// Simple example program demonstrating query expansion.
//
// Copyright (c) 2003 James Aylett
// Copyright (c) 2004,2006,2007 Olly Betts
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by 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, see
// <https://www.gnu.org/licenses/>.

using System;

class SimpleExpand {
    public static void Main(string[] argv) {
        // We require at least two command line arguments.
        if (argv.Length < 2) {
            Console.Error.WriteLine("Usage: SimpleExpand PATH_TO_DATABASE QUERY [-- [DOCID...]]");
            Environment.Exit(1);
        }

        try {
            // Open the database for searching.
            Xapian.Database database = new Xapian.Database(argv[0]);

            // Start an enquire session.
            Xapian.Enquire enquire = new Xapian.Enquire(database);

            // Create an RSet to add the listed docids to.
            Xapian.RSet rset = new Xapian.RSet();

            // Combine command line arguments up to "--" with spaces between
            // them, so that simple queries don't have to be quoted at the
            // shell level.
            string query_string = argv[1];
            for (int i = 2; i < argv.Length; ++i) {
                if (argv[i] == "--") {
                    while (++i < argv.Length) {
                        rset.AddDocument(Convert.ToUInt32(argv[i]));
                    }
                    break;
                }
                query_string += ' ';
                query_string += argv[i];
            }

            // Parse the query string to produce a Xapian::Query object.
            Xapian.QueryParser qp = new Xapian.QueryParser();
            Xapian.Stem stemmer = new Xapian.Stem("english");
            qp.SetStemmer(stemmer);
            qp.SetDatabase(database);
            qp.SetStemmingStrategy(Xapian.QueryParser.stem_strategy.STEM_SOME);
            Xapian.Query query = qp.ParseQuery(query_string);
            Console.WriteLine("Parsed query is: " + query.GetDescription());

            // Find the top 10 results for the query.
            enquire.SetQuery(query);
            Xapian.MSet matches = enquire.GetMSet(0, 10, rset);

            // Display the results.
            Console.WriteLine("{0} results found.", matches.GetMatchesEstimated());
            Console.WriteLine("Matches 1-{0}:", matches.Size());

            Xapian.MSetIterator m = matches.Begin();
            while (m != matches.End()) {
                Console.WriteLine("{0}: {1}% docid={2} [{3}]\n",
                                  m.GetRank() + 1,
                                  m.GetPercent(),
                                  m.GetDocId(),
                                  m.GetDocument().GetData());
                ++m;
            }

            // If no relevant docids were given, invent an RSet containing the
            // top 5 matches (or all the matches if there are less than 5).
            if (rset.Empty()) {
                int c = 5;
                Xapian.MSetIterator i = matches.Begin();
                while (c-- > 0 && i != matches.End()) {
                    rset.AddDocument(i.GetDocId());
                    ++i;
                }
            }

            // Generate an ESet containing terms that the user might want to
            // add to the query.
            Xapian.ESet eset = enquire.GetESet(10, rset);

            Console.WriteLine(eset.Size());
            // List the terms.
            for (Xapian.ESetIterator t = eset.Begin(); t != eset.End(); ++t) {
                Console.WriteLine("{0}: weight = {1}",
                                  t.GetTerm(), t.GetWeight());
            }
        } catch (Exception e) {
            Console.Error.WriteLine("Exception: " + e.ToString());
            Environment.Exit(1);
        }
    }
}
