/**
 *  search
 *  Copyright 2012 by Michael Peter Christen, mc@yacy.net, Frankfurt am Main, Germany
 *  First released 14.08.2012 at http://yacy.net
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program in the file lgpl21.txt
 *  If not, see <http://www.gnu.org/licenses/>.
 */

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import net.yacy.cora.document.UTF8;
import net.yacy.cora.federate.solr.Ranking;
import net.yacy.cora.federate.solr.connector.EmbeddedSolrConnector;
import net.yacy.cora.federate.solr.responsewriter.GSAResponseWriter;
import net.yacy.cora.protocol.HeaderFramework;
import net.yacy.cora.protocol.RequestHeader;
import net.yacy.kelondro.logging.Log;
import net.yacy.search.Switchboard;
import net.yacy.search.query.AccessTracker;
import net.yacy.search.query.QueryGoal;
import net.yacy.search.query.QueryModifier;
import net.yacy.search.query.SearchEvent;
import net.yacy.search.schema.CollectionSchema;
import net.yacy.server.serverObjects;
import net.yacy.server.serverSwitch;

import org.apache.solr.common.SolrException;
import org.apache.solr.common.params.CommonParams;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.response.ResultContext;
import org.apache.solr.response.SolrQueryResponse;
import org.apache.solr.util.FastWriter;


// try
// http://localhost:8090/gsa/searchresult?q=chicken+teriyaki&output=xml&client=test&site=test&sort=date:D:S:d1

/**
 * This is a gsa result formatter for solr search results.
 * The result format is implemented according to
 * https://developers.google.com/search-appliance/documentation/68/xml_reference#results_xml
 */
public class searchresult {

    private final static GSAResponseWriter responseWriter = new GSAResponseWriter();

    /**
     * get the right mime type for this streamed result page
     * @param header
     * @param post
     * @param env
     * @return
     */
    public static String mime(final RequestHeader header, final serverObjects post, final serverSwitch env) {
        return "text/xml";
    }


    /**
     * @param header
     * @param post
     * @param env
     * @param out
     * @return
     */
    public static serverObjects respond(final RequestHeader header, final serverObjects post, final serverSwitch env, final OutputStream out) {

        // this uses the methods in the jetty servlet environment and can be removed if jetty in implemented
        Switchboard sb = (Switchboard) env;

        // remember the peer contact for peer statistics
        final String clientip = header.get(HeaderFramework.CONNECTION_PROP_CLIENTIP, "<unknown>"); // read an artificial header addendum
        final String userAgent = header.get(HeaderFramework.USER_AGENT, "<unknown>");
        sb.peers.peerActions.setUserAgent(clientip, userAgent);

        // check if user is allowed to search (can be switched in /ConfigPortal.html)
        boolean authenticated = sb.adminAuthenticated(header) >= 2;
        final boolean searchAllowed = authenticated || sb.getConfigBool("publicSearchpage", true);
        if (!searchAllowed) return null;

        // check post
        if (post == null) return null;
        Log.logInfo("GSA Query", post.toString());
        sb.intermissionAllThreads(3000); // tell all threads to do nothing for a specific time
        
        // rename post fields according to result style
        //post.put(CommonParams.Q, post.remove("q")); // same as solr
        //post.put(CommonParams.START, post.remove("start")); // same as solr
        //post.put(, post.remove("client"));//required, example: myfrontend
        //post.put(, post.remove("output"));//required, example: xml,xml_no_dtd
        String originalQuery = post.get(CommonParams.Q, "");
        post.put("originalQuery", originalQuery);
        
        // get a solr query string
        QueryGoal qg = new QueryGoal(originalQuery, originalQuery);
        StringBuilder solrQ = qg.collectionQueryString(sb.index.fulltext().getDefaultConfiguration(), 0);
        post.put("defType", "edismax");
        post.put(CommonParams.Q, solrQ.toString());
        post.put(CommonParams.ROWS, post.remove("num"));
        post.put(CommonParams.ROWS, Math.min(post.getInt(CommonParams.ROWS, 10), (authenticated) ? 5000 : 100));
        
        // set ranking
        if (post.containsKey("sort")) {
            // if a gsa-style sort attribute is given, use this to set the solr sort attribute
            GSAResponseWriter.Sort sort = new GSAResponseWriter.Sort(post.get(CommonParams.SORT, ""));
            String sorts = sort.toSolr();
            if (sorts == null) {
                post.remove(CommonParams.SORT);
            } else {
                post.put(CommonParams.SORT, sorts);
            }
        } else {
            // if no such sort attribute is given, use the ranking as configured for YaCy
            Ranking ranking = sb.index.fulltext().getDefaultConfiguration().getRanking(0);
            String bq = ranking.getBoostQuery();
            String bf = ranking.getBoostFunction();
            if (bq.length() > 0) post.put("bq", bq);
            if (bf.length() > 0) post.put("boost", bf); // a boost function extension, see http://wiki.apache.org/solr/ExtendedDisMax#bf_.28Boost_Function.2C_additive.29
        }
        post.put(CommonParams.FL,
                CollectionSchema.content_type.getSolrFieldName() + ',' +
                CollectionSchema.id.getSolrFieldName() + ',' +
                CollectionSchema.sku.getSolrFieldName() + ',' +
                CollectionSchema.title.getSolrFieldName() + ',' +
                CollectionSchema.description.getSolrFieldName() + ',' +
                CollectionSchema.load_date_dt.getSolrFieldName() + ',' +
                CollectionSchema.last_modified.getSolrFieldName() + ',' +
                CollectionSchema.size_i.getSolrFieldName());
        post.put("hl", "true");
        post.put("hl.q", originalQuery);
        post.put("hl.fl", CollectionSchema.h1_txt.getSolrFieldName() + "," + CollectionSchema.h2_txt.getSolrFieldName() + "," + CollectionSchema.text_t.getSolrFieldName());
        post.put("hl.alternateField", CollectionSchema.description.getSolrFieldName());
        post.put("hl.simple.pre", "<b>");
        post.put("hl.simple.post", "</b>");
        post.put("hl.fragsize", Integer.toString(SearchEvent.SNIPPET_MAX_LENGTH));
        
        //String[] access = post.remove("access");
        //String[] entqr = post.remove("entqr");

        // add sites operator
        String[] site = post.remove("site"); // example: col1|col2
        if (site != null && site[0].length() > 0) {
            String origfq = post.get(CommonParams.FQ);
            String sitefq = QueryModifier.parseCollectionExpression(site[0]);
            post.put(CommonParams.FQ, origfq == null || origfq.length() == 0 ? sitefq :
                "(" + origfq + ") AND (" + sitefq + ")");
        }
        
        // get the embedded connector
        EmbeddedSolrConnector connector = sb.index.fulltext().getDefaultEmbeddedConnector();
        if (connector == null) return null;

        // do the solr request
        SolrQueryRequest req = connector.request(post.toSolrParams(null));
        SolrQueryResponse response = null;
        Exception e = null;
        try {response = connector.query(req);} catch (SolrException ee) {e = ee;}
        if (response != null) e = response.getException();
        if (e != null) {
            Log.logException(e);
            return null;
        }

        // set some context for the writer
        /*
        Map<Object,Object> context = req.getContext();
        context.put("ip", header.get("CLIENTIP", ""));
        context.put("client", "vsm_frontent");
        context.put("sort", sort.sort);
        context.put("site", site == null ? "" : site);
        context.put("access", access == null ? "p" : access[0]);
        context.put("entqr", entqr == null ? "3" : entqr[0]);
        */
        
        // write the result directly to the output stream
        Writer ow = new FastWriter(new OutputStreamWriter(out, UTF8.charset));
        try {
            responseWriter.write(ow, req, response);
            ow.flush();
        } catch (IOException e1) {
        } finally {
            req.close();
            try {ow.close();} catch (IOException e1) {}
        }

        // log result
        Object rv = response.getValues().get("response");
        if (rv != null && rv instanceof ResultContext) {
            AccessTracker.addToDump(originalQuery, Integer.toString(((ResultContext) rv).docs.matches()));
        }
        return null;
    }
}