From b269af850ab36f03536cb010da373e0cfa87c873 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Sun, 31 May 2026 20:32:11 +0200
Subject: DirectMessage: history diff including replaced messages

---
 src/Erebos/DirectMessage.hs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

(limited to 'src/Erebos/DirectMessage.hs')

diff --git a/src/Erebos/DirectMessage.hs b/src/Erebos/DirectMessage.hs
index d9de7c7..62a25a2 100644
--- a/src/Erebos/DirectMessage.hs
+++ b/src/Erebos/DirectMessage.hs
@@ -13,6 +13,7 @@ module Erebos.DirectMessage (
 
     DirectMessageThread(..),
     dmThreadToList, dmThreadToListSince, dmThreadToListUnread, dmThreadToListSinceUnread,
+    dmThreadToListChange,
     dmThreadView,
 
     watchDirectMessageThreads,
@@ -54,8 +55,8 @@ instance ConversationType DirectMessageThread DirectMessage where
 
     convReference = refDigest . storedRef . head . idDataF . msgPeer
 
-    convMessageListSince mbSince thread = ( 0, ) $
-        threadToListHelper (msgSeen thread) (maybe S.empty (S.fromAscList . msgHead) mbSince) (msgHead thread)
+    convMessageListSince Nothing      thread = ( 0, ) $ dmThreadToListUnread thread
+    convMessageListSince (Just since) thread = dmThreadToListChange since thread
 
 
 data DirectMessage = DirectMessage
@@ -340,6 +341,18 @@ threadToListHelper seen used msgs = map (\msg -> ( fromStored msg, isNew msg ))
     cmp = comparing $ zonedTimeToUTC . msgTime . fromStored
     isNew msg = not $ any (msg `precedesOrEquals`) seen
 
+dmThreadToListChange :: DirectMessageThread -> DirectMessageThread -> ( Int, [ ( DirectMessage, Bool ) ] )
+dmThreadToListChange since thread =
+    ( graphSize $ graphRemoveTips bottom $ graphFromTips (msgHead since)
+    , map (\msg -> ( fromStored msg, isNew msg )) $ graphToList cmp $ graphRemoveTips bottom $ graphFromTips (msgHead thread)
+    )
+  where
+    cmp = comparing $ zonedTimeToUTC . msgTime . fromStored
+    isNew msg = not $ any (msg `precedesOrEquals`) (msgSeen thread)
+    bottom
+        | msgSeen since == msgSeen thread = msgHead since
+        | otherwise = commonAncestors (msgHead since) (msgSeen since)
+
 dmThreadView :: [ Stored MessageState ] -> [ DirectMessageThread ]
 dmThreadView = helper []
     where helper used ms' = case filterAncestors ms' of
-- 
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