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.util.HashSet;
import java.util.Vector;
import java.io.File;

import org.apache.log4j.*;

/** action for GS2 style classifier browsing */
public class GS2BrowseAction extends Action {
    
    public static final String CLASSIFIER_ARG = "cl";

    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.action.GS2BrowseAction.class.getName());    

    /** process the request */
    public Node process (Node message_node) {

	Element message = this.converter.nodeToElement(message_node);

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

	// the result
	Element result = this.doc.createElement(GSXML.MESSAGE_ELEM);
	Element response = classifierBrowse(request);
	result.appendChild(response);
	return result;
    }
    

    protected Element classifierBrowse(Element request) {

	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_paramList = (Element)GSXML.getChildByTagName(request, GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
	HashMap params = GSXML.extractParams(cgi_paramList, false);
	
	String service_name = (String)params.get(GSParams.SERVICE);
	String collection = (String)params.get(GSParams.COLLECTION);
	if (collection == null || collection.equals("")) {
	    logger.error("classifierBrowse, need to specify a collection!");
	    return page_response;
	   
	}
	
	String lang = request.getAttribute(GSXML.LANG_ATT);
	String uid = request.getAttribute(GSXML.USER_ID_ATT);
	String to = GSPath.appendLink(collection, service_name);
	
	// the first part of the response is the service description 
	// for now get this again from the service. 
	// this should be cached somehow later on. 
	
	Element info_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
	Element info_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_DESCRIBE, to, lang, uid); 
	info_message.appendChild(info_request);
	
	// also get the format stuff now if there is some
	Element format_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_FORMAT, to, lang, uid);
	info_message.appendChild(format_request);
	// process the requests

	Element info_response = (Element) this.mr.process(info_message);

	// the two responses
	NodeList responses = info_response.getElementsByTagName(GSXML.RESPONSE_ELEM);
	Element service_response = (Element)responses.item(0);
	Element format_response = (Element)responses.item(1);

	Element service_description = (Element)GSXML.getChildByTagName(service_response, GSXML.SERVICE_ELEM);
	page_response.appendChild(this.doc.importNode(service_description, true));
	
	//append site metadata
	addSiteMetadata( page_response, lang, uid);

	// if rt=d, then we are just displaying the service
	String request_type = (String)params.get(GSParams.REQUEST_TYPE);
	if (request_type.equals("d")) {
	    //return the page that we have so far
	    return page_response;
	}
    
	// get the node that the user has clicked on
	String classifier_node = (String)params.get(CLASSIFIER_ARG);
	
	// if the node is not defined, return the page that we have so far
	if (classifier_node ==null || classifier_node.equals("")) {
	    return page_response;
	}
	
	// the id of the classifier is the top id of the selected node
	String top_id = OID.getTop(classifier_node);
	HashSet doc_meta_names = new HashSet();
	HashSet class_meta_names = new HashSet();
	// add in the defaults
	doc_meta_names.add("Title");
	class_meta_names.add("Title");
	
	// add the format info into the response
	Element format_elem = (Element)GSXML.getChildByTagName(format_response, GSXML.FORMAT_ELEM);
	if (format_elem != null) {
	    
	    // find the one for the classifier we are in
	    Element this_format = GSXML.getNamedElement(format_elem, GSXML.CLASSIFIER_ELEM, GSXML.NAME_ATT, top_id);
	    if (this_format == null) {
		this_format = (Element)GSXML.getChildByTagName(format_elem, GSXML.DEFAULT_ELEM);
	    }

	    if (this_format != null) {
		Element new_format = GSXML.duplicateWithNewName(this.doc, this_format, GSXML.FORMAT_ELEM, false);
		extractMetadataNames(new_format, doc_meta_names, class_meta_names);
		// set the format type
		new_format.setAttribute(GSXML.TYPE_ATT, "browse");

		page_response.appendChild(new_format);
	    }
	}
	
	// find out if this classifier is horizontal at top
	Element class_list = (Element)GSXML.getChildByTagName(service_description, GSXML.CLASSIFIER_ELEM+GSXML.LIST_MODIFIER);
	Element this_classifier = GSXML.getNamedElement(class_list, GSXML.CLASSIFIER_ELEM, GSXML.NAME_ATT, top_id);
	boolean horizontal_at_top = false;
	if (!this_classifier.getAttribute("horizontalAtTop").equals("")) {
	    horizontal_at_top = true;
	}
	if (top_id.equals(classifier_node) && horizontal_at_top) {
	    // we have asked for a top node - if the first list is horizontal, we will select the first element of that list
	    // this is a hack. also it craps out if the classifier really isn't horizontalAtTop. - 
	    classifier_node = classifier_node+".1";
		    
	}

	// get the browse structure for the selected node
	Element classify_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
	Element classify_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_PROCESS, to, lang, uid);
	classify_message.appendChild(classify_request);
	    
	//Create a parameter list to specify the required structure information
	// for now, always get ancestors and children
	Element param_list = this.doc.createElement(GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
	classify_request.appendChild(param_list);
	Element param = this.doc.createElement(GSXML.PARAM_ELEM);
	param_list.appendChild(param);
	param.setAttribute(GSXML.NAME_ATT, "structure");
	param.setAttribute(GSXML.VALUE_ATT, "ancestors");
	param = this.doc.createElement(GSXML.PARAM_ELEM);
	param_list.appendChild(param);
	param.setAttribute(GSXML.NAME_ATT, "structure");
	param.setAttribute(GSXML.VALUE_ATT, "children");

	// put the classifier node into a classifier node list
	Element classifier_list = this.doc.createElement(GSXML.CLASS_NODE_ELEM+GSXML.LIST_MODIFIER);
	Element classifier = this.doc.createElement(GSXML.CLASS_NODE_ELEM);
	classifier.setAttribute(GSXML.NODE_ID_ATT, classifier_node);
	classifier_list.appendChild(classifier);
	classify_request.appendChild(classifier_list);
	    
	if (horizontal_at_top && !classifier_node.equals(top_id)) {
	    // also put the top id in, to get the persistant horizontal info
	    classifier = this.doc.createElement(GSXML.CLASS_NODE_ELEM);
	    classifier.setAttribute(GSXML.NODE_ID_ATT, top_id);
	    classifier_list.appendChild(classifier);
	}
	// process the request
	Element classify_response = (Element)this.mr.process(classify_message);
	String path = GSPath.appendLink(GSXML.RESPONSE_ELEM, GSXML.CLASS_NODE_ELEM+GSXML.LIST_MODIFIER);
	Element class_node_list = (Element)GSXML.getNodeByPath(classify_response, path);
	
	path = GSPath.appendLink(GSXML.CLASS_NODE_ELEM, GSXML.NODE_STRUCTURE_ELEM);
	// assume that we always get back the top level CL1 node - this becomes the page_classifier node
	path = GSPath.appendLink(path, GSXML.CLASS_NODE_ELEM);
	Element cl_structure = (Element)GSXML.getNodeByPath(class_node_list,
							    path);
	if (cl_structure ==null) {
	    logger.error("classifier structure request returned no structure");
	    return page_response;
	}   
    
	Element page_classifier = null;
	if (horizontal_at_top && !classifier_node.equals(top_id)) {
	    // get the info for the top node
	    Element top_node = GSXML.getNamedElement(class_node_list, GSXML.CLASS_NODE_ELEM, GSXML.NODE_ID_ATT, top_id);
	    if (top_node !=null) {
		path = GSPath.appendLink(GSXML.NODE_STRUCTURE_ELEM, GSXML.CLASS_NODE_ELEM);
		Element top_structure = (Element)GSXML.getNodeByPath(top_node, path);	    
		// add this as the classifier elem
		page_classifier = GSXML.duplicateWithNewName(this.doc, top_structure,  GSXML.CLASSIFIER_ELEM, true);
		page_response.appendChild(page_classifier);
		// now replace the child with the structure from the other request
		Element new_classifier = (Element)GSXML.getChildByTagName(cl_structure, GSXML.CLASS_NODE_ELEM);
		String replace_name = new_classifier.getAttribute(GSXML.NODE_ID_ATT);
		
		// find the appropriate child
		Element old_classifier = GSXML.getNamedElement(page_classifier, GSXML.CLASS_NODE_ELEM, GSXML.NODE_ID_ATT, replace_name);
		page_classifier.replaceChild(this.doc.importNode(new_classifier, true), old_classifier);
		page_classifier.setAttribute(GSXML.NAME_ATT, top_id);
	    } else {
		// add the single classifier node as the page classifier 
		page_classifier = GSXML.duplicateWithNewName(this.doc, cl_structure,  GSXML.CLASSIFIER_ELEM, true);
		page_response.appendChild(page_classifier);
		page_classifier.setAttribute(GSXML.NAME_ATT, top_id);
	    }
	    
	} else {
	    // add the single classifier node as the page classifier 
	    page_classifier = GSXML.duplicateWithNewName(this.doc, cl_structure,  GSXML.CLASSIFIER_ELEM, true);
	    page_response.appendChild(page_classifier);
	    page_classifier.setAttribute(GSXML.NAME_ATT, top_id);
	}
	// get the metadata for each classifier node, 
	// then for each document node

	Element metadata_message = this.doc.createElement(GSXML.MESSAGE_ELEM);

	boolean did_classifier = false;
	boolean did_documents = false;
	
    
	// if there are classifier nodes 
	// create a metadata request for the classifier, and add it to 
	// the the message
	NodeList cl_nodes = page_classifier.getElementsByTagName(GSXML.CLASS_NODE_ELEM);
	
	if (cl_nodes.getLength() > 0) {
	    did_classifier = true;
	    Element cl_meta_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_PROCESS, to+"MetadataRetrieve", lang, uid);
	    metadata_message.appendChild(cl_meta_request);
	    
	    Element new_cl_nodes_list = this.doc.createElement(GSXML.CLASS_NODE_ELEM+GSXML.LIST_MODIFIER);
	    cl_meta_request.appendChild(new_cl_nodes_list);
	    
	    for (int c=0; c<cl_nodes.getLength(); c++) {

		Element cl = this.doc.createElement(GSXML.CLASS_NODE_ELEM);
		cl.setAttribute(GSXML.NODE_ID_ATT, ((Element)cl_nodes.item(c)).getAttribute(GSXML.NODE_ID_ATT));
		new_cl_nodes_list.appendChild(cl);
	    }

	    // create and add in the param list - for now get all the metadata
	    // should be based on info sent in from the recept, and the 
	    // format stuff
	    Element cl_param_list  = createMetadataParamList(class_meta_names);
	    cl_meta_request.appendChild(cl_param_list);
	    
	}

	// if there are document nodes in the classification (happens 
	// sometimes), create a second request for document metadata and 
	// append to the message
	NodeList doc_nodes = page_classifier.getElementsByTagName(GSXML.DOC_NODE_ELEM);
	if (doc_nodes.getLength() > 0) {
	    did_documents = true;
	    Element doc_meta_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_PROCESS, GSPath.appendLink(collection, "DocumentMetadataRetrieve"), lang, uid);
	    metadata_message.appendChild(doc_meta_request);
	    
	    Element doc_list = this.doc.createElement(GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
	    doc_meta_request.appendChild(doc_list);
	    
	    for (int c=0; c<doc_nodes.getLength(); c++) {
		
		Element d = this.doc.createElement(GSXML.DOC_NODE_ELEM);
		d.setAttribute(GSXML.NODE_ID_ATT, ((Element)doc_nodes.item(c)).getAttribute(GSXML.NODE_ID_ATT));
		doc_list.appendChild(d);
	    }

	    // create and add in the param list - add all for now
	    Element doc_param_list  = createMetadataParamList(doc_meta_names);
	    doc_meta_request.appendChild(doc_param_list);

	}
	
	// process the metadata requests
	Element metadata_response = (Element)this.mr.process(metadata_message);
	if (did_classifier) {
	    // the classifier one will be the first response
	    // add the metadata lists for each node back into the 
	    // page_classifier nodes
	    path = GSPath.appendLink(GSXML.RESPONSE_ELEM, 
				   GSXML.CLASS_NODE_ELEM+GSXML.LIST_MODIFIER);
            Node pathNode = GSXML.getNodeByPath(metadata_response, path);
            if (pathNode ==null){
	        return page_response; 
	    }
	    //NodeList meta_response_cls = (Element)pathNode.getChildNodes(); // can't handle empty elements from converting formatted strings (with empty newlines) into XML
	    NodeList meta_response_cls = ((Element)pathNode).getElementsByTagName(GSXML.CLASS_NODE_ELEM);
	    for (int i = 0; i < cl_nodes.getLength(); i++) {
		GSXML.mergeMetadataLists(cl_nodes.item(i), meta_response_cls.item(i));
	    }
	}

	if (did_documents) {
	    NodeList meta_response_docs = null;
	    if (!did_classifier) {
		// its the first response
		path = GSPath.appendLink(GSXML.RESPONSE_ELEM, 
					 GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
		Node pathNode = GSXML.getNodeByPath(metadata_response, path);
		if (pathNode ==null){
		    return page_response;
                 }

		meta_response_docs = pathNode.getChildNodes();
		

	    } else { // its the second response
                Node nodes = GSXML.getChildByTagName(metadata_response.getElementsByTagName(GSXML.RESPONSE_ELEM).item(1), GSXML.DOC_NODE_ELEM+GSXML.LIST_MODIFIER);
		if (nodes ==null){
		    return page_response;
                 }
		meta_response_docs = nodes.getChildNodes();
	    }
	    
	    for (int i = 0; i < doc_nodes.getLength(); i++) {
		GSXML.mergeMetadataLists(doc_nodes.item(i), meta_response_docs.item(i));
	    }
	}
	    

	logger.debug("(GS2BrowseAction) Page:\n" + this.converter.getPrettyString(page_response));
	return page_response;
    }

   
    protected void extractMetadataNames(Element new_format, HashSet doc_meta_names, HashSet class_meta_names) {

	NodeList templates = new_format.getElementsByTagName("gsf:template");
	for (int i=0; i<templates.getLength(); i++) {
	    Element template = (Element)templates.item(i);
	    String match = template.getAttribute("match");
	    if (match.equals("documentNode")) {
		extractMetadataNames(template, doc_meta_names);
	    } else if (match.equals("classifierNode")) {
		extractMetadataNames(template, class_meta_names);
	    }
	}
    }

}