package uk.ac.ebi.intenz.webapp.controller;
   
   import uk.ac.ebi.intenz.mapper.EnzymeEntryMapper;
   import uk.ac.ebi.intenz.webapp.utilities.IntEnzMessenger;
   import uk.ac.ebi.rhea.mapper.MapperException;
   
   import javax.servlet.RequestDispatcher;
   import javax.servlet.ServletContext;
   import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  import java.sql.Connection;
  import java.sql.SQLException;
  
  import org.apache.log4j.Logger;
  
  /**
   * A database command always relies on a connection to the database.
   *
   * @author Michael Darsow
   * @version 0.9 - 21-July-2003
   */
  public abstract class DatabaseCommand extends Command {
  
     Logger LOGGER = Logger.getLogger(DatabaseCommand.class);
  
    protected final String databaseErrorMessage = "\nIt was not possible to retrieve any information from the database. " +
            "\nIt would be very kind of you, if you could report this error to " +
            "<a href=\"http://www.ebi.ac.uk/support/\">EBI Support</a>.\n" +
            "Sorry for any inconvenience this error might have caused.";
  
    protected ServletContext context;
  
    protected HttpServletRequest request;
  
    protected HttpServletResponse response;
  
    protected Connection con;
  
  	protected final EnzymeEntryMapper enzymeEntryMapper =
  			new EnzymeEntryMapper();
  
    /**
     * Initialises the attributes which will be used to extract information for the command execution.
     *
     * @param context  The servlet context.
     * @param request  The request object.
     * @param response The response object.
     * @param con      A logical connection.
     */
    public void init(ServletContext context, HttpServletRequest request, HttpServletResponse response, Connection con) {
      this.context = context;
      this.request = request;
      this.response = response;
      this.con = con;
    }
  
    /**
     * Forwards to the given target.
     *
     * @param target A valid URI.
     * @throws ServletException
     * @throws IOException
     */
    protected void forward(String target) throws ServletException, IOException {
      closeConnection();
      RequestDispatcher dispatcher = context.getRequestDispatcher(target);
      dispatcher.forward(request, response);
    }
  
    /**
     * Closes the database connection or forwards to an error page if any error occured.
     * 
     * @throws ServletException
     * @throws IOException
     */
    protected void closeConnection() throws ServletException, IOException {
      try {
  
         if (con != null && !con.isClosed()){
            LOGGER.debug("Closing connection");
           con.close();
         }
      } catch (SQLException e) {
         LOGGER.error("Closing connection", e);
        IntEnzMessenger.sendError(this.getClass().toString(), e.getMessage(), (String) request.getSession().getAttribute("user"));
        request.setAttribute("message", "The following database error occured:\n" + e.getMessage() +
                this.databaseErrorMessage);
        RequestDispatcher dispatcher = context.getRequestDispatcher("/error.jsp");
        dispatcher.forward(request, response);
      }
    }
    
  	protected void close() {
  		enzymeEntryMapper.close();
  	}
  
  	@Override
 	protected void finalize() throws Throwable {
 		close();
 	}
 
 }