/*
    * 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 org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.jdom2.Document;
  import org.jdom2.Element;
  import org.mycore.common.MCRException;
  import org.mycore.datamodel.classifications2.MCRCategoryDAOFactory;
  import org.mycore.datamodel.classifications2.MCRCategoryID;
  import org.mycore.datamodel.common.MCRActiveLinkException;
  import org.xml.sax.SAXParseException;
  
  import com.google.gson.JsonObject;
  
  /**
   * This class holds all information of a metadata object.
   * For persistence operations see methods of {@link MCRMetadataManager}.
   *  
   * @author Jens Kupferschmidt
   * @author Mathias Hegner
   * @author Thomas Scheffler (yagee)
   * @version $Revision$ $Date$
   */
  public final class MCRObject extends MCRBase {
  
      private static final Logger LOGGER = LogManager.getLogger();
  
      public static final String ROOT_NAME = "mycoreobject";
  
      /**
       * constant value for the object id length
       */
      public static final int MAX_LABEL_LENGTH = 256;
  
      /**
       * the object content
       */
      private final MCRObjectStructure structure;
  
      private final MCRObjectMetadata metadata;
  
      protected String mcrLabel = null;
  
      /**
       * This is the constructor of the MCRObject class. It creates an instance of
       * the parser class and the metadata class. <br>
       * The constructor reads the following information from the property file:
       * <ul>
       * <li>MCR.XMLParser.Class</li>
       * </ul>
       * 
       * @exception MCRException
       *                general Exception of MyCoRe
       */
      public MCRObject() throws MCRException {
          super();
          structure = new MCRObjectStructure();
          metadata = new MCRObjectMetadata();
          mcrLabel = "";
      }
  
      public MCRObject(byte[] bytes, boolean valid) throws SAXParseException {
          this();
          setFromXML(bytes, valid);
      }
  
      public MCRObject(Document doc) {
          this();
          setFromJDOM(doc);
      }
  
      public MCRObject(URI uri) throws SAXParseException, IOException {
          this();
          setFromURI(uri);
      }
  
      /**
       * This method returns the instance of the MCRObjectMetadata class. If there
      * was no MCRObjectMetadata found, null will be returned.
      * 
      * @return the instance of the MCRObjectMetadata class
      */
     public MCRObjectMetadata getMetadata() {
         return metadata;
     }
 
     /**
      * This method return the instance of the MCRObjectStructure class. If this
      * was not found, null was returned.
      * 
      * @return the instance of the MCRObjectStructure class
      */
     public MCRObjectStructure getStructure() {
         return structure;
     }
 
     /**
      * This methode return the object label. If this is not set, null was
      * returned.
      * 
      * @return the lable as a string
      */
     public String getLabel() {
         return mcrLabel;
     }
 
     /**
      * This method set the object label.
      * 
      * @param label
      *            the object 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);
             }
         }
     }
 
     /**
      * 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 structure data of the object
         Element structureElement = jdomDocument.getRootElement().getChild("structure");
         if (structureElement != null) {
             structure.setFromDOM(structureElement);
         }
 
         // get the metadata of the object
         Element metadataElement = jdomDocument.getRootElement().getChild("metadata");
 
         if (metadataElement != null) {
             metadata.setFromDOM(metadataElement);
         }
     }
 
     /**
      * This method creates 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 {
         try {
             Document doc = super.createXML();
             Element elm = doc.getRootElement();
             if (mcrLabel != null) {
                 elm.setAttribute("label", mcrLabel);
             }
             elm.addContent(structure.createXML());
             elm.addContent(metadata.createXML());
             elm.addContent(mcrService.createXML());
             return doc;
         } catch (MCRException exc) {
             throw new MCRException("The content of '" + mcrId + "' is invalid.", exc);
         }
     }
 
     /**
      * Creates the JSON representation of this object. Extends the {@link MCRBase#createJSON()}
      * method with the following content:
      * 
      * <pre>
      *   {
      *     id: "mycore_project_00000001",
      *     version: "3.0"
      *     label: "my mycore object",
      *     
      *     structure: {@link MCRObjectStructure#createJSON},
      *     metadata: {@link MCRObjectMetadata#createJSON},
      *     service: {@link MCRObjectService#createJSON},
      *   }
      * </pre>
      * 
      * @return a json gson representation of this object
      */
     @Override
     public JsonObject createJSON() {
         JsonObject object = super.createJSON();
         if (mcrLabel != null) {
             object.addProperty("label", mcrLabel);
         }
         object.add("structure", structure.createJSON());
         object.add("metadata", metadata.createJSON());
         object.add("service", mcrService.createJSON());
         return object;
     }
 
     @Override
     protected String getRootTagName() {
         return ROOT_NAME;
     }
 
     /**
      * The method print all informations about this MCRObject.
      */
     public void debug() {
         if (LOGGER.isDebugEnabled()) {
             if (mcrId == null) {
                 LOGGER.debug("MCRObject ID : missing");
             } else {
                 LOGGER.debug("MCRObject ID : {}", mcrId);
             }
             LOGGER.debug("MCRObject Label : {}", mcrLabel);
             LOGGER.debug("MCRObject Schema : {}", mcrSchema);
             LOGGER.debug("");
         }
         structure.debug();
         metadata.debug();
     }
 
     /**
      * Validates this MCRObject. 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 structure part is null or invalid</li>
      *  <li>the metadata part is null or invalid</li>
      *  </ul>
      * 
      * @throws MCRException the MCRObject is invalid
      */
     @Override
     public void validate() {
         super.validate();
         MCRObjectStructure structure = getStructure();
         MCRObjectMetadata metadata = getMetadata();
         if (structure == null) {
             throw new MCRException("The <structure> part of '" + getId() + "' is undefined.");
         }
         if (metadata == null) {
             throw new MCRException("The <metadata> part of '" + getId() + "' is undefined.");
         }
         try {
             structure.validate();
         } catch (MCRException exc) {
             throw new MCRException("The <structure> part of '" + getId() + "' is invalid.", exc);
         }
         if (getId().equals(getParent())) {
             throw new MCRException("This object '" + getId() + "' cannot be parent/child of itself.");
         }
         try {
             metadata.validate();
         } catch (MCRException exc) {
             throw new MCRException("The <metadata> part of '" + getId() + "' is invalid.", exc);
         }
     }
 
     /**
      * @return true if the MCRObject has got a parent mcrobject, false otherwise 
      */
     public boolean hasParent() {
         return getStructure().getParentID() != null;
     }
 
     public MCRObjectID getParent() {
         return getStructure().getParentID();
     }
 
     public void checkLinkTargets() {
         for (int i = 0; i < getMetadata().size(); i++) {
             MCRMetaElement elm = getMetadata().getMetadataElement(i);
             for (int j = 0; j < elm.size(); j++) {
                 MCRMetaInterface inf = elm.getElement(j);
                 if (inf instanceof MCRMetaClassification) {
                     String classID = ((MCRMetaClassification) inf).getClassId();
                     String categID = ((MCRMetaClassification) inf).getCategId();
                     boolean exists = MCRCategoryDAOFactory.getInstance().exist(new MCRCategoryID(classID, categID));
                     if (exists) {
                         continue;
                     }
                     MCRActiveLinkException activeLink = new MCRActiveLinkException(
                         "Failure while adding link!. Destination does not exist.");
                     String destination = classID + "##" + categID;
                     activeLink.addLink(getId().toString(), destination);
                     // throw activeLink;
                     // TODO: should trigger undo-Event
                 }
                 if (inf instanceof MCRMetaLinkID) {
                     MCRObjectID destination = ((MCRMetaLinkID) inf).getXLinkHrefID();
                     if (MCRMetadataManager.exists(destination)) {
                         continue;
                     }
                     MCRActiveLinkException activeLink = new MCRActiveLinkException(
                         "Failure while adding link!. Destination does not exist.");
                     activeLink.addLink(getId().toString(), destination.toString());
                     // throw activeLink;
                     // TODO: should trigger undo-Event
                 }
             }
         }
     }
 
 }