source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/LibraryServlet.java@ 23968

package org.greenstone.gsdl3;

import org.greenstone.gsdl3.comms.*;
import org.greenstone.gsdl3.core.*;
import org.greenstone.gsdl3.util.*;
import org.greenstone.gsdl3.action.PageAction; // used to get the default action
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.Enumeration;
import java.util.ArrayList;
import java.util.HashMap;
import java.io.File;
import java.util.Hashtable;
import org.apache.log4j.*;

// Apache Commons
import org.apache.commons.lang3.*;

/** a servlet to serve the greenstone library - we are using servlets instead
 * of cgi
 * the init method is called only once - the first time the servlet classes
 * are loaded. Each time a request comes in to the servlet, the session()
 * method is called in a new thread (calls doGet/doPut etc)
 * takes the a=p&p=home type args and builds a simple request to send to
 * its receptionist, which returns a result in html, cos output=html
 * is set in the request
 * 
 * 18/Jul/07 xiao
 * modify to make the cached parameters collection-specific.
 * Most of the work is done in doGet(), except adding an inner class UserSessionCache.
 * 
 * @see Receptionist
 */
public class LibraryServlet extends HttpServlet {
  
  /** the receptionist to send messages to */
  protected Receptionist recept=null;

  /** the default language - is specified by setting a servlet param,
   * otherwise DEFAULT_LANG is used*/
  protected String default_lang= null;
  
  /** Whether or not client-side XSLT support should be exposed */
  protected boolean supports_client_xslt = false;

  /** The default default - used if a default lang is not specified
   * in the servlet params */
  protected final String DEFAULT_LANG = "en";

  /** container Document to create XML Nodes */
  protected Document doc=null;

  /** a converter class to parse XML and create Docs */
  protected XMLConverter converter=null;

  /** the cgi stuff - the Receptionist can add new args to this
   *
   * its used by the servlet to determine what args to save */
  protected GSParams params = null;
  
  /** user id - new one per session. This doesn't work if session state is saved between restarts - this requires this value to be saved too. */
  protected int next_user_id = 0;

  /** a hash that contains all the active session IDs mapped to the cached items
   *  It is updated whenever the whole site or a particular collection is reconfigured
   *  using the command a=s&sa=c or a=s&sa=c&c=xxx
   *  It is in the form: sid -> (UserSessionCache object)
   */
  protected Hashtable session_ids_table = new Hashtable();
 
  /** the maximum interval that the cached info remains in session_ids_table (in seconds) 
   *  This is set in web.xml
   */
  protected int session_expiration = 1800;
  
  static Logger logger = Logger.getLogger(org.greenstone.gsdl3.LibraryServlet.class.getName());
  
  /** initialise the servlet
   */
  public void init(ServletConfig config) throws ServletException {
    // always call super.init;
    super.init(config);
    // disable preferences - does this work anyway??
    //System.setProperty("java.util.prefs.PreferencesFactory", "org.greenstone.gsdl3.util.DisabledPreferencesFactory");
    
    String library_name = config.getInitParameter(GSConstants.LIBRARY_NAME);
    String gsdl3_home = config.getInitParameter(GSConstants.GSDL3_HOME);
    String interface_name = config.getInitParameter(GSConstants.INTERFACE_NAME);
    
    String allowXslt = (String)config.getInitParameter(GSConstants.ALLOW_CLIENT_SIDE_XSLT);
    supports_client_xslt = allowXslt != null && allowXslt.equals("true");
    
    this.default_lang = config.getInitParameter(GSConstants.DEFAULT_LANG);
    String sess_expire = config.getInitParameter(GSXML.SESSION_EXPIRATION);
    
    if (sess_expire != null && !sess_expire.equals("")) {
      this.session_expiration = Integer.parseInt(sess_expire);
    }
    
    if (library_name == null || interface_name ==null) {
      // must have this
      System.err.println("initialisation parameters not all set!");
      System.err.println(" you must have libraryname and interfacename");
      System.exit(1);
    }
    
    String site_name = config.getInitParameter(GSConstants.SITE_NAME);
    String remote_site_name = null;
    String remote_site_type = null;
    String remote_site_address = null;
    
    if (site_name == null) {
      // no site, try for communicator
      remote_site_name = config.getInitParameter("remote_site_name");
      remote_site_type = config.getInitParameter("remote_site_type");
      remote_site_address = config.getInitParameter("remote_site_address");
      if (remote_site_name == null || remote_site_type == null || remote_site_address == null) {
        System.err.println("initialisation paramters not all set!");
        System.err.println("if site_name is not set, then you must have remote_site_name, remote_site_type and remote_site_address set");
        System.exit(1);
      }
    }
    
    if (this.default_lang == null) {
      // choose english
      this.default_lang = DEFAULT_LANG;
    }
    
    HashMap config_params = new HashMap();
    
    config_params.put(GSConstants.LIBRARY_NAME, library_name);
    config_params.put(GSConstants.INTERFACE_NAME, interface_name);  
    config_params.put(GSConstants.ALLOW_CLIENT_SIDE_XSLT, supports_client_xslt);
    
    if (site_name != null) {
      config_params.put(GSConstants.SITE_NAME, site_name);
    }
    this.converter = new XMLConverter();
    this.doc = this.converter.newDOM();
    
    // the receptionist -the servlet will talk to this
    String recept_name = (String)config.getInitParameter("receptionist_class");
    if (recept_name == null) {
      this.recept = new DefaultReceptionist();
    } else {
      try {
        this.recept = (Receptionist)Class.forName("org.greenstone.gsdl3.core."+recept_name).newInstance();
      } catch (Exception e) { // cant use this new one, so use normal one
        System.err.println("LibraryServlet configure exception when trying to use a new Receptionist "+recept_name+": "+e.getMessage());
        e.printStackTrace();
        this.recept = new DefaultReceptionist();
      }
    }
    this.recept.setConfigParams(config_params);
    
    // the receptionist uses a MessageRouter or Communicator to send its requests to. We either create a MessageRouter here for the designated site (if site_name set), or we create a Communicator for a remote site. The is given to teh Receptionist, and the servlet never talks to it again.directly.
    if (site_name != null) {
      String mr_name = (String)config.getInitParameter("messagerouter_class");
      MessageRouter message_router = null;
      if (mr_name == null) { // just use the normal MR
        message_router = new MessageRouter();
      } else { // try the specified one
        try {
          message_router = (MessageRouter)Class.forName("org.greenstone.gsdl3.core."+mr_name).newInstance();
        } catch (Exception e) { // cant use this new one, so use normal one
          System.err.println("LibraryServlet configure exception when trying to use a new MessageRouter "+mr_name+": "+e.getMessage());
          e.printStackTrace();
          message_router = new MessageRouter();
        }
      }
      
      message_router.setSiteName(site_name);
      message_router.setLibraryName(library_name);
      message_router.configure();
      this.recept.setMessageRouter(message_router);
    } else {
      // talking to a remote site, create a communicator
      Communicator communicator = null;
      // we need to create the XML to configure the communicator
      Element site_elem = this.doc.createElement(GSXML.SITE_ELEM);
      site_elem.setAttribute(GSXML.TYPE_ATT, remote_site_type);
      site_elem.setAttribute(GSXML.NAME_ATT, remote_site_name);
      site_elem.setAttribute(GSXML.ADDRESS_ATT, remote_site_address);
      
      if (remote_site_type.equals(GSXML.COMM_TYPE_SOAP_JAVA)) {
        communicator = new SOAPCommunicator();
      } else {
        System.err.println("LibraryServlet.init Error: invalid Communicator type: "+remote_site_type);
        System.exit(1);
      }
      
      if (!communicator.configure(site_elem)) {
        System.err.println("LibraryServlet.init Error: Couldn't configure communicator");
        System.exit(1);
      }
      this.recept.setMessageRouter(communicator);
    }
    
    // the params arg thingy
    
    String params_name = (String)config.getInitParameter("params_class");
    if (params_name == null) {
      this.params = new GSParams();
    } else {
      try {
        this.params = (GSParams)Class.forName("org.greenstone.gsdl3.util."+params_name).newInstance();
      } catch (Exception e) {
        System.err.println("LibraryServlet configure exception when trying to use a new params thing "+params_name+": "+e.getMessage());
        e.printStackTrace();
        this.params = new GSParams();
      }
    }
    // pass it to the receptionist
    this.recept.setParams(this.params);
    this.recept.configure();
    
  }
  
  
  private void logUsageInfo(HttpServletRequest request){
    String usageInfo = "";
    
    //session-info: get params stored in the session
    HttpSession session = request.getSession(true);
    Enumeration attributeNames = session.getAttributeNames();
    while(attributeNames.hasMoreElements()) {
      String name = (String)attributeNames.nextElement();
      usageInfo +=name+"="+session.getAttribute(name)+" ";
    }
    
    //logged info = general-info + session-info
    usageInfo =
      request.getServletPath()+" "+ //serlvet
      "["+request.getQueryString()+"]" +" "+ //the query string
      "["+usageInfo.trim()+"]" +" "+ // params stored in a session
      request.getRemoteAddr()+" "+   //remote address
      request.getRequestedSessionId()+" "+ //session id
      request.getHeader("user-agent")+" "; //the remote brower info
    
    logger.info(usageInfo);
    
  }
  
  public class UserSessionCache implements HttpSessionBindingListener {

    String session_id = "";
    
    /** a hash that maps the session ID to a hashtable that maps the coll_name to its parameters 
     *  coll_name -> Hashtable (param_name -> param_value)
     */
    protected Hashtable coll_name_params_table = null;
    
    public UserSessionCache(String id, Hashtable table) {
      session_id = id;      
      coll_name_params_table = (table == null)? new Hashtable() : table;      
    }

    protected void cleanupCache(String coll_name) {
      if (coll_name_params_table.containsKey(coll_name)) {
        coll_name_params_table.remove(coll_name);
      }
    }

    protected Hashtable getParamsTable() {
      return coll_name_params_table;
    }

    public void valueBound(HttpSessionBindingEvent event) {
      // Do nothing
    }

    public void valueUnbound(HttpSessionBindingEvent event) {
      if(session_ids_table.containsKey(session_id)) {
        session_ids_table.remove(session_id);
      }
    }

    public int tableSize() {
      return (coll_name_params_table == null)? 0 : coll_name_params_table.size();
    }

  }
  
  public void doGet (HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    logUsageInfo (request);

    String query_string = request.getQueryString();
    if (query_string!=null){
      String[] query_arr = StringUtils.split(query_string, "&");
      boolean redirect = false;
      String href = null;
      String rl = null;
      String[] nameval = new String[2]; // Reuse it for memory efficiency purposes  

      for (int i=0;i<query_arr.length;i++){

        if (query_arr[i].startsWith("el=")){
          if (query_arr[i].substring(query_arr[i].indexOf("=")+1,query_arr[i].length()).equals("direct")){
            redirect = true;
          }
        }else if(query_arr[i].startsWith("href=")){
          href = query_arr[i].substring(query_arr[i].indexOf("=")+1,query_arr[i].length());
          href = StringUtils.replace(href, "%2f", "/");
          href = StringUtils.replace(href, "%7e", "~");
          href = StringUtils.replace(href, "%3f", "?");
          href = StringUtils.replace(href, "%3A", "\\:");
        }else if(query_arr[i].startsWith("rl=")){
          rl = query_arr[i].substring(query_arr[i].indexOf("=")+1,query_arr[i].length());
        }
      }

      //if query_string contains "el=", the web page will be redirected to the external URl, otherwise a greenstone page with an external URL will be displayed
      //"rl=0" this is an external link
      //"rl=1" this is an internal link
      if ((redirect) && (href != null) && (rl.equals("0"))){// This is an external link, the web page is re-directed to the external URL (&el=&rl=0&href="http://...")
        response.setContentType("text/xml");
        response.sendRedirect(href);
      }
    }
    
    // Nested Diagnostic Configurator to identify the client for
    HttpSession session = request.getSession (true);
    session.setMaxInactiveInterval(session_expiration);
    String uid = (String)session.getAttribute (GSXML.USER_ID_ATT);
    if (uid ==null) {
      uid = ""+getNextUserId ();
      session.setAttribute (GSXML.USER_ID_ATT, uid);
    }
    request.setCharacterEncoding ("UTF-8");
    response.setContentType ("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter ();
    
    String lang = request.getParameter (GSParams.LANGUAGE);
    if (lang==null || lang.equals ("")) {
      // try the session cached lang
      lang = (String)session.getAttribute (GSParams.LANGUAGE);
      if (lang==null || lang.equals ("")) {
        // still not set, use the default
        lang = this.default_lang;
      }
    }
    
    // set the lang in the session
    session.setAttribute (GSParams.LANGUAGE, lang);
    
    String output = request.getParameter (GSParams.OUTPUT);
    if (output==null || output.equals ("")) {
      output = "html"; // uses html by default
    }
    
    // If server output, force a switch to traditional interface
    //output = (output.equals("server")) ? "html" : output;
    
    // Force change the output mode if client-side XSLT is supported - server vs. client
    // BUT only if the library allows client-side transforms    
    if(supports_client_xslt) {
        // MUST be done before the xml_message is built
        Cookie[] cookies = request.getCookies();
        Cookie xsltCookie = null;
        
        // The client has cookies enabled and a value set - use it!
        if(cookies != null) {
            for(Cookie c : cookies) {
                if(c.getName().equals("supportsXSLT")) {
                    xsltCookie = c;
                    break;
                }
            }
            output = (xsltCookie != null && xsltCookie.getValue().equals("true") && output.equals("html")) ? "xsltclient" : output;
        }
    }
    
    // the request to the receptionist
    Element xml_message = this.doc.createElement (GSXML.MESSAGE_ELEM);
    Element xml_request = GSXML.createBasicRequest (this.doc, GSXML.REQUEST_TYPE_PAGE, "", lang, uid);
    xml_request.setAttribute (GSXML.OUTPUT_ATT, output);
    
    xml_message.appendChild (xml_request);
    
    String action = request.getParameter (GSParams.ACTION);
    String subaction = request.getParameter (GSParams.SUBACTION);
    String collection = request.getParameter(GSParams.COLLECTION);
    String service = request.getParameter(GSParams.SERVICE);

    // We clean up the cache session_ids_table if system
    // commands are issued (and also don't need to do caching for this request)
    boolean should_cache = true;
    if(action != null && action.equals(GSParams.SYSTEM)) {
      should_cache = false;

      // we may want to remove all collection cache info, or just a specific collection
      boolean clean_all = true; 
      String clean_collection = null;
      // system commands are to activate/deactivate stuff
      // collection param is in the sc parameter.
      // don't like the fact that it is hard coded here
      String coll = request.getParameter(GSParams.SYSTEM_CLUSTER);
      if (coll != null && !coll.equals("")) {
        clean_all = false;
        clean_collection = coll;
      } else {
        // check other system types
        if (subaction.equals("a") || subaction.equals("d")) {
          String module_name = request.getParameter("sn");
          if (module_name != null && !module_name.equals("")) {
            clean_all = false;
            clean_collection = module_name;
          }
        }
      }
      if (clean_all) {
        session_ids_table = new Hashtable(); 
        session.removeAttribute(GSXML.USER_SESSION_CACHE_ATT);
      } else {
        // just clean up info for clean_collection
        ArrayList cache_list = new ArrayList(session_ids_table.values());
        for (int i=0; i<cache_list.size(); i++) {
          UserSessionCache cache = (UserSessionCache)cache_list.get(i);
          cache.cleanupCache(clean_collection);
        }
    
      }

    }
    
    // cache_key is the collection name, or service name
    String cache_key = collection;
    if (cache_key == null || cache_key.equals("")) {
      cache_key = service;
    }
    
    // logger.info("should_cache= " + should_cache);

    //clear the collection-specific cache in the session, since we have no way to know whether this session is 
    //about the same collection as the last session or not.
    Enumeration attributeNames = session.getAttributeNames();
    while(attributeNames.hasMoreElements()) {
      String name = (String)attributeNames.nextElement();
      if (!name.equals (GSXML.USER_SESSION_CACHE_ATT)
        && !name.equals (GSParams.LANGUAGE) 
        && !name.equals (GSXML.USER_ID_ATT)) {

        session.removeAttribute(name);
      }
    }
       
    UserSessionCache session_cache = null;
    Hashtable param_table = null;    
    Hashtable table = null;
    String sid = session.getId();
    if (should_cache == true && cache_key != null && !cache_key.equals("")) {
      if (session_ids_table.containsKey(sid)) {
        session_cache = (UserSessionCache)session_ids_table.get(sid);
        param_table = session_cache.getParamsTable();
        logger.info("collections in table: " + tableToString(param_table));
        if (param_table.containsKey(cache_key)) {
          //logger.info("existing table: " + collection);
          table = (Hashtable)param_table.get(cache_key);
        } else {
          table = new Hashtable();
          param_table.put(cache_key, table);
          //logger.info("new table: " + collection);
        }
      } else {
        param_table = new Hashtable();
        table = new Hashtable();
        param_table.put(cache_key, table);
        session_cache = new UserSessionCache(sid, param_table);
        session_ids_table.put(sid, session_cache);
        session.setAttribute(GSXML.USER_SESSION_CACHE_ATT, session_cache);
        //logger.info("new session id");
      }
    }

    if (action==null || action.equals ("")) {
      // should we do all the following stuff if using default page?
      // display the home page  - the default page
      xml_request.setAttribute (GSXML.ACTION_ATT, "p");
      xml_request.setAttribute (GSXML.SUBACTION_ATT, PageAction.HOME_PAGE);
    }
    else {
      xml_request.setAttribute (GSXML.ACTION_ATT, action);
      if (subaction != null) {
        xml_request.setAttribute (GSXML.SUBACTION_ATT, subaction);
      }
      
      //  create the param list for the greenstone request - includes
      // the params from the current request and any others from the saved session
      Element xml_param_list = this.doc.createElement (GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
      xml_request.appendChild (xml_param_list);
      
      Enumeration params = request.getParameterNames ();
      while(params.hasMoreElements ()) {
        String name = (String)params.nextElement ();
        if (!name.equals (GSParams.ACTION) 
          && !name.equals (GSParams.SUBACTION) 
          && !name.equals (GSParams.LANGUAGE) 
          && !name.equals (GSParams.OUTPUT)) {// we have already dealt with these
          
          String value="";
          String [] values = request.getParameterValues (name);
          value = values[0];
          if (values.length > 1) {
            for (int i=1; i< values.length; i++) {
              value += ","+values[i];
            }
          }
          // either add it to the param list straight away, or save it to the session and add it later
          if (this.params.shouldSave (name) && table != null) {
            table.put(name, value);
          } else {
            Element param = this.doc.createElement (GSXML.PARAM_ELEM);
            param.setAttribute (GSXML.NAME_ATT, name);
            param.setAttribute (GSXML.VALUE_ATT, GSXML.xmlSafe (value));
            xml_param_list.appendChild (param);
          }
        }
      }
      //put everything in the table into the session
      // do we need to do this? why not just put from table into param list
      if (table != null) {
        Enumeration keys = table.keys ();
        while(keys.hasMoreElements ()) {
          String name = (String)keys.nextElement();
          session.setAttribute(name, (String)table.get(name));
        }
      }
      
      // put in all the params from the session cache
      params = session.getAttributeNames ();
      while(params.hasMoreElements ()) {
        String name = (String)params.nextElement ();
        
        if ( !name.equals (GSXML.USER_SESSION_CACHE_ATT) 
          && !name.equals (GSParams.LANGUAGE) 
          && !name.equals (GSXML.USER_ID_ATT)) { 

          // lang and uid are stored but we dont want it in the param list cos its already in the request
          Element param = this.doc.createElement (GSXML.PARAM_ELEM);
          param.setAttribute (GSXML.NAME_ATT, name);
          String value =  GSXML.xmlSafe ((String)session.getAttribute (name));

          // ugly hack to undo : escaping
          value = StringUtils.replace(value, "%3A", "\\:");
          param.setAttribute (GSXML.VALUE_ATT,value);
          xml_param_list.appendChild (param);
        }
      }
    }
      
    if (!output.equals("html") && !output.equals("server") && !output.equals("xsltclient")) {
      response.setContentType ("text/xml"); // for now use text
    }
    
    //GSXML.printXMLNode(xml_message);
    
    Node xml_result = this.recept.process(xml_message);
    encodeURLs (xml_result, response);
    out.println (this.converter.getPrettyString (xml_result));
    
    displaySize(session_ids_table);

  } //end of doGet(HttpServletRequest, HttpServletResponse)

  //a debugging method
  private void displaySize(Hashtable table) {
    if(table == null) {
      logger.info("cached table is null");
      return;
    }
    if (table.size() == 0) {
      logger.info("cached table size is zero");
      return;
    }
    int num_cached_coll = 0;
    ArrayList cache_list = new ArrayList(table.values());
    for (int i=0; i<cache_list.size(); i++) {
      num_cached_coll += ((UserSessionCache)cache_list.get(i)).tableSize();
    }
    logger.info("Number of sessions : total number of cached collection info = " + table.size() + " : " + num_cached_coll);
  }

  /** merely a debugging method! */
  private String tableToString(Hashtable table) {
    String str = "";
    Enumeration keys = table.keys ();
    while(keys.hasMoreElements ()) {
      String name = (String)keys.nextElement();
      str += name + ", ";
    }
    return str;
  }

  /** this goes through each URL and adds in a session id if needed--
   * its needed if the browser doesn't accept cookies
   * also escapes things if needed
   */
  protected void encodeURLs(Node dataNode, HttpServletResponse response) {
    
    if (dataNode == null) {
      return;
    }

    Element data =null;

    short nodeType = dataNode.getNodeType();
    if (nodeType == Node.DOCUMENT_NODE) {
      Document docNode = (Document)dataNode;
      data = docNode.getDocumentElement() ;
    }
    else {
      data = (Element)dataNode;
    }

    if ( data != null ) {

        // get all the <a> elements
        NodeList hrefs = data.getElementsByTagName("a");
        // Instead of calculating each iteration...
        int hrefscount = hrefs.getLength();

        for (int i=0; hrefs!=null && i < hrefscount; i++) {
          Element a = (Element)hrefs.item(i);
          // ugly hack to get rid of : in the args - interferes with session handling
          String href = a.getAttribute("href");
          if (!href.equals("")) {
            if (href.indexOf("?")!=-1) {
              String[] parts = StringUtils.split(href, "\\?", -1);
              if (parts.length == 1)
              {
                parts[0] = StringUtils.replace(parts[0], ":", "%3A");
                href = "?"+parts[0];
              }
              else
              {
                parts[1] = StringUtils.replace(parts[1], ":", "%3A");
                href = parts[0]+"?"+parts[1];
              }
              
            }
            a.setAttribute("href", response.encodeURL(href));
          }
        }
        
        // now find any submit bits - get all the <form> elements
        NodeList forms = data.getElementsByTagName("form");
        int formscount = forms.getLength();
        for (int i=0; forms!=null && i < formscount; i++) {
          Element form = (Element)forms.item(i);
          form.setAttribute("action", response.encodeURL(form.getAttribute("action")));
        }
        // are these the only cases where URLs occur??
        // we should only do this for greenstone urls?
    }
    
  }
  
  synchronized protected int getNextUserId() {
    next_user_id++;
    return next_user_id;
  }
  
  public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {

    doGet(request,response);
    
  }

}