From 2cf4018e336670505fed0fc18654d67ac225d810 Mon Sep 17 00:00:00 2001
From: "t.ruspekhofer" <t.ruspekhofer@gmail.com>
Date: Sat, 12 Mar 2022 23:00:37 +0100
Subject: [PATCH] reworked GetTimeZoneValue to ust the date to determine
 daylight saving times

---
 Lieb/Data/TimeZoneService.cs | 21 ++++++---------------
 Lieb/Pages/_Host.cshtml      |  5 +++--
 2 files changed, 9 insertions(+), 17 deletions(-)

diff --git a/Lieb/Data/TimeZoneService.cs b/Lieb/Data/TimeZoneService.cs
index 0def12b..1344b84 100644
--- a/Lieb/Data/TimeZoneService.cs
+++ b/Lieb/Data/TimeZoneService.cs
@@ -6,9 +6,6 @@ namespace Lieb.Data
     {
         private readonly IJSRuntime _jsRuntime;
 
-        private TimeSpan? _userOffset;
-        private int _offsetInMinutes;
-
         public TimeZoneService(IJSRuntime jsRuntime)
         {
             _jsRuntime = jsRuntime;
@@ -16,24 +13,18 @@ namespace Lieb.Data
 
         public async ValueTask<DateTimeOffset> GetLocalDateTime(DateTimeOffset dateTime)
         {
-            if (_userOffset == null)
-            {
-                _offsetInMinutes = await _jsRuntime.InvokeAsync<int>("GetTimezoneValue");
-                _userOffset = TimeSpan.FromMinutes(-_offsetInMinutes);
-            }
+                int offsetInMinutes = await _jsRuntime.InvokeAsync<int>("GetTimezoneValue", dateTime);
+                TimeSpan userOffset = TimeSpan.FromMinutes(-offsetInMinutes);
 
-            return dateTime.ToOffset(_userOffset.Value);
+            return dateTime.ToOffset(userOffset);
         }
 
         public async ValueTask<DateTimeOffset> GetUTCDateTime(DateTimeOffset dateTime)
         {
-            if (_userOffset == null)
-            {
-                _offsetInMinutes = await _jsRuntime.InvokeAsync<int>("GetTimezoneValue");
-                _userOffset = TimeSpan.FromMinutes(-_offsetInMinutes);
-            }
+            int offsetInMinutes = await _jsRuntime.InvokeAsync<int>("GetTimezoneValue", dateTime);
+            TimeSpan userOffset = TimeSpan.FromMinutes(-offsetInMinutes);
 
-            return new DateTimeOffset(dateTime.DateTime.AddMinutes(_offsetInMinutes), new TimeSpan(0));
+            return new DateTimeOffset(dateTime.DateTime.AddMinutes(offsetInMinutes), new TimeSpan(0));
         }
 
         public async ValueTask<string> GetUserTimeZone()
diff --git a/Lieb/Pages/_Host.cshtml b/Lieb/Pages/_Host.cshtml
index cf6953e..bfe1a25 100644
--- a/Lieb/Pages/_Host.cshtml
+++ b/Lieb/Pages/_Host.cshtml
@@ -8,9 +8,10 @@
 @(await Html.RenderComponentAsync<App>(RenderMode.Server))
 <!--<component type="typeof(App)" render-mode="ServerPrerendered" />-->
 <script>
-    function GetTimezoneValue() {
+    function GetTimezoneValue(dateTime) {
         // Returns the time difference in minutes between UTC time and local time.
-        return new Date().getTimezoneOffset();
+        date = new Date(dateTime);
+        return date.getTimezoneOffset();
     }
 </script>
 <script>