source: trunk/gsdl3/src/java/org/greenstone/gsdl3/action/PageAction.java@ 4717

package org.greenstone.gsdl3.action;

import org.greenstone.gsdl3.core.ModuleInterface;
import org.greenstone.gsdl3.util.*;
// XML classes
import org.w3c.dom.Node; 
import org.w3c.dom.NodeList; 
import org.w3c.dom.Document; 
import org.w3c.dom.Element;

import java.util.HashMap;
import java.io.File;

public class PageAction extends Action {

    public static final String HOME_PAGE = "home";
    public static final String ABOUT_PAGE = "about";

    public Element process (Element message) {
    
    Element request = (Element) GSXML.getChildByTagName(message, GSXML.REQUEST_ELEM);
    // the page name is the subaction
    String page_name = request.getAttribute(GSXML.SUBACTION_ATT);
    if (page_name.equals("")) { // if no page specified, assume home page
        page_name = HOME_PAGE;
    }
    Element result = doc_.createElement(GSXML.MESSAGE_ELEM);
    Element response;
    if (page_name.equals(HOME_PAGE)) {
        response = homePage(request);
    } else if (page_name.equals(ABOUT_PAGE)) {
        response = aboutPage(request);
    } else { // unknown page
    
        System.err.println("PageAction Error: unknown page specified!");
        response =  unknownPage(request);
    }

    result.appendChild(doc_.importNode(response, true));
    return result;
    }


    protected Element homePage(Element request) {
    
    String lang = request.getAttribute(GSXML.LANG_ATT);
    
    // first, get the message router info
    Element coll_list_message = doc_.createElement(GSXML.MESSAGE_ELEM);
    Element coll_list_request = GSXML.createBasicRequest(doc_, GSXML.REQUEST_TYPE_DESCRIBE, "", lang);
    coll_list_message.appendChild(coll_list_request);
    Element coll_list_response = (Element)mr_.process(coll_list_message);
    if (coll_list_response==null) {
        System.err.println("PageAction Error: couldn't query the message router!");
        return null;
    }
    
    // second, get the metadata for each collection - we only want specific
    // elements but for now, we'll just get it all
    NodeList colls = coll_list_response.getElementsByTagName(GSXML.COLLECTION_ELEM);
    // we will send all the requests in a single message
    Element metadata_message = doc_.createElement(GSXML.MESSAGE_ELEM);
    for (int i=0; i<colls.getLength(); i++) {
        Element c = (Element)colls.item(i);
        String name = c.getAttribute(GSXML.NAME_ATT);       
        
        Element metadata_request = GSXML.createBasicRequest(doc_,  GSXML.REQUEST_TYPE_DESCRIBE, name, lang);
        metadata_message.appendChild(metadata_request);
    }

    Element metadata_response = (Element)mr_.process(metadata_message);

    NodeList coll_responses = metadata_response.getElementsByTagName(GSXML.RESPONSE_ELEM);
    // check that have same number of responses as collections
    if (colls.getLength() != coll_responses.getLength()) {
        System.err.println("PageAction Error: didn't get a response for each collection - somethings gone wrong!");
        // for now, dont use the metadata
    } else {
        for (int i=0; i<colls.getLength(); i++) {
        Element c1 = (Element)colls.item(i);
        Element c2 = (Element)coll_responses.item(i);
        if (c1.getAttribute(GSXML.NAME_ATT).equals(c2.getAttribute(GSXML.FROM_ATT))) {
            // add the metadata to the original response   
            GSXML.mergeMetadataLists(c1, GSXML.getChildByTagName(c2, GSXML.COLLECTION_ELEM));  
        } else {
            System.err.println("PageAction Error: response does not correspond to request!");
        } 
        
        }
    }

    //now the full response message is in coll_list_response
    // return the response element
    Element response = (Element) GSXML.getChildByTagName(coll_list_response, GSXML.RESPONSE_ELEM);
    return response;
    
    } // homePage

    protected Element aboutPage(Element request) {

    String lang = request.getAttribute(GSXML.LANG_ATT);
    // extract the params from the cgi-request, 
    Element cgi_paramList = (Element)GSXML.getChildByTagName(request, GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
    HashMap params = GSXML.extractParams(cgi_paramList, false);
    
    String coll_name = (String)params.get(GSCGI.COLLECTION_ARG);
    if (coll_name == null || coll_name.equals("")) {
        System.err.println("PageAction Error: about page requested with no collection or cluster specified!");
        // return an empty response
        return doc_.createElement(GSXML.RESPONSE_ELEM);
    }
    
    // get the collection or cluster description
    Element coll_about_message = doc_.createElement(GSXML.MESSAGE_ELEM);
    
    Element coll_about_request = GSXML.createBasicRequest(doc_, GSXML.REQUEST_TYPE_DESCRIBE,  coll_name, lang);
    coll_about_message.appendChild(coll_about_request);
    
    Element coll_about_response = (Element)mr_.process(coll_about_message);

    // get the response element and return it
    Element response = (Element) GSXML.getChildByTagName(coll_about_response, GSXML.RESPONSE_ELEM);
    return response;
    
    }

    /** if we dont know the page type, use this method */
    protected Element unknownPage(Element request) {
    
    String lang = request.getAttribute(GSXML.LANG_ATT);
    String page_name = request.getAttribute(GSXML.SUBACTION_ATT);

    // extract the params from the cgi-request, 
    Element cgi_paramList = (Element)GSXML.getChildByTagName(request, GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
    HashMap params = GSXML.extractParams(cgi_paramList, false);
    
    String coll_name = (String)params.get(GSCGI.COLLECTION_ARG);
    if (coll_name == null || coll_name.equals("")) {
        // just return an empty response
        return doc_.createElement(GSXML.RESPONSE_ELEM);
    }
    
    // else get the coll description - actually this is the same as for the about page - should we merge these two methods??
    
    // if there is a service specified should we get the service description instead??
    // get the collection or cluster description
    Element coll_about_message = doc_.createElement(GSXML.MESSAGE_ELEM);
    
    Element coll_about_request = GSXML.createBasicRequest(doc_, GSXML.REQUEST_TYPE_DESCRIBE,  coll_name, lang);
    coll_about_message.appendChild(coll_about_request);
    
    Element coll_about_response = (Element)mr_.process(coll_about_message);

    // add the response to the page get teh response element and return it
    Element response = (Element) GSXML.getChildByTagName(coll_about_response, GSXML.RESPONSE_ELEM);
    return response;
    
    }
}