using MediaBrowser.Common.Configuration;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Persistence;
using MediaBrowser.Model.Logging;
using MediaBrowser.Model.Serialization;
using System;
using System.Collections.Concurrent;
using System.Data;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

namespace MediaBrowser.Server.Implementations.Sqlite
{
    /// <summary>
    /// Class SQLiteUserDataRepository
    /// </summary>
    public class SQLiteUserDataRepository : SqliteRepository, IUserDataRepository
    {
        private readonly ConcurrentDictionary<string, Task<UserItemData>> _userData = new ConcurrentDictionary<string, Task<UserItemData>>();
        
        /// <summary>
        /// The repository name
        /// </summary>
        public const string RepositoryName = "SQLite";

        /// <summary>
        /// Gets the name of the repository
        /// </summary>
        /// <value>The name.</value>
        public string Name
        {
            get
            {
                return RepositoryName;
            }
        }

        /// <summary>
        /// Gets a value indicating whether [enable delayed commands].
        /// </summary>
        /// <value><c>true</c> if [enable delayed commands]; otherwise, <c>false</c>.</value>
        protected override bool EnableDelayedCommands
        {
            get
            {
                return false;
            }
        }
        
        private readonly IJsonSerializer _jsonSerializer;

        /// <summary>
        /// The _app paths
        /// </summary>
        private readonly IApplicationPaths _appPaths;

        /// <summary>
        /// Initializes a new instance of the <see cref="SQLiteUserDataRepository" /> class.
        /// </summary>
        /// <param name="appPaths">The app paths.</param>
        /// <param name="jsonSerializer">The json serializer.</param>
        /// <param name="logManager">The log manager.</param>
        /// <exception cref="System.ArgumentNullException">
        /// jsonSerializer
        /// or
        /// appPaths
        /// </exception>
        public SQLiteUserDataRepository(IApplicationPaths appPaths, IJsonSerializer jsonSerializer, ILogManager logManager)
            : base(logManager)
        {
            if (jsonSerializer == null)
            {
                throw new ArgumentNullException("jsonSerializer");
            }
            if (appPaths == null)
            {
                throw new ArgumentNullException("appPaths");
            }

            _jsonSerializer = jsonSerializer;
            _appPaths = appPaths;
        }

        /// <summary>
        /// Opens the connection to the database
        /// </summary>
        /// <returns>Task.</returns>
        public async Task Initialize()
        {
            var dbFile = Path.Combine(_appPaths.DataPath, "userdata.db");

            await ConnectToDb(dbFile).ConfigureAwait(false);

            string[] queries = {

                                "create table if not exists useritemdata (key nvarchar, userId GUID, Rating float null, PlaybackPositionTicks bigint, PlayCount int, IsFavorite bit, Played bit, LastPlayedDate bigint null)",
                                "create unique index if not exists useritemdataindex on useritemdata (key, userId)",
                                
                                "create table if not exists schema_version (table_name primary key, version)",
                                //pragmas
                                "pragma temp_store = memory"
                               };

            RunQueries(queries);
        }

        /// <summary>
        /// Saves the user data.
        /// </summary>
        /// <param name="userId">The user id.</param>
        /// <param name="key">The key.</param>
        /// <param name="userData">The user data.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        /// <exception cref="System.ArgumentNullException">userData
        /// or
        /// cancellationToken
        /// or
        /// userId
        /// or
        /// userDataId</exception>
        public async Task SaveUserData(Guid userId, string key, UserItemData userData, CancellationToken cancellationToken)
        {
            if (userData == null)
            {
                throw new ArgumentNullException("userData");
            }
            if (cancellationToken == null)
            {
                throw new ArgumentNullException("cancellationToken");
            }
            if (userId == Guid.Empty)
            {
                throw new ArgumentNullException("userId");
            }
            if (string.IsNullOrEmpty(key))
            {
                throw new ArgumentNullException("key");
            }

            cancellationToken.ThrowIfCancellationRequested();

            try
            {
                await PersistUserData(userId, key, userData, cancellationToken).ConfigureAwait(false);

                var newValue = Task.FromResult(userData);

                // Once it succeeds, put it into the dictionary to make it available to everyone else
                _userData.AddOrUpdate(GetInternalKey(userId, key), newValue, delegate { return newValue; });
            }
            catch (Exception ex)
            {
                Logger.ErrorException("Error saving user data", ex);

                throw;
            }
        }

        /// <summary>
        /// Gets the internal key.
        /// </summary>
        /// <param name="userId">The user id.</param>
        /// <param name="key">The key.</param>
        /// <returns>System.String.</returns>
        private string GetInternalKey(Guid userId, string key)
        {
            return userId + key;
        }

        /// <summary>
        /// Persists the user data.
        /// </summary>
        /// <param name="userId">The user id.</param>
        /// <param name="key">The key.</param>
        /// <param name="userData">The user data.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        public async Task PersistUserData(Guid userId, string key, UserItemData userData, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();

            using (var cmd = connection.CreateCommand())
            {
                cmd.CommandText = "replace into useritemdata (key, userId, Rating,PlaybackPositionTicks,PlayCount,IsFavorite,Played,LastPlayedDate) values (@1, @2, @3, @4, @5, @6, @7, @8)";
                cmd.AddParam("@1", key);
                cmd.AddParam("@2", userId);

                cmd.AddParam("@3", userData.Rating);
                cmd.AddParam("@4", userData.PlaybackPositionTicks);
                cmd.AddParam("@5", userData.PlayCount);
                cmd.AddParam("@6", userData.IsFavorite);
                cmd.AddParam("@7", userData.Played);

                if (userData.LastPlayedDate.HasValue)
                {
                    cmd.AddParam("@8", userData.LastPlayedDate.Value.Ticks);
                }
                else
                {
                    cmd.AddParam("@8", null);
                }

                using (var tran = connection.BeginTransaction())
                {
                    try
                    {
                        cmd.Transaction = tran;

                        await cmd.ExecuteNonQueryAsync(cancellationToken);

                        tran.Commit();
                    }
                    catch (OperationCanceledException)
                    {
                        tran.Rollback();
                    }
                    catch (Exception e)
                    {
                        Logger.ErrorException("Failed to commit transaction.", e);
                        tran.Rollback();
                    }
                }
            }
        }

        /// <summary>
        /// Gets the user data.
        /// </summary>
        /// <param name="userId">The user id.</param>
        /// <param name="key">The key.</param>
        /// <returns>Task{UserItemData}.</returns>
        /// <exception cref="System.ArgumentNullException">
        /// userId
        /// or
        /// key
        /// </exception>
        public Task<UserItemData> GetUserData(Guid userId, string key)
        {
            if (userId == Guid.Empty)
            {
                throw new ArgumentNullException("userId");
            }
            if (string.IsNullOrEmpty(key))
            {
                throw new ArgumentNullException("key");
            }
            
            return _userData.GetOrAdd(GetInternalKey(userId, key), keyName => RetrieveUserData(userId, key));
        }

        /// <summary>
        /// Retrieves the user data.
        /// </summary>
        /// <param name="userId">The user id.</param>
        /// <param name="key">The key.</param>
        /// <returns>Task{UserItemData}.</returns>
        private async Task<UserItemData> RetrieveUserData(Guid userId, string key)
        {
            using (var cmd = connection.CreateCommand())
            {
                cmd.CommandText = "select Rating,PlaybackPositionTicks,PlayCount,IsFavorite,Played,LastPlayedDate from useritemdata where key = @key and userId=@userId";

                var idParam = cmd.Parameters.Add("@key", DbType.String);
                idParam.Value = key;

                var userIdParam = cmd.Parameters.Add("@userId", DbType.Guid);
                userIdParam.Value = userId;

                var userdata = new UserItemData();

                using (var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SequentialAccess | CommandBehavior.SingleResult | CommandBehavior.SingleRow).ConfigureAwait(false))
                {
                    if (reader.Read())
                    {
                        if (!reader.IsDBNull(0))
                        {
                            userdata.Rating = reader.GetDouble(0);
                        }
                        userdata.PlaybackPositionTicks = reader.GetInt64(1);
                        userdata.PlayCount = reader.GetInt32(2);
                        userdata.IsFavorite = reader.GetBoolean(3);
                        userdata.Played = reader.GetBoolean(4);

                        var ticks = (long?) reader.GetValue(5);

                        if (ticks.HasValue)
                        {
                            userdata.LastPlayedDate = new DateTime(ticks.Value);
                        }
                    }
                }

                return userdata;
            }
        }
    }
}