/*
 * Created on 25.11.2003
 *
 * (c) Stabsstelle IKT-Strategie des Bundes
 */
package at.gv.egovernment.moa.spss.slinterface.servlets;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;

import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.log4j.Logger;
import org.w3c.dom.Document;

import at.gv.egovernment.moa.spss.slinterface.Constants;
import at.gv.egovernment.moa.spss.slinterface.Utils;
import at.gv.egovernment.moa.spss.slinterface.moainvoker.MOAInvoker;

/**
 * @author Gregor Karlinger (mailto:gregor.karlinger@cio.gv.at) 
 */
public class ReturnServlet extends HttpServlet
{

  private static Logger logger_ = Logger.getLogger(Constants.LH_SERVLETS_);

  /**
   * Default constructor.
   */
  public ReturnServlet()
  {
    super();
  }
  
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException
  {
    // Get session
    HttpSession session = request.getSession(false);
    if (session == null)
    {
      String message = "No session available.";
      logger_.error(message);
      throw new ServletException(message);
    }
    
    // Get original SL request from session
    SLRequest slRequest = (SLRequest) session.getAttribute("slRequest");
    if (slRequest == null)
    {
      String message = "Session object \"slRequest\" not available.";
      logger_.error(message);
      throw new ServletException(message);
    }
    
    // Get SL response from session
    Document slResponseDoc = (Document) session.getAttribute("slResponseDoc");
    if (slResponseDoc == null)
    {
      String message = "Session object \"slResponseDoc\" not available.";
      logger_.error(message);
      throw new ServletException(message);
    }
    
    URLConnection dataURLConn;
    try
    {
      // Open connection to DataURL
      URL dataURL = new URL(slRequest.dataUrl_);
      dataURLConn = dataURL.openConnection();
      dataURLConn.setDoOutput(true);
      OutputStream dataURLOS = dataURLConn.getOutputStream();     
      MOAInvoker.serializeDocument(slResponseDoc, dataURLOS);
      dataURLOS.flush();
    }
    catch (Exception e)
    {
      String message = "Sending SL XML response to DataURL failed.";
      logger_.error(message, e);
      throw new ServletException(message, e);
    }

    // Forward response from DataURL to client
    forwardResponse(dataURLConn, response);
    
    session.invalidate();
  }

  /* ---------------------------------------------------------------------------------------------------- */

  private void forwardResponse(URLConnection dataURLConn, ServletResponse response) throws ServletException
  {
    // Make sure that content type of DataURL response is text/html
    String dataURLContentType = dataURLConn.getContentType();
    if (dataURLContentType == null || !dataURLContentType.startsWith("text/html"))
    {
      String message = "Unsupported content type of DataURL response: \"" + dataURLContentType + "\".";
      logger_.error(message);
      throw new ServletException(message);
    }
    
    try
    {
      InputStream dataURLIS = dataURLConn.getInputStream();
      byte[] dataURLResponse = Utils.readFromInputStream(dataURLIS);
      response.setContentType("text/html");
      OutputStream responseOS = response.getOutputStream();
      responseOS.write(dataURLResponse);
      responseOS.flush();
    }
    catch (Exception e)
    {
      String message = "Forwarding DataURL response to client failed.";
      logger_.error(message, e);
      throw new ServletException(message, e);
    }
  }
}