common/CordonelAssemblyLine/Model/ExeConfig.cs

namespace CordonelAssemblyLine.Model
{
    using System.Configuration;
    using System.Linq;
    using System.Runtime.CompilerServices;

    public class ExeConfig
    {
        public static readonly string DllFilePath 
             = typeof(ExeConfig).Assembly.Location;
        public static readonly ExeConfig Current = new ExeConfig();

        public int PickingSlot
        {
            get
            {
                _ = int.TryParse(GetValue(), out var value);

                return value;
            }
            set => SetValue(value);
        }

        public string PickingBarcode
        {
            get => GetValue();
            set => SetValue(value);
        }

        public int LeakSlot
        {
            get
            {
                _ = int.TryParse(GetValue(), out var value);

                return value;
            }
            set => SetValue(value);
        }

        public int LeakStationId
        {
            get
            {
                _ = int.TryParse(GetValue(), out var value);

                return value;
            }
            set => SetValue(value);
        }

        public string LeakTester
        {
            get => GetValue();
            set => SetValue(value);
        }

        public int MarriageSlot
        {
            get
            {
                _ = int.TryParse(GetValue(), out var value);

                return value;
            }
            set => SetValue(value);
        }

        public string MarriageBarcode
        {
            get => GetValue();
            set => SetValue(value);
        }

        private static string GetValue([CallerMemberName] string key = "")
        {
            if (string.IsNullOrWhiteSpace(key))
            {
                return default(string);
            }
            
            var configuration = ConfigurationManager.OpenExeConfiguration(DllFilePath);
            var settings = configuration?.AppSettings?.Settings ?? new KeyValueConfigurationCollection();

            if (!settings.AllKeys.Contains(key))
            {
                return default(string);
            }

            return settings[key].Value;
        }

        private static void SetValue(object value, [CallerMemberName] string key = "")
        {
            if (string.IsNullOrWhiteSpace(key))
            {
                return;
            }

            var dll = typeof(ExeConfig).Assembly.Location;
            var configuration = ConfigurationManager.OpenExeConfiguration(DllFilePath);
            var settings = configuration?.AppSettings?.Settings ?? new KeyValueConfigurationCollection();

            if (!settings.AllKeys.Contains(key))
            {
                settings.Add(key, string.Empty);
            }

            settings[key].Value = $"{value}";

            configuration.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");
        }
    }
}