/*
    * 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 static org.mycore.common.MCRConstants.DEFAULT_ENCODING;
  import static org.mycore.common.MCRConstants.XLINK_NAMESPACE;
  import static org.mycore.common.MCRConstants.XSI_NAMESPACE;
  
  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.MCRCoreVersion;
  import org.mycore.common.MCRException;
  import org.mycore.common.config.MCRConfiguration2;
  import org.mycore.common.content.MCRByteContent;
  import org.mycore.common.content.MCRURLContent;
  import org.mycore.common.xml.MCRXMLParserFactory;
  import org.xml.sax.SAXParseException;
  
  import com.google.gson.JsonObject;
  
  /**
   * This class is a abstract basic class for objects in the MyCoRe Project. It is
   * the frame to produce a full functionality object.
   * 
   * @author Jens Kupferschmidt
   * @version $Revision$ $Date$
   */
  public abstract class MCRBase {
  
      protected static final String MCR_ENCODING;
  
      // the DOM document
      protected Document jdomDocument = null;
  
      // the object content
      protected MCRObjectID mcrId = null;
  
      protected String mcrVersion = null;
  
      protected String mcrSchema = null;
  
      protected final MCRObjectService mcrService;
  
      // other
      protected static final String NL;
  
      protected static final String SLASH;
  
      protected boolean importMode = false;
  
      // logger
      private static final Logger LOGGER = LogManager.getLogger();
  
      static {
          NL = System.getProperty("line.separator");
          SLASH = System.getProperty("file.separator");
          // Default Encoding
          MCR_ENCODING = MCRConfiguration2.getString("MCR.Metadata.DefaultEncoding").orElse(DEFAULT_ENCODING);
          if (LOGGER.isDebugEnabled()) {
              LOGGER.debug("Encoding = {}", MCR_ENCODING);
          }
      }
  
      /**
       * This is the constructor of the MCRBase class. It make an instance of the
       * parser class and the metadata class. <br>
       * 
       * @exception MCRException
       *                general Exception of MyCoRe
       */
      public MCRBase() throws MCRException {
          mcrVersion = MCRCoreVersion.getVersion();
          mcrSchema = "";
  
          // Service class
          mcrService = new MCRObjectService();
      }
  
     protected void setFromJDOM(Document doc) {
         jdomDocument = doc;
         setUp();
     }
 
     protected void setUp() {
         if (jdomDocument == null) {
             throw new MCRException("The JDOM document is null or empty.");
         }
 
         Element rootElement = jdomDocument.getRootElement();
         setId(MCRObjectID.getInstance(rootElement.getAttributeValue("ID")));
         setVersion(rootElement.getAttributeValue("version"));
         setSchema(rootElement.getAttribute("noNamespaceSchemaLocation", XSI_NAMESPACE).getValue());
 
         // get the service data of the object
         Element serviceElement = rootElement.getChild("service");
         if (serviceElement != null) {
             mcrService.setFromDOM(serviceElement);
         }
     }
 
     /**
      * This methode return the object id. If this is not set, null was returned.
      * 
      * @return the id as MCRObjectID
      */
     public final MCRObjectID getId() {
         return mcrId;
     }
 
     /**
      * This methode return the MyCoRe version of the data structure.
      * 
      * @return the version as a string
      */
     public final String getVersion() {
         return mcrVersion;
     }
 
     /**
      * Method returns the object schema. If the schema is not set <code>null</code> will be returned.
      * 
      * @return the schema as a string
      */
     public final String getSchema() {
         return mcrSchema;
     }
 
     /**
      * This methode return the instance of the MCRObjectService class. If this
      * was not found, null was returned.
      * 
      * @return the instance of the MCRObjectService class
      */
     public final MCRObjectService getService() {
         return mcrService;
     }
 
     /**
      * This method read the XML input stream from an URI to build up the
      * MyCoRe-Object.
      * 
      * @param uri
      *            an URI
      * @exception MCRException
      *                general Exception of MyCoRe
      */
     protected final void setFromURI(URI uri) throws MCRException, SAXParseException, IOException {
         Document jdom = MCRXMLParserFactory.getParser().parseXML(new MCRURLContent(uri.toURL()));
         setFromJDOM(jdom);
     }
 
     /**
      * This method read the XML input stream from a byte array to build up the
      * MyCoRe-Object.
      * 
      * @param xml
      *            a XML string
      * @exception MCRException
      *                general Exception of MyCoRe
      */
     protected final void setFromXML(byte[] xml, boolean valid) throws MCRException, SAXParseException {
         Document jdom = MCRXMLParserFactory.getParser(valid).parseXML(new MCRByteContent(xml));
         setFromJDOM(jdom);
     }
 
     /**
      * This method set the object ID.
      * 
      * @param id
      *            the object ID
      */
     public void setId(MCRObjectID id) {
         mcrId = id;
     }
 
     /**
      * This methods set the MyCoRe version to the string 'Version 1.3'.
      */
     public final void setVersion(String version) {
         mcrVersion = version != null ? version : MCRCoreVersion.getVersion();
     }
 
     /**
      * This methode set the object schema.
      * 
      * @param schema
      *            the object schema
      */
     public final void setSchema(String schema) {
         if (schema == null) {
             mcrSchema = "";
 
             return;
         }
 
         mcrSchema = schema.trim();
     }
 
     /**
      * This method 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
      */
     public Document createXML() throws MCRException {
         validate();
         Element elm = new Element(getRootTagName());
         Document doc = new Document(elm);
         elm.addNamespaceDeclaration(XSI_NAMESPACE);
         elm.addNamespaceDeclaration(XLINK_NAMESPACE);
         elm.setAttribute("noNamespaceSchemaLocation", mcrSchema, XSI_NAMESPACE);
         elm.setAttribute("ID", mcrId.toString());
         elm.setAttribute("version", mcrVersion);
         return doc;
     }
 
     /**
      * Creates the JSON representation of this object.
      * 
      * <pre>
      *   {
      *     id: "mycore_project_00000001",
      *     version: "3.0"
      *   }
      * </pre>
      * 
      */
     public JsonObject createJSON() {
         JsonObject object = new JsonObject();
         object.addProperty("id", mcrId.toString());
         object.addProperty("version", mcrVersion);
         return object;
     }
 
     protected abstract String getRootTagName();
 
     /**
      * This method check the validation of the content of this class. The method
      * returns <em>true</em> if
      * <ul>
      * <li>the mcr_id value is valid
      * </ul>
      * otherwise the method return <em>false</em>
      * 
      * @return a boolean value
      */
     public boolean isValid() {
         try {
             validate();
             return true;
         } catch (MCRException exc) {
             LOGGER.warn("The content of this object '{}' is invalid.", mcrId, exc);
         }
         return false;
     }
 
     /**
      * Validates the content of this class. 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>
      *  </ul>
      * 
      * @throws MCRException the content is invalid
      */
     public void validate() throws MCRException {
         if (mcrId == null) {
             throw new MCRException("MCRObjectID is undefined.");
         }
         if (getSchema() == null || getSchema().length() == 0) {
             throw new MCRException("XML Schema of '" + mcrId + "' is undefined.");
         }
         MCRObjectService service = getService();
         if (service == null) {
             throw new MCRException("The <service> part of '" + mcrId + "' is undefined.");
         }
         try {
             service.validate();
         } catch (MCRException exc) {
             throw new MCRException("The <service> part of '" + mcrId + "' is invalid.", exc);
         }
     }
 
     public boolean isImportMode() {
         return importMode;
     }
 
     public void setImportMode(boolean importMode) {
         this.importMode = importMode;
     }
 
     @Override
     public String toString() {
         return this.mcrId.toString();
     }
 }