From 10207f840ce3515dddfde36288575f203c52840f Mon Sep 17 00:00:00 2001
From: Ivan Tashkinov <ivantashkinov@gmail.com>
Date: Sun, 31 Jan 2021 22:36:46 +0300
Subject: [PATCH] [#3213] ActivityPub: temporarily reverted to previous
 hashtags filtering implementation due to blank results issue.

---
 lib/pleroma/web/activity_pub/activity_pub.ex | 106 ++++++++++++++-------------
 1 file changed, 54 insertions(+), 52 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index cda8d3f54..fd0144aad 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -722,24 +722,53 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp restrict_embedded_tag_reject_any(query, _), do: query
 
+  # Groups by all bindings to allow aggregation on hashtags
+  defp group_by_all_bindings(query) do
+    # Expecting named bindings: :object, :bookmark, :thread_mute, :report_note
+    cond do
+      Enum.count(query.aliases) == 4 ->
+        from([a, o, b3, b4, b5] in query, group_by: [a.id, o.id, b3.id, b4.id, b5.id])
+
+      Enum.count(query.aliases) == 3 ->
+        from([a, o, b3, b4] in query, group_by: [a.id, o.id, b3.id, b4.id])
+
+      Enum.count(query.aliases) == 2 ->
+        from([a, o, b3] in query, group_by: [a.id, o.id, b3.id])
+
+      true ->
+        from([a, o] in query, group_by: [a.id, o.id])
+    end
+  end
+
+  defp restrict_hashtag_reject_any(_query, %{tag_reject: _tag_reject, skip_preload: true}) do
+    raise_on_missing_preload()
+  end
+
+  defp restrict_hashtag_reject_any(query, %{tag_reject: tags_reject}) when is_list(tags_reject) do
+    query
+    |> group_by_all_bindings()
+    |> join(:left, [_activity, object], hashtag in assoc(object, :hashtags), as: :hashtag)
+    |> having(
+      [hashtag: hashtag],
+      fragment("not(array_agg(?) && (?))", hashtag.name, ^tags_reject)
+    )
+  end
+
+  defp restrict_hashtag_reject_any(query, %{tag_reject: tag_reject}) when is_binary(tag_reject) do
+    restrict_hashtag_reject_any(query, %{tag_reject: [tag_reject]})
+  end
+
+  defp restrict_hashtag_reject_any(query, _), do: query
+
   defp restrict_hashtag_all(_query, %{tag_all: _tag, skip_preload: true}) do
     raise_on_missing_preload()
   end
 
   defp restrict_hashtag_all(query, %{tag_all: tags}) when is_list(tags) do
-    from(
-      [_activity, object] in query,
-      where:
-        fragment(
-          """
-          (SELECT array_agg(hashtags.name) FROM hashtags JOIN hashtags_objects
-            ON hashtags_objects.hashtag_id = hashtags.id WHERE hashtags.name = ANY(?)
-              AND hashtags_objects.object_id = ?) @> ?
-          """,
-          ^tags,
-          object.id,
-          ^tags
-        )
+    Enum.reduce(
+      tags,
+      query,
+      fn tag, acc -> restrict_hashtag_any(acc, %{tag: tag}) end
     )
   end
 
@@ -754,19 +783,18 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
   end
 
   defp restrict_hashtag_any(query, %{tag: tags}) when is_list(tags) do
-    from(
-      [_activity, object] in query,
-      where:
-        fragment(
-          """
-          EXISTS (SELECT 1 FROM hashtags JOIN hashtags_objects
-            ON hashtags_objects.hashtag_id = hashtags.id WHERE hashtags.name = ANY(?)
-              AND hashtags_objects.object_id = ? LIMIT 1)
-          """,
-          ^tags,
-          object.id
-        )
-    )
+    query =
+      from(
+        [_activity, object] in query,
+        join: hashtag in assoc(object, :hashtags),
+        where: hashtag.name in ^tags
+      )
+
+    if length(tags) > 1 do
+      distinct(query, [activity], true)
+    else
+      query
+    end
   end
 
   defp restrict_hashtag_any(query, %{tag: tag}) when is_binary(tag) do
@@ -775,32 +803,6 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp restrict_hashtag_any(query, _), do: query
 
-  defp restrict_hashtag_reject_any(_query, %{tag_reject: _tag_reject, skip_preload: true}) do
-    raise_on_missing_preload()
-  end
-
-  defp restrict_hashtag_reject_any(query, %{tag_reject: tags_reject}) when is_list(tags_reject) do
-    from(
-      [_activity, object] in query,
-      where:
-        fragment(
-          """
-          NOT EXISTS (SELECT 1 FROM hashtags JOIN hashtags_objects
-            ON hashtags_objects.hashtag_id = hashtags.id WHERE hashtags.name = ANY(?)
-              AND hashtags_objects.object_id = ? LIMIT 1)
-          """,
-          ^tags_reject,
-          object.id
-        )
-    )
-  end
-
-  defp restrict_hashtag_reject_any(query, %{tag_reject: tag_reject}) when is_binary(tag_reject) do
-    restrict_hashtag_reject_any(query, %{tag_reject: [tag_reject]})
-  end
-
-  defp restrict_hashtag_reject_any(query, _), do: query
-
   defp raise_on_missing_preload do
     raise "Can't use the child object without preloading!"
   end