using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Gma.DataStructures.StringSearch;
using MySql.Data.MySqlClient;
using Sony.Filtr.Database;

namespace Sony.Filtr.PlaylistGeneration.Autocomplete
{
    public class DBMemoryFactory : IAutocompleteFactory
    {
        private static readonly Lazy<ConcurrentTrie<string>> Trie = new Lazy<ConcurrentTrie<string>>(
            () =>
            {
                var trie = new ConcurrentTrie<string>();
                var artists = GetArtists();
                foreach (var artist in artists)
                {
                    trie.Add(artist.ToLowerInvariant(), artist);
                }
                return trie;
            }
        );

        private static readonly Lazy<List<string>> ArtistList = new Lazy<List<string>>(GetArtists);

        public async Task<List<ArtistAutocompleteResult>> SearchArtistsAsync(string search, int count)
        {
            //var artists = ArtistList.Value.Where(a=> Matches(search, a)).Take(count).ToList();
            var artists = Trie.Value.Retrieve(search.ToLowerInvariant()).Take(count).ToList();
            return artists.Select(a => new ArtistAutocompleteResult()
            {
                Name = a,
                Score = 1
            }).ToList();
        }

        private static bool Matches(string search, string a)
        {
            return a.StartsWith(search, StringComparison.InvariantCultureIgnoreCase)
                || a.StartsWith(string.Format("the {0}", search), StringComparison.InvariantCultureIgnoreCase);
        }

        private static List<string> GetArtists()
        {
            List<string> artists = new List<string>();
            using (MySqlConnection conn = new MySqlConnection(DatabaseHandler.GetConnectionString()))
            {
                conn.Open();
                MySqlCommand cmd = new MySqlCommand("SELECT strArtistName FROM tblAutocompleteArtists", conn);

                var reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    artists.Add(reader.GetString(0));
                }

                conn.Close();
            }
            return artists;
        }

        public async Task IndexArtistAsync(string artistName)
        {
            using (var conn = DatabaseHandler.GetOpenConnection())
            {
                var cmd = conn.CreateCommand();
                cmd.CommandText = "INSERT IGNORE INTO tblAutocompleteArtists (strArtistName) VALUES (@strArtistName)";
                cmd.Parameters.AddWithValue("@strArtistName", artistName);

                await cmd.ExecuteNonQueryAsync();
            }
        }
    }
}