/*
 *    AbstractGS2FieldSearch.java
 *    Copyright (C) 2006 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *   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.*;

// 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;

import org.apache.log4j.*;


abstract public class AbstractGS2FieldSearch 
    extends AbstractGS2Search 
{

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

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

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

    // some stuff for config files
    protected static final String SEARCH_TYPE_ELEM = "searchType";
    protected static final String SEARCH_TYPE_PLAIN = "plain";
    protected static final String SEARCH_TYPE_FORM = "form";
    protected static final String SEARCH_TYPE_FORM_SIMPLE = "simple";
    protected static final String SEARCH_TYPE_FORM_ADVANCED = "advanced";

    protected static final String DEFAULT_LEVEL_ELEM = "defaultLevel";
    protected static final String LEVEL_ELEM = "level";
    protected static final String FIELD_ATT = "field";


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

    protected String AND_OPERATOR = "&";
    protected String OR_OPERATOR = "|";
    protected String NOT_OPERATOR = "!";
    
   // the default level for retrieval - and we'll use it for searching too
    protected String default_level=null;
    // the default field for searching
    protected String default_field = null;
    // which search services will we offer??
    protected boolean plain_search = false;
    protected boolean simple_form_search = false;
    protected boolean advanced_form_search = false;


    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.service.AbstractGS2FieldSearch.class.getName());

    /** constructor */
    public AbstractGS2FieldSearch()
    {
    }

    public void cleanUp() {
	super.cleanUp();
    }

    /** configure this service */
    public boolean configure(Element info, Element extra_info)
    {
	if (!super.configure(info, extra_info)){
	    return false;
	}
	// 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)
	Element 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("")) {
	    logger.error("default level not specified!");
	    return false;
	}

	// 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 the 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);
		if (this.does_case) {
		    createParameter(FIELD_CASE_PARAM, multiparam, lang);
		}
		if (this.does_stem) {
		    createParameter(FIELD_STEM_PARAM, multiparam, lang);
		}
		if (this.does_accent) {
		    createParameter(FIELD_ACCENT_PARAM, multiparam, lang);
		}
		createParameter(FIELD_FIELD_PARAM, multiparam, lang);    
		
	    } 
	}
	return service;
	
    }
    
    /** add in the level params to TextQuery */
    protected void addCustomQueryParams(Element param_list, String lang) 
    {
	createParameter(LEVEL_PARAM, param_list, lang);
	super.addCustomQueryParams(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 {
		// we need to set the level, but hidden, in case there is an invalid level saved
		param = GSXML.createParameterDescription(this.doc, LEVEL_PARAM, "", GSXML.PARAM_TYPE_INVISIBLE, (String)level_ids.get(0), null, null);
	    }
	} 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)};
	    
	    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) || name.equals(FIELD_ACCENT_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++) {
	    String shortname = ((Element)fields.item(i)).getAttribute(GSXML.SHORTNAME_ATT);
	    String name = ((Element)fields.item(i)).getAttribute(GSXML.NAME_ATT);
	    if (name.equals("")) {
		// no name, ignore
		continue;
	    }
	    // TODO change field so that name is the id, and full metadata name is somthing else
	    if (shortname.equals("")) {
		shortname = name;
	    }
	    index_ids.add(shortname);
	    // 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(name);
	}
    }


    // 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
	    logger.error("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) {
	    logger.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 the appropriate query system
	if (!setUpQueryer(params)) {
	    return result;
	}
	
	// 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
	Object query_result = runQuery(query);
	
	// 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 = numDocsMatched(query_result);
	
	GSXML.addMetadata(this.doc, metadata_list, "numDocsMatched", ""+totalDocs);

	// Create a document list to store the matching documents, and add them
	String [] docs = getDocIDs(query_result);
	String [] doc_ranks = getDocRanks(query_result);

	// add a metadata item to specify docs returned
	int docs_returned = docs.length;
	if (does_paging) {
	    int maxdocs = Integer.parseInt((String)params.get(MAXDOCS_PARAM));
	    docs_returned = (maxdocs < (int)totalDocs ? maxdocs : (int)totalDocs);
	}
	GSXML.addMetadata(this.doc, metadata_list, "numDocsReturned", ""+docs_returned);
	// 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);
	if (docs.length>0) {
	    Element document_list = this.doc.createElement(GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
	    result.appendChild(document_list);
	    for (int d = 0; d < docs.length; d++) {
		String doc_id = internalNum2OID(docs[d]);
		Element doc_node = createDocNode(doc_id, doc_ranks[d]);
		document_list.appendChild(doc_node);
	    }
	}
	// Create a term list to store the term information, and add it
	Element term_list = this.doc.createElement(GSXML.TERM_ELEM+GSXML.LIST_MODIFIER);
	result.appendChild(term_list);
	addTermInfo(term_list, params, query_result);

	return result;
    }

    /** methods to handle actually doing the query */
    /** do any initialisation of the query object */
    abstract protected boolean setUpQueryer(HashMap params);
    /** do the query */
    abstract protected Object runQuery(String query);
    /** get the total number of docs that match */
    abstract protected long numDocsMatched(Object query_result);
    /** get the list of doc ids */
    abstract protected String [] getDocIDs(Object query_result);
    /** get the list of doc ranks */
    abstract protected String [] getDocRanks(Object query_result);
    /** add in term info if available */
    abstract protected boolean addTermInfo(Element term_list, HashMap params,
					   Object query_result);
    
    /** combines all the field params into a single query
     * - for simple field query */
    /** We assume the combination (AND/OR) is done by the match param */
    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);
	
	for (int i=0; i<texts.length; i++) {
	    String q = texts[i].trim();
	    if (!q.equals("")) {
		final_query.append(" "+addFieldInfo(q, fields[i]));
	    }
	}

	return final_query.toString();
    }

    abstract protected String addFieldInfo(String query, String field);
    
    /** 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 [] cases = null;
	String [] stems = null;
	String [] accents = null;
	if (does_case) {
	    String case_line = (String)params.get(FIELD_CASE_PARAM);
	    cases = case_line.split(",", -1);
	}
	if (does_stem) {
	    String stem_line = (String)params.get(FIELD_STEM_PARAM);
	    stems = stem_line.split(",", -1);
	}
	if (does_accent) {
	    String accent_line = (String)params.get(FIELD_ACCENT_PARAM);
	    accents = accent_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 = AND_OPERATOR;
		} else if (x.equals(FIELD_COMBINE_PARAM_OR)) {
		    combine = OR_OPERATOR;
		} else if (x.equals(FIELD_COMBINE_PARAM_NOT)) {
		    combine = NOT_OPERATOR;
		} 
		
	    }

	    String q = texts[i].trim();
	    boolean modified = false;
	    if (!q.equals("")) {
		String c = null;
		String s = null;
		String a = null;
		if (does_case) {
		    modified = true;
		    c = cases[i];
		}
		if (does_stem) {
		    modified = true;
		    s = stems[i];
		}
		if (does_accent) {
		    modified = true;
		    a = accents[i];
		}
		if (modified) {
		    q = addStemOptions(q, s, c, a);
		}
		addQueryElem(final_query, q, fields[i], combine);
	    }
	}
	return final_query.toString();
    }
    
    abstract protected void addQueryElem(StringBuffer final_query, 
					 String query, String field, 
					 String combine);
    abstract protected String addStemOptions(String query, String stem,
					     String casef, String accent);
    
}