Implement search with PostgreSQL trigrams

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Rename function to reflect that we only get one result

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Add loggers and make Ecto call parallels during search

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Implement trigrams for events & replace pg similarity operator % with <%

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Fix tests

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/events/events.ex

@@ -248,7 +248,19 @@ defmodule Mobilizon.Events do
 
     query =
       from(e in Event,
-        where: e.visibility == ^:public and ilike(e.title, ^like_sanitize(name)),
+        where:
+          e.visibility == ^:public and
+            fragment(
+              "f_unaccent(?) %> f_unaccent(?)",
+              e.title,
+              ^name
+            ),
+        order_by:
+          fragment(
+            "word_similarity(?, ?) desc",
+            e.title,
+            ^name
+          ),
         preload: [:organizer_actor]
       )
       |> paginate(page, limit)
@@ -256,11 +268,6 @@ defmodule Mobilizon.Events do
     Repo.all(query)
   end
 
-  # Sanitize the LIKE queries
-  defp like_sanitize(value) do
-    "%" <> String.replace(value, ~r/([\\%_])/, "\\1") <> "%"
-  end
-
   @doc """
   Creates a event.