Local time rendering for events.

Wino.Calendar.ViewModels/Data/CalendarItemViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.ObjectModel;
+using System.Diagnostics;
 using CommunityToolkit.Mvvm.ComponentModel;
 using Itenso.TimePeriod;
 using Wino.Core.Domain.Entities.Calendar;
@@ -22,6 +23,16 @@ public partial class CalendarItemViewModel : ObservableObject, ICalendarItem, IC
 
     public DateTime EndDateTime => CalendarItem.EndDateTime;
 
+    /// <summary>
+    /// Gets the start date and time in the local time zone for display purposes.
+    /// </summary>
+    public DateTime LocalStartDateTime => ConvertToLocalTime();
+
+    /// <summary>
+    /// Gets the end date and time in the local time zone for display purposes.
+    /// </summary>
+    public DateTime LocalEndDateTime => ConvertToLocalTime();
+
     public ITimePeriod Period => CalendarItem.Period;
 
     public bool IsRecurringEvent => !string.IsNullOrEmpty(CalendarItem.RecurrenceRules) || !string.IsNullOrEmpty(CalendarItem.RecurringEventId);
@@ -31,11 +42,50 @@ public partial class CalendarItemViewModel : ObservableObject, ICalendarItem, IC
 
     public ObservableCollection<CalendarEventAttendee> Attendees { get; } = new ObservableCollection<CalendarEventAttendee>();
 
-    public CalendarItemType ItemType => ((ICalendarItem)CalendarItem).ItemType;
+    public CalendarItemType ItemType => CalendarItem.ItemType;
 
     public CalendarItemViewModel(CalendarItem calendarItem)
     {
         CalendarItem = calendarItem;
+
+        Debug.WriteLine($"{Title} : {ItemType}");
+    }
+
+    /// <summary>
+    /// Converts a DateTime to local time based on the provided timezone.
+    /// If timezone is empty or null, assumes the DateTime is in UTC.
+    /// </summary>
+    /// <param name="dateTime">The DateTime to convert</param>
+    /// <param name="timeZone">The timezone string. If empty/null, assumes UTC.</param>
+    /// <returns>DateTime converted to local time</returns>
+    private DateTime ConvertToLocalTime()
+    {
+        // All day events ignore time zones and are treated as local time.
+        if (ItemType == CalendarItemType.AllDay || ItemType == CalendarItemType.MultiDayAllDay || ItemType == CalendarItemType.RecurringAllDay)
+            return CalendarItem.StartDateTime;
+
+        if (string.IsNullOrEmpty(CalendarItem.TimeZone))
+        {
+            // If no timezone specified, assume it's UTC and convert to local time
+            return DateTime.SpecifyKind(CalendarItem.StartDateTime, DateTimeKind.Utc).ToLocalTime();
+        }
+
+        try
+        {
+            // Parse the timezone and convert to local time
+            var sourceTimeZone = TimeZoneInfo.FindSystemTimeZoneById(CalendarItem.TimeZone);
+            return TimeZoneInfo.ConvertTimeToUtc(CalendarItem.StartDateTime, sourceTimeZone).ToLocalTime();
+        }
+        catch (TimeZoneNotFoundException)
+        {
+            // If timezone is not found, fallback to treating as UTC
+            return DateTime.SpecifyKind(CalendarItem.StartDateTime, DateTimeKind.Utc).ToLocalTime();
+        }
+        catch (InvalidTimeZoneException)
+        {
+            // If timezone is invalid, fallback to treating as UTC
+            return DateTime.SpecifyKind(CalendarItem.StartDateTime, DateTimeKind.Utc).ToLocalTime();
+        }
     }
 
     public override string ToString() => CalendarItem.Title;