From 80b44f0292ff36b87389c7b72a6b498de8c9b5bc Mon Sep 17 00:00:00 2001
From: Travis Ralston <travpc@gmail.com>
Date: Wed, 4 Mar 2020 12:05:47 -0700
Subject: [PATCH 1/2] Always calculate the category of a room

All the update triggers for the RoomListStore go through the `setRoomCategory` function, so by returning early we're not actually calculating where a room should be in the list.
---
 src/stores/RoomListStore.js | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/src/stores/RoomListStore.js b/src/stores/RoomListStore.js
index 561d865b66..aec307d28e 100644
--- a/src/stores/RoomListStore.js
+++ b/src/stores/RoomListStore.js
@@ -479,12 +479,6 @@ class RoomListStore extends Store {
     _setRoomCategory(room, category) {
         if (!room) return; // This should only happen in tests
 
-        if (!this._state.orderImportantFirst) {
-            // XXX bail here early to avoid https://github.com/vector-im/riot-web/issues/9216
-            // this may mean that category updates are missed whilst not ordering by importance first
-            return;
-        }
-
         const listsClone = {};
 
         // Micro optimization: Support lazily loading the last timestamp in a room

From 8e3fea9d0fb1a6b097754b656c2c5e8d1dcdb7ae Mon Sep 17 00:00:00 2001
From: Travis Ralston <travpc@gmail.com>
Date: Wed, 4 Mar 2020 12:09:05 -0700
Subject: [PATCH 2/2] Use an algorithmic comparator for room list ops

Not all algorithms are timestamp based.
---
 src/stores/RoomListStore.js | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/stores/RoomListStore.js b/src/stores/RoomListStore.js
index aec307d28e..89edc9a8ef 100644
--- a/src/stores/RoomListStore.js
+++ b/src/stores/RoomListStore.js
@@ -372,6 +372,14 @@ class RoomListStore extends Store {
     _slotRoomIntoList(room, category, tag, existingEntries, newList, lastTimestampFn) {
         const targetCategoryIndex = CATEGORY_ORDER.indexOf(category);
 
+        let categoryComparator = (a, b) => lastTimestampFn(a.room) >= lastTimestampFn(b.room);
+        const sortAlgorithm = getListAlgorithm(tag, this._state.algorithm);
+        if (sortAlgorithm === ALGO_RECENT) {
+            categoryComparator = (a, b) => this._recentsComparator(a, b, lastTimestampFn);
+        } else if (sortAlgorithm === ALGO_ALPHABETIC) {
+            categoryComparator = (a, b) => this._lexicographicalComparator(a, b);
+        }
+
         // The slotting algorithm works by trying to position the room in the most relevant
         // category of the list (red > grey > etc). To accomplish this, we need to consider
         // a couple cases: the category existing in the list but having other rooms in it and
@@ -449,7 +457,7 @@ class RoomListStore extends Store {
                 // based on most recent timestamp.
                 const changedBoundary = entryCategoryIndex > targetCategoryIndex;
                 const currentCategory = entryCategoryIndex === targetCategoryIndex;
-                if (changedBoundary || (currentCategory && lastTimestampFn(room) >= lastTimestampFn(entry.room))) {
+                if (changedBoundary || (currentCategory && categoryComparator({room}, entry) <= 0)) {
                     if (changedBoundary) {
                         // If we changed a boundary, then we've gone too far - go to the top of the last
                         // section instead.