/*
 * Created on 15.12.2003
 *
 * (c) Stabsstelle IKT-Strategie des Bundes
 */
package at.gv.egovernment.moa.spss.slinterface;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Properties;

import javax.servlet.http.HttpSession;

import org.apache.log4j.Logger;

/**
 * @author Gregor Karlinger (mailto:gregor.karlinger@cio.gv.at) 
 */
public class URLRewriter
{
  private static Logger logger_ = Logger.getLogger(Constants.LH_LISTENERS_);

  Properties initProps_;

  /**
   * Flag indicating whether rewriting should take place or not.
   */
  boolean doRewrite_;
  
  /**
   * Class that manges the rewriting of URLs for the result pages. Necessary as workaround for the deploy-
   * ment in the Federal Chancellory.
   */
  public URLRewriter(Properties initProps)
  {
    initProps_ = initProps;
    doRewrite_ = Boolean.valueOf(initProps_.getProperty(Constants.IP_REW_)).booleanValue();
  }
  
  /**
   * Rewrites the specified URL. 
   * 
   * @param url A URL relative to the root of the web application server containing MOA SL.
   * 
   * @param session The session which will be considered in the rewritten URL.
   * 
   * @return A URL fitting for the proxy component running at the Federal Chancellory.
   */
  public String rewrite(String url, HttpSession session)
  { 
    if (doRewrite_)
    {
      // Get remote IP address and resolve to remote to remote domain name
      String remoteAddr = (String)session.getAttribute("remoteAddr");
      String remoteName = null;
      if (remoteAddr != null) 
      {
        remoteName = initProps_.getProperty(Constants.IP_REW_DNS_LOOKUP_PREFIX_ + remoteAddr);
        logger_.debug("Remote address lookup succeeded for IP " + remoteAddr + ", using " + remoteName);
      }
      if (remoteName == null)
      {
        remoteName = initProps_.getProperty(Constants.IP_REW_DNS_LOOKUP_DEFAULT_);
        logger_.debug("Remote address lookup failed for IP " + remoteAddr + ", using default: " + remoteName);
      }
      
      // Get proxy URL and replace proxy URL hostname placeholder with remote domain name
      String proxyURLStr = initProps_.getProperty(Constants.IP_REW_PROXYURL_);
      int pHStartIndex = proxyURLStr.indexOf(initProps_.getProperty(Constants.IP_REW_PROXYURL_HOSTDUMMY_));
      proxyURLStr = proxyURLStr.substring(0, pHStartIndex) 
        + remoteName 
        + proxyURLStr.substring(pHStartIndex 
            + initProps_.getProperty(Constants.IP_REW_PROXYURL_HOSTDUMMY_).length());
      
      String slInterfaceURLParamName = initProps_.getProperty(Constants.IP_REW_MOASL_URLPARAMNAME_);
      String slInterfaceWebAppServURLStr = initProps_.getProperty(Constants.IP_REW_MOASL_WEBAPPSERV_URL_);
      
      if (proxyURLStr == null || 
        slInterfaceURLParamName == null || 
        slInterfaceWebAppServURLStr == null ||
        "".equals(proxyURLStr.trim()) ||
        "".equals(slInterfaceURLParamName.trim()) ||
        "".equals(slInterfaceWebAppServURLStr.trim()))
      {
        logger_.warn("Some params for URL rewriting are not available; rewriting disabled:" +
          " proxyURL: \"" + proxyURLStr + "\"," +
          " slInterfaceURLParamName: \"" + slInterfaceURLParamName + "\"," +
          " slInterfaceWebAppServURLStr: \"" + slInterfaceWebAppServURLStr + "\"");
        return url;  
      }
      
      URL slInterfaceURL = null;
      try
      {
        slInterfaceURL = new URL(slInterfaceWebAppServURLStr + url);
      }
      catch (MalformedURLException e)
      {
        logger_.warn("Parameter \"slInterfaceURL\" is not a valid URL: \"" + slInterfaceWebAppServURLStr + url + "\"");
        return url;
      }
      URL proxyURL = null;
      try
      {
        proxyURL = new URL(proxyURLStr);
      }
      catch (MalformedURLException e)
      {
        logger_.warn("Parameter \"proxyURL\" is not a valid URL: \"" + proxyURLStr + "\"");
        return url;
      }
  
      String sessionId = session.getId();
      String sessionIdParam = (sessionId != null) ? (";" + "jsessionid=" + sessionId) : "";
      String returnValue = 
        proxyURL.getProtocol() +
        "://" +
        proxyURL.getHost() +
        ((proxyURL.getPort() != -1) ? (":" + proxyURL.getPort()) : "") + 
        proxyURL.getPath() +
        ((proxyURL.getQuery() != null) ? "?" + proxyURL.getQuery() + "&" : "?") +
        slInterfaceURLParamName + "=" +
        slInterfaceURL.getProtocol() +
        "://" +
        slInterfaceURL.getHost() +
        ((slInterfaceURL.getPort() != -1) ? (":" + slInterfaceURL.getPort()) : "") +
        slInterfaceURL.getPath() + 
        sessionIdParam +
        ((slInterfaceURL.getQuery() != null) ? "?" + escapeQueryPart(slInterfaceURL.getQuery()) : ""); 
        
      logger_.debug("Rewritten URL: " + returnValue);
      return returnValue;
    }
    else
    {
      logger_.debug("URL rewriting disabled via configuration. URL \"" + url + "\" remains unchanged.");
      return url;
    }
  }
  
  private String escapeQueryPart(String query)
  {
    StringBuffer querySB = new StringBuffer();
    for (int i = 0; i < query.length(); i++)
    {
      if (query.charAt(i) == '&')
      {
        querySB.append("%26");
      }
      else
      {
        querySB.append(query.charAt(i));
      } 
    }
    return querySB.toString();
  }
}