/**
 * 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 nokogiri.internals.c14n;

import java.util.Iterator;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;


import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

/**
 * Implements &quot; <A
 * HREF="http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718/">Exclusive XML
 * Canonicalization, Version 1.0 </A>&quot; <BR />
 * Credits: During restructuring of the Canonicalizer framework, Ren??
 * Kollmorgen from Software AG submitted an implementation of ExclC14n which
 * fitted into the old architecture and which based heavily on my old (and slow)
 * implementation of "Canonical XML". A big "thank you" to Ren?? for this.
 * <BR />
 * <i>THIS </i> implementation is a complete rewrite of the algorithm.
 *
 * @author Christian Geuer-Pollmann <geuerp@apache.org>
 * @version $Revision: 1147448 $
 * @see <a href="http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718/ Exclusive#">
 *          XML Canonicalization, Version 1.0</a>
 */
public abstract class Canonicalizer20010315Excl extends CanonicalizerBase
{

  private static final String XML_LANG_URI = Constants.XML_LANG_SPACE_SpecNS;
  private static final String XMLNS_URI = Constants.NamespaceSpecNS;

  /**
    * This Set contains the names (Strings like "xmlns" or "xmlns:foo") of
    * the inclusive namespaces.
    */
  private SortedSet<String> inclusiveNSSet;

  private final SortedSet<Attr> result = new TreeSet<Attr>(COMPARE);

  /**
   * Constructor Canonicalizer20010315Excl
   *
   * @param includeComments
   */
  public
  Canonicalizer20010315Excl(boolean includeComments)
  {
    super(includeComments);
  }

  /**
   * Method engineCanonicalizeSubTree
   * @inheritDoc
   * @param rootNode
   *
   * @throws CanonicalizationException
   */
  @Override
  public byte[]
  engineCanonicalizeSubTree(Node rootNode, CanonicalFilter filter)
  throws CanonicalizationException
  {
    return engineCanonicalizeSubTree(rootNode, "", null);
  }

  /**
   * Method engineCanonicalizeSubTree
   *  @inheritDoc
   * @param rootNode
   * @param inclusiveNamespaces
   *
   * @throws CanonicalizationException
   */
  @Override
  public byte[]
  engineCanonicalizeSubTree(
    Node rootNode, String inclusiveNamespaces, CanonicalFilter filter
  ) throws CanonicalizationException
  {
    return engineCanonicalizeSubTree(rootNode, inclusiveNamespaces, null, filter);
  }

  /**
   * Method engineCanonicalizeSubTree
   * @param rootNode
   * @param inclusiveNamespaces
   * @param excl A element to exclude from the c14n process.
   * @return the rootNode c14n.
   * @throws CanonicalizationException
   */
  public byte[]
  engineCanonicalizeSubTree(
    Node rootNode, String inclusiveNamespaces, Node excl, CanonicalFilter filter
  ) throws CanonicalizationException
  {
    inclusiveNSSet = InclusiveNamespaces.prefixStr2Set(inclusiveNamespaces);
    return super.engineCanonicalizeSubTree(rootNode, excl, filter);
  }

  @Override
  protected Iterator<Attr>
  handleAttributesSubtree(Element element, NameSpaceSymbTable ns)
  throws CanonicalizationException
  {
    // result will contain the attrs which have to be output
    final SortedSet<Attr> result = this.result;
    result.clear();

    // The prefix visibly utilized (in the attribute or in the name) in
    // the element
    SortedSet<String> visiblyUtilized = new TreeSet<String>();
    if (inclusiveNSSet != null && !inclusiveNSSet.isEmpty()) {
      visiblyUtilized.addAll(inclusiveNSSet);
    }

    if (element.hasAttributes()) {
      NamedNodeMap attrs = element.getAttributes();
      int attrsLength = attrs.getLength();
      for (int i = 0; i < attrsLength; i++) {
        Attr attribute = (Attr) attrs.item(i);
        String NName = attribute.getLocalName();
        String NNodeValue = attribute.getNodeValue();

        if (!XMLNS_URI.equals(attribute.getNamespaceURI())) {
          // Not a namespace definition.
          // The Element is output element, add the prefix (if used) to
          // visiblyUtilized
          String prefix = attribute.getPrefix();
          if (prefix != null && !(prefix.equals(XML) || prefix.equals(XMLNS))) {
            visiblyUtilized.add(prefix);
          }
          // Add to the result.
          result.add(attribute);
        } else if (!(XML.equals(NName) && XML_LANG_URI.equals(NNodeValue))
                   && ns.addMapping(NName, NNodeValue, attribute)
                   && C14nHelper.namespaceIsRelative(NNodeValue)) {
          // The default mapping for xml must not be output.
          // New definition check if it is relative.
          Object exArgs[] = {element.getTagName(), NName, attribute.getNodeValue()};
          throw new CanonicalizationException(
            "c14n.Canonicalizer.RelativeNamespace", exArgs
          );
        }
      }
    }
    String prefix;
    if (element.getNamespaceURI() != null
        && !(element.getPrefix() == null || element.getPrefix().length() == 0)) {
      prefix = element.getPrefix();
    } else {
      prefix = XMLNS;
    }
    visiblyUtilized.add(prefix);

    for (String s : visiblyUtilized) {
      Attr key = ns.getMapping(s);
      if (key != null) {
        result.add(key);
      }
    }

    return result.iterator();
  }

  /**
   * @inheritDoc
   * @param element
   * @throws CanonicalizationException
   */
  @Override
  protected final Iterator<Attr>
  handleAttributes(Element element, NameSpaceSymbTable ns)
  throws CanonicalizationException
  {
    // result will contain the attrs which have to be output
    final SortedSet<Attr> result = this.result;
    result.clear();

    // The prefix visibly utilized (in the attribute or in the name) in
    // the element
    Set<String> visiblyUtilized = null;
    // It's the output selected.
    boolean isOutputElement = isVisibleDO(element, ns.getLevel()) == 1;
    if (isOutputElement) {
      visiblyUtilized = new TreeSet<String>();
      if (inclusiveNSSet != null && !inclusiveNSSet.isEmpty()) {
        visiblyUtilized.addAll(inclusiveNSSet);
      }
    }

    if (element.hasAttributes()) {
      NamedNodeMap attrs = element.getAttributes();
      int attrsLength = attrs.getLength();
      for (int i = 0; i < attrsLength; i++) {
        Attr attribute = (Attr) attrs.item(i);

        String NName = attribute.getLocalName();
        String NNodeValue = attribute.getNodeValue();

        if (!XMLNS_URI.equals(attribute.getNamespaceURI())) {
          if (isVisible(attribute) && isOutputElement) {
            // The Element is output element, add the prefix (if used)
            // to visibyUtilized
            String prefix = attribute.getPrefix();
            if (prefix != null && !(prefix.equals(XML) || prefix.equals(XMLNS))) {
              visiblyUtilized.add(prefix);
            }
            // Add to the result.
            result.add(attribute);
          }
        } else if (isOutputElement && !isVisible(attribute) && !XMLNS.equals(NName)) {
          ns.removeMappingIfNotRender(NName);
        } else {
          if (!isOutputElement && isVisible(attribute)
              && inclusiveNSSet.contains(NName)
              && !ns.removeMappingIfRender(NName)) {
            Node n = ns.addMappingAndRender(NName, NNodeValue, attribute);
            if (n != null) {
              result.add((Attr)n);
              if (C14nHelper.namespaceIsRelative(attribute)) {
                Object exArgs[] = { element.getTagName(), NName, attribute.getNodeValue() };
                throw new CanonicalizationException(
                  "c14n.Canonicalizer.RelativeNamespace", exArgs
                );
              }
            }
          }

          if (ns.addMapping(NName, NNodeValue, attribute)
              && C14nHelper.namespaceIsRelative(NNodeValue)) {
            // New definition check if it is relative
            Object exArgs[] = { element.getTagName(), NName, attribute.getNodeValue() };
            throw new CanonicalizationException(
              "c14n.Canonicalizer.RelativeNamespace", exArgs
            );
          }
        }
      }
    }

    if (isOutputElement) {
      // The element is visible, handle the xmlns definition
      Attr xmlns = element.getAttributeNodeNS(XMLNS_URI, XMLNS);
      if (xmlns != null && !isVisible(xmlns)) {
        // There is a definition but the xmlns is not selected by the
        // xpath. then xmlns=""
        ns.addMapping(XMLNS, "", nullNode);
      }

      String prefix;
      if (element.getNamespaceURI() != null
          && !(element.getPrefix() == null || element.getPrefix().length() == 0)) {
        prefix = element.getPrefix();
      } else {
        prefix = XMLNS;
      }
      visiblyUtilized.add(prefix);

      for (String s : visiblyUtilized) {
        Attr key = ns.getMapping(s);
        if (key != null) {
          result.add(key);
        }
      }
    }

    return result.iterator();
  }

  /*
  protected void circumventBugIfNeeded(XMLSignatureInput input)
      throws CanonicalizationException, ParserConfigurationException,
             IOException, SAXException {
      if (!input.isNeedsToBeExpanded() || inclusiveNSSet.isEmpty() || inclusiveNSSet.isEmpty()) {
          return;
      }
      Document doc = null;
      if (input.getSubNode() != null) {
          doc = XMLUtils.getOwnerDocument(input.getSubNode());
      } else {
          doc = XMLUtils.getOwnerDocument(input.getNodeSet());
      }
      XMLUtils.circumventBug2650(doc);
  }
  */
}