Add BytesValueConverter

app/Desktop/App.axaml

@@ -105,6 +105,7 @@
     <Application.Resources>
 
         <common:NumberValueConverter x:Key="NumberValueConverter" />
+        <common:BytesValueConverter x:Key="BytesValueConverter" />
 
         <system:Double x:Key="ControlContentThemeFontSize">14</system:Double>
         <CornerRadius x:Key="ControlCornerRadius">0</CornerRadius>

app/Desktop/Common/BytesValueConverter.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Globalization;
+using Avalonia.Data.Converters;
+
+namespace DHT.Desktop.Common {
+	sealed class BytesValueConverter : IValueConverter {
+		private static readonly string[] Units = {
+			"B",
+			"kB",
+			"MB",
+			"GB",
+			"TB"
+		};
+
+		private const int Scale = 1000;
+
+		private static string Convert(ulong size) {
+			int power = size == 0L ? 0 : (int) Math.Log(size, Scale);
+			int unit = power >= Units.Length ? Units.Length - 1 : power;
+			if (unit == 0) {
+				return string.Format(Program.Culture, "{0:n0}", size) + " " + Units[unit];
+			}
+			else {
+				double humanReadableSize = size / Math.Pow(Scale, unit);
+				return string.Format(Program.Culture, "{0:n0}", humanReadableSize) + " " + Units[unit];
+			}
+		}
+
+		public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture) {
+			if (value is long size and >= 0L) {
+				return Convert((ulong) size);
+			}
+			else if (value is ulong usize) {
+				return Convert(usize);
+			}
+			else {
+				return "-";
+			}
+		}
+
+		public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture) {
+			throw new NotSupportedException();
+		}
+	}
+}