feat: add active parameter

Author: lucacervello

lib/next_ls.ex

@@ -831,8 +831,8 @@ defmodule NextLS do
     text = Enum.join(lsp.assigns.documents[uri], "\n")
 
     signature_help =
-      case SignatureHelp.fetch_mod_and_name(text, {position.line + 1, position.character + 1}) do
-        {:ok, {mod, name}} ->
+      case SignatureHelp.fetch(text, {position.line + 1, position.character + 1}) do
+        {:ok, {mod, name, param_index}} ->
           docs =
             dispatch(lsp.assigns.registry, :runtimes, fn entries ->
               [result] =
@@ -844,7 +844,7 @@ defmodule NextLS do
             end)
 
           docs
-          |> SignatureHelp.format(name)
+          |> SignatureHelp.format(name, param_index)
           |> List.first()
 
         {:error, :not_found} ->

lib/next_ls/helpers/ast_helpers.ex

@@ -204,11 +204,11 @@ defmodule NextLS.ASTHelpers do
         ast
         |> Zipper.zip()
         |> Zipper.find(fn
-          {{:., _, _}, _metadata, _} = node ->
-            range = Sourceror.get_range(node)
+          {:|>, _, [_, {{:., _, _}, _metadata, _} = func_node]} ->
+            inside?(func_node, position)
 
-            Sourceror.compare_positions(range.start, position) == :lt &&
-              Sourceror.compare_positions(range.end, position) == :gt
+          {{:., _, _}, _metadata, _} = node ->
+            inside?(node, position)
 
           _ ->
             false
@@ -220,5 +220,25 @@ defmodule NextLS.ASTHelpers do
         {:error, :not_found}
       end
     end
+
+    def find_params_index(ast, {line, column}) do
+      ast
+      |> Sourceror.get_args()
+      |> Enum.map(&Sourceror.get_meta/1)
+      |> Enum.find_index(fn meta ->
+        if meta[:closing] do
+          line <= meta[:closing][:line] and line >= meta[:line]
+        else
+          meta[:line] == line and column <= meta[:column]
+        end
+      end)
+    end
+
+    defp inside?(node, position) do
+      range = Sourceror.get_range(node)
+
+      Sourceror.compare_positions(range.start, position) == :lt &&
+        Sourceror.compare_positions(range.end, position) == :gt
+    end
   end
 end

lib/next_ls/signature_help.ex

@@ -8,7 +8,7 @@ defmodule NextLS.SignatureHelp do
   alias GenLSP.Structures.SignatureInformation
   alias NextLS.ASTHelpers
 
-  def fetch_mod_and_name(text, position) do
+  def fetch(text, position) do
     ast =
       text
       |> Spitfire.parse(literal_encoder: &{:ok, {:__literal__, &2, [&1]}})
@@ -19,37 +19,56 @@ defmodule NextLS.SignatureHelp do
 
     with {:ok, result} <- ASTHelpers.Function.find_remote_function_call_within(ast, position) do
       case result do
-        {{:., _, [{:__aliases__, _, modules}, name]}, _, _} -> {:ok, {Module.concat(modules), name}}
+        {:|>, _, [_, {{:., _, [{:__aliases__, _, modules}, name]}, _, _} = node]} ->
+          param_index = ASTHelpers.Function.find_params_index(node, position)
+
+          if param_index do
+            {:ok, {Module.concat(modules), name, param_index + 1}}
+          else
+            {:ok, {Module.concat(modules), name, nil}}
+          end
+
+        {{:., _, [{:__aliases__, _, modules}, name]}, _, _} = node ->
+          param_index = ASTHelpers.Function.find_params_index(node, position)
+
+          {:ok, {Module.concat(modules), name, param_index}}
+
+        _otherwise ->
+          {:error, :not_found}
       end
     end
   end
 
-  def format({:ok, {:docs_v1, _, _lang, content_type, _, _, docs}}, func_name) do
+  def format({:ok, {:docs_v1, _, _lang, content_type, _, _, docs}}, func_name, param_index) do
     for {{_, name, _arity}, _, [signature], fdoc, _} <- docs, name == func_name do
       params_info =
         signature
         |> Spitfire.parse!()
-        |> then(fn {_, _, args} ->
-          Enum.map(args, fn {name, _, _} ->
-            %ParameterInformation{
-              label: Atom.to_string(name)
-            }
-          end)
+        |> Sourceror.get_args()
+        |> Enum.map(fn {name, _, _} ->
+          %ParameterInformation{
+            label: Atom.to_string(name)
+          }
         end)
 
       %SignatureHelp{
         signatures: [
           %SignatureInformation{
             label: signature,
             parameters: params_info,
-            documentation: maybe_doc(content_type, fdoc)
+            documentation: maybe_doc(content_type, fdoc),
+            active_parameter: param_index
           }
         ]
       }
     end
   end
 
-  def format({:ok, {:error, :module_not_found}}, _func_name) do
+  def format({:ok, {:error, :module_not_found}}, _func_name, _param_index) do
+    []
+  end
+
+  def format({:error, :not_ready}, _func_name, _param_index) do
     []
   end