/**
 * 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 org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;

/**
 * Temporary swapped static functions from the normalizer Section
 *
 * @author Christian Geuer-Pollmann
 */
public class C14nHelper
{

  /**
   * Constructor C14nHelper
   *
   */
  private
  C14nHelper()
  {
    // don't allow instantiation
  }

  /**
   * Method namespaceIsRelative
   *
   * @param namespace
   * @return true if the given namespace is relative.
   */
  public static boolean
  namespaceIsRelative(Attr namespace)
  {
    return !namespaceIsAbsolute(namespace);
  }

  /**
   * Method namespaceIsRelative
   *
   * @param namespaceValue
   * @return true if the given namespace is relative.
   */
  public static boolean
  namespaceIsRelative(String namespaceValue)
  {
    return !namespaceIsAbsolute(namespaceValue);
  }

  /**
   * Method namespaceIsAbsolute
   *
   * @param namespace
   * @return true if the given namespace is absolute.
   */
  public static boolean
  namespaceIsAbsolute(Attr namespace)
  {
    return namespaceIsAbsolute(namespace.getValue());
  }

  /**
   * Method namespaceIsAbsolute
   *
   * @param namespaceValue
   * @return true if the given namespace is absolute.
   */
  public static boolean
  namespaceIsAbsolute(String namespaceValue)
  {
    // assume empty namespaces are absolute
    if (namespaceValue.length() == 0) {
      return true;
    }
    return namespaceValue.indexOf(':') > 0;
  }

  /**
   * This method throws an exception if the Attribute value contains
   * a relative URI.
   *
   * @param attr
   * @throws CanonicalizationException
   */
  public static void
  assertNotRelativeNS(Attr attr) throws CanonicalizationException
  {
    if (attr == null) {
      return;
    }

    String nodeAttrName = attr.getNodeName();
    boolean definesDefaultNS = nodeAttrName.equals("xmlns");
    boolean definesNonDefaultNS = nodeAttrName.startsWith("xmlns:");

    if ((definesDefaultNS || definesNonDefaultNS) && namespaceIsRelative(attr)) {
      String parentName = attr.getOwnerElement().getTagName();
      String attrValue = attr.getValue();
      Object exArgs[] = { parentName, nodeAttrName, attrValue };

      throw new CanonicalizationException(
        "c14n.Canonicalizer.RelativeNamespace", exArgs
      );
    }
  }

  /**
   * This method throws a CanonicalizationException if the supplied Document
   * is not able to be traversed using a TreeWalker.
   *
   * @param document
   * @throws CanonicalizationException
   */
  public static void
  checkTraversability(Document document)
  throws CanonicalizationException
  {
    if (!document.isSupported("Traversal", "2.0")) {
      Object exArgs[] = {document.getImplementation().getClass().getName() };

      throw new CanonicalizationException(
        "c14n.Canonicalizer.TraversalNotSupported", exArgs
      );
    }
  }

  /**
   * This method throws a CanonicalizationException if the supplied Element
   * contains any relative namespaces.
   *
   * @param ctxNode
   * @throws CanonicalizationException
   * @see C14nHelper#assertNotRelativeNS(Attr)
   */
  public static void
  checkForRelativeNamespace(Element ctxNode)
  throws CanonicalizationException
  {
    if (ctxNode != null) {
      NamedNodeMap attributes = ctxNode.getAttributes();

      for (int i = 0; i < attributes.getLength(); i++) {
        C14nHelper.assertNotRelativeNS((Attr) attributes.item(i));
      }
    } else {
      throw new CanonicalizationException("Called checkForRelativeNamespace() on null");
    }
  }

  public static String
  getErrorMessage(String message, Object... exArgs)
  {
    StringBuffer sb = new StringBuffer(message);
    for (Object arg : exArgs) {
      sb.append(", ").append(arg.toString());
    }
    return new String(sb);
  }
}