UI timezone

DiunaBI.UI.Shared/Services/DateTimeHelper.cs

@@ -0,0 +1,80 @@
+using Microsoft.JSInterop;
+
+namespace DiunaBI.UI.Shared.Services;
+
+public class DateTimeHelper
+{
+    private readonly IJSRuntime _jsRuntime;
+    private TimeZoneInfo? _userTimeZone;
+    private bool _initialized = false;
+
+    public DateTimeHelper(IJSRuntime jsRuntime)
+    {
+        _jsRuntime = jsRuntime;
+    }
+
+    public async Task InitializeAsync()
+    {
+        if (_initialized) return;
+
+        try
+        {
+            // Get the user's timezone from JavaScript
+            var timeZoneId = await _jsRuntime.InvokeAsync<string>("eval", "Intl.DateTimeFormat().resolvedOptions().timeZone");
+
+            // Try to find the TimeZoneInfo
+            try
+            {
+                _userTimeZone = TimeZoneInfo.FindSystemTimeZoneById(timeZoneId);
+            }
+            catch
+            {
+                // Fallback to local timezone if the IANA timezone ID is not found
+                _userTimeZone = TimeZoneInfo.Local;
+            }
+        }
+        catch
+        {
+            // Fallback to local timezone if JavaScript interop fails
+            _userTimeZone = TimeZoneInfo.Local;
+        }
+
+        _initialized = true;
+    }
+
+    public string FormatDateTime(DateTime? dateTime, string format = "yyyy-MM-dd HH:mm:ss")
+    {
+        if (!dateTime.HasValue)
+            return "-";
+
+        if (!_initialized)
+        {
+            // If not initialized yet, just format as-is (will be UTC)
+            return dateTime.Value.ToString(format);
+        }
+
+        // Convert UTC to user's timezone
+        var localDateTime = TimeZoneInfo.ConvertTimeFromUtc(dateTime.Value, _userTimeZone ?? TimeZoneInfo.Local);
+        return localDateTime.ToString(format);
+    }
+
+    public string FormatDate(DateTime? dateTime, string format = "yyyy-MM-dd")
+    {
+        return FormatDateTime(dateTime, format);
+    }
+
+    public string FormatTime(DateTime? dateTime, string format = "HH:mm:ss")
+    {
+        return FormatDateTime(dateTime, format);
+    }
+
+    public string GetTimeZoneAbbreviation()
+    {
+        if (!_initialized || _userTimeZone == null)
+            return "UTC";
+
+        return _userTimeZone.IsDaylightSavingTime(DateTime.Now)
+            ? _userTimeZone.DaylightName
+            : _userTimeZone.StandardName;
+    }
+}