From bbec0d93d2fd8df4de38ea937246d7bfca78e13c Mon Sep 17 00:00:00 2001
From: Vitor Pamplona <vitor@vitorpamplona.com>
Date: Mon, 8 Sep 2025 19:38:18 -0400
Subject: [PATCH] Avoids breaking the contract (changes during sorting)

---
 .../nip28Chats/DiscoverChatFeedFilter.kt      | 24 ++++++++++++-------
 .../DiscoverCommunityFeedFilter.kt            | 23 +++++++++++-------
 .../nip90DVMs/DiscoverNIP89FeedFilter.kt      |  7 +++++-
 3 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip28Chats/DiscoverChatFeedFilter.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip28Chats/DiscoverChatFeedFilter.kt
index e881f0119..ab004dfc0 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip28Chats/DiscoverChatFeedFilter.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip28Chats/DiscoverChatFeedFilter.kt
@@ -103,18 +103,26 @@ open class DiscoverChatFeedFilter(
     }
 
     override fun sort(items: Set<Note>): List<Note> {
+        // precache to avoid breaking the contract
         val lastNote =
             items.associateWith { note ->
                 LocalCache.getPublicChatChannelIfExists(note.idHex)?.lastNote?.createdAt() ?: 0
             }
 
-        return items
-            .sortedWith(
-                compareBy(
-                    { lastNote[it] },
-                    { it.createdAt() },
-                    { it.idHex },
-                ),
-            ).reversed()
+        val createdNote =
+            items.associateWith { note ->
+                note.createdAt() ?: 0
+            }
+
+        val comparator: Comparator<Note> =
+            compareByDescending<Note> {
+                lastNote[it]
+            }.thenByDescending {
+                createdNote[it]
+            }.thenBy {
+                it.idHex
+            }
+
+        return items.sortedWith(comparator)
     }
 }
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip72Communities/DiscoverCommunityFeedFilter.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip72Communities/DiscoverCommunityFeedFilter.kt
index dc67bfc4f..e45a11bed 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip72Communities/DiscoverCommunityFeedFilter.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip72Communities/DiscoverCommunityFeedFilter.kt
@@ -125,13 +125,20 @@ open class DiscoverCommunityFeedFilter(
                 max
             }
 
-        return items
-            .sortedWith(
-                compareBy(
-                    { lastNotesCreatedAt[it] },
-                    { it.createdAt() },
-                    { it.idHex },
-                ),
-            ).reversed()
+        val createdNote =
+            items.associateWith { note ->
+                note.createdAt() ?: 0
+            }
+
+        val comparator: Comparator<Note> =
+            compareByDescending<Note> {
+                lastNotesCreatedAt[it]
+            }.thenByDescending {
+                createdNote[it]
+            }.thenBy {
+                it.idHex
+            }
+
+        return items.sortedWith(comparator)
     }
 }
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip90DVMs/DiscoverNIP89FeedFilter.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip90DVMs/DiscoverNIP89FeedFilter.kt
index a69801e0e..1731d7248 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip90DVMs/DiscoverNIP89FeedFilter.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip90DVMs/DiscoverNIP89FeedFilter.kt
@@ -113,11 +113,16 @@ open class DiscoverNIP89FeedFilter(
         val participantCounts =
             items.associateWith { counter.countFollowsThatParticipateOn(it, followingKeySet) }
 
+        val createdNote =
+            items.associateWith { note ->
+                ((note.event?.createdAt ?: 0) / 86400).toInt()
+            }
+
         val feedOrder: Comparator<Note> =
             compareByDescending<Note> {
                 participantCounts[it]
             }.thenByDescending {
-                ((it.event?.createdAt ?: 0) / 86400).toInt()
+                createdNote[it]
             }.thenBy { it.idHex }
 
         return items.sortedWith(feedOrder)