From 65aeaefa417d971d05f660a18f683b65d9a7bffb Mon Sep 17 00:00:00 2001
From: Oneric <oneric@oneric.stub>
Date: Thu, 2 May 2024 22:44:48 +0200
Subject: [PATCH] =?UTF-8?q?meilisearch:=20respect=20meili=E2=80=99s=20resu?=
 =?UTF-8?q?lt=20ranking?=
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Meilisearch is already configured to return results sorted by a
particular ranking configured in the meilisearch CLI task.
Resorting the returned top results by date partially negates this and
runs counter to what someone with tweaked settings expects.

Issue and fix identified by AdamK2003 in
https://akkoma.dev/AkkomaGang/akkoma/pulls/579
But instead of using a O(n^2) resorting, this commit directly
retrieves results in the correct order from the database.

Closes: https://akkoma.dev/AkkomaGang/akkoma/pulls/579
---
 CHANGELOG.md                      |  3 +++
 lib/pleroma/activity.ex           | 21 +++++++++++++++++++++
 lib/pleroma/search/meilisearch.ex |  4 +---
 test/pleroma/activity_test.exs    | 20 ++++++++++++++++++++
 4 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d3034464..c7a838612 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## Added
 - Implement [FEP-67ff](https://codeberg.org/fediverse/fep/src/branch/main/fep/67ff/fep-67ff.md) (federation documentation)
 
+## Fixed
+- Meilisearch: order of results returned from our REST API now actually matches how Meilisearch ranks results
+
 ## 2024.04
 
 ## Added
diff --git a/lib/pleroma/activity.ex b/lib/pleroma/activity.ex
index bf851f808..f820cbdae 100644
--- a/lib/pleroma/activity.ex
+++ b/lib/pleroma/activity.ex
@@ -258,6 +258,27 @@ defmodule Pleroma.Activity do
 
   def get_create_by_object_ap_id(_), do: nil
 
+  @doc """
+  Accepts a list of `ap__id`.
+  Returns a query yielding Create activities for the given objects,
+  in the same order as they were specified in the input list.
+  """
+  @spec get_presorted_create_by_object_ap_id([String.t()]) :: Ecto.Queryable.t()
+  def get_presorted_create_by_object_ap_id(ap_ids) do
+    from(
+      a in Activity,
+      join:
+        ids in fragment(
+          "SELECT * FROM UNNEST(?::text[]) WITH ORDINALITY AS ids(ap_id, ord)",
+          ^ap_ids
+        ),
+      on:
+        ids.ap_id == fragment("?->>'object'", a.data) and
+          fragment("?->>'type'", a.data) == "Create",
+      order_by: [asc: ids.ord]
+    )
+  end
+
   @doc """
   Accepts `ap_id` or list of `ap_id`.
   Returns a query.
diff --git a/lib/pleroma/search/meilisearch.ex b/lib/pleroma/search/meilisearch.ex
index cecb7bd00..822c95b4a 100644
--- a/lib/pleroma/search/meilisearch.ex
+++ b/lib/pleroma/search/meilisearch.ex
@@ -5,7 +5,6 @@ defmodule Pleroma.Search.Meilisearch do
   alias Pleroma.Activity
 
   import Pleroma.Search.DatabaseSearch
-  import Ecto.Query
 
   @behaviour Pleroma.Search.SearchBackend
 
@@ -91,14 +90,13 @@ defmodule Pleroma.Search.Meilisearch do
 
       try do
         hits
-        |> Activity.create_by_object_ap_id()
+        |> Activity.get_presorted_create_by_object_ap_id()
         |> Activity.with_preloaded_object()
         |> Activity.restrict_deactivated_users()
         |> maybe_restrict_local(user)
         |> maybe_restrict_author(author)
         |> maybe_restrict_blocked(user)
         |> maybe_fetch(user, query)
-        |> order_by([object: obj], desc: obj.data["published"])
         |> Pleroma.Repo.all()
       rescue
         _ -> maybe_fetch([], user, query)
diff --git a/test/pleroma/activity_test.exs b/test/pleroma/activity_test.exs
index 4f9144f91..1943746cb 100644
--- a/test/pleroma/activity_test.exs
+++ b/test/pleroma/activity_test.exs
@@ -41,6 +41,26 @@ defmodule Pleroma.ActivityTest do
     assert activity == found_activity
   end
 
+  test "returns activities by object's AP id in requested presorted order" do
+    a1 = insert(:note_activity)
+    o1 = Object.normalize(a1, fetch: false).data["id"]
+
+    a2 = insert(:note_activity)
+    o2 = Object.normalize(a2, fetch: false).data["id"]
+
+    a3 = insert(:note_activity)
+    o3 = Object.normalize(a3, fetch: false).data["id"]
+
+    a4 = insert(:note_activity)
+    o4 = Object.normalize(a4, fetch: false).data["id"]
+
+    found_activities =
+      Activity.get_presorted_create_by_object_ap_id([o3, o2, o4, o1])
+      |> Repo.all()
+
+    assert found_activities == [a3, a2, a4, a1]
+  end
+
   test "preloading a bookmark" do
     user = insert(:user)
     user2 = insert(:user)