source: trunk/gsdl3/src/java/org/greenstone/gsdl3/LibraryServlet.java@ 6301

package org.greenstone.gsdl3;

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.NodeList;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.Enumeration;
import java.util.HashMap;
import java.io.File;

/** 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
 * @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;
    /** 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 GSCGI cgi = null;
    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;

    
    /** 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 site_name = config.getInitParameter(GSConstants.SITE_NAME);
    String interface_name = config.getInitParameter(GSConstants.INTERFACE_NAME);
    this.default_lang = config.getInitParameter(GSConstants.DEFAULT_LANG);
    if (library_name == null || gsdl3_home == null || site_name ==null ||  interface_name ==null) {
        // must have this
        System.err.println("initialisation parameters not all set!");
        System.err.println(" you must have libraryname, gsdl3home, sitename,  interfacename");
        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.GSDL3_HOME, gsdl3_home);
    config_params.put(GSConstants.SITE_NAME, site_name);
    config_params.put(GSConstants.INTERFACE_NAME, interface_name);
    
    this.converter = new XMLConverter();
    this.doc = this.converter.newDOM();
    
    // now try and create MR and recpt
    // new message router - create it and pass reference to recept.
    // the servlet wont use this directly
    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.setSiteHome(GSFile.siteHome(gsdl3_home, 
                           site_name));
    message_router.configure();
    
    // 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);
    this.recept.setMessageRouter(message_router);
    // 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();
    
    }
    
    public void doGet(HttpServletRequest request,
              HttpServletResponse response)
    throws ServletException, IOException {
    
    HttpSession session = request.getSession(true);
    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
    }

    // 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);
    if (action==null || action.equals("")) {
        // should we do all the following stuff if using default page?
        // display the home page  - the default page
        action = "p";
        subaction = PageAction.HOME_PAGE;
        xml_request.setAttribute(GSXML.ACTION_ATT, action);
        xml_request.setAttribute(GSXML.SUBACTION_ATT, subaction);
        
    } 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)) {         
            session.setAttribute(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 in all the params from the session cache
        params = session.getAttributeNames();
        while(params.hasMoreElements()) {
        String name = (String)params.nextElement();
        
        if ( !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);
            param.setAttribute(GSXML.VALUE_ATT, GSXML.xmlSafe((String)session.getAttribute(name)));
            xml_param_list.appendChild(param);
        }
        }

    
    }
    
    if (!output.equals("html")) {
        response.setContentType("text/xml"); // for now use text
    }
    
    Element xml_result = this.recept.process(xml_message);
    encodeURLs(xml_result, response);
    out.println(this.converter.getPrettyString(xml_result));
    }

    /** this goes through each URL and adds in a session id if needed--
     * its needed if the browser doesn't accept cookies
     */
    protected void encodeURLs(Element data, HttpServletResponse response) {
    
    if (data == null) {
        return;
    }
    // get all the <a> elements
    NodeList hrefs = data.getElementsByTagName("a");
    for (int i=0; i<hrefs.getLength(); i++) {
        Element a = (Element)hrefs.item(i);
        a.setAttribute("href", response.encodeURL(a.getAttribute("href")));
    }
    
    // now find any submit bits - get all the <form> elements
    NodeList forms = data.getElementsByTagName("form");
    for (int i=0; i<forms.getLength(); 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;
    }

}