LSP: Support formatting RBS file

To keep RBS files clean, this adds a new feature to format RBS file to
Steep LSP.

lib/steep/server/interaction_worker.rb

@@ -6,6 +6,7 @@ class InteractionWorker < BaseWorker
       ApplyChangeJob = _ = Class.new()
       HoverJob = _ = Struct.new(:id, :path, :line, :column, keyword_init: true)
       CompletionJob = _ = Struct.new(:id, :path, :line, :column, :trigger, keyword_init: true)
+      FormattingJob = _ = Struct.new(:id, :path, keyword_init: true)
       SignatureHelpJob = _ = Struct.new(:id, :path, :line, :column, keyword_init: true)
 
       LSP = LanguageServer::Protocol
@@ -54,6 +55,13 @@ def handle_job(job)
                 result: process_latest_job(job) { process_signature_help(job) }
               }
             )
+          when FormattingJob
+            writer.write(
+              {
+                id: job.id,
+                result: process_latest_job(job) { process_formatting(job) }
+              }
+            )
           end
         end
       end
@@ -125,6 +133,12 @@ def handle_request(request)
           line, column = params[:position].yield_self {|hash| [hash[:line]+1, hash[:character]] }
 
           queue_job SignatureHelpJob.new(id: id, path: path, line: line, column: column)
+        when "textDocument/formatting"
+          id = request[:id]
+          params = request[:params]
+          path = project.relative_path(PathHelper.to_pathname!(params[:textDocument][:uri]))
+
+          queue_job FormattingJob.new(id: id, path: path)
         end
       end
 
@@ -494,6 +508,41 @@ def process_signature_help(job)
         # Reuse the latest result to keep SignatureHelp opened while typing
         @last_signature_help_result if @last_signature_help_line == job.line
       end
+
+      def process_formatting(job)
+        Steep.logger.tagged("#response_to_formatting") do
+          Steep.measure "Generating response" do
+            if (targets = project.targets_for_path(job.path)).is_a?(Array)
+              target = targets[0] or raise
+              sig_service = service.signature_services[target.name] or raise
+              file = sig_service.files[job.path]
+
+              parsed = RBS::Parser.parse_signature(file.content)
+              new_text = StringIO.new.tap do |out|
+                RBS::Writer.new(out: out).write(parsed[1] + parsed[2])
+              end.string
+
+              [
+                LSP::Interface::TextEdit.new(
+                  range: LSP::Interface::Range.new(
+                    start: LSP::Interface::Position.new(
+                      line: 0,
+                      character: 0
+                    ),
+                    end: LSP::Interface::Position.new(
+                      line: file.content.count("\n") + 1,
+                      character: 0
+                    )
+                  ),
+                  new_text: new_text
+                )
+              ]
+            else
+              nil
+            end
+          end
+        end
+      end
     end
   end
 end

lib/steep/server/master.rb

@@ -610,7 +610,8 @@ def process_message_from_client(message)
                       definition_provider: true,
                       declaration_provider: false,
                       implementation_provider: true,
-                      type_definition_provider: true
+                      type_definition_provider: true,
+                      document_formatting_provider: true
                     )
                   )
                 }
@@ -828,6 +829,29 @@ def process_message_from_client(message)
             )
           end
 
+        when "textDocument/formatting"
+          if interaction_worker
+            if message[:params][:textDocument][:uri].to_s =~ /\.rbs$/i
+              result_controller << send_request(method: message[:method], params: message[:params], worker: interaction_worker) do |handler|
+                handler.on_completion do |response|
+                  job_queue << SendMessageJob.to_client(
+                    message: {
+                      id: message[:id],
+                      result: response[:result]
+                    }
+                  )
+                end
+              end
+            else
+              job_queue << SendMessageJob.to_client(
+                message: {
+                  id: message[:id],
+                  result: nil
+                }
+              )
+            end
+          end
+
         when "$/typecheck"
           request = controller.make_request(
             guid: message[:params][:guid],

sig/steep/server/interaction_worker.rbs

@@ -36,6 +36,14 @@ module Steep
         def initialize: (id: String, path: Pathname, line: Integer, column: Integer, trigger: String) -> void
       end
 
+      class FormattingJob
+        attr_reader id: String
+
+        attr_reader path: Pathname
+
+        def initialize: (id: String, path: Pathname) -> void
+      end
+
       class SignatureHelpJob
         attr_reader id: String
 
@@ -48,7 +56,7 @@ module Steep
         def initialize: (id: String, path: Pathname, line: Integer, column: Integer) -> void
       end
 
-      type job = ApplyChangeJob | HoverJob | CompletionJob | SignatureHelpJob
+      type job = ApplyChangeJob | HoverJob | CompletionJob | FormattingJob | SignatureHelpJob
 
       module LSP = LanguageServer::Protocol
 
@@ -85,6 +93,8 @@ module Steep
       def format_completion_item_for_rbs: (Services::SignatureService, RBS::TypeName, CompletionJob job, String complete_text, Integer prefix_size) -> LanguageServer::Protocol::Interface::CompletionItem
 
       def format_completion_item: (CompletionProvider::item item) -> LanguageServer::Protocol::Interface::CompletionItem
+
+      def process_formatting: (FormattingJob job) -> Array[LanguageServer::Protocol::Interface::TextEdit]?
     end
   end
 end

test/interaction_worker_test.rb

@@ -442,5 +442,37 @@ class Qux
       end
     end
   end
+
+  def test_handle_formatting_request
+    in_tmpdir do
+      project = Project.new(steepfile_path: current_dir + "Steepfile")
+      Project::DSL.parse(project, <<EOF)
+target :lib do
+  check "lib"
+  signature "sig"
 end
+EOF
+      worker = Server::InteractionWorker.new(project: project, reader: worker_reader, writer: worker_writer, queue: [])
+
+      worker.service.update(
+        changes: {
+          Pathname("sig/hello.rbs") => [ContentChange.string(<<RUBY)]
+class Foo
+  def baz: () -> String | () -> Integer
+    end
+RUBY
+        }
+      ) {}
 
+      response = worker.process_formatting(
+        InteractionWorker::FormattingJob.new(
+          path: Pathname("sig/hello.rbs")
+        )
+      )
+
+      assert_instance_of Array, response
+      assert_equal 1, response.size
+      assert_instance_of LanguageServer::Protocol::Interface::TextEdit, response[0]
+    end
+  end
+end