/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.mycore.datamodel.classifications2.utils;
  
  import static org.mycore.common.MCRConstants.XLINK_NAMESPACE;
  
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.SortedSet;
  import java.util.TreeSet;
  
  import org.jdom2.Document;
  import org.jdom2.Element;
  import org.jdom2.Namespace;
  import org.mycore.common.MCRException;
  import org.mycore.datamodel.classifications2.MCRCategory;
  import org.mycore.datamodel.classifications2.MCRCategoryID;
  import org.mycore.datamodel.classifications2.MCRLabel;
  import org.mycore.datamodel.classifications2.impl.MCRCategoryImpl;
  
  public class MCRXMLTransformer {
  
      public static MCRCategory getCategory(Document xml) throws URISyntaxException {
          MCRCategoryImpl category = new MCRCategoryImpl();
          category.setRoot(category);
          final String classID = xml.getRootElement().getAttributeValue("ID");
          category.setLevel(0);
          category.setId(MCRCategoryID.rootID(classID));
          setURL(xml.getRootElement(), category);
          //setChildren has to be called before setParent (below) can be called without
          //database access see: org.mycore.datamodel.classifications2.impl.MCRAbstractCategoryImpl.getChildren()
          category.setChildren(new ArrayList<>());
          buildChildCategories(classID, xml.getRootElement().getChild("categories").getChildren("category"), category);
          try {
              category.setLabels(getLabels(xml.getRootElement().getChildren("label")));
          } catch (NullPointerException | IllegalArgumentException ex) {
              throw new MCRException("Error while adding labels to classification: " + classID, ex);
          }
          return category;
      }
  
      public static MCRCategory buildCategory(String classID, Element e, MCRCategory parent) throws URISyntaxException {
          MCRCategoryImpl category = new MCRCategoryImpl();
          //setId must be called before setParent (info important)
          category.setId(new MCRCategoryID(classID, e.getAttributeValue("ID")));
          category.setRoot(parent.getRoot());
          category.setChildren(new ArrayList<>());
          category.setParent(parent);
          try {
              category.setLabels(getLabels(e.getChildren("label")));
          } catch (NullPointerException | IllegalArgumentException ex) {
              throw new MCRException("Error while adding labels to category: " + category.getId(), ex);
          }
          category.setLevel(parent.getLevel() + 1);
          setURL(e, category);
          buildChildCategories(classID, e.getChildren("category"), category);
          return category;
      }
  
      private static List<MCRCategory> buildChildCategories(String classID, List<Element> elements, MCRCategory parent)
          throws URISyntaxException {
          List<MCRCategory> children = new ArrayList<>(elements.size());
          for (Object o : elements) {
              children.add(buildCategory(classID, (Element) o, parent));
          }
          return children;
      }
  
      public static SortedSet<MCRLabel> getLabels(List<Element> elements)
          throws NullPointerException, IllegalArgumentException {
          SortedSet<MCRLabel> labels = new TreeSet<MCRLabel>();
          for (Element labelElement : elements) {
              MCRLabel label = getLabel(labelElement);
              labels.add(label);
          }
          return labels;
      }
  
      public static MCRLabel getLabel(Element labelElement) throws NullPointerException, IllegalArgumentException {
          String lang = labelElement.getAttributeValue("lang", Namespace.XML_NAMESPACE);
          return new MCRLabel(lang, labelElement.getAttributeValue("text"),
             labelElement.getAttributeValue("description"));
     }
 
     private static void setURL(Element e, MCRCategory category) throws URISyntaxException {
         if (e.getChild("url") != null) {
             final String uri = e.getChild("url").getAttributeValue("href", XLINK_NAMESPACE);
             if (uri != null) {
                 category.setURI(new URI(uri));
             }
         }
     }
 
 }