From 0e2a613136987e5a8eb60aebb94df4b165a7a9e2 Mon Sep 17 00:00:00 2001
From: Evan Sarkar <evan.official666@gmail.com>
Date: Sat, 28 Mar 2026 04:49:48 +0530
Subject: [PATCH] fix: respect DateTimeKind in ToDateTimeOffset

ToDateTimeOffset always used TimeZoneInfo.Local offset, which
throws 0x80070057 when passed a DateTime with DateTimeKind.Utc.
Now checks DateTimeKind and uses TimeSpan.Zero for UTC DateTimes.

Fixes #330
---
 src/Extensions/DateTimeExtensions.cs | 9 +++++++--
 tests/DateTimeExtensionsTests.cs     | 9 +++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/Extensions/DateTimeExtensions.cs b/src/Extensions/DateTimeExtensions.cs
index 153a8c71..3693a68d 100644
--- a/src/Extensions/DateTimeExtensions.cs
+++ b/src/Extensions/DateTimeExtensions.cs
@@ -8,13 +8,18 @@ namespace WinUI.TableView.Extensions;
 internal static class DateTimeExtensions
 {
     /// <summary>
-    /// Converts a DateTime to a DateTimeOffset using the local time zone.
+    /// Converts a DateTime to a DateTimeOffset, respecting the DateTime's Kind.
+    /// Uses UTC offset for UTC DateTimes and local offset otherwise.
     /// </summary>
     /// <param name="dateTime">The DateTime to convert.</param>
     /// <returns>A DateTimeOffset representing the same point in time as the DateTime.</returns>
     public static DateTimeOffset ToDateTimeOffset(this DateTime dateTime)
     {
-        return new DateTimeOffset(dateTime, TimeZoneInfo.Local.GetUtcOffset(dateTime));
+        var offset = dateTime.Kind == DateTimeKind.Utc
+            ? TimeSpan.Zero
+            : TimeZoneInfo.Local.GetUtcOffset(dateTime);
+
+        return new DateTimeOffset(dateTime, offset);
     }
 
     /// <summary>
diff --git a/tests/DateTimeExtensionsTests.cs b/tests/DateTimeExtensionsTests.cs
index 1a2159b9..2a450086 100644
--- a/tests/DateTimeExtensionsTests.cs
+++ b/tests/DateTimeExtensionsTests.cs
@@ -16,6 +16,15 @@ public void ToDateTimeOffset_FromDateTime_UsesLocalOffset()
         Assert.AreEqual(expected, dto);
     }
 
+    [TestMethod]
+    public void ToDateTimeOffset_FromUtcDateTime_UsesZeroOffset()
+    {
+        var dt = new DateTime(2024, 1, 2, 3, 4, 5, DateTimeKind.Utc);
+        var dto = dt.ToDateTimeOffset();
+        var expected = new DateTimeOffset(dt, TimeSpan.Zero);
+        Assert.AreEqual(expected, dto);
+    }
+
     [TestMethod]
     public void ToDateTimeOffset_FromTimeSpan_UsesTodayDate()
     {