[4274] Fix/improve search token-autocomplete

apps/block_scout_web/lib/block_scout_web/controllers/chain_controller.ex

@@ -94,23 +94,11 @@ defmodule BlockScoutWeb.ChainController do
   def search(conn, _), do: not_found(conn)
 
   def token_autocomplete(conn, %{"q" => term}) when is_binary(term) do
-    if term == "" do
-      json(conn, "{}")
-    else
-      result_tokens =
-        term
-        |> String.trim()
-        |> Chain.search_token()
-
-      result_contracts =
-        term
-        |> String.trim()
-        |> Chain.search_contract()
+    result_tokens = Chain.search_token(term)
+    result_contracts = Chain.search_contract(term)
+    result = result_tokens ++ result_contracts
 
-      result = result_tokens ++ result_contracts
-
-      json(conn, result)
-    end
+    json(conn, result)
   end
 
   def token_autocomplete(conn, _) do

apps/block_scout_web/test/block_scout_web/controllers/chain_controller_test.exs

@@ -128,6 +128,38 @@ defmodule BlockScoutWeb.ChainControllerTest do
 
       assert Enum.count(json_response(conn, 200)) == 4
     end
+
+    test "find by several words" do
+      insert(:token, name: "first Token")
+      insert(:token, name: "second Token")
+
+      conn =
+        build_conn()
+        |> get("/token-autocomplete?q=fir+tok")
+
+      assert Enum.count(json_response(conn, 200)) == 1
+    end
+
+    test "find by empty query" do
+      insert(:token, name: "MaGiCt0k3n")
+      insert(:smart_contract, name: "MagicContract")
+
+      conn =
+        build_conn()
+        |> get("/token-autocomplete?q=")
+
+      assert Enum.count(json_response(conn, 200)) == 0
+    end
+
+    test "find by non-latin characters" do
+      insert(:token, name: "someToken")
+
+      conn =
+        build_conn()
+        |> get("/token-autocomplete?q=%E0%B8%B5%E0%B8%AB")
+
+      assert Enum.count(json_response(conn, 200)) == 0
+    end
   end
 
   describe "GET search/2" do

apps/explorer/lib/explorer/chain.ex

@@ -1083,51 +1083,64 @@ defmodule Explorer.Chain do
     end
   end
 
-  @spec search_token(String.t()) :: [Token.t()]
-  def search_token(word) do
-    term =
-      word
-      |> String.replace(~r/[^a-zA-Z0-9]/, " ")
-      |> String.replace(~r/ +/, " & ")
+  defp prepare_search_term(string) do
+    case Regex.scan(~r/[a-zA-Z0-9]+/, string) do
+      [_ | _] = words ->
+        term_final =
+          words
+          |> Enum.map(fn [word] -> word <> ":*" end)
+          |> Enum.join(" & ")
 
-    term_final = term <> ":*"
+        {:some, term_final}
 
-    query =
-      from(token in Token,
-        where: fragment("to_tsvector('english', symbol || ' ' || name ) @@ to_tsquery(?)", ^term_final),
-        select: %{
-          contract_address_hash: token.contract_address_hash,
-          symbol: token.symbol,
-          name:
-            fragment(
-              "'<b>' || coalesce(?, '') || '</b>' || ' (' || coalesce(?, '') || ') ' || '<i>' || coalesce(?::varchar(255), '') || ' holder(s)' || '</i>'",
-              token.name,
-              token.symbol,
-              token.holder_count
-            )
-        },
-        order_by: [desc: token.holder_count]
-      )
+      _ ->
+        :none
+    end
+  end
 
-    Repo.all(query)
+  @spec search_token(String.t()) :: [Token.t()]
+  def search_token(string) do
+    case prepare_search_term(string) do
+      {:some, term} ->
+        query =
+          from(token in Token,
+            where: fragment("to_tsvector('english', symbol || ' ' || name ) @@ to_tsquery(?)", ^term),
+            select: %{
+              contract_address_hash: token.contract_address_hash,
+              symbol: token.symbol,
+              name:
+                fragment(
+                  "'<b>' || coalesce(?, '') || '</b>' || ' (' || coalesce(?, '') || ') ' || '<i>' || coalesce(?::varchar(255), '') || ' holder(s)' || '</i>'",
+                  token.name,
+                  token.symbol,
+                  token.holder_count
+                )
+            },
+            order_by: [desc: token.holder_count]
+          )
+
+        Repo.all(query)
+
+      _ ->
+        []
+    end
   end
 
   @spec search_contract(String.t()) :: [SmartContract.t()]
-  def search_contract(word) do
-    term =
-      word
-      |> String.replace(~r/[^a-zA-Z0-9]/, " ")
-      |> String.replace(~r/ +/, " & ")
+  def search_contract(string) do
+    case prepare_search_term(string) do
+      {:some, term} ->
+        query =
+          from(smart_contract in SmartContract,
+            where: fragment("to_tsvector('english', name ) @@ to_tsquery(?)", ^term),
+            select: %{contract_address_hash: smart_contract.address_hash, name: smart_contract.name}
+          )
 
-    term_final = term <> ":*"
+        Repo.all(query)
 
-    query =
-      from(smart_contract in SmartContract,
-        where: fragment("to_tsvector('english', name ) @@ to_tsquery(?)", ^term_final),
-        select: %{contract_address_hash: smart_contract.address_hash, name: smart_contract.name}
-      )
-
-    Repo.all(query)
+      _ ->
+        []
+    end
   end
 
   @doc """