/*
 *    AbstractMGPPSearch.java
 *    Copyright (C) 2005 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.greenstone.gsdl3.service;

// greenstone classes
import org.greenstone.mgpp.*;
import org.greenstone.gsdl3.util.GSXML;
import org.greenstone.gsdl3.util.GSFile;

// XML classes
import org.w3c.dom.Document;
import org.w3c.dom.Element; 
import org.w3c.dom.NodeList;

// java classes
import java.util.Iterator;
import java.util.Set;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.Vector;
import java.io.File;


/** Partially implements a generic MGPP search service
 *
 * @author <a href="mailto:kjdon@cs.waikato.ac.nz">Katherine Don</a>
 */

abstract public class AbstractMGPPSearch
    extends AbstractSearch
{

    // extra services offered by mgpp collections
    private static final String FIELD_QUERY_SERVICE = "FieldQuery";
    private static final String ADVANCED_FIELD_QUERY_SERVICE = "AdvancedFieldQuery";

    // extra parameters used
    // private static final String INDEX_FIELD_PARAM = "index";
    private static final String LEVEL_PARAM = "level";
    private static final String RANK_PARAM = "sortBy";
    private static final String RANK_PARAM_RANK = "1";
    private static final String RANK_PARAM_NONE = "0";
    private static final String SIMPLE_FIELD_PARAM = "simpleField";
    private static final String ADVANCED_FIELD_PARAM = "complexField";

    // more params for field query
    private static final String FIELD_QUERY_PARAM = "fqv";
    private static final String FIELD_STEM_PARAM = "fqs";
    private static final String FIELD_CASE_PARAM = "fqc";
    private static final String FIELD_FIELD_PARAM = "fqf";
    private static final String FIELD_COMBINE_PARAM = "fqk";
    private static final String FIELD_COMBINE_PARAM_AND = "0";
    private static final String FIELD_COMBINE_PARAM_OR = "1";
    private static final String FIELD_COMBINE_PARAM_NOT = "2";

    // some stuff for config files
    private static final String SEARCH_TYPE_ELEM = "searchType";
    private static final String SEARCH_TYPE_PLAIN = "plain";
    private static final String SEARCH_TYPE_FORM = "form";
    private static final String SEARCH_TYPE_FORM_SIMPLE = "simple";
    private static final String SEARCH_TYPE_FORM_ADVANCED = "advanced";
    protected static final String DEFAULT_INDEX_ELEM = "defaultIndex";
    protected static final String DEFAULT_LEVEL_ELEM = "defaultLevel";
    protected static final String LEVEL_ELEM = "level";

    protected static final String EQUIV_TERM_ELEM = "equivTerm";

    protected static final String STEM_ATT = "stem";
    protected static final String NUM_DOCS_MATCH_ATT = "numDocsMatch";
    protected static final String FREQ_ATT = "freq";

    private static final int TEXT_QUERY = 0;
    private static final int SIMPLE_QUERY = 1;
    private static final int ADVANCED_QUERY = 2;

    protected static final String INDEX_STEM_ELEM = "indexStem";
    protected static final String FIELD_ATT = "field";
    private MGPPWrapper mgpp_src=null;

     /** the default index */
    protected String default_index = null;
   // the default level for retrieval - and we'll use it for searching too
    private String default_level=null;
    // the default field for searching
    private String default_field = null;
    // which search services will we offer??
    private boolean plain_search = false;
    private boolean simple_form_search = false;
    private boolean advanced_form_search = false;

    /** the stem used for the index files */
    protected String index_stem = null;

    public AbstractMGPPSearch()
    {
	this.mgpp_src = new MGPPWrapper();
    }

    public boolean configure(Element info, Element extra_info)
    {
	// Do generic configuration
	if (super.configure(info, extra_info) == false)
	    return false;
	
	// Do specific configuration
	System.out.println("Configuring AbstractMGPPSearch...");

	// do we support any of the extended features?
	does_chunking = true;
	// Get the default index out of <defaultIndex> (buildConfig.xml)
	Element def = (Element) GSXML.getChildByTagName(info, DEFAULT_INDEX_ELEM);
	if (def != null) {
	    this.default_index = def.getAttribute(GSXML.NAME_ATT);
	}
	if (this.default_index == null || this.default_index.equals("")) {
	    System.err.println("Error: default index not specified!");
	    return false;
	}
	// the index stem is either specified in the config file or is "index"
	Element index_stem_elem = (Element) GSXML.getChildByTagName(info, INDEX_STEM_ELEM);
	if (index_stem_elem != null) {
	    this.index_stem = index_stem_elem.getAttribute(GSXML.NAME_ATT);
	}
	if (this.index_stem == null || this.index_stem.equals("")) {
	    System.err.println("AbstractMGPPSearch.configure(): indexStem element not found, stem will default to collection name");
	    this.index_stem = this.cluster_name;
	}

		// the generic config has set up the text query service, but we may not want it
	Element search_type_list = (Element) GSXML.getChildByTagName(info, SEARCH_TYPE_ELEM + GSXML.LIST_MODIFIER);
	if (search_type_list == null) {
	    // assume form and plain
	    this.plain_search = true;
	    this.simple_form_search = true;
	    this.advanced_form_search = true;
	} else {
	    NodeList types = search_type_list.getElementsByTagName(SEARCH_TYPE_ELEM);
	    for (int i=0; i<types.getLength(); i++) {
		Element t = (Element)types.item(i);
		String type_name = t.getAttribute(GSXML.NAME_ATT);
		if (type_name.equals(SEARCH_TYPE_PLAIN)) {
		    this.plain_search = true;
		} else if (type_name.equals(SEARCH_TYPE_FORM)) {
		    String type_type = t.getAttribute(GSXML.TYPE_ATT);
		    if (type_type.equals("")) {
			this.simple_form_search = true;
			this.advanced_form_search = true;
		    } else if (type_type.equals(SEARCH_TYPE_FORM_SIMPLE)) {
			this.simple_form_search = true;
		    } else if (type_type.equals(SEARCH_TYPE_FORM_ADVANCED)) {
			this.advanced_form_search = true;
			
		    }
		}
	    }
	}

	if (!this.plain_search) {
	    // need to remove the TextQuery service
	    Element tq_service = GSXML.getNamedElement(short_service_info, GSXML.SERVICE_ELEM, GSXML.NAME_ATT, TEXT_QUERY_SERVICE);
	    short_service_info.removeChild(tq_service);
	    
	}

       
	// Get the default level out of <defaultLevel> (buildConfig.xml)
	def = (Element) GSXML.getChildByTagName(info, DEFAULT_LEVEL_ELEM);
	if (def != null) {
	    this.default_level = def.getAttribute(GSXML.NAME_ATT);
	}
	if (this.default_level == null || this.default_level.equals("")) {
	    System.err.println("Error: default level not specified!");
	    return false;
	}

	// the default level is also the level which gdbm is expecting
	// this must not be overwritten
	this.mgpp_src.setReturnLevel(this.default_level);
	// return term info
	this.mgpp_src.setReturnTerms(true);
	// set the default - this may be overwritten by query params
	this.mgpp_src.setQueryLevel(this.default_level);

	// set up the extra services which are available for this collection
	// check the config info - if there is no field list, then there is no fielded searching
	
	Element field_list = (Element) GSXML.getChildByTagName(info, GSXML.FIELD_ELEM+GSXML.LIST_MODIFIER);
	if (field_list==null) {
	    // nothing more to do
	    return true;
	}

	// the format info is the same for all services
	Element format_info = (Element)format_info_map.get(TEXT_QUERY_SERVICE);

	// find the default field - use the first one
	Element first_field = (Element)GSXML.getChildByTagName(field_list, GSXML.FIELD_ELEM);
	default_field = first_field.getAttribute(GSXML.SHORTNAME_ATT);
	// else set up the fielded query services
	
	if (this.simple_form_search) {
	    // set up short_service_info_ - for now just has id and type - name will be added in on teh fly
	    Element fq_service = this.doc.createElement(GSXML.SERVICE_ELEM);
	    fq_service.setAttribute(GSXML.TYPE_ATT, GSXML.SERVICE_TYPE_QUERY);
	    fq_service.setAttribute(GSXML.NAME_ATT, FIELD_QUERY_SERVICE);
	    this.short_service_info.appendChild(fq_service);

	    if (format_info != null) {
		this.format_info_map.put(FIELD_QUERY_SERVICE, format_info);
	    }
	}
	
	if (this.advanced_form_search) {
	    Element afq_service = this.doc.createElement(GSXML.SERVICE_ELEM);
	    afq_service.setAttribute(GSXML.TYPE_ATT, GSXML.SERVICE_TYPE_QUERY);
	    afq_service.setAttribute(GSXML.NAME_ATT, ADVANCED_FIELD_QUERY_SERVICE);
	    this.short_service_info.appendChild(afq_service);
	    
	    if (format_info != null) {
		this.format_info_map.put(ADVANCED_FIELD_QUERY_SERVICE, format_info);
	    }
	}
	return true;

    }
    protected Element getServiceDescription(String service_id, String lang, String subset) {
	// should we check that the service is actually on offer? presumably we wont get asked for services that we haven't advertised previously.
	
	if (!service_id.equals(FIELD_QUERY_SERVICE) && !service_id.equals(ADVANCED_FIELD_QUERY_SERVICE)) {
	    return super.getServiceDescription(service_id, lang, subset);
	}
	
	
	Element service = this.doc.createElement(GSXML.SERVICE_ELEM);
	service.setAttribute(GSXML.TYPE_ATT, GSXML.SERVICE_TYPE_QUERY);
	service.setAttribute(GSXML.NAME_ATT, service_id);
	if (subset == null || subset.equals(GSXML.DISPLAY_TEXT_ELEM+GSXML.LIST_MODIFIER)) {
	    service.appendChild(GSXML.createDisplayTextElement(this.doc, GSXML.DISPLAY_TEXT_NAME, getTextString(service_id+".name", lang)));
	    service.appendChild(GSXML.createDisplayTextElement(this.doc, GSXML.DISPLAY_TEXT_SUBMIT, getTextString(service_id+".submit", lang)));
	    service.appendChild(GSXML.createDisplayTextElement(this.doc, GSXML.DISPLAY_TEXT_DESCRIPTION, getTextString(service_id+".description", lang)));
	
	}
	if (subset == null || subset.equals(GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER)) {
	    Element param_list = this.doc.createElement(GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);	
	    service.appendChild(param_list);
	    if (service_id.equals(FIELD_QUERY_SERVICE)) {
		
		addCustomQueryParams(param_list, lang);
		createParameter(MAXDOCS_PARAM, param_list, lang);
		// create a multi param for the fields etc
		// text box, field
		Element multiparam = null;
		Element param=null;
		multiparam = GSXML.createParameterDescription(this.doc, SIMPLE_FIELD_PARAM, "", GSXML.PARAM_TYPE_MULTI, null, null, null);
		multiparam.setAttribute("occurs", "4");
		param_list.appendChild(multiparam);
		
		// the components
		createParameter(FIELD_QUERY_PARAM, multiparam,  lang);
		createParameter(FIELD_FIELD_PARAM, multiparam,  lang);
		
	    } else { 
		createParameter(LEVEL_PARAM, param_list,  lang);
		createParameter(RANK_PARAM, param_list, lang);
		createParameter(MAXDOCS_PARAM, param_list,  lang);
		
		
		// create a multi param for the fields etc
		// text box, stem, case, field
		
		Element multiparam = null;
		Element param=null;
		
		multiparam = GSXML.createParameterDescription(this.doc, ADVANCED_FIELD_PARAM, "", GSXML.PARAM_TYPE_MULTI, null, null, null);
		multiparam.setAttribute("occurs", "4");
		param_list.appendChild(multiparam);
		
		createParameter(FIELD_COMBINE_PARAM, multiparam,  lang);
		createParameter(FIELD_QUERY_PARAM, multiparam,  lang);
		createParameter(FIELD_CASE_PARAM, multiparam,  lang);
		createParameter(FIELD_STEM_PARAM, multiparam,  lang);
		createParameter(FIELD_FIELD_PARAM, multiparam,  lang);    
		
	    } 
	}
	return service;
	
    }

    /** add in the mgpp specific params to TextQuery */
    protected void addCustomQueryParams(Element param_list, String lang) 
    {
	createParameter(LEVEL_PARAM, param_list, lang);
	createParameter(CASE_PARAM, param_list, lang);
	createParameter(STEM_PARAM, param_list, lang);
	createParameter(MATCH_PARAM, param_list, lang);
	createParameter(RANK_PARAM, param_list, lang);

    }

    /** create a param and add to the list */
    protected void createParameter(String name, Element param_list, String lang) 
    {
	Element param = null;
	if (name.equals(LEVEL_PARAM)) {
	    ArrayList level_ids = new ArrayList();
	    ArrayList level_names = new ArrayList();
	    getLevelData(level_ids, level_names, lang);
	    if (level_ids.size()>1) {
		// the first one is the default
		param = GSXML.createParameterDescription2(this.doc, LEVEL_PARAM, getTextString("param."+LEVEL_PARAM, lang), GSXML.PARAM_TYPE_ENUM_SINGLE, (String)level_ids.get(0), level_ids, level_names);
	    }
	    
	} else if (name.equals(RANK_PARAM)) {
	    String [] vals1 = {RANK_PARAM_RANK, RANK_PARAM_NONE };
	    String [] vals1_texts = { getTextString("param."+RANK_PARAM+"."+RANK_PARAM_RANK, lang), getTextString("param."+RANK_PARAM+"."+RANK_PARAM_NONE, lang, "MGPPSearch")};
	    
	    param = GSXML.createParameterDescription(this.doc, RANK_PARAM, getTextString("param."+RANK_PARAM, lang), GSXML.PARAM_TYPE_ENUM_SINGLE, RANK_PARAM_RANK, vals1, vals1_texts );
	    
	} else if (name.equals(FIELD_QUERY_PARAM)) {
	    param = GSXML.createParameterDescription(this.doc, FIELD_QUERY_PARAM, getTextString("param."+FIELD_QUERY_PARAM, lang), GSXML.PARAM_TYPE_STRING, null, null, null);
	    
	    
	} else if (name.equals(FIELD_CASE_PARAM) || name.equals(FIELD_STEM_PARAM)) {
	    String[] bool_ops = {"0", "1"};
	    String[] bool_texts = {getTextString("param.boolean.off", lang, "AbstractSearch"),getTextString("param.boolean.on", lang, "AbstractSearch")}; 
	    param = GSXML.createParameterDescription(this.doc, name, getTextString("param."+name, lang), GSXML.PARAM_TYPE_BOOLEAN, BOOLEAN_PARAM_ON, bool_ops, bool_texts);
	    
	} else if (name.equals(FIELD_FIELD_PARAM)) {
	    ArrayList fields = new ArrayList();
	    ArrayList field_names = new ArrayList();
	    getIndexData(fields, field_names, lang);
	    // the field list -  read from config file
	    param = GSXML.createParameterDescription2(this.doc, name, getTextString("param."+name, lang), GSXML.PARAM_TYPE_ENUM_SINGLE, (String)fields.get(0), fields, field_names );
	    
	} else if (name.equals(FIELD_COMBINE_PARAM)) {
	    
	    String []vals = {FIELD_COMBINE_PARAM_AND, FIELD_COMBINE_PARAM_OR, FIELD_COMBINE_PARAM_NOT};
	    String []val_texts = {getTextString("param."+FIELD_COMBINE_PARAM+"."+FIELD_COMBINE_PARAM_AND, lang), getTextString("param."+FIELD_COMBINE_PARAM+"."+FIELD_COMBINE_PARAM_OR, lang), getTextString("param."+FIELD_COMBINE_PARAM+"."+FIELD_COMBINE_PARAM_NOT, lang)}; 
		
	    
	    param = GSXML.createParameterDescription(this.doc, FIELD_COMBINE_PARAM, "", GSXML.PARAM_TYPE_ENUM_SINGLE, FIELD_COMBINE_PARAM_AND, vals, val_texts);
	    param.setAttribute(GSXML.PARAM_IGNORE_POS_ATT, "0");
	}

	if (param != null) {
	    param_list.appendChild(param);
	} else {
	    super.createParameter(name, param_list, lang);
	}
    }
    
    // should cache some of this
    protected void getLevelData(ArrayList level_ids, ArrayList level_names, String lang) 
    {
	Element level_list = (Element)GSXML.getChildByTagName(this.config_info, LEVEL_ELEM+GSXML.LIST_MODIFIER);
	NodeList levels = level_list.getElementsByTagName(LEVEL_ELEM);
	for (int i=0; i<levels.getLength(); i++) {
	    level_ids.add(((Element)levels.item(i)).getAttribute(GSXML.NAME_ATT));
	    level_names.add(getTextString("level."+level_ids.get(i), lang));
	}
	
    }
    protected void getIndexData(ArrayList index_ids, ArrayList index_names, String lang){
	// we currently only have one index, and use the field data as the index
		    
	// the field list -  read from config file
	Element field_list = (Element)GSXML.getChildByTagName(this.config_info, GSXML.FIELD_ELEM+GSXML.LIST_MODIFIER);
	NodeList fields = field_list.getElementsByTagName(GSXML.FIELD_ELEM);
	for (int i=0; i< fields.getLength();i++) {
	    index_ids.add(((Element)fields.item(i)).getAttribute(GSXML.SHORTNAME_ATT));
	    // should these be changed to a text element based on lang?
	    // or is the name of a metadata element eg dc:Title its 
	    // name in all langs
	    index_names.add(((Element)fields.item(i)).getAttribute(GSXML.NAME_ATT));
	    
	}
    }

    // the following three functions are needed so the base class can 
    // call the process+SERVICE_NAME methods
    /** process a text query */
    protected Element processTextQuery(Element request) {
	return processAnyQuery(request, TEXT_QUERY);
    }

    /** process a field query */    
    protected Element processFieldQuery(Element request) {
	return processAnyQuery(request, SIMPLE_QUERY);
    }

    /** process an advanced field query */
    protected Element processAdvancedFieldQuery(Element request) {
	return processAnyQuery(request, ADVANCED_QUERY);
    }
    
    /** process a  query */
    protected Element processAnyQuery(Element request, int query_type)
    {

	String service_name=null;
	String empty_query_test_param=null;
	// set up the type specific bits
	switch (query_type) {
	case TEXT_QUERY:
	    service_name = TEXT_QUERY_SERVICE; 
	    empty_query_test_param = QUERY_PARAM;
	    break;
	case SIMPLE_QUERY:
	    service_name = FIELD_QUERY_SERVICE;
	    empty_query_test_param = FIELD_QUERY_PARAM;
	    break;
	case ADVANCED_QUERY:
	    service_name = ADVANCED_FIELD_QUERY_SERVICE;
	    empty_query_test_param = FIELD_QUERY_PARAM;
	    break;
	default:
	    // should never get here
	    System.err.println("AbstractMGPPSearch: wrong query type!!");
	    return null;
	}
	
	// Create a new (empty) result message
	Element result = this.doc.createElement(GSXML.RESPONSE_ELEM);
	result.setAttribute(GSXML.FROM_ATT, service_name);
	result.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_PROCESS);
	
	// Get the parameters of the request
	Element param_list = (Element) GSXML.getChildByTagName(request, GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
	if (param_list == null) {
	    System.err.println("Error: TextQuery request had no paramList.");
	    return result;  // Return the empty result
	}

	// Process the request parameters
	HashMap params = GSXML.extractParams(param_list, false);

	// Make sure a query has been specified
	String query = (String) params.get(empty_query_test_param);
	if (query == null || query.equals("")) {
	    return result;  // Return the empty result
	}

	// If a field hasn't been specified, use the default - for textQuery
	String field = (String) params.get(INDEX_PARAM); 
	if (field == null) {
	    field = default_field;
	}
	
	// set up mgpp_src
	String indexdir = GSFile.collectionBaseDir(this.site_home, this.cluster_name) +
	    File.separatorChar + GSFile.collectionIndexPath(this.index_stem, this.default_index);
	this.mgpp_src.loadIndexData(indexdir);
	setStandardQueryParams(params);
	
	// if field search, create the query string
	switch (query_type) {
	case TEXT_QUERY:
	    query = addFieldInfo(query, field);
	    break;
	case SIMPLE_QUERY:
	    query = parseFieldQueryParams(params);
	    break;
	case ADVANCED_QUERY:
	    query = parseAdvancedFieldQueryParams(params);
	    break;
	}
	// run the query
       	this.mgpp_src.runQuery(query);
	MGPPQueryResult mqr= this.mgpp_src.getQueryResult();

	// build up the response
	
	// Create a metadata list to store information about the query results
	// should we be using metadataList? or something else?
	Element metadata_list = this.doc.createElement(GSXML.METADATA_ELEM+GSXML.LIST_MODIFIER); 
	result.appendChild(metadata_list);
	
	// Add a metadata element specifying the number of matching documents
	long totalDocs = mqr.getTotalDocs();
	GSXML.addMetadata(this.doc, metadata_list, "numDocsMatched", ""+totalDocs);

	// Create a document list to store the matching documents, and add them
	Vector docs = mqr.getDocs();

	// add a metadata item to specify docs returned
	GSXML.addMetadata(this.doc, metadata_list, "numDocsReturned", ""+docs.size());
	// add a metadata item to specify what actual query was done - eg if stuff was stripped out etc. and then we can use the query later, cos we don't know which parameter was the query
	GSXML.addMetadata(this.doc, metadata_list, "query", query);
	Element document_list = this.doc.createElement(GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
	result.appendChild(document_list);
	for (int d = 0; d < docs.size(); d++) {
	    long docnum = ((MGPPDocInfo) docs.elementAt(d)).num_;
	    float rank = ((MGPPDocInfo) docs.elementAt(d)).rank_;
	    String doc_id = MGPPNum2OID(docnum);
	    Element doc_node = createDocNode(doc_id, Float.toString(rank));
	    //doc_node.setAttribute("rank", Float.toString(rank));
	    document_list.appendChild(doc_node);
	}

	// Create a term list to store the term information, and add it
	String query_level = (String)params.get(LEVEL_PARAM); // the current query level
	Element term_list = this.doc.createElement(GSXML.TERM_ELEM+GSXML.LIST_MODIFIER);
	result.appendChild(term_list);
	Vector terms = mqr.getTerms();
	for (int t = 0; t < terms.size(); t++) {
	    MGPPTermInfo term_info = (MGPPTermInfo) terms.get(t);
	    
	    Element term_elem = this.doc.createElement(GSXML.TERM_ELEM);
	    term_elem.setAttribute(GSXML.NAME_ATT, term_info.term_);
	    term_elem.setAttribute(STEM_ATT, "" + term_info.stem_method_);
	    term_elem.setAttribute(FREQ_ATT, "" + term_info.term_freq_);
	    term_elem.setAttribute(NUM_DOCS_MATCH_ATT, "" + term_info.match_docs_);
	    field = term_info.tag_;
	    if (field.equals(query_level)) {
		// ignore
		field = "";
	    }
	    term_elem.setAttribute(FIELD_ATT, field);
	    
	    Vector equiv_terms = term_info.equiv_terms_;
	    Element equiv_term_list = this.doc.createElement(EQUIV_TERM_ELEM+GSXML.LIST_MODIFIER);
	    term_elem.appendChild(equiv_term_list);
	    
	    for (int et = 0; et < equiv_terms.size(); et++) {
		String equiv_term = (String) equiv_terms.get(et);

		Element equiv_term_elem = this.doc.createElement(GSXML.TERM_ELEM);
		equiv_term_elem.setAttribute(GSXML.NAME_ATT, equiv_term);
		equiv_term_elem.setAttribute(NUM_DOCS_MATCH_ATT, "");
		equiv_term_elem.setAttribute(FREQ_ATT, "");
		equiv_term_list.appendChild(equiv_term_elem);
	    }

	    term_list.appendChild(term_elem);
	}

	return result;
    }

    // should probably use a list rather than map
    protected boolean setStandardQueryParams(HashMap params) {

	Set entries = params.entrySet();
	Iterator i = entries.iterator();
	while (i.hasNext()) {
	    Map.Entry m = (Map.Entry)i.next();
	    String name = (String)m.getKey();
	    String value = (String)m.getValue();
	   
	    if (name.equals(CASE_PARAM)) {
		boolean val = (value.equals(BOOLEAN_PARAM_ON)?true:false);
		this.mgpp_src.setCase(val);		
	    } else if (name.equals(STEM_PARAM)) {
		boolean val = (value.equals(BOOLEAN_PARAM_ON)?true:false);
		this.mgpp_src.setStem(val);
	    } else if (name.equals(MAXDOCS_PARAM)&& !value.equals("")) {
		int docs = Integer.parseInt(value);
		this.mgpp_src.setMaxDocs(docs);
	    } else if (name.equals(LEVEL_PARAM)) {
		this.mgpp_src.setQueryLevel(value);
	    } else if (name.equals(MATCH_PARAM)) {
		int mode;
		if (value.equals(MATCH_PARAM_ALL)) mode=1;
		else mode=0;
		this.mgpp_src.setMatchMode(mode);
	    } else if (name.equals(RANK_PARAM)) {
		if (value.equals(RANK_PARAM_RANK)) {
		    this.mgpp_src.setSortByRank(true);
		} else if (value.equals(RANK_PARAM_NONE)) {
		    this.mgpp_src.setSortByRank(false);
		}
	    } // ignore any others
	}
	return true;
    }

    protected String addFieldInfo(String query, String field) {
	if (field.equals("") || field.equals("ZZ")) {
	    return query;
	}
	return "["+query+"]:"+field;
    }
    /** combines all the field params into a single query
     * - for simple field query */
    protected String parseFieldQueryParams(HashMap params) {

	StringBuffer final_query = new StringBuffer(256);
	String text_line = (String)params.get(FIELD_QUERY_PARAM);
	String[] texts = text_line.split(",", -1);
	String field_line = (String)params.get(FIELD_FIELD_PARAM);
	String[] fields = field_line.split(",", -1);
	String combine="&";
	String match = (String)params.get(MATCH_PARAM);
	if (match.equals(MATCH_PARAM_SOME)) {
	    combine = "|";
	}
	
	for (int i=0; i<texts.length; i++) {

	    String q = texts[i].trim();
	    if (!q.equals("")) {
		addQueryElem(final_query, q, fields[i], combine);
	    }
	}

	return final_query.toString();
    }

    /** combines all the field params into a single query
     * - for advanced field query */   
    protected String parseAdvancedFieldQueryParams(HashMap params) {

	StringBuffer final_query = new StringBuffer(256);
	String text_line = (String)params.get(FIELD_QUERY_PARAM);
	String[] texts = text_line.split(",", -1);
	String field_line = (String)params.get(FIELD_FIELD_PARAM);
	String[] fields = field_line.split(",", -1);
	String case_line = (String)params.get(FIELD_CASE_PARAM);
	String[] cases = case_line.split(",", -1);
	String stem_line = (String)params.get(FIELD_STEM_PARAM);
	String[] stems = stem_line.split(",", -1);
	String  combine_line = (String)params.get(FIELD_COMBINE_PARAM);
	String [] combines = combine_line.split(",", -1);
	String combine = "&";
	for (int i=0; i<texts.length; i++) {
	    if (i==0) {// assume first one is blank
		combine = "";
	    } else {
		String x = combines[i]; 
		if (x.equals(FIELD_COMBINE_PARAM_AND)) {
		    combine = "&";
		} else if (x.equals(FIELD_COMBINE_PARAM_OR)) {
		    combine = "|";
		} else if (x.equals(FIELD_COMBINE_PARAM_NOT)) {
		    combine = "!";
		} 
		
	    }

	    String q = texts[i].trim();
	    if (!q.equals("")) {
		q = addStemAndCase(q, stems[i], cases[i]);
		addQueryElem(final_query, q, fields[i], combine);
	    }
	}

	return final_query.toString();
    }

    protected void addQueryElem(StringBuffer s, String q, String f, String c) {

	String combine="";
	if (s.length()>0) {
	    combine = " "+c+" ";
	}
	if (f.equals("")||f.equals("ZZ")) {
	    s.append(combine+q);
	} else {
	    s.append(combine+"["+q+"]:"+f);
	}
    }
    
    protected String addStemAndCase(String q, String s, String c) {
	String mods = "#";
	if (c.equals("1")) {
	    mods += "i";
	} else {
	    mods += "c";
	}
	if (s.equals("1")) {
	    mods += "s";
	} else {
	    mods+= "u";
	}
	StringBuffer temp = new StringBuffer();
	String [] terms = q.split(" ");
	for (int i=0; i<terms.length; i++) {
	    String t = terms[i].trim();
	    
	    if (!t.equals("") && !t.equals("TX")) {
		temp.append(" "+t+mods);
	    }
	}
	return temp.toString();
    }

    /** convert MGPP internal id to Greenstone oid */
    abstract protected String MGPPNum2OID(long docnum);

}