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

namespace MediaBrowser.Server.Implementations.Persistence
{
    /// <summary>
    /// Class SQLiteUserRepository
    /// </summary>
    public class SqliteUserRepository : BaseSqliteRepository, IUserRepository
    {
        private IDbConnection _connection;
        private readonly IServerApplicationPaths _appPaths;
        private readonly IJsonSerializer _jsonSerializer;

        public SqliteUserRepository(ILogManager logManager, IServerApplicationPaths appPaths, IJsonSerializer jsonSerializer) : base(logManager)
        {
            _appPaths = appPaths;
            _jsonSerializer = jsonSerializer;
        }

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

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

            _connection = await SqliteExtensions.ConnectToDb(dbFile, Logger).ConfigureAwait(false);
            
            string[] queries = {

                                "create table if not exists users (guid GUID primary key, data BLOB)",
                                "create index if not exists idx_users on users(guid)",
                                "create table if not exists schema_version (table_name primary key, version)",

                                //pragmas
                                "pragma temp_store = memory",

                                "pragma shrink_memory"
                               };

            _connection.RunQueries(queries, Logger);
        }

        /// <summary>
        /// Save a user in the repo
        /// </summary>
        /// <param name="user">The user.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        /// <exception cref="System.ArgumentNullException">user</exception>
        public async Task SaveUser(User user, CancellationToken cancellationToken)
        {
            if (user == null)
            {
                throw new ArgumentNullException("user");
            }

            cancellationToken.ThrowIfCancellationRequested();

            var serialized = _jsonSerializer.SerializeToBytes(user);

            cancellationToken.ThrowIfCancellationRequested();

            await WriteLock.WaitAsync(cancellationToken).ConfigureAwait(false);
            
            IDbTransaction transaction = null;

            try
            {
                transaction = _connection.BeginTransaction();

                using (var cmd = _connection.CreateCommand())
                {
                    cmd.CommandText = "replace into users (guid, data) values (@1, @2)";
                    cmd.Parameters.Add(cmd, "@1", DbType.Guid).Value = user.Id;
                    cmd.Parameters.Add(cmd, "@2", DbType.Binary).Value = serialized;

                    cmd.Transaction = transaction;

                    cmd.ExecuteNonQuery();
                }

                transaction.Commit();
            }
            catch (OperationCanceledException)
            {
                if (transaction != null)
                {
                    transaction.Rollback();
                }

                throw;
            }
            catch (Exception e)
            {
                Logger.ErrorException("Failed to save user:", e);

                if (transaction != null)
                {
                    transaction.Rollback();
                }

                throw;
            }
            finally
            {
                if (transaction != null)
                {
                    transaction.Dispose();
                }

                WriteLock.Release();
            }
        }

        /// <summary>
        /// Retrieve all users from the database
        /// </summary>
        /// <returns>IEnumerable{User}.</returns>
        public IEnumerable<User> RetrieveAllUsers()
        {
            using (var cmd = _connection.CreateCommand())
            {
                cmd.CommandText = "select data from users";

                using (var reader = cmd.ExecuteReader(CommandBehavior.SequentialAccess | CommandBehavior.SingleResult))
                {
                    while (reader.Read())
                    {
                        using (var stream = reader.GetMemoryStream(0))
                        {
                            var user = _jsonSerializer.DeserializeFromStream<User>(stream);
                            yield return user;
                        }
                    }
                }
            }
        }

        /// <summary>
        /// Deletes the user.
        /// </summary>
        /// <param name="user">The user.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        /// <exception cref="System.ArgumentNullException">user</exception>
        public async Task DeleteUser(User user, CancellationToken cancellationToken)
        {
            if (user == null)
            {
                throw new ArgumentNullException("user");
            }

            cancellationToken.ThrowIfCancellationRequested();

            await WriteLock.WaitAsync(cancellationToken).ConfigureAwait(false);

            IDbTransaction transaction = null;

            try
            {
                transaction = _connection.BeginTransaction();

                using (var cmd = _connection.CreateCommand())
                {
                    cmd.CommandText = "delete from users where guid=@guid";

                    cmd.Parameters.Add(cmd, "@guid", DbType.Guid).Value = user.Id;

                    cmd.Transaction = transaction;

                    cmd.ExecuteNonQuery();
                }

                transaction.Commit();
            }
            catch (OperationCanceledException)
            {
                if (transaction != null)
                {
                    transaction.Rollback();
                }

                throw;
            }
            catch (Exception e)
            {
                Logger.ErrorException("Failed to delete user:", e);

                if (transaction != null)
                {
                    transaction.Rollback();
                }

                throw;
            }
            finally
            {
                if (transaction != null)
                {
                    transaction.Dispose();
                }

                WriteLock.Release();
            }
        }

        protected override void CloseConnection()
        {
            if (_connection != null)
            {
                if (_connection.IsOpen())
                {
                    _connection.Close();
                }

                _connection.Dispose();
                _connection = null;
            }
        }
    }
}