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using System;
using System.Data;
using System.Threading;
using System.Threading.Tasks;

namespace MySql.Data.MySqlClient
{
    public partial class MySqlHelper
    {
        #region DataRow

        /// <summary>
        /// Asynchronous version of ExecuteDataRow.
        /// </summary>
        /// <param name="connectionString">The settings to be used for the connection.</param>
        /// <param name="commandText">The command to execute.</param>
        /// <param name="parms">The parameters to use for the command.</param>
        /// <returns>The DataRow containing the first row of the resultset.</returns>
        public static Task<DataRow> ExecuteDataRowAsync(string connectionString, string commandText, params MySqlParameter[] parms)
        {
            return ExecuteDataRowAsync(connectionString, commandText, CancellationToken.None, parms);
        }

        /// <summary>
        /// Asynchronous version of ExecuteDataRow.
        /// </summary>
        /// <param name="connectionString">The settings to be used for the connection.</param>
        /// <param name="commandText">The command to execute.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <param name="parms">The parameters to use for the command.</param>
        /// <returns>The DataRow containing the first row of the resultset.</returns>
        public static Task<DataRow> ExecuteDataRowAsync(string connectionString, string commandText, CancellationToken cancellationToken, params MySqlParameter[] parms)
        {
            var result = new TaskCompletionSource<DataRow>();
            if (cancellationToken == CancellationToken.None || !cancellationToken.IsCancellationRequested)
            {
                try
                {
                    var row = ExecuteDataRow(connectionString, commandText, parms);
                    result.SetResult(row);
                }
                catch (Exception ex)
                {
                    result.SetException(ex);
                }
            }
            else
            {
                result.SetCanceled();
            }

            return result.Task;
        }
        #endregion

        #region DataSet

        /// <summary>
        /// Executes a single SQL command and returns the first row of the resultset.  A new MySqlConnection object
        /// is created, opened, and closed during this method.
        /// </summary>
        /// <param name="connectionString">Settings to be used for the connection</param>
        /// <param name="commandText">Command to execute</param>
        /// <param name="parms">Parameters to use for the command</param>
        /// <returns>DataRow containing the first row of the resultset</returns>
        public static DataRow ExecuteDataRow(string connectionString, string commandText, params MySqlParameter[] parms)
        {
            DataSet ds = ExecuteDataset(connectionString, commandText, parms);
            if (ds == null)
            {
                return null;
            }

            if (ds.Tables.Count == 0)
            {
                return null;
            }

            if (ds.Tables[0].Rows.Count == 0)
            {
                return null;
            }

            return ds.Tables[0].Rows[0];
        }

        /// <summary>
        /// Executes a single SQL command and returns the resultset in a <see cref="DataSet"/>.  
        /// A new MySqlConnection object is created, opened, and closed during this method.
        /// </summary>
        /// <param name="connectionString">Settings to be used for the connection</param>
        /// <param name="commandText">Command to execute</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static DataSet ExecuteDataset(string connectionString, string commandText)
        {
            // pass through the call providing null for the set of SqlParameters
            return ExecuteDataset(connectionString, commandText, (MySqlParameter[])null);
        }

        /// <summary>
        /// Executes a single SQL command and returns the resultset in a <see cref="DataSet"/>.  
        /// A new MySqlConnection object is created, opened, and closed during this method.
        /// </summary>
        /// <param name="connectionString">Settings to be used for the connection</param>
        /// <param name="commandText">Command to execute</param>
        /// <param name="commandParameters">Parameters to use for the command</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static DataSet ExecuteDataset(string connectionString, string commandText, params MySqlParameter[] commandParameters)
        {
            // create & open a SqlConnection, and dispose of it after we are done.
            using (MySqlConnection cn = new MySqlConnection(connectionString))
            {
                cn.Open();

                // call the overload that takes a connection in place of the connection string
                return ExecuteDataset(cn, commandText, commandParameters);
            }
        }

        /// <summary>
        /// Executes a single SQL command and returns the resultset in a <see cref="DataSet"/>.  
        /// The state of the <see cref="MySqlConnection"/> object remains unchanged after execution
        /// of this method.
        /// </summary>
        /// <param name="connection"><see cref="MySqlConnection"/> object to use</param>
        /// <param name="commandText">Command to execute</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static DataSet ExecuteDataset(MySqlConnection connection, string commandText)
        {
            // pass through the call providing null for the set of SqlParameters
            return ExecuteDataset(connection, commandText, (MySqlParameter[])null);
        }

        /// <summary>
        /// Executes a single SQL command and returns the resultset in a <see cref="DataSet"/>.  
        /// The state of the <see cref="MySqlConnection"/> object remains unchanged after execution
        /// of this method.
        /// </summary>
        /// <param name="connection"><see cref="MySqlConnection"/> object to use</param>
        /// <param name="commandText">Command to execute</param>
        /// <param name="commandParameters">Parameters to use for the command</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static DataSet ExecuteDataset(MySqlConnection connection, string commandText, params MySqlParameter[] commandParameters)
        {
            // create a command and prepare it for execution
            MySqlCommand cmd = new MySqlCommand();
            cmd.Connection = connection;
            cmd.CommandText = commandText;
            cmd.CommandType = CommandType.Text;

            if (commandParameters != null)
            {
                foreach (MySqlParameter p in commandParameters)
                {
                    cmd.Parameters.Add(p);
                }
            }

            // create the DataAdapter & DataSet
            MySqlDataAdapter da = new MySqlDataAdapter(cmd);
            DataSet ds = new DataSet();

            // fill the DataSet using default values for DataTable names, etc.
            da.Fill(ds);

            // detach the MySqlParameters from the command object, so they can be used again.			
            cmd.Parameters.Clear();

            // return the dataset
            return ds;
        }

        /// <summary>
        /// Updates the given table with data from the given <see cref="DataSet"/>
        /// </summary>
        /// <param name="connectionString">Settings to use for the update</param>
        /// <param name="commandText">Command text to use for the update</param>
        /// <param name="ds"><see cref="DataSet"/> containing the new data to use in the update</param>
        /// <param name="tablename">Tablename in the dataset to update</param>
        public static void UpdateDataSet(string connectionString, string commandText, DataSet ds, string tablename)
        {
            MySqlConnection cn = new MySqlConnection(connectionString);
            cn.Open();
            MySqlDataAdapter da = new MySqlDataAdapter(commandText, cn);
            MySqlCommandBuilder cb = new MySqlCommandBuilder(da);
            cb.ToString();
            da.Update(ds, tablename);
            cn.Close();
        }

        /// <summary>
        /// Async version of ExecuteDataset
        /// </summary>
        /// <param name="connectionString">Settings to be used for the connection</param>
        /// <param name="commandText">Command to execute</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static Task<DataSet> ExecuteDatasetAsync(string connectionString, string commandText)
        {
            return ExecuteDatasetAsync(connectionString, commandText, CancellationToken.None, (MySqlParameter[])null);
        }

        public static Task<DataSet> ExecuteDatasetAsync(string connectionString, string commandText, CancellationToken cancellationToken)
        {
            return ExecuteDatasetAsync(connectionString, commandText, cancellationToken, (MySqlParameter[])null);
        }

        /// <summary>
        /// Async version of ExecuteDataset
        /// </summary>
        /// <param name="connectionString">Settings to be used for the connection</param>
        /// <param name="commandText">Command to execute</param>
        /// <param name="commandParameters">Parameters to use for the command</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static Task<DataSet> ExecuteDatasetAsync(string connectionString, string commandText, params MySqlParameter[] commandParameters)
        {
            return ExecuteDatasetAsync(connectionString, commandText, CancellationToken.None, commandParameters);
        }

        public static Task<DataSet> ExecuteDatasetAsync(string connectionString, string commandText, CancellationToken cancellationToken, params MySqlParameter[] commandParameters)
        {
            var result = new TaskCompletionSource<DataSet>();
            if (cancellationToken == CancellationToken.None || !cancellationToken.IsCancellationRequested)
            {
                try
                {
                    var dataset = ExecuteDataset(connectionString, commandText, commandParameters);
                    result.SetResult(dataset);
                }
                catch (Exception ex)
                {
                    result.SetException(ex);
                }
            }
            else
            {
                result.SetCanceled();
            }

            return result.Task;
        }

        /// <summary>
        /// Async version of ExecuteDataset
        /// </summary>
        /// <param name="connection"><see cref="MySqlConnection"/> object to use</param>
        /// <param name="commandText">Command to execute</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static Task<DataSet> ExecuteDatasetAsync(MySqlConnection connection, string commandText)
        {
            return ExecuteDatasetAsync(connection, commandText, CancellationToken.None, (MySqlParameter[])null);
        }

        public static Task<DataSet> ExecuteDatasetAsync(MySqlConnection connection, string commandText, CancellationToken cancellationToken)
        {
            return ExecuteDatasetAsync(connection, commandText, cancellationToken, (MySqlParameter[])null);
        }

        /// <summary>
        /// Async version of ExecuteDataset
        /// </summary>
        /// <param name="connection"><see cref="MySqlConnection"/> object to use</param>
        /// <param name="commandText">Command to execute</param>
        /// <param name="commandParameters">Parameters to use for the command</param>
        /// <returns><see cref="DataSet"/> containing the resultset</returns>
        public static Task<DataSet> ExecuteDatasetAsync(MySqlConnection connection, string commandText, params MySqlParameter[] commandParameters)
        {
            return ExecuteDatasetAsync(connection, commandText, CancellationToken.None, commandParameters);
        }

        public static Task<DataSet> ExecuteDatasetAsync(MySqlConnection connection, string commandText, CancellationToken cancellationToken, params MySqlParameter[] commandParameters)
        {
            var result = new TaskCompletionSource<DataSet>();
            if (cancellationToken == CancellationToken.None || !cancellationToken.IsCancellationRequested)
            {
                try
                {
                    var dataset = ExecuteDataset(connection, commandText, commandParameters);
                    result.SetResult(dataset);
                }
                catch (Exception ex)
                {
                    result.SetException(ex);
                }
            }
            else
            {
                result.SetCanceled();
            }

            return result.Task;
        }

        /// <summary>
        /// Async version of UpdateDataset
        /// </summary>
        /// <param name="connectionString">Settings to use for the update</param>
        /// <param name="commandText">Command text to use for the update</param>
        /// <param name="ds"><see cref="DataSet"/> containing the new data to use in the update</param>
        /// <param name="tablename">Tablename in the dataset to update</param>
        public static Task UpdateDataSetAsync(string connectionString, string commandText, DataSet ds, string tablename)
        {
            return UpdateDataSetAsync(connectionString, commandText, ds, tablename, CancellationToken.None);
        }

        public static Task UpdateDataSetAsync(string connectionString, string commandText, DataSet ds, string tablename, CancellationToken cancellationToken)
        {
            var result = new TaskCompletionSource<bool>();
            if (cancellationToken == CancellationToken.None || !cancellationToken.IsCancellationRequested)
            {
                try
                {
                    UpdateDataSet(connectionString, commandText, ds, tablename);
                    result.SetResult(true);
                }
                catch (Exception ex)
                {
                    result.SetException(ex);
                }
            }
            else
            {
                result.SetCanceled();
            }

            return result.Task;
        }


        #endregion

    }
}