/*
    * Copyright 2000-2001,2004 The Apache Software Foundation.
    * 
    * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
    * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.jetspeed.portal.portlets;
  
  import org.apache.ecs.ConcreteElement;
  import org.apache.ecs.StringElement;
  import org.apache.jetspeed.portal.portlets.AbstractPortlet;
  import org.apache.turbine.util.RunData;
  
  import java.io.BufferedInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.InputStream;
  import java.net.URL;
  import java.net.URLConnection;
  
  
  /***  
   *   This portlet class is intended to be used for internal URLs that will 
   *   not work properly if they are part of the same request as the Jetspeed/Turbine
   *   controller servlet--Struts-mapped URLs are an example of these.
   *   <br>
   *   ServletProxyPortlet uses an application context-relative URL as an input parameter.  It uses data obtained from
   *   <code>org.apache.turbine.util.RunData</code> to construct an absolute URL and append the session id to it. Using this
   *   URL, it constructs a java.net.URL object, retrieves the content from it, and converts the content to a String.  Finally,
   *   it returns an ECS StringElement created with this String for Jetspeed to render as a portlet.  Content is returned as-is;
   *   no filtering is performed on the html before returning it.
   *   <br/><br/>
   *   This portlet accepts 3 parameters:<br/>
   *
   *   URL (required) 		  -- the web application-context relative URL (a query string may be used to pass parameters)<br/>
   *   session_token (optional) -- token key used by the web server to pass the session id on the query string<br/>
   *   protocol (optional)	  -- protocol to use to make the URL request
   *
   * @author <a href="mailto:joe.barefoot@motiva.com">Joe Barefoot</a>
   */
  
  
  public class ServletProxyPortlet extends AbstractPortlet
  {
      private final static int BUFFER_SIZE = 2048;
  
      /*** The name of the parameter to hold our application context-relative URL */
      public static final String URL_PARAMETER_NAME = "URL";
  	/*** The name of the parameter to hold the protocol to use (optional, default is http) **/
  	public static final String PROTOCOL_PARAMETER_NAME = "protocol";
  	/*** The name of the parameter to hold the token by which the session ID is passed on the query string (optional, default is jsessionid)
  	 *  This is included to accomodate all web servers, as the token is usually different from one server to another.
  	 */
  	public static final String SESSION_TOKEN_PARAMETER_NAME = "session_token";
  
  	/*** The default protocol used to construct the URL -- http */
  	public static final String DEFAULT_PROTOCOL = "http";
  	/*** The default token to use to pass the session ID on the query String -- jsessionid */
  	public static final String DEFAULT_SESSION_TOKEN = "jsessionid";
  
      /***  Gets content by proxy (java.net.URL) from an internal URL and returns it
  	 *
  	 * @param rundata The RunData object for the current request
  	 * @return an ECS StringElement
  	 */
      public ConcreteElement getContent(RunData rundata)
      {
          String servletURL = processURL(rundata);
  		if(servletURL == null)
  		{
  			return new StringElement("ServletInvokerPortlet:  Must specify a URL using the URL parameter");
  		}
          String content;
  
          //  This is probably not robust for large content returns, but should work okay within an application context with small amounts of content.
          try
          {
  
              URL url = new URL(servletURL);
              URLConnection connection = url.openConnection();
              InputStream stream = connection.getInputStream();
              BufferedInputStream in = new BufferedInputStream(stream);
              int length = 0;
              byte[] buf = new byte[BUFFER_SIZE];
              ByteArrayOutputStream out = new ByteArrayOutputStream();
              while ((in != null) && ((length = in.read(buf)) != -1))
              {
                  // the data has already been read into buf
                  out.write(buf, 0, length);
              }
              content = out.toString();
             return new StringElement(content);
         }
         catch (Exception e)
         {
             String message = "ServletInvokerPortlet: Error invoking " + servletURL + ": " + e.getMessage();
             return new StringElement(message);
         }
 
     }
 
 	/***  Constructs a full URL to retrieve content from.  Override to append custom (default) query parameters, etc.
 	 *
 	 * @param rundata The RunData object for the current request
 	 * @return  An absolute URL with the session ID appended
 	 */
     protected String processURL(RunData rundata)
     {
         String servletURL = getPortletConfig().getInitParameter(URL_PARAMETER_NAME);
 		if( servletURL == null) // short-circuit
 		{
 			return null;
 		}
 		String protocol = getPortletConfig().getInitParameter(PROTOCOL_PARAMETER_NAME);
 		if(protocol == null)
 		{
 			protocol = DEFAULT_PROTOCOL;
 		}
 		String token = getPortletConfig().getInitParameter(SESSION_TOKEN_PARAMETER_NAME);
 		if(token == null)
 		{
 			token = DEFAULT_SESSION_TOKEN;
 		}
 
 
         String queryString = new String();
         int queryIndex = servletURL.indexOf("?");
         if(queryIndex > 0)
         {
             queryString = servletURL.substring(queryIndex);
             servletURL = servletURL.substring(0, queryIndex);
         }
         servletURL = protocol + "://" + rundata.getServerName() + ":" + rundata.getServerPort() + rundata.getContextPath() + servletURL + ";" + token + "=" + rundata.getSession().getId() + queryString;
         return servletURL;
     }
 
 }