// Copyright (c) 2020-present schick Informatik
// Description: The new and mighty DB manager that uses async methods and 
// connection pooling.. will try it out in Maersk/PO numbers and expand over the whole
// app later

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

using log4net;

namespace bsmd.database
{
    public static class DBManagerAsync
    {
        #region Fields

        private static ILog _log = LogManager.GetLogger(typeof(DBManagerAsync));
        private static readonly SemaphoreSlim _asyncSemaphore = new SemaphoreSlim(1);

        #endregion

        #region Properties

        public static string ConnectionString { get; set; }

        #endregion

        #region public methods



        #endregion

        #region async DB access methods

        

        internal static async Task<SqlDataReader> PerformCommandAsync(SqlCommand cmd)
        {
            SqlDataReader reader = null;

            // await _asyncSemaphore.WaitAsync();
            try
            {
                using (SqlConnection connection = new SqlConnection(ConnectionString))
                {
                    await connection.OpenAsync();
                    reader = await cmd.ExecuteReaderAsync();
                }
            }
            catch (SqlException ex)
            {
                Trace.WriteLine("SQL Exception:" + ex.Message);
                _log.Error("Error performing command", ex);
                _log.DebugFormat("Query: {0}", cmd.CommandText);
                _log.Debug("Parameters:");
                for (int i = 0; i < cmd.Parameters.Count; i++)
                {
                    _log.DebugFormat("{0}:{1}", cmd.Parameters[i].ParameterName, cmd.Parameters[i].Value);
                }
            }
            finally
            {
                // _asyncSemaphore.Release();
            }

            return reader;
        }

        internal static async Task<int> PerformNonQuery(SqlCommand cmd)
        {
            int result = -1;
            // await _asyncSemaphore.WaitAsync();
            try
            {
                using (SqlConnection connection = new SqlConnection(ConnectionString))
                {
                    await connection.OpenAsync();
                    result = await cmd.ExecuteNonQueryAsync();
                }
            }
            catch (SqlException ex)
            {
                Trace.WriteLine("SQL Exception:" + ex.Message);
                _log.Error("Error performing command", ex);
                _log.DebugFormat("Query: {0}", cmd.CommandText);
                _log.Debug("Parameters:");
                for (int i = 0; i < cmd.Parameters.Count; i++)
                {
                    _log.DebugFormat("{0}:{1}", cmd.Parameters[i].ParameterName, cmd.Parameters[i].Value);
                }
            }

            return result;
        }

        internal static async Task<int?> PerformReadIntQuery(SqlCommand cmd)
        {
            int? result = null;

            try
            {
                using (SqlConnection connection = new SqlConnection(ConnectionString))
                {
                    object r = await cmd.ExecuteScalarAsync();
                    if (r == null) { result = null; }
                    else if (r == DBNull.Value) { result = null; }
                    else { result = (int)r; }
                }
            }
            catch (SqlException ex)
            {
                _log.Error("Error performing command", ex);
                _log.DebugFormat("Query: {0}", cmd.CommandText);
                _log.Debug("Parameters:");
                for (int i = 0; i < cmd.Parameters.Count; i++)
                {
                    _log.DebugFormat("{0}:{1}", cmd.Parameters[i].ParameterName, cmd.Parameters[i].Value);
                }
            }

            return result;
        }

        #endregion

    }
}