/*
    * The MIT License
    *
    * Original work sponsored and donated by National Board of e-Health (NSI), Denmark (http://www.nsi.dk)
    *
    * Copyright (C) 2011 National Board of e-Health (NSI), Denmark (http://www.nsi.dk)
    *
    * 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.
   *
   * $HeadURL$
   * $Id$
   */
  
  package dk.sosi.seal.model;
  
  import dk.sosi.seal.model.constants.Tag;
  import dk.sosi.seal.xml.XmlUtil;
  import org.w3c.dom.*;
  
  import java.text.ParseException;
  import java.util.*;
  
  /**
   * Abstract class used by classes directly modifying an underlying DOM model object.
   * 
   * @author ads
   */
  public class AbstractDOMInfoExtractor {
  
      /** The underlying DOM representation */
      protected Element dom;
      private Map<String, String> namespaces;
  
      /**
       * Converts the attribute of the supplied <code>Element</code> to a <code>Date</code> using <code>XMLUtil.getDateFormat(true)...</code>.
       * 
       * @param element
       *            The <code>Element</code> to retrieve the attribute from.
       * @param attribute
       *            The name of the attribute to convert.
       * @return The converted <code>Date</code> object.
       */
      protected Date convertToDate(Element element, String attribute) {
          String value;
          if(attribute != null) {
              value = element.getAttribute(attribute);
          } else {
              value = element.getTextContent();
          }
  
          try {
              return XmlUtil.getDateFormat(true).parse(value);
          } catch (ParseException e) {
              throw new ModelException("Invalid date format of " + (attribute != null ? attribute : "text contents") + " (" + value + ")", e);
          }
      }
  
      /**
       * Filter the supplied <code>NodeList</code> and retrieve the <code>Element</code> havning the supplied attribute matching the supplied value.<br />
       * 
       * @param nl
       *            The <code>NodeList</code> to filter.
       * @param attribute
       *            The attribute to test.
       * @param value
       *            The value to filter for.
       * @return The matching <code>Element</code> or <code>null</code> if no mathces was found.
       */
      protected Element getFilteredElement(List<Element> nl, String attribute, String value) {
          for (int i = 0; i < nl.size(); i++) {
              Element tmp = nl.get(i);
  
              String val = tmp.getAttribute(attribute);
              if(val != null) {
                  if(val.equals(value)) {
                      return tmp;
                  }
              }
          }
          return null;
      }
  
      /**
      * Retrieve the <code>Element</code> identified by the supplied tag path structure.<br />
      * This method will traverse the DOM retrieve the first child for each specified tag.
      * 
      * @param tags
      *            List of tag names to traverse.
      * @return The <code>Element</code> matching the final tag in the list.
      */
     protected Element getTag(Tag... tags) {
         if(tags.length == 1) {
             return dom;
         }
         return getFirstElement(getTags(tags));
     }
 
     /**
      * Retrieve the <code>NodeList</code> identified by the supplied tag path structure.<br />
      * This method will traverse the DOM retrieve the first child for each specified tag.
      * 
      * @param tags
      *            List of tag names to traverse.
      * @return The <code>NodeList</code> matching the final tag in the list.
      */
     protected List<Element> getTags(Tag... tags) {
         Element elm = dom;
 
         for (int i = 1; i < tags.length - 1; i++) {
             Tag tag = tags[i];
             elm = getFirstElement(getElements(elm, tag, true));
         }
 
         Tag tag = tags[tags.length - 1];
         return getElements(elm, tag, false);
     }
 
     private List<Element> getElements(Element elm, Tag tag, boolean onlyFirst) {
         List<Element> res = new ArrayList<Element>();
 
         if (elm == null) {
              return res;
         }
 
         NodeList childNodes = elm.getChildNodes();
         for (int i = 0; i < childNodes.getLength(); i++) {
             Node childNode = childNodes.item(i);
             if(childNode instanceof Element) {
                 Element childElm = (Element)childNode;
                 if(matches(childElm, tag)) {
                     res.add(childElm);
                     if(onlyFirst) {
                         break;
                     }
                 }
             }
         }
         return res;
     }
 
     private boolean matches(Element childElm, Tag tag) {
         if(childElm.getLocalName() != null) {
             if(childElm.getNamespaceURI() != null) {
                 return childElm.getNamespaceURI().equals(tag.getNS()) && tag.getTagName().equals(childElm.getLocalName());
             }
             return tag.getTagName().equals(childElm.getLocalName());
         }
 
         String tn = childElm.getTagName();
         int colonIndex = tn.indexOf(':');
 
         if(colonIndex == -1) {
             if(tag.getNS() == null) {
                 return tag.getTagName().equals(tn);
             }
             return false;
         }
 
         String nsPrefix = getNamesSpaces().get(tag.getNS());
         return childElm.getTagName().equals(nsPrefix + ":" + tag.getTagName());
     }
 
     private Map<String, String> getNamesSpaces() {
         if(namespaces == null) {
             namespaces = new HashMap<String, String>();
             
             NamedNodeMap attributes = dom.getAttributes();
             for (int i = 0; i < attributes.getLength(); i++) {
                 Attr attribute = (Attr)attributes.item(i);
                 
                 String name = attribute.getName();
                 String value = attribute.getValue();
                 
                 if(name.startsWith("xmlns:")) {
                     namespaces.put(value, name.substring("xmlns:".length()));
                 }
             }
         }
         return namespaces;
     }
 
     private Element getFirstElement(List<Element> nodeList) {
         if(nodeList.isEmpty()) {
             return null;
         }
         return nodeList.get(0);
     }
 }