source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/action/QueryAction.java@ 28854

package org.greenstone.gsdl3.action;

import java.io.Serializable;
import java.util.HashMap;
import java.util.HashSet;

import org.apache.log4j.Logger;
import org.greenstone.gsdl3.util.GSParams;
import org.greenstone.gsdl3.util.GSPath;
import org.greenstone.gsdl3.util.GSXML;
import org.greenstone.gsdl3.util.GSXSLT;
import org.greenstone.gsdl3.util.UserContext;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/** action class for queries */
public class QueryAction extends Action
{

    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.action.QueryAction.class.getName());

    /**
     * process - processes a request.
     */
    public Node process(Node message_node)
    {
        Element message = this.converter.nodeToElement(message_node);
        Document doc = message.getOwnerDocument();
        
        // get the request - assume there is only one
        Element request = (Element) GSXML.getChildByTagName(message, GSXML.REQUEST_ELEM);

        // create the return message
        Element result = doc.createElement(GSXML.MESSAGE_ELEM);
        Element response = basicQuery(request);
        result.appendChild(doc.importNode(response, true));
        return result;
    }

    /**
     * a generic query handler this gets the service description, does the query
     * (just passes all the params to the service, then gets the titles for any
     * results
     */
    protected Element basicQuery(Element request)
    {
        // the result
        Document doc = request.getOwnerDocument();
        Element page_response = doc.createElement(GSXML.RESPONSE_ELEM);

        // extract the params from the cgi-request, and check that we have a coll specified
        Element cgi_param_list = (Element) GSXML.getChildByTagName(request, GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
        HashMap<String, Serializable> params = GSXML.extractParams(cgi_param_list, false);

        String request_type = (String) params.get(GSParams.REQUEST_TYPE);
        String service_name = (String) params.get(GSParams.SERVICE);
        String collection = (String) params.get(GSParams.COLLECTION);

        // collection may be null or empty when we are doing cross coll services
        if (collection == null || collection.equals(""))
        {
            collection = null;
        }

        UserContext userContext = new UserContext(request);
        String to = service_name;
        if (collection != null)
        {
            to = GSPath.prependLink(to, collection);
        }

        // get the format info - there may be global format info in the collection that searching needs
        Element format_elem = getFormatInfo(to, userContext);
        // set the format type
        format_elem.setAttribute(GSXML.TYPE_ATT, "search");
        // for now just add to the response
        page_response.appendChild(doc.importNode(format_elem, true));

        if (request_type.indexOf("d") != -1)
        {
            // we have been asked for the service description
            Element mr_info_message = doc.createElement(GSXML.MESSAGE_ELEM);
            Element mr_info_request = GSXML.createBasicRequest(doc, GSXML.REQUEST_TYPE_DESCRIBE, to, userContext);
            mr_info_message.appendChild(mr_info_request);

            // process the message
            Element mr_info_response = (Element) this.mr.process(mr_info_message);
            // the response

            Element service_response = (Element) GSXML.getChildByTagName(mr_info_response, GSXML.RESPONSE_ELEM);

            Element service_description = (Element) doc.importNode(GSXML.getChildByTagName(service_response, GSXML.SERVICE_ELEM), true);
            page_response.appendChild(service_description);
        }

        if (request_type.indexOf("r") == -1)
        {
            // just a display request, no actual processing to do
            //append site metadata
            addSiteMetadata(page_response, userContext);
            addInterfaceOptions(page_response);
            return page_response;
        }

        // check that we have some service params
        HashMap service_params = (HashMap) params.get("s1");
        if (service_params == null)
        { // no query
            //append site metadata
            addSiteMetadata(page_response, userContext);
            addInterfaceOptions(page_response);
            return page_response;
        }

        // create the query request
        Element mr_query_message = doc.createElement(GSXML.MESSAGE_ELEM);
        Element mr_query_request = GSXML.createBasicRequest(doc, GSXML.REQUEST_TYPE_PROCESS, to, userContext);
        mr_query_message.appendChild(mr_query_request);

        Element query_param_list = doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
        GSXML.addParametersToList(doc, query_param_list, service_params);
        mr_query_request.appendChild(query_param_list);

        logger.debug(GSXML.xmlNodeToString(mr_query_message));

        // do the query
        Element mr_query_response = (Element) this.mr.process(mr_query_message);

        // check for errors
        if (processErrorElements(mr_query_response, page_response))
        {
            //append site metadata
            addSiteMetadata(page_response, userContext);
            addInterfaceOptions(page_response);
            return page_response;
        }

        Element query_response = (Element) GSXML.getChildByTagName(mr_query_response, GSXML.RESPONSE_ELEM);
        Element query_result_metadata_list = (Element) GSXML.getChildByTagName(query_response, GSXML.METADATA_ELEM + GSXML.LIST_MODIFIER);
        if (query_result_metadata_list == null)
        {
            logger.error("No query result metadata.\n");
        }
        else
        { // add it into the page response
            page_response.appendChild(doc.importNode(query_result_metadata_list, true));
        }

        Element query_term_info_list = (Element) GSXML.getChildByTagName(query_response, GSXML.TERM_ELEM + GSXML.LIST_MODIFIER);
        if (query_term_info_list == null)
        {
            logger.error("No query term information.\n");
        }
        else
        { // add it into the page response
            page_response.appendChild(doc.importNode(query_term_info_list, true));
        }

        Element facet_list = (Element) GSXML.getChildByTagName(query_response, GSXML.FACET_ELEM + GSXML.LIST_MODIFIER);
        if (facet_list == null)
        {
            logger.error("No query term information.\n");
        }
        else
        { // add it into the page response
            page_response.appendChild(doc.importNode(facet_list, true));
        }

        // check that there are some documents - for now check the list, but later should use a numdocs metadata elem   
        Element document_list = (Element) GSXML.getChildByTagName(query_response, GSXML.DOC_NODE_ELEM + GSXML.LIST_MODIFIER);
        // documentList not present if no docs found
        if (document_list == null)
        {
            // add in a dummy doc node list - used by the display. need to think about this
            page_response.appendChild(doc.createElement(GSXML.DOC_NODE_ELEM + GSXML.LIST_MODIFIER));
            //append site metadata
            addSiteMetadata(page_response, userContext);
            addInterfaceOptions(page_response);
            return page_response;
        }

        // now we check to see if there is metadata already - some search services return predefined metadata. if there is some, don't do a metadata request
        NodeList doc_metadata = document_list.getElementsByTagName(GSXML.METADATA_ELEM + GSXML.LIST_MODIFIER);
        if (doc_metadata.getLength() > 0)
        {
            logger.error("have already found metadata!");
            // append the doc list to the result
            page_response.appendChild(doc.importNode(document_list, true));
            //append site metadata
            addSiteMetadata(page_response, userContext);
            addInterfaceOptions(page_response);
            return page_response;
        }

        // get the metadata elements needed from the format statement if any
        HashSet<String> metadata_names = new HashSet<String>();
        metadata_names.add("Title");
        // we already got the format element earlier
        if (format_elem != null)
        {
          getRequiredMetadataNames(format_elem, metadata_names);
        }

        // paging of the results is done here - we filter the list to remove unwanted entries before retrieving metadata
        Element filtered_doc_list = filterDocList(doc, params, service_params, document_list);

        // do the metadata request on the filtered list
        Element mr_metadata_message = doc.createElement(GSXML.MESSAGE_ELEM);
        to = "DocumentMetadataRetrieve";
        if (collection != null)
        {
            to = GSPath.prependLink(to, collection);
        }
        Element mr_metadata_request = GSXML.createBasicRequest(doc, GSXML.REQUEST_TYPE_PROCESS, to, userContext);
        mr_metadata_message.appendChild(mr_metadata_request);

        // just get all for now - the receptionist should perhaps pass in some
        // metadata that it wants, and QueryAction should look through the format stuff to see if there is any other?

        Element extraMetaListElem = (Element) GSXML.getChildByTagName(request, GSXML.EXTRA_METADATA + GSXML.LIST_MODIFIER);
        if(extraMetaListElem != null)
        {
            NodeList extraMetaList = extraMetaListElem.getElementsByTagName(GSXML.EXTRA_METADATA);
            for(int i = 0; i < extraMetaList.getLength(); i++)
            {
                metadata_names.add(((Element)extraMetaList.item(i)).getAttribute(GSXML.NAME_ATT));
            }
        }

        Element dm_param_list = createMetadataParamList(doc,metadata_names);

        mr_metadata_request.appendChild(dm_param_list);

        // add in the doc node list too
        mr_metadata_request.appendChild(filtered_doc_list);

        Element mr_metadata_response = (Element) this.mr.process(mr_metadata_message);

        // check for errors
        processErrorElements(mr_metadata_response, page_response);

        Element metadata_response = (Element) GSXML.getChildByTagName(mr_metadata_response, GSXML.RESPONSE_ELEM);

        Element query_result_document_list = (Element) GSXML.getChildByTagName(metadata_response, GSXML.DOC_NODE_ELEM + GSXML.LIST_MODIFIER);

        if (query_result_document_list != null)
        {
            page_response.appendChild(doc.importNode(query_result_document_list, true));
        }

        logger.debug("Query page:\n" + this.converter.getPrettyString(page_response));
        //append site metadata
        addSiteMetadata(page_response, userContext);
        addInterfaceOptions(page_response);
        return page_response;
    }

    /** this filters out some of the doc results for result paging */
    protected Element filterDocList(Document doc, HashMap<String, Serializable> params, HashMap service_params, Element orig_doc_list)
    {

        // check the hits_per_page param - is it a service param??
        String hits_pp = (String) service_params.get("hitsPerPage");
        if (hits_pp == null)
        {
            // the service is doing the paging, so we want to display all of the returned docs(???)
            //    return (Element)doc.importNode(orig_doc_list, true);
            // try hitsPerPage in the globle param
            hits_pp = (String) params.get("hitsPerPage");
        }

        int hits = 20;
        if (hits_pp != null && !hits_pp.equals(""))
        {
            try
            {
                hits = Integer.parseInt(hits_pp);
            }
            catch (Exception e)
            {
                hits = 20;
            }
        }

        if (hits == -1)
        { // all
            return (Element) doc.importNode(orig_doc_list, true);
        }
        NodeList result_docs = orig_doc_list.getElementsByTagName(GSXML.DOC_NODE_ELEM);

        int num_docs = result_docs.getLength();
        if (num_docs <= hits)
        {
            // too few docs to do paging
            return (Element) doc.importNode(orig_doc_list, true);
        }

        // now we need our own doc list
        Element result_list = doc.createElement(GSXML.DOC_NODE_ELEM + GSXML.LIST_MODIFIER);

        String start_p = (String) service_params.get("startPage");
        if (start_p == null)
        {
            start_p = (String) params.get("startPage");
        }

        int start = 1;
        if (start_p != null && !start_p.equals(""))
        {
            try
            {
                start = Integer.parseInt(start_p);
            }
            catch (Exception e)
            {
                start = 1;
            }
        }

        int start_from = (start - 1) * hits;
        int end_at = (start * hits) - 1;

        if (start_from > num_docs)
        {
            // something has gone wrong
            return result_list;
        }

        if (end_at > num_docs)
        {
            end_at = num_docs - 1;
        }

        // now we finally have the docs numbers to use
        for (int i = start_from; i <= end_at; i++)
        {
            result_list.appendChild(doc.importNode(result_docs.item(i), true));
        }

        return result_list;
    }

}