Refactor last commit

DiscordChatExporter.Gui/Converters/TimeSpanToDateTimeConverter.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Globalization;
+using System.Windows.Data;
+
+namespace DiscordChatExporter.Gui.Converters
+{
+    [ValueConversion(typeof(TimeSpan?), typeof(DateTime?))]
+    public class TimeSpanToDateTimeConverter : IValueConverter
+    {
+        public static TimeSpanToDateTimeConverter Instance { get; } = new TimeSpanToDateTimeConverter();
+
+        public object? Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is TimeSpan timeSpanValue)
+                return DateTime.Today.Add(timeSpanValue);
+
+            return default(DateTime?);
+        }
+
+        public object? ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is DateTime dateTimeValue)
+                return dateTimeValue.TimeOfDay;
+
+            return default(TimeSpan?);
+        }
+    }
+}