/** This is a simple Lucene XML Search class. This is NOT the one 
    used by Greenstone Lucene collections. This is used by the custom 
    gberg collection */

package org.greenstone.gsdl3.service;

// Greenstone classes
import java.io.File;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;

import org.apache.log4j.Logger;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.greenstone.gsdl3.util.GSFile;
import org.greenstone.gsdl3.util.GSXML;
import org.greenstone.gsdl3.util.XMLConverter;

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

public class LuceneSearch extends AbstractTextSearch
{
	static Logger logger = Logger.getLogger(org.greenstone.gsdl3.service.LuceneSearch.class.getName());

	protected static final String INDEX_ELEM = "index";

	protected ArrayList<String> index_ids;

	public LuceneSearch()
	{
		index_ids = new ArrayList<String>();
	}

	public boolean configure(Element info, Element extra_info)
	{
		if (!super.configure(info, extra_info))
		{
			return false;
		}

		default_index = "idx";

		// cache index info read from config file
		Element index_list = (Element) GSXML.getChildByTagName(this.config_info, INDEX_ELEM + GSXML.LIST_MODIFIER);
		if (index_list != null)
		{
			NodeList indexes = index_list.getElementsByTagName(INDEX_ELEM);
			int len = indexes.getLength();
			// now add even if there is only one
			for (int i = 0; i < len; i++)
			{
				Element index = (Element) indexes.item(i);
				index_ids.add(index.getAttribute(GSXML.NAME_ATT));
			}
		}
		else
		{
			// there is only one index, so we assume the default
			index_ids.add(this.default_index);
		}

		return true;
	}

	protected void getIndexData(ArrayList<String> index_ids, ArrayList<String> index_names, String lang)
	{
		// copying exercise for index_ids, 
		for (int i = 0; i < this.index_ids.size(); i++)
		{
			index_ids.add(this.index_ids.get(i));
		}

		// But need to work out display name from scratch as this uses
		// the 'lang' parameter

		Element index_list = (Element) GSXML.getChildByTagName(this.config_info, INDEX_ELEM + GSXML.LIST_MODIFIER);
		if (index_list != null)
		{
			NodeList indexes = index_list.getElementsByTagName(INDEX_ELEM);
			int len = indexes.getLength();
			// now add even if there is only one
			for (int i = 0; i < len; i++)
			{
				Element index = (Element) indexes.item(i);
				index_names.add(getDisplayText(index, GSXML.DISPLAY_TEXT_NAME, lang, "en"));

			}
		}
		else
		{
			// there is only one index, so we assume the default
			index_names.add("default index");
		}
	}

	protected void initResultElement(Element result, Element doc_node_list, Element metadata_list)
	{
		// Create a new (empty) result message
		result.setAttribute(GSXML.FROM_ATT, QUERY_SERVICE);
		result.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_PROCESS);
		result.appendChild(doc_node_list);
		result.appendChild(metadata_list);
	}

	protected boolean hasParamList(Element request, Element metadata_list)
	{
		// 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.");
			GSXML.addMetadata(metadata_list, "numDocsMatched", "0");
			return false; // signal that an empty result should be return
		}

		return true;
	}

	protected boolean hasQueryString(Element param_list, Element metadata_list)
	{
		// Process the request parameters to make sure a query has been specified
		HashMap<String, Serializable> params = GSXML.extractParams(param_list, false);
		String query_string = (String) params.get(QUERY_PARAM);

		if (query_string == null || query_string.equals(""))
		{
			logger.error("TextQuery request had no query string.");
			GSXML.addMetadata(metadata_list, "numDocsMatched", "0");
			return false; // signal that an empty result should be return
		}

		return true;
	}

	/** Process a text query - implemented by concrete subclasses */
	protected Element processTextQuery(Element request)
	{
	  Document result_doc = XMLConverter.newDOM();
		Element result = result_doc.createElement(GSXML.RESPONSE_ELEM);
		Element doc_node_list = result_doc.createElement(GSXML.DOC_NODE_ELEM + GSXML.LIST_MODIFIER);
		Element metadata_list = result_doc.createElement(GSXML.METADATA_ELEM + GSXML.LIST_MODIFIER);
		initResultElement(result, doc_node_list, metadata_list);

		if (!hasParamList(request, metadata_list))
		{
			return result;
		}

		Element param_list = (Element) GSXML.getChildByTagName(request, GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
		if (!hasQueryString(param_list, metadata_list))
		{
			return result;
		}

		HashMap<String, Serializable> params = GSXML.extractParams(param_list, false);
		String query_string = (String) params.get(QUERY_PARAM);

		// Get the index
		String index = (String) params.get(INDEX_PARAM);
		if (index == null || index.equals(""))
		{
			index = this.default_index; // assume the default
		}

		try
		{
			String index_dir = GSFile.collectionIndexDir(this.site_home, this.cluster_name);
			index_dir += File.separator + index;
			Directory index_dir_dir = FSDirectory.open(new File(index_dir));
			IndexReader reader = DirectoryReader.open(index_dir_dir); //deprecated: IndexReader.open(index_dir_dir);
			IndexSearcher searcher = new IndexSearcher(reader);

			Term term = new Term("content", query_string);

			Query query = new TermQuery(term);

			TopDocs hits = searcher.search(query, Integer.MAX_VALUE);

			GSXML.addMetadata(metadata_list, "numDocsMatched", "" + hits.scoreDocs.length);

			for (int i = 0; i < hits.scoreDocs.length; i++)
			{
				int lucene_doc_num = hits.scoreDocs[i].doc;
				org.apache.lucene.document.Document luc_doc = reader.document(lucene_doc_num);
				String node_id = luc_doc.get("nodeID");
				Element node = result_doc.createElement(GSXML.DOC_NODE_ELEM);
				node.setAttribute(GSXML.NODE_ID_ATT, node_id);
				doc_node_list.appendChild(node);
			}
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}

		return result;
	}
}