[MM-35345]: fix unreads in threads and migration (#17938)

Summary
Fix unreads query for threads to check deleted option
Normalize unreads query to look for threads after given time
Fix migration to only run once, and increment timestamp by one so that threads are definitely marked as read.

Ticket Link
Fixes issues with https://mattermost.atlassian.net/browse/MM-35345
And possibly some issues with thread unreads.

store/sqlstore/thread_store.go

@@ -130,7 +130,6 @@ func (s *SqlThreadStore) GetThreadsForUser(userId, teamId string, opts model.Get
 		model.Post
 	}
 
-	unreadRepliesQuery := "SELECT COUNT(Posts.Id) From Posts Where Posts.RootId=ThreadMemberships.PostId AND Posts.CreateAt >= ThreadMemberships.LastViewed"
 	fetchConditions := sq.And{
 		sq.Or{sq.Eq{"Channels.TeamId": teamId}, sq.Eq{"Channels.TeamId": ""}},
 		sq.Eq{"ThreadMemberships.UserId": userId},
@@ -159,7 +158,7 @@ func (s *SqlThreadStore) GetThreadsForUser(userId, teamId string, opts model.Get
 			LeftJoin("ThreadMemberships ON Posts.RootId = ThreadMemberships.PostId").
 			LeftJoin("Channels ON Posts.ChannelId = Channels.Id").
 			Where(fetchConditions).
-			Where("Posts.CreateAt >= ThreadMemberships.LastViewed").ToSql()
+			Where("Posts.CreateAt > ThreadMemberships.LastViewed").ToSql()
 
 		totalUnreadThreads, err := s.GetMaster().SelectInt(repliesQuery, repliesQueryArgs...)
 		totalUnreadThreadsChan <- store.StoreResult{Data: totalUnreadThreads, NErr: errors.Wrapf(err, "failed to get count unread on threads for user id=%s", userId)}
@@ -218,6 +217,24 @@ func (s *SqlThreadStore) GetThreadsForUser(userId, teamId string, opts model.Get
 		if opts.Unread {
 			newFetchConditions = sq.And{newFetchConditions, sq.Expr("ThreadMemberships.LastViewed < Threads.LastReplyAt")}
 		}
+
+		unreadRepliesFetchConditions := sq.And{
+			sq.Expr("Posts.RootId = ThreadMemberships.PostId"),
+			sq.Expr("Posts.CreateAt > ThreadMemberships.LastViewed"),
+		}
+		if !opts.Deleted {
+			unreadRepliesFetchConditions = sq.And{
+				unreadRepliesFetchConditions,
+				sq.Expr("Posts.DeleteAt = 0"),
+			}
+		}
+
+		unreadRepliesQuery, _ := sq.
+			Select("COUNT(Posts.Id)").
+			From("Posts").
+			Where(unreadRepliesFetchConditions).
+			MustSql()
+
 		var threads []*JoinedThread
 		query, args, _ := s.getQueryBuilder().
 			Select(`Threads.*,
@@ -358,7 +375,7 @@ func (s *SqlThreadStore) GetThreadForUser(teamId string, threadMembership *model
 		From("Posts").
 		Where(sq.And{
 			sq.Eq{"Posts.RootId": threadMembership.PostId},
-			sq.GtOrEq{"Posts.CreateAt": threadMembership.LastViewed},
+			sq.Gt{"Posts.CreateAt": threadMembership.LastViewed},
 			sq.Eq{"Posts.DeleteAt": 0},
 		}).MustSql()
 
@@ -651,8 +668,8 @@ func (s *SqlThreadStore) CollectThreadsWithNewerReplies(userId string, channelId
 			sq.Eq{"Threads.ChannelId": channelIds},
 			sq.Eq{"ChannelMembers.UserId": userId},
 			sq.Or{
-				sq.Expr("Threads.LastReplyAt >= ChannelMembers.LastViewedAt"),
-				sq.GtOrEq{"Threads.LastReplyAt": timestamp},
+				sq.Expr("Threads.LastReplyAt > ChannelMembers.LastViewedAt"),
+				sq.Gt{"Threads.LastReplyAt": timestamp},
 			},
 		}).
 		ToSql()