From 22de3f67d536472428da6e98befce822e15dba6d Mon Sep 17 00:00:00 2001
From: Lukasz Samson <lukaszsamson@gmail.com>
Date: Tue, 14 Nov 2023 19:02:00 +0100
Subject: [PATCH] handle no signature on callback

---
 lib/elixir_sense/core/introspection.ex        |  2 +-
 .../suggestion/reducers/callbacks.ex          | 41 ++++++++++++++-----
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/lib/elixir_sense/core/introspection.ex b/lib/elixir_sense/core/introspection.ex
index f0c828f2..705cb256 100644
--- a/lib/elixir_sense/core/introspection.ex
+++ b/lib/elixir_sense/core/introspection.ex
@@ -429,7 +429,7 @@ defmodule ElixirSense.Core.Introspection do
           kind: kind,
           arity: arity,
           callback: "@#{kind} #{name}(#{args})",
-          signature: "",
+          signature: nil,
           doc: doc,
           metadata: metadata |> Map.put(:optional, key in optional_callbacks)
         }
diff --git a/lib/elixir_sense/providers/suggestion/reducers/callbacks.ex b/lib/elixir_sense/providers/suggestion/reducers/callbacks.ex
index 6af38b4d..720c2f7d 100644
--- a/lib/elixir_sense/providers/suggestion/reducers/callbacks.ex
+++ b/lib/elixir_sense/providers/suggestion/reducers/callbacks.ex
@@ -43,23 +43,44 @@ defmodule ElixirSense.Providers.Suggestion.Reducers.Callbacks do
                 Introspection.get_callbacks_with_docs(mod),
               def_prefix?(hint, spec) or Matcher.match?("#{name}", hint) do
             desc = Introspection.extract_summary_from_docs(doc)
-            [_, args_str] = Regex.run(~r/.\(([^\)]*)\)/u, signature)
 
-            args_list =
-              args_str
-              |> String.split(",")
-              |> Enum.map(&String.trim/1)
+            {args, args_list} =
+              if signature do
+                match_res = Regex.run(~r/.\(([^\)]*)\)/u, signature)
+
+                unless match_res do
+                  raise "unable to get arguments from #{inspect(signature)}"
+                end
+
+                [_, args_str] = match_res
+
+                args_list =
+                  args_str
+                  |> String.split(",")
+                  |> Enum.map(&String.trim/1)
+
+                args =
+                  args_str
+                  |> String.replace("\n", " ")
+                  |> String.split(",")
+                  |> Enum.map_join(", ", &String.trim/1)
+
+                {args, args_list}
+              else
+                if arity == 0 do
+                  {"", []}
+                else
+                  args_list = for _ <- 1..arity, do: "term"
+                  {Enum.join(args_list, ", "), args_list}
+                end
+              end
 
             %{
               type: :callback,
               subtype: kind,
               name: Atom.to_string(name),
               arity: arity,
-              args:
-                args_str
-                |> String.replace("\n", " ")
-                |> String.split(",")
-                |> Enum.map_join(", ", &String.trim/1),
+              args: args,
               args_list: args_list,
               origin: mod_name,
               summary: desc,