From f256adadcaf9b340678a5af2441f93e28f57d91d Mon Sep 17 00:00:00 2001
From: Jonathan Bourdon <lowrad0@hotmail.com>
Date: Sat, 20 Jul 2024 04:35:34 -0400
Subject: [PATCH] Fix some edge cases in the streaming of messages

---
 .../Features/Messages/Handlers/GetMessages.cs | 22 +++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/Web/Features/Messages/Handlers/GetMessages.cs b/src/Web/Features/Messages/Handlers/GetMessages.cs
index 188dd7e..242558f 100644
--- a/src/Web/Features/Messages/Handlers/GetMessages.cs
+++ b/src/Web/Features/Messages/Handlers/GetMessages.cs
@@ -31,12 +31,26 @@ public class GetMessages(
             .Where(c => c.SubjectId == req.SubjectId)
             .Where(c => c.ParentId == null);
 
-        query = query.OrderByDescending(c => c.CreatedAt);
+        if (req.LastId.HasValue)
+        {
+            var lastMessage = await context
+                .Messages
+                .Where(c => c.Id == req.LastId.Value)
+                .Select(c => new { c.CreatedAt, c.Id })
+                .FirstOrDefaultAsync(cancellationToken: ct);
 
-        if (req.LastId is not null)
-            query = query.Where(c => c.Id < req.LastId.Value);
+            if (lastMessage != null)
+            {
+                query = query
+                    .Where(c => c.CreatedAt < lastMessage.CreatedAt
+                                || (c.CreatedAt == lastMessage.CreatedAt && c.Id < lastMessage.Id));
+            }
+        }
 
-        query = query.Take(req.PageSize);
+        query = query
+            .OrderByDescending(c => c.CreatedAt)
+            .ThenByDescending(c => c.Id)
+            .Take(req.PageSize);
 
         var messages = await query.ToListAsync(cancellationToken: ct);