using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.Logging;

namespace MediaBrowser.Server.Implementations.Persistence
{
    /// <summary>
    /// Class SQLiteExtensions
    /// </summary>
    public static class SqliteExtensions
    {
        /// <summary>
        /// Connects to db.
        /// </summary>
        /// <param name="dbPath">The db path.</param>
        /// <param name="logger">The logger.</param>
        /// <returns>Task{IDbConnection}.</returns>
        /// <exception cref="System.ArgumentNullException">dbPath</exception>
        public static async Task<IDbConnection> ConnectToDb(string dbPath, ILogger logger)
        {
            if (string.IsNullOrEmpty(dbPath))
            {
                throw new ArgumentNullException("dbPath");
            }

            logger.Info("Sqlite {0} opening {1}", SQLiteConnection.SQLiteVersion, dbPath);

            var connectionstr = new SQLiteConnectionStringBuilder
            {
                PageSize = 4096,
                CacheSize = 2000,
                SyncMode = SynchronizationModes.Normal,
                DataSource = dbPath,
                JournalMode = SQLiteJournalModeEnum.Wal
            };

            var connection = new SQLiteConnection(connectionstr.ConnectionString);

            await connection.OpenAsync().ConfigureAwait(false);

            return connection;
        }

        public static void BindGetSimilarityScore(IDbConnection connection, ILogger logger)
        {
            var sqlConnection = (SQLiteConnection)connection;
            SimiliarToFunction.Logger = logger;
            sqlConnection.BindFunction(new SimiliarToFunction());
        }

        public static void BindFunction(this SQLiteConnection connection, SQLiteFunction function)
        {
            var attributes = function.GetType().GetCustomAttributes(typeof(SQLiteFunctionAttribute), true).Cast<SQLiteFunctionAttribute>().ToArray();
            if (attributes.Length == 0)
            {
                throw new InvalidOperationException("SQLiteFunction doesn't have SQLiteFunctionAttribute");
            }
            connection.BindFunction(attributes[0], function);
        }
    }

    [SQLiteFunction(Name = "GetSimilarityScore", Arguments = 13, FuncType = FunctionType.Scalar)]
    public class SimiliarToFunction : SQLiteFunction
    {
        internal static ILogger Logger;

        private readonly Dictionary<string, int> _personTypeScores = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase)
        {
            { PersonType.Actor, 3},
            { PersonType.Director, 5},
            { PersonType.Composer, 2},
            { PersonType.GuestStar, 3},
            { PersonType.Writer, 2},
            { PersonType.Conductor, 2},
            { PersonType.Producer, 2},
            { PersonType.Lyricist, 2}
        };

        public override object Invoke(object[] args)
        {
            var score = 0;

            var inputOfficialRating = args[0] as string;
            var rowOfficialRating = args[1] as string;
            if (!string.IsNullOrWhiteSpace(inputOfficialRating) && string.Equals(inputOfficialRating, rowOfficialRating))
            {
                score += 10;
            }

            long? inputYear = args[2] == null ? (long?)null : (long)args[2];
            long? rowYear = args[3] == null ? (long?)null : (long)args[3];

            if (inputYear.HasValue && rowYear.HasValue)
            {
                var diff = Math.Abs(inputYear.Value - rowYear.Value);

                // Add if they came out within the same decade
                if (diff < 10)
                {
                    score += 2;
                }

                // And more if within five years
                if (diff < 5)
                {
                    score += 2;
                }
            }

            // genres
            score += GetListScore(args, 4, 5);

            // tags
            score += GetListScore(args, 6, 7);

            // keywords
            score += GetListScore(args, 8, 9);

            // studios
            score += GetListScore(args, 10, 11, 3);

            var rowPeopleNamesText = (args[12] as string) ?? string.Empty;
            var rowPeopleNames = rowPeopleNamesText.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries);

            foreach (var name in rowPeopleNames)
            {
                // TODO: Send along person types
                score += 3;
            }

            //Logger.Debug("Returning score {0}", score);
            return score;
        }

        private int GetListScore(object[] args, int index1, int index2, int value = 10)
        {
            var score = 0;

            var inputGenres = args[index1] as string;
            var rowGenres = args[index2] as string;
            var inputGenreList = string.IsNullOrWhiteSpace(inputGenres) ? new string[] { } : inputGenres.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries);
            var rowGenresList = string.IsNullOrWhiteSpace(rowGenres) ? new string[] { } : rowGenres.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries);

            foreach (var genre in inputGenreList)
            {
                if (rowGenresList.Contains(genre, StringComparer.OrdinalIgnoreCase))
                {
                    score += value;
                }
            }

            return score;
        }
    }
}