Fixed the display date of the calendar items. Created test project for core library, included tests for recurring calendar events.

Wino.Calendar.ViewModels/CalendarAppShellViewModel.cs

@@ -293,6 +293,30 @@ public partial class CalendarAppShellViewModel : CalendarBaseViewModel,
 
     #endregion
 
+    protected override void RegisterRecipients()
+    {
+        base.RegisterRecipients();
+
+        UnregisterRecipients();
+
+        Messenger.Register<VisibleDateRangeChangedMessage>(this);
+        Messenger.Register<CalendarEnableStatusChangedMessage>(this);
+        Messenger.Register<NavigateManageAccountsRequested>(this);
+        Messenger.Register<CalendarDisplayTypeChangedMessage>(this);
+        Messenger.Register<DetailsPageStateChangedMessage>(this);
+    }
+
+    protected override void UnregisterRecipients()
+    {
+        base.UnregisterRecipients();
+
+        Messenger.Unregister<VisibleDateRangeChangedMessage>(this);
+        Messenger.Unregister<CalendarEnableStatusChangedMessage>(this);
+        Messenger.Unregister<NavigateManageAccountsRequested>(this);
+        Messenger.Unregister<CalendarDisplayTypeChangedMessage>(this);
+        Messenger.Unregister<DetailsPageStateChangedMessage>(this);
+    }
+
     public void Receive(VisibleDateRangeChangedMessage message) => HighlightedDateRange = message.DateRange;
 
     /// <summary>

Wino.Calendar.ViewModels/CalendarPageViewModel.cs

@@ -658,7 +658,7 @@ public partial class CalendarPageViewModel : CalendarBaseViewModel,
             // Check all the events for the given date range and calendar.
             // Then find the day representation for all the events returned, and add to the collection.
 
-            var events = await _calendarService.GetCalendarEventsAsync(calendarViewModel, dayRangeRenderModel).ConfigureAwait(false);
+            var events = await _calendarService.GetCalendarEventsAsync(calendarViewModel, dayRangeRenderModel.Period).ConfigureAwait(false);
 
             foreach (var @event in events)
             {

Wino.Calendar.ViewModels/Data/CalendarItemViewModel.cs

@@ -17,13 +17,71 @@ public partial class CalendarItemViewModel : ObservableObject, ICalendarItem, IC
 
     public IAccountCalendar AssignedCalendar => CalendarItem.AssignedCalendar;
 
-    public DateTime StartDate { get => CalendarItem.StartDate; set => CalendarItem.StartDate = value; }
+    /// <summary>
+    /// Gets or sets the start date in local time based on the event's timezone.
+    /// The underlying CalendarItem stores dates in UTC.
+    /// </summary>
+    public DateTime StartDate
+    {
+        get
+        {
+            // Convert from UTC stored in database to local time using the event's timezone
+            var startDateTimeOffset = CalendarItem.StartDateTimeOffset;
+            return startDateTimeOffset.LocalDateTime;
+        }
+        set
+        {
+            // When setting, convert from local time to UTC for storage
+            // Preserve the timezone information
+            if (!string.IsNullOrEmpty(CalendarItem.StartTimeZone))
+            {
+                try
+                {
+                    var timeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById(CalendarItem.StartTimeZone);
+                    var utcDateTime = TimeZoneInfo.ConvertTimeToUtc(value, timeZoneInfo);
+                    CalendarItem.StartDate = utcDateTime;
+                }
+                catch
+                {
+                    // If timezone lookup fails, assume value is already in UTC
+                    CalendarItem.StartDate = value;
+                }
+            }
+            else
+            {
+                // No timezone info, assume UTC
+                CalendarItem.StartDate = value;
+            }
+        }
+    }
 
-    public DateTime EndDate => CalendarItem.EndDate;
+    /// <summary>
+    /// Gets the end date in local time based on the event's timezone.
+    /// The underlying CalendarItem stores dates in UTC.
+    /// </summary>
+    public DateTime EndDate
+    {
+        get
+        {
+            // Convert from UTC stored in database to local time using the event's timezone
+            var endDateTimeOffset = CalendarItem.EndDateTimeOffset;
+            return endDateTimeOffset.LocalDateTime;
+        }
+    }
 
     public double DurationInSeconds { get => CalendarItem.DurationInSeconds; set => CalendarItem.DurationInSeconds = value; }
 
-    public ITimePeriod Period => CalendarItem.Period;
+    /// <summary>
+    /// Gets the time period in local time.
+    /// </summary>
+    public ITimePeriod Period
+    {
+        get
+        {
+            // Return a period using local times for UI display
+            return new TimeRange(StartDate, EndDate);
+        }
+    }
 
     public bool IsAllDayEvent => CalendarItem.IsAllDayEvent;
     public bool IsMultiDayEvent => CalendarItem.IsMultiDayEvent;
@@ -32,7 +90,7 @@ public partial class CalendarItemViewModel : ObservableObject, ICalendarItem, IC
     public bool IsRecurringParent => CalendarItem.IsRecurringParent;
 
     [ObservableProperty]
-    private bool _isSelected;
+    public partial bool IsSelected { get; set; }
 
     public ObservableCollection<CalendarEventAttendee> Attendees { get; } = new ObservableCollection<CalendarEventAttendee>();
 
@@ -42,4 +100,4 @@ public partial class CalendarItemViewModel : ObservableObject, ICalendarItem, IC
     }
 
     public override string ToString() => CalendarItem.Title;
-}
+}

Wino.Calendar.ViewModels/Interfaces/IAccountCalendarStateService.cs

@@ -2,9 +2,7 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
-using System.Linq;
 using Wino.Calendar.ViewModels.Data;
-using Wino.Core.Domain.Entities.Shared;
 
 namespace Wino.Calendar.ViewModels.Interfaces;
 
@@ -26,5 +24,5 @@ public interface IAccountCalendarStateService : INotifyPropertyChanged
     /// Enumeration of currently selected calendars.
     /// </summary>
     IEnumerable<AccountCalendarViewModel> ActiveCalendars { get; }
-    IEnumerable<IGrouping<MailAccount, AccountCalendarViewModel>> GroupedAccountCalendarsEnumerable { get; }
+    // IEnumerable<IGrouping<MailAccount, AccountCalendarViewModel>> GroupedAccountCalendarsEnumerable { get; }
 }