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.Text; 
import org.w3c.dom.Document; 
import org.w3c.dom.Element; 

import java.util.HashMap;
import java.util.HashSet;
import java.util.Vector;
import java.util.Map;
import java.util.Iterator;
import java.io.File;

import org.apache.log4j.*;

/** action class for queries 
 * this is used when querying isn't collection specific, but it occurs across all collections in the site. The service description is assumed to be known by the xslt so we dont ask for it. we just pass all the service params to the TextQuery service of all the collections */
public class NoCollQueryAction extends Action {
    
    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.action.NoCollQueryAction.class.getName());
    /** process - processes a request.
     */ 
    public Element process (Element message) {

	// get the request - assume there is only one
	Element request = (Element)GSXML.getChildByTagName(message, GSXML.REQUEST_ELEM);

	// create the return message
	Element result = this.doc.createElement(GSXML.MESSAGE_ELEM);
	// for now we only have one type of query - subaction not used
	Element response = basicQuery(request);
	result.appendChild(this.doc.importNode(response, true));
	return result;
    }
    
    /** a generic query handler 
     * this gets the service description, does the query (just passes all teh 
     * params to the service, then gets the titles for any results 
     */
    protected Element basicQuery(Element request) {
	
	// the result
	Element page_response = this.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 params = GSXML.extractParams(cgi_param_list, false);
	
	String request_type = (String)params.get(GSParams.REQUEST_TYPE);
	String lang = request.getAttribute(GSXML.LANG_ATT);
	String uid = request.getAttribute(GSXML.USER_ID_ATT);
	if (request_type.equals("d")) {
	    // display the query page
	    // the only info we need to return is the collection list cos the xslt does teh rest
	    
	    Element coll_list = getCollectionList(lang, uid);
	    page_response.appendChild(this.doc.importNode(coll_list, true));
	    return page_response;
	    
	}
	
	// else we have a query
	String service_name = (String)params.get(GSParams.SERVICE);
	if (service_name == null || service_name.equals("")) {
	    service_name = "TextQuery";
	}
  	String query_coll_list = (String)params.get(GSParams.COLLECTION);
	
  	if (query_coll_list == null || query_coll_list.equals("")) {
  	    logger.error("no collections were specified!");
  	    Element coll_list = getCollectionList(lang, uid);
  	    page_response.appendChild(this.doc.importNode(coll_list, true));
  	    return page_response; 
  	}

	// service paramList
	HashMap service_params = (HashMap)params.get("s1");
	if (service_params == null) { // no query
	    return page_response;
	}
	Element query_param_list = this.doc.createElement(GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
	GSXML.addParametersToList(this.doc, query_param_list, service_params);
	
	// we will do a query for each coll
	String [] colls = query_coll_list.split(",");
	
	Element mr_query_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
	
	for (int i=0; i< colls.length; i++) {
	    String to = GSPath.appendLink(colls[i], service_name);
	    Element mr_query_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_PROCESS, to, lang, uid);
	    mr_query_message.appendChild(mr_query_request);
	    mr_query_request.appendChild(query_param_list.cloneNode(true));
	    
	}
	
	// do the query
       	Element mr_query_response = (Element)this.mr.process(mr_query_message);

	
	// get the Title metadata for each node - need Node title and root title
	Element mr_meta_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
	NodeList responses = mr_query_response.getElementsByTagName(GSXML.RESPONSE_ELEM);
	for (int j=0; j<responses.getLength(); j++) {
	    Element document_list = (Element)GSXML.getChildByTagName((Element)responses.item(j), GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
	    if (document_list != null) {
		String coll_name = extractCollName(((Element)responses.item(j)).getAttribute(GSXML.FROM_ATT));
		String path = GSPath.appendLink(coll_name, "DocumentMetadataRetrieve");
		Element mr_meta_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_PROCESS, path, lang, uid);
		mr_meta_message.appendChild(mr_meta_request);
		mr_meta_request.appendChild(this.doc.importNode(document_list, true));
		// metadata params 
		Element param_list = this.doc.createElement(GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
		Element param = GSXML.createParameter(this.doc, "metadata", "Title");
		param_list.appendChild(param);
		param = GSXML.createParameter(this.doc, "metadata", "root_Title");
		param_list.appendChild(param);
		mr_meta_request.appendChild(param_list);
		
	    }
	}
	
	// do the request
	Element mr_meta_response = (Element)this.mr.process(mr_meta_message);

	// the result 
	Element result_doc_list = this.doc.createElement(GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
	page_response.appendChild(result_doc_list);

	responses = mr_meta_response.getElementsByTagName(GSXML.RESPONSE_ELEM);
	for (int j=0; j<responses.getLength(); j++) {
	    Element document_list = (Element)GSXML.getChildByTagName((Element)responses.item(j), GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
	    String coll_name = extractCollName(((Element)responses.item(j)).getAttribute(GSXML.FROM_ATT));
	    
	    mergeDocLists(result_doc_list, document_list, coll_name );
	}
	
	
	return page_response;
    }

    protected String extractCollName(String path) {
	return GSPath.removeLastLink(path);
    }

    protected void mergeDocLists(Element result_list, Element from_list, String collection) {

	Document owner = result_list.getOwnerDocument();
	Node child = from_list.getFirstChild();
	while (child != null && child.getNodeType() == Node.ELEMENT_NODE) {
	    ((Element)child).setAttribute("collection", collection);
	    result_list.appendChild(owner.importNode(child, true));
	    child = child.getNextSibling();
	}
	
    }


    protected Element getCollectionList(String lang, String uid) {
	
	// first, get the message router info
	Element coll_list_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
	Element coll_list_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_DESCRIBE, "", lang, uid);
	coll_list_message.appendChild(coll_list_request);
	Element coll_list_response = (Element)this.mr.process(coll_list_message);
	if (coll_list_response==null) {
	    logger.error("couldn't query the message router!");
	    return null;
	}
	
	// second, get the display info for each collection 
	NodeList colls = coll_list_response.getElementsByTagName(GSXML.COLLECTION_ELEM);

	Element coll_param_list = this.doc.createElement(GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
	Element param = GSXML.createParameter(this.doc, GSXML.SUBSET_PARAM, GSXML.DISPLAY_TEXT_ELEM+GSXML.LIST_MODIFIER); 
	coll_param_list.appendChild(param);
	// we will send all the requests in a single message
	Element metadata_message = this.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(this.doc,  GSXML.REQUEST_TYPE_DESCRIBE, name, lang, uid);
	    metadata_request.appendChild(coll_param_list.cloneNode(true));
	    metadata_message.appendChild(metadata_request);
	}
	
	Element metadata_response = (Element)this.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()) {
	    logger.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 collection data into the original response
		    GSXML.mergeElements(c1, (Element)GSXML.getChildByTagName(c2, GSXML.COLLECTION_ELEM));
		} else {
		    logger.error("response does not correspond to request!");
		} 
		
	    }
	}

	String path = GSPath.appendLink(GSXML.RESPONSE_ELEM, GSXML.COLLECTION_ELEM+GSXML.LIST_MODIFIER);
	Element response = (Element) GSXML.getNodeByPath(coll_list_response, path);
	return response;

    }
}