Fix counting of posts, remove redundant limit offset for queries

store/sqlstore/post_store.go

@@ -2983,9 +2983,7 @@ func (s *SqlPostStore) GetTopDMsForUserSince(userID string, since int64, offset
 		Join("Posts as p on p.ChannelId = vch.Id").
 		Where(sq.Gt{
 			"p.UpdateAt": since,
-		}).GroupBy("vch.id").
-		Limit(uint64(limit)).
-		Offset(uint64(offset))
+		}).GroupBy("vch.id")
 
 	topDMsBuilder = topDMsBuilder.OrderBy("MessageCount DESC").Limit(uint64(limit)).Offset(uint64(offset))
 
@@ -3006,7 +3004,14 @@ func (s *SqlPostStore) GetTopDMsForUserSince(userID string, since int64, offset
 
 func postProcessTopDMs(userID string, topDMs []*model.TopDM) []*model.TopDM {
 	for _, topDM := range topDMs {
+		// divide message count by 2, because it's counted twice due to channel memberships being 2 for dms.
+		topDM.MessageCount = topDM.MessageCount / 2
 		participants := strings.Split(topDM.Participants, ",")
+		if len(participants) == 1 {
+			// chatting to self
+			topDM.SecondParticipant = userID
+			continue
+		}
 		if participants[0] == userID {
 			topDM.SecondParticipant = participants[1]
 		} else {