From 6f2a00a2ce937c25f3448e40636d2f0fee4b2ac1 Mon Sep 17 00:00:00 2001
From: Kegan Dougal <kegan@matrix.org>
Date: Mon, 6 Nov 2023 12:33:30 +0000
Subject: [PATCH] Review comments

---
 state/storage.go           | 11 +++++++----
 tests-e2e/timeline_test.go |  2 +-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/state/storage.go b/state/storage.go
index a97cd3c..76b0825 100644
--- a/state/storage.go
+++ b/state/storage.go
@@ -7,6 +7,8 @@ import (
 	"os"
 	"strings"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/matrix-org/sliding-sync/sync2"
 
 	"github.com/getsentry/sentry-go"
@@ -716,17 +718,18 @@ func (s *Storage) LatestEventsInRooms(userID string, roomIDs []string, to int64,
 			if err != nil {
 				return fmt.Errorf("room %s failed to SelectEventsBetween: %s", roomID, err)
 			}
-			// keep pushing to the front so we end up with A,B,C
 			for _, ev := range events {
 				if latestEventNID == 0 { // set first time and never again
 					latestEventNID = ev.NID
 				}
-				roomEvents = append([]json.RawMessage{ev.JSON}, roomEvents...)
+				roomEvents = append(roomEvents, ev.JSON)
 				earliestEventNID = ev.NID
 				if len(roomEvents) >= limit {
 					break
 				}
 			}
+			// we want the most recent event to be last, so reverse the slice now in-place.
+			slices.Reverse(roomEvents)
 			latestEvents := LatestEvents{
 				LatestNID: latestEventNID,
 				Timeline:  roomEvents,
@@ -747,8 +750,8 @@ func (s *Storage) LatestEventsInRooms(userID string, roomIDs []string, to int64,
 }
 
 // visibleEventNIDsBetweenForRooms determines which events a given user has permission to see.
-// It accepts a nid range [from, to]. For each given room, it calculates the NID ranges
-// [A1, B1], [A2, B2], ... within [from, to] in which the user has permission to see events.
+// It accepts a nid range [from, to]. For each given room, it calculates the NID range
+// [A1, B1] within [from, to] in which the user has permission to see events.
 func (s *Storage) visibleEventNIDsBetweenForRooms(userID string, roomIDs []string, from, to int64) (map[string][2]int64, error) {
 	// load *THESE* joined rooms for this user at from (inclusive)
 	var membershipEvents []Event
diff --git a/tests-e2e/timeline_test.go b/tests-e2e/timeline_test.go
index 6eb973b..0a8f9c4 100644
--- a/tests-e2e/timeline_test.go
+++ b/tests-e2e/timeline_test.go
@@ -11,7 +11,7 @@ import (
 )
 
 // Regression test to make sure that given:
-// - Alice invite Bob
+// - Alice invite Bob (shared history visibility)
 // - Alice send message
 // - Bob join room
 // The proxy returns: