return namespace;
      }
  
      private String getNamespace(final DomElement element, final String prefix) {
          final Map<String, DomAttr> attributes = element.getAttributesMap();
          final String xmlns = "xmlns:";
          final int xmlnsLength = xmlns.length();
  
          for (final Map.Entry<String, DomAttr> entry : attributes.entrySet()) {
              final String name = entry.getKey();
              if (name.startsWith(xmlns) && name.regionMatches(xmlnsLength, prefix, 0, prefix.length())) {
                  return entry.getValue().getValue();
              }
          }
          for (final DomNode child : element.getChildren()) {
              if (child instanceof DomElement) {
                  final String namespace = getNamespace((DomElement) child, prefix);
                  if (namespace != null) {
                      return namespace;
                  }
              }
          }
          return null;
      }
  }