/*
    * 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.frontend.servlets;
  
  import static org.mycore.access.MCRAccessManager.PERMISSION_READ;
  
  import java.io.IOException;
  
  import javax.xml.transform.TransformerException;
  
  import org.mycore.access.MCRAccessManager;
  import org.mycore.common.MCRException;
  import org.mycore.common.MCRSession;
  import org.mycore.common.MCRSessionMgr;
  import org.mycore.common.content.MCRContent;
  import org.mycore.datamodel.common.MCRXMLMetadataManager;
  import org.mycore.datamodel.metadata.MCRMetadataManager;
  import org.mycore.datamodel.metadata.MCRObjectID;
  import org.xml.sax.SAXException;
  
  import jakarta.servlet.ServletException;
  import jakarta.servlet.http.HttpServletRequest;
  import jakarta.servlet.http.HttpServletResponse;
  
  /**
   * Serves a given MCROBject.
   * <em>.../receive/{MCRObjectID}</em>
   * 
   * @author Thomas Scheffler (yagee)
   */
  public class MCRObjectServlet extends MCRContentServlet {
      private static final long serialVersionUID = 1L;
  
      private static final int REV_CURRENT = 0;
  
      private static final String I18N_ERROR_PREFIX = "component.base.error";
  
      private MCRXMLMetadataManager metadataManager = null;
  
      @Override
      public void init() throws ServletException {
          super.init();
          metadataManager = MCRXMLMetadataManager.instance();
      }
  
      @Override
      public MCRContent getContent(final HttpServletRequest req, final HttpServletResponse resp) throws IOException {
          final MCRObjectID mcrid = getMCRObjectID(req, resp);
          if (mcrid == null) {
              return null;
          }
          if (!MCRAccessManager.checkPermission(mcrid, PERMISSION_READ)) { // check read permission for ID
              final MCRSession currentSession = MCRSessionMgr.getCurrentSession();
              resp.sendError(
                  HttpServletResponse.SC_UNAUTHORIZED,
                  getErrorI18N(I18N_ERROR_PREFIX, "accessDenied", mcrid.toString(), currentSession.getUserInformation()
                      .getUserID(), currentSession.getCurrentIP()));
              return null;
          }
          String rev = null;
          final String revision = getProperty(req, "r");
          if (revision != null) {
              rev = revision;
          }
          MCRContent localObject = (rev == null) ? requestLocalObject(mcrid, resp) : requestVersionedObject(mcrid,
              resp, rev);
          if (localObject == null) {
              return null;
          }
          try {
              return getLayoutService().getTransformedContent(req, resp, localObject);
          } catch (TransformerException | SAXException e) {
              throw new IOException(e);
          }
      }
  
      private MCRContent requestLocalObject(MCRObjectID mcrid, final HttpServletResponse resp) throws IOException {
          if (MCRMetadataManager.exists(mcrid)) {
              return metadataManager.retrieveContent(mcrid);
          }
          resp.sendError(HttpServletResponse.SC_NOT_FOUND, getErrorI18N(I18N_ERROR_PREFIX, "notFound", mcrid));
          return null;
      }
 
     private MCRContent requestVersionedObject(final MCRObjectID mcrid, final HttpServletResponse resp, final String rev)
         throws IOException {
         MCRXMLMetadataManager xmlMetadataManager = MCRXMLMetadataManager.instance();
         if (xmlMetadataManager.listRevisions(mcrid) != null) {
             MCRContent content = xmlMetadataManager.retrieveContent(mcrid, rev);
             if (content != null) {
                 return content;
             }
             resp.sendError(HttpServletResponse.SC_NOT_FOUND,
                 getErrorI18N(I18N_ERROR_PREFIX, "revisionNotFound", rev, mcrid));
             return null;
         }
         resp.sendError(HttpServletResponse.SC_BAD_REQUEST, getErrorI18N(I18N_ERROR_PREFIX, "noVersions", mcrid));
         return null;
     }
 
     private MCRObjectID getMCRObjectID(final HttpServletRequest req, final HttpServletResponse resp)
         throws IOException {
         final String pathInfo = req.getPathInfo();
         final String id = pathInfo == null ? null : pathInfo.substring(1);
 
         MCRObjectID mcrid = null;
         if (id != null) {
             try {
                 mcrid = MCRObjectID.getInstance(id); // create Object with given ID, only ID syntax check performed
             } catch (final MCRException e) {
                 // handle exception: invalid ID syntax, set HTTP error 400 "Invalid request"
                 resp.sendError(HttpServletResponse.SC_BAD_REQUEST, getErrorI18N(I18N_ERROR_PREFIX, "invalidID", id));
                 return null; // sorry, no object to return
             }
         }
         return mcrid;
     }
 }