/**
    * Copyright 2005-2006 the original author or authors.
    *
    * Licensed under the Gnu General Pubic License, Version 2.0 (the
    * "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.opensource.org/licenses/gpl-license.php
    *
   * This program 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.
   */
  package org.figure8.join.services.remoting.xmlrpc;
  
  import org.figure8.join.core.setup.BootstrapUtil;
  import org.figure8.join.core.setup.BootstrapManager;
  import org.figure8.join.util.LogUtil;
  
  import org.apache.commons.logging.Log;
  import org.apache.xmlrpc.XmlRpcServer;
  import org.springframework.web.context.WebApplicationContext;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  /**
   * This is a servlet that initialized a <code>XmlRpcServer</code> if required conditions
   * are present. It retrieves the "xmlRpcHandler" component from a {@link WebApplicationContext}
   * as a handler for XmlRpcServer.
   * @author <a href="mailto:laurent.broudoux@free.fr">Laurent Broudoux</a>
   * @version $Revision: 1.1 $
   */
  public class XmlRpcServlet extends HttpServlet{
  
     // Static -------------------------------------------------------------------
  
     /** Get a commons logger. */
     private static final Log log = LogUtil.getLog(XmlRpcServlet.class);
  
     
     // Attributes ---------------------------------------------------------------
  
     /** The wrapped Xml-rpc server that processes request */
     private XmlRpcServer xmlrpc = null;
  
  
     // Override of HttpServlet --------------------------------------------------
  
     /**
      * Service a GET method Http call.
      * @param request The container Http request wrapper
      * @param response The container Http rseponse wrapper
      * @throws ServletException if iniatilization of Xml-Rpc service fails
      * @throws IOException if input or outputstream cannot be read/written/closed
      */
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException{
        // Do the same thing as post...
        doPost(request, response);
     }
  
     /**
      * Service a POST method Http call.
      * @param request The container Http request wrapper
      * @param response The container Http rseponse wrapper
      * @throws ServletException if iniatilization of Xml-Rpc service fails
      * @throws IOException if input or outputstream cannot be read/written/closed
      */
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException{
        
        // Initialize the XmlRpc server if necessary.
        if (xmlrpc == null){
           log.info("XmlRpc service is not yet initialized, launch initialization...");
           setupXmlRpcServer();  
           log.info("XmlRpc service is now initialized");
        }
        
        // Service the request after having traced its origin.
        if (log.isDebugEnabled())
           log.debug("Servicing a XmlRpc request coming from " + request.getRemoteAddr() + " on " + request.getRequestURI());
        
        try{
           serviceXmlRpcRequest(request, response);
        }
        catch (IOException ioe){
           // Just log to keep a trace before propagating.
           log.warn("IOException while servicing a XmlRpc request: " + ioe.getMessage());
           throw ioe;
        }
     }
  
 
    // Protected ----------------------------------------------------------------
    
    /**
     * Service the request using the XmlRpcServer.
     * @param request The container Http request wrapper
     * @param response The container Http rseponse wrapper
     * @throws IOException if input or outputstream cannot be read/written/closed
     */
    protected void serviceXmlRpcRequest(HttpServletRequest request, HttpServletResponse response)
          throws IOException{
       
       // Process request input stream by XmlRpc handler.
       InputStream is = request.getInputStream();
       byte result[] = xmlrpc.execute(is);
       is.close();
       
       // Write result on response output stream.
       response.setContentType("text/xml");
       response.setContentLength(result.length);
       OutputStream out = response.getOutputStream();
       out.write(result);
       out.flush();  
    }
    
    /**
     * Setup the Xml-Rpc server if application setup is complete
     * and we are on synchronous side of it.
     * @throws ServletException if conditions are not present or initialization of XmlRpc handler fails
     */
    protected void setupXmlRpcServer() throws ServletException{
       
       // First, ensure that setup is complete.
       BootstrapManager manager = BootstrapUtil.getBootstrapManager();
       if (!manager.isSetupComplete()){
          log.error("Application is not yet setup. Do not start XmlRpcServer");
          throw new ServletException("You must setup Join before using Xml-Rpc service");
       }
       // Then, ensure that we are on synchronous side of application.
       if (!manager.isSynchronousSide()){
          log.error("Not the synchronous side of application. Do not start XmlRpcServer");  
          throw new ServletException("You cannot use Xml-Rpc service on asynchronous side of Join");
       }
       
       // Finally, we can try rerieving an appropriate request handler.
       XmlRpcHandler handler = null;
       try{
          String wacAttributeName = getInitParameter("wacAttributeName");
          WebApplicationContext wac = (WebApplicationContext)getServletContext().getAttribute(wacAttributeName);
          handler = (XmlRpcHandler)wac.getBean("xmlRpcHandler");
       }
       catch (Exception e){
          // Log and propagate as a servlet exception.
          log.error("Exception when trying to retrieve xmlRpcHandler");
          log.error("Here's the details message: " + e.getMessage());
          throw new ServletException("Exception while initializing Join Xml-Rpc services");
       }
       // Start server and register.
       xmlrpc = new XmlRpcServer();
       xmlrpc.addHandler("join", handler);
    }
 }