/*
    * 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.metadata;
  
  import java.io.IOException;
  import java.net.URI;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.jdom2.Document;
  import org.jdom2.Element;
  import org.jdom2.filter.Filters;
  import org.jdom2.xpath.XPathExpression;
  import org.jdom2.xpath.XPathFactory;
  import org.mycore.common.MCRException;
  import org.xml.sax.SAXParseException;
  
  import com.google.gson.JsonObject;
  
  /**
   * This class holds all information of a derivate. For persistence operations
   * see methods of {@link MCRMetadataManager}.
   * 
   * @author Jens Kupferschmidt
   * @author Thomas Scheffler
   * @version $Revision$ $Date: 2010-09-30 17:49:21 +0200 (Thu, 30 Sep
   *          2010) $
   */
  public final class MCRDerivate extends MCRBase {
  
      private static final Logger LOGGER = LogManager.getLogger();
  
      public static final String ROOT_NAME = "mycorederivate";
  
      public static final int MAX_LABEL_LENGTH = 256;
  
      // the object content
      private MCRObjectDerivate mcrDerivate;
  
      private int order;
  
      protected String mcrLabel = null;
  
      /**
       * This is the constructor of the MCRDerivate class. It make an instance of
       * the parser class and the metadata class.
       * 
       * @exception MCRException
       *                general Exception of MyCoRe
       */
      public MCRDerivate() throws MCRException {
          super();
          mcrDerivate = new MCRObjectDerivate(getId());
          order = 1;
      }
  
      public MCRDerivate(byte[] bytes, boolean valid) throws SAXParseException {
          this();
          setFromXML(bytes, valid);
      }
  
      public MCRDerivate(Document doc) {
          this();
          setFromJDOM(doc);
      }
  
      public MCRDerivate(URI uri) throws SAXParseException, IOException {
          this();
          setFromURI(uri);
      }
  
      /**
       * This methode return the instance of the MCRObjectDerivate class. If this
       * was not found, null was returned.
       * 
       * @return the instance of the MCRObjectDerivate class
       */
      public MCRObjectDerivate getDerivate() {
          return mcrDerivate;
     }
 
     /**
      * The given DOM was convert into an internal view of metadata. This are the
      * object ID and the object label, also the blocks structure, flags and
      * metadata.
      * 
      * @exception MCRException
      *                general Exception of MyCoRe
      */
     @Override
     protected void setUp() throws MCRException {
         super.setUp();
         setLabel(jdomDocument.getRootElement().getAttributeValue("label"));
 
         // get the derivate data of the object
         Element derivateElement = jdomDocument.getRootElement().getChild("derivate");
         mcrDerivate = new MCRObjectDerivate(mcrId, derivateElement);
     }
 
     /**
      * This methode create a XML stream for all object data.
      * 
      * @exception MCRException
      *                if the content of this class is not valid
      * @return a JDOM Document with the XML data of the object as byte array
      */
     @Override
     public Document createXML() throws MCRException {
         Document doc = super.createXML();
         Element elm = doc.getRootElement();
         elm.setAttribute("order", String.valueOf(order));
         if (mcrLabel != null) {
             elm.setAttribute("label", mcrLabel);
         }
         elm.addContent(mcrDerivate.createXML());
         elm.addContent(mcrService.createXML());
         return doc;
     }
 
     @Override
     protected String getRootTagName() {
         return ROOT_NAME;
     }
 
     /**
      * Reads all files and urns from the derivate.
      * 
      * @return A {@link Map} which contains the files as key and the urns as value.
      * If no URN assigned the map will be empty.
      */
     public Map<String, String> getUrnMap() {
         Map<String, String> fileUrnMap = new HashMap<>();
 
         XPathExpression<Element> filesetPath = XPathFactory.instance().compile("./mycorederivate/derivate/fileset",
             Filters.element());
 
         Element result = filesetPath.evaluateFirst(this.createXML());
         if (result == null) {
             return fileUrnMap;
         }
         String urn = result.getAttributeValue("urn");
 
         if (urn != null) {
             XPathExpression<Element> filePath = XPathFactory
                 .instance()
                 .compile("./mycorederivate/derivate/fileset[@urn='" + urn + "']/file", Filters.element());
             List<Element> files = filePath.evaluate(this.createXML());
 
             for (Element currentFileElement : files) {
                 String currentUrn = currentFileElement.getChildText("urn");
                 String currentFile = currentFileElement.getAttributeValue("name");
                 fileUrnMap.put(currentFile, currentUrn);
             }
         }
         return fileUrnMap;
     }
 
     /**
      * This methode return the label or null if it was not set. 
      * 
      * @return the label as a string
      */
     public String getLabel() {
         return mcrLabel;
     }
 
     /**
      * The method print all informations about this MCRObject.
      */
     public void debug() {
         if (LOGGER.isDebugEnabled()) {
             LOGGER.debug("MCRDerivate ID : {}", mcrId);
             LOGGER.debug("MCRDerivate Schema : {}", mcrSchema);
             LOGGER.debug("");
         }
     }
 
     /**
      * Validates this MCRDerivate. This method throws an exception if:
      *  <ul>
      *  <li>the mcr_id is null</li>
      *  <li>the XML schema is null or empty</li>
      *  <li>the service part is null or invalid</li>
      *  <li>the MCRObjectDerivate is null or invalid</li>
      *  </ul>
      * 
      * @throws MCRException the MCRDerivate is invalid
      */
     @Override
     public void validate() throws MCRException {
         super.validate();
         MCRObjectDerivate derivate = getDerivate();
         if (derivate == null) {
             throw new MCRException("The <derivate> part of '" + getId() + "' is undefined.");
         }
         try {
             derivate.validate();
         } catch (Exception exc) {
             throw new MCRException("The <derivate> part of '" + getId() + "' is invalid.", exc);
         }
     }
 
     /**
      * @return the {@link MCRObjectID} of the owner of the derivate
      */
     public MCRObjectID getOwnerID() {
         return this.getDerivate().getMetaLink().getXLinkHrefID();
     }
 
     @Override
     public void setId(MCRObjectID id) {
         super.setId(id);
         this.mcrDerivate.setDerivateID(id);
     }
 
     /**
      * This method set the derivate label.
      * 
      * @param label - the derivate label
      */
     public void setLabel(String label) {
         if (label == null) {
             mcrLabel = label;
         } else {
             mcrLabel = label.trim();
             if (mcrLabel.length() > MAX_LABEL_LENGTH) {
                 mcrLabel = mcrLabel.substring(0, MAX_LABEL_LENGTH);
             }
         }
     }
 
     public int getOrder() {
         return order;
     }
 
     public void setOrder(int order) {
         this.order = order;
     }
 
     @Override
     protected void setFromJDOM(Document doc) {
         super.setFromJDOM(doc);
         this.order = Optional.ofNullable(doc.getRootElement().getAttributeValue("order"))
             .map(Integer::valueOf)
             .orElse(1);
     }
 
     @Override
     public JsonObject createJSON() {
         JsonObject base = super.createJSON();
         if (mcrLabel != null) {
             base.addProperty("label", mcrLabel);
         }
         return base;
     }
 }