Calendar - mail mapping.

Wino.Core.Domain/Entities/Mail/MailInvitationCalendarMapping.cs

@@ -0,0 +1,31 @@
+using System;
+using SQLite;
+
+namespace Wino.Core.Domain.Entities.Mail;
+
+/// <summary>
+/// Maps a calendar invitation mail item to a persisted calendar event.
+/// </summary>
+public class MailInvitationCalendarMapping
+{
+    [PrimaryKey]
+    public Guid Id { get; set; }
+
+    public Guid AccountId { get; set; }
+
+    /// <summary>
+    /// MailCopy.Id value of the invitation mail.
+    /// </summary>
+    public string MailCopyId { get; set; }
+
+    /// <summary>
+    /// iCalendar UID extracted from invitation MIME/ICS content.
+    /// </summary>
+    public string InvitationUid { get; set; }
+
+    public Guid CalendarId { get; set; }
+    public Guid CalendarItemId { get; set; }
+    public string CalendarRemoteEventId { get; set; }
+
+    public DateTime UpdatedAtUtc { get; set; } = DateTime.UtcNow;
+}

Wino.Core.Domain/Models/MailItem/HtmlPreviewVisitor.cs

@@ -48,9 +48,22 @@ public class HtmlPreviewVisitor : MimeVisitor
 
     protected override void VisitMultipartAlternative(MultipartAlternative alternative)
     {
-        // walk the multipart/alternative children backwards from greatest level of faithfulness to the least faithful
+        // Prefer rich body alternatives first, and only fall back to calendar text if nothing else exists.
         for (int i = alternative.Count - 1; i >= 0 && Body == null; i--)
+        {
+            if (IsCalendarText(alternative[i]))
+                continue;
+
             alternative[i].Accept(this);
+        }
+
+        for (int i = alternative.Count - 1; i >= 0 && Body == null; i--)
+        {
+            if (!IsCalendarText(alternative[i]))
+                continue;
+
+            alternative[i].Accept(this);
+        }
     }
 
     protected override void VisitMultipartRelated(MultipartRelated related)
@@ -241,6 +254,10 @@ public class HtmlPreviewVisitor : MimeVisitor
         Body = converter.Convert(entity.Text);
     }
 
+    private static bool IsCalendarText(MimeEntity entity)
+        => entity is TextPart textPart &&
+           textPart.ContentType?.MimeType?.Equals("text/calendar", StringComparison.OrdinalIgnoreCase) == true;
+
     protected override void VisitTnefPart(TnefPart entity)
     {
         // extract any attachments in the MS-TNEF part