From cf425da609e0756445467d02509937fb435f1db7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andreas=20M=C3=BCller?= <webmaster@am-wd.de>
Date: Sun, 25 Feb 2024 09:44:36 +0100
Subject: [PATCH] Added VersionStringComparer

---
 AMWD.Common/Comparer/VersionStringComparer.cs | 86 +++++++++++++++++++
 CHANGELOG.md                                  |  1 +
 .../Comparer/VersionStringComparerTests.cs    | 67 +++++++++++++++
 3 files changed, 154 insertions(+)
 create mode 100644 AMWD.Common/Comparer/VersionStringComparer.cs
 create mode 100644 UnitTests/Common/Comparer/VersionStringComparerTests.cs

diff --git a/AMWD.Common/Comparer/VersionStringComparer.cs b/AMWD.Common/Comparer/VersionStringComparer.cs
new file mode 100644
index 0000000..aa5e1b2
--- /dev/null
+++ b/AMWD.Common/Comparer/VersionStringComparer.cs
@@ -0,0 +1,86 @@
+using System;
+using System.Collections.Generic;
+using System.Text.RegularExpressions;
+
+namespace AMWD.Common.Comparer
+{
+	/// <summary>
+	/// Defines a method to compare two <see cref="Version"/> strings.
+	/// </summary>
+#if NET8_0_OR_GREATER
+	public partial class VersionStringComparer : IComparer<string>
+	{
+		private readonly Regex _versionRegex = VersionRegex();
+#else
+
+	public class VersionStringComparer : IComparer<string>
+	{
+		private readonly Regex _versionRegex = new("([0-9.]+)");
+#endif
+
+		/// <summary>
+		/// Compares two <see cref="Version"/> strings and returns a value indicating
+		/// whether one is less than, equal to, or greater than the other.
+		/// </summary>
+		/// <param name="x">The first version string.</param>
+		/// <param name="y">The second version string.</param>
+		/// <returns>
+		/// A signed integer that indicates the relative values of x and y, as shown in the following table:
+		/// <list type="table">
+		///   <listheader>
+		///     <term>Value</term>
+		///     <description>Meaning</description>
+		///   </listheader>
+		///   <item>
+		///     <term>-1</term>
+		///     <description>x is less than y</description>
+		///   </item>
+		///   <item>
+		///     <term>0</term>
+		///     <description>x equals y</description>
+		///   </item>
+		///   <item>
+		///     <term>1</term>
+		///     <description>x is greater than y</description>
+		///   </item>
+		/// </list>
+		/// </returns>
+		public int Compare(string x, string y)
+		{
+			if (string.IsNullOrWhiteSpace(x) && string.IsNullOrWhiteSpace(y))
+				return 0;
+
+			if (string.IsNullOrWhiteSpace(x))
+				return -1;
+
+			if (string.IsNullOrWhiteSpace(y))
+				return 1;
+
+			string xMainVersion = _versionRegex.Match(x).Groups[1].Value;
+			string yMainVersion = _versionRegex.Match(y).Groups[1].Value;
+
+			string xAppendix = x.ReplaceStart(xMainVersion, "");
+			string yAppendix = y.ReplaceStart(yMainVersion, "");
+
+			if (xMainVersion.IndexOf('.') < 0)
+				xMainVersion += ".0";
+
+			if (yMainVersion.IndexOf('.') < 0)
+				yMainVersion += ".0";
+
+			var xVersion = Version.Parse(xMainVersion);
+			var yVersion = Version.Parse(yMainVersion);
+
+			int versionResult = xVersion.CompareTo(yVersion);
+			if (versionResult != 0)
+				return versionResult;
+
+			return xAppendix.CompareTo(yAppendix);
+		}
+
+#if NET8_0_OR_GREATER
+		[GeneratedRegex("([0-9.]+)")]
+		private static partial Regex VersionRegex();
+#endif
+	}
+}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e8b6cc..cb6784f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `ArReader` and `ArWriter` for Unix archives
 - `TarReader` and `TarWriter` for TAR archives
+- `VersionStringComparer` to compare version strings (SemVer)
 
 ### Changed
 
diff --git a/UnitTests/Common/Comparer/VersionStringComparerTests.cs b/UnitTests/Common/Comparer/VersionStringComparerTests.cs
new file mode 100644
index 0000000..a24d496
--- /dev/null
+++ b/UnitTests/Common/Comparer/VersionStringComparerTests.cs
@@ -0,0 +1,67 @@
+using AMWD.Common.Comparer;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace UnitTests.Common.Comparer
+{
+	[TestClass]
+	public class VersionStringComparerTests
+	{
+		[DataTestMethod]
+		[DataRow(null, "0")]
+		[DataRow("", "0")]
+		[DataRow("0", "1")]
+		[DataRow("1.0", "1.1")]
+		[DataRow("1.0.0", "1.0.1")]
+		[DataRow("1.0.0.0", "1.0.0.1")]
+		[DataRow("1.0.0.0-RC1", "1.0.0.0-RC2")]
+		public void ShouldBeLessThan(string x, string y)
+		{
+			// Arrange
+			var comparer = new VersionStringComparer();
+
+			// Act
+			int result = comparer.Compare(x, y);
+
+			// Assert
+			Assert.AreEqual(-1, result);
+		}
+
+		[DataTestMethod]
+		[DataRow("0", null)]
+		[DataRow("0", "")]
+		[DataRow("1", "0")]
+		[DataRow("1.1", "1.0")]
+		[DataRow("1.0.1", "1.0.0")]
+		[DataRow("1.0.0.1", "1.0.0.0")]
+		[DataRow("1.0.0.0-RC2", "1.0.0.0-RC1")]
+		public void ShouldBeGreaterThan(string x, string y)
+		{
+			// Arrange
+			var comparer = new VersionStringComparer();
+
+			// Act
+			int result = comparer.Compare(x, y);
+
+			// Assert
+			Assert.AreEqual(1, result);
+		}
+
+		[DataTestMethod]
+		[DataRow(null, null)]
+		[DataRow("", "")]
+		[DataRow("1", "1")]
+		[DataRow("1.2.3", "1.2.3")]
+		[DataRow("1.2.3-alpha", "1.2.3-alpha")]
+		public void ShouldBeEqual(string x, string y)
+		{
+			// Arrange
+			var comparer = new VersionStringComparer();
+
+			// Act
+			int result = comparer.Compare(x, y);
+
+			// Assert
+			Assert.AreEqual(0, result);
+		}
+	}
+}