From 704a3830556d94e0dbc39873480e9ba95a143be9 Mon Sep 17 00:00:00 2001
From: Ivan Tashkinov <ivantashkinov@gmail.com>
Date: Wed, 8 Jul 2020 13:14:18 +0300
Subject: [PATCH] Improved search results for localized nickname match. Tweaked
 user search to rank nickname matches higher than name matches.

---
 lib/pleroma/user/search.ex |  8 +++++++-
 test/tasks/user_test.exs   | 16 ++++++++--------
 test/user_search_test.exs  | 35 +++++++++++++++++++++++++++++------
 3 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/lib/pleroma/user/search.ex b/lib/pleroma/user/search.ex
index 42ff1de78..7ff1c7e24 100644
--- a/lib/pleroma/user/search.ex
+++ b/lib/pleroma/user/search.ex
@@ -88,15 +88,21 @@ defp to_tsquery(query_string) do
     |> Enum.join(" | ")
   end
 
+  # Considers nickname match, localized nickname match, name match; preferences nickname match
   defp trigram_rank(query, query_string) do
     from(
       u in query,
       select_merge: %{
         search_rank:
           fragment(
-            "similarity(?, trim(? || ' ' || coalesce(?, '')))",
+            "similarity(?, ?) + \
+              similarity(?, regexp_replace(?, '@.+', '')) + \
+              similarity(?, trim(coalesce(?, '')))",
             ^query_string,
             u.nickname,
+            ^query_string,
+            u.nickname,
+            ^query_string,
             u.name
           )
       }
diff --git a/test/tasks/user_test.exs b/test/tasks/user_test.exs
index 9220d23fc..7bb49b038 100644
--- a/test/tasks/user_test.exs
+++ b/test/tasks/user_test.exs
@@ -464,17 +464,17 @@ test "it returns users matching" do
       moot = insert(:user, nickname: "moot")
       kawen = insert(:user, nickname: "kawen", name: "fediverse expert moon")
 
-      {:ok, user} = User.follow(user, kawen)
+      {:ok, user} = User.follow(user, moon)
 
       assert [moon.id, kawen.id] == User.Search.search("moon") |> Enum.map(& &1.id)
-      res = User.search("moo") |> Enum.map(& &1.id)
-      assert moon.id in res
-      assert moot.id in res
-      assert kawen.id in res
-      assert [moon.id, kawen.id] == User.Search.search("moon fediverse") |> Enum.map(& &1.id)
 
-      assert [kawen.id, moon.id] ==
-               User.Search.search("moon fediverse", for_user: user) |> Enum.map(& &1.id)
+      res = User.search("moo") |> Enum.map(& &1.id)
+      assert Enum.sort([moon.id, moot.id, kawen.id]) == Enum.sort(res)
+
+      assert [kawen.id, moon.id] == User.Search.search("expert fediverse") |> Enum.map(& &1.id)
+
+      assert [moon.id, kawen.id] ==
+               User.Search.search("expert fediverse", for_user: user) |> Enum.map(& &1.id)
     end
   end
 
diff --git a/test/user_search_test.exs b/test/user_search_test.exs
index f030523d3..758822072 100644
--- a/test/user_search_test.exs
+++ b/test/user_search_test.exs
@@ -46,30 +46,53 @@ test "accepts offset parameter" do
       assert length(User.search("john", limit: 3, offset: 3)) == 2
     end
 
-    test "finds a user by full or partial nickname" do
+    defp clear_virtual_fields(user) do
+      Map.merge(user, %{search_rank: nil, search_type: nil})
+    end
+
+    test "finds a user by full nickname or its leading fragment" do
       user = insert(:user, %{nickname: "john"})
 
       Enum.each(["john", "jo", "j"], fn query ->
         assert user ==
                  User.search(query)
                  |> List.first()
-                 |> Map.put(:search_rank, nil)
-                 |> Map.put(:search_type, nil)
+                 |> clear_virtual_fields()
       end)
     end
 
-    test "finds a user by full or partial name" do
+    test "finds a user by full name or leading fragment(s) of its words" do
       user = insert(:user, %{name: "John Doe"})
 
       Enum.each(["John Doe", "JOHN", "doe", "j d", "j", "d"], fn query ->
         assert user ==
                  User.search(query)
                  |> List.first()
-                 |> Map.put(:search_rank, nil)
-                 |> Map.put(:search_type, nil)
+                 |> clear_virtual_fields()
       end)
     end
 
+    test "is not [yet] capable of matching by non-leading fragments (e.g. by domain)" do
+      user1 = insert(:user, %{nickname: "iamthedude"})
+      insert(:user, %{nickname: "arandom@dude.com"})
+
+      assert [] == User.search("dude")
+
+      # Matching by leading fragment works, though
+      user1_id = user1.id
+      assert ^user1_id = User.search("iam") |> List.first() |> Map.get(:id)
+    end
+
+    test "ranks full nickname match higher than full name match" do
+      nicknamed_user = insert(:user, %{nickname: "hj@shigusegubu.club"})
+      named_user = insert(:user, %{nickname: "xyz@sample.com", name: "HJ"})
+
+      results = User.search("hj")
+
+      assert [nicknamed_user.id, named_user.id] == Enum.map(results, & &1.id)
+      assert Enum.at(results, 0).search_rank > Enum.at(results, 1).search_rank
+    end
+
     test "finds users, considering density of matched tokens" do
       u1 = insert(:user, %{name: "Bar Bar plus Word Word"})
       u2 = insert(:user, %{name: "Word Word Bar Bar Bar"})