/*
    * 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.common.xsl;
  
  import javax.xml.transform.ErrorListener;
  import javax.xml.transform.SourceLocator;
  import javax.xml.transform.TransformerException;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.apache.xml.utils.WrappedRuntimeException;
  
  /**
   * @author Thomas Scheffler (yagee)
   *
   */
  public class MCRErrorListener implements ErrorListener {
      private static Logger LOGGER = LogManager.getLogger(MCRErrorListener.class);
  
      private TransformerException exceptionThrown;
  
      private String lastMessage;
  
      public static MCRErrorListener getInstance() {
          return new MCRErrorListener();
      }
  
      private MCRErrorListener() {
          this.exceptionThrown = null;
      }
  
      public TransformerException getExceptionThrown() {
          return exceptionThrown;
      }
  
      private boolean triggerException(TransformerException e) {
          if (exceptionThrown != null) {
              return false;
          } else {
              exceptionThrown = e;
              return true;
          }
      }
  
      /* (non-Javadoc)
       * @see javax.xml.transform.ErrorListener#warning(javax.xml.transform.TransformerException)
       */
      @Override
      public void warning(TransformerException exception) throws TransformerException {
          exception = unwrapException(exception);
          StackTraceElement[] stackTrace = exception.getStackTrace();
          if (stackTrace.length > 0 && stackTrace[0].getMethodName().equals("message")) {
              //org.apache.xalan.transformer.MsgMgr.message to print a message
              String messageAndLocation = getMyMessageAndLocation(exception);
              this.lastMessage = messageAndLocation;
              LOGGER.info(messageAndLocation);
          } else {
              LOGGER.warn("Exception while XSL transformation:{}", exception.getMessageAndLocation());
          }
      }
  
      /* (non-Javadoc)
       * @see javax.xml.transform.ErrorListener#error(javax.xml.transform.TransformerException)
       */
      @Override
      public void error(TransformerException exception) throws TransformerException {
          exception = unwrapException(exception);
          if (triggerException(exception)) {
              LOGGER.error("Exception while XSL transformation:{}", exception.getMessageAndLocation());
          }
          throw exception;
      }
  
      /* (non-Javadoc)
       * @see javax.xml.transform.ErrorListener#fatalError(javax.xml.transform.TransformerException)
       */
      @Override
      public void fatalError(TransformerException exception) throws TransformerException {
          exception = unwrapException(exception);
          StackTraceElement[] stackTrace = exception.getStackTrace();
          if (stackTrace.length > 0 && stackTrace[0].getMethodName().equals("execute")
              && stackTrace[0].getClassName().endsWith("ElemMessage")) {
              LOGGER.debug("Original exception: ", exception);
             exception = new TransformerException(lastMessage);
         }
         if (triggerException(exception)) {
             LOGGER.fatal("Exception while XSL transformation.", exception);
         }
         throw exception;
     }
 
     public static TransformerException unwrapException(TransformerException exception) {
         Throwable cause = exception.getCause();
         while (cause != null) {
             if (cause instanceof TransformerException) {
                 return unwrapException((TransformerException) cause);
             }
             if (cause instanceof WrappedRuntimeException) {
                 cause = ((WrappedRuntimeException) cause).getException();
             } else {
                 cause = cause.getCause();
             }
         }
         return exception;
     }
 
     public static String getMyMessageAndLocation(TransformerException exception) {
         SourceLocator locator = exception.getLocator();
         StringBuilder msg = new StringBuilder();
         if (locator != null) {
             String systemID = locator.getSystemId();
             int line = locator.getLineNumber();
             int col = locator.getColumnNumber();
             if (systemID != null) {
                 msg.append("SystemID: ");
                 msg.append(systemID);
             }
             if (line != 0) {
                 msg.append(" [");
                 msg.append(line);
                 if (col != 0) {
                     msg.append(',');
                     msg.append(col);
                 }
                 msg.append("]");
             }
         }
         msg.append(": ");
         msg.append(exception.getMessage());
         return msg.toString();
     }
 }