Add Rails Runner client

lib/ruby_lsp/ruby_lsp_rails/runner_client.rb

@@ -0,0 +1,84 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "json"
+require "open3"
+
+# NOTE: We should avoid printing to stderr since it causes problems. We never read the standard error pipe
+# from the client, so it will become full and eventually hang or crash.
+# Instead, return a response with an `error` key.
+
+module RubyLsp
+  module Rails
+    class RunnerClient
+      extend T::Sig
+
+      sig { void }
+      def initialize
+        stdin, stdout, stderr, wait_thread = Open3.popen3(
+          "bin/rails",
+          "runner",
+          "#{__dir__}/server.rb",
+          "start",
+        )
+        @stdin = T.let(stdin, IO)
+        @stdout = T.let(stdout, IO)
+        @stderr = T.let(stderr, IO)
+        @wait_thread = T.let(wait_thread, Process::Waiter)
+        @stdin.binmode # for Windows compatibility
+        @stdout.binmode # for Windows compatibility
+      end
+
+      sig { params(name: String).returns(T.nilable(T::Hash[Symbol, T.untyped])) }
+      def model(name)
+        make_request("model", name: name)
+      end
+
+      sig { void }
+      def shutdown
+        send_notification("shutdown")
+        Thread.pass while @wait_thread.alive?
+        [@stdin, @stdout, @stderr].each(&:close)
+      end
+
+      sig { returns(T::Boolean) }
+      def stopped?
+        [@stdin, @stdout, @stderr].all?(&:closed?) && !@wait_thread.alive?
+      end
+
+      private
+
+      sig { params(request: T.untyped, params: T.untyped).returns(T.untyped) }
+      def make_request(request, params = nil)
+        send_message(request, params)
+        read_response
+      end
+
+      sig { params(request: T.untyped, params: T.untyped).void }
+      def send_message(request, params = nil)
+        message = { method: request }
+        message[:params] = params if params
+        json = message.to_json
+
+        @stdin.write("Content-Length: #{json.length}\r\n\r\n", json)
+      end
+
+      alias_method :send_notification, :send_message
+
+      sig { returns(T.nilable(T::Hash[Symbol, T.untyped])) }
+      def read_response
+        headers = @stdout.gets("\r\n\r\n")
+        raw_response = @stdout.read(T.must(headers)[/Content-Length: (\d+)/i, 1].to_i)
+
+        response = JSON.parse(T.must(raw_response), symbolize_names: true)
+
+        if response[:error]
+          warn("Ruby LSP Rails error: " + response[:error])
+          return
+        end
+
+        response.fetch(:result)
+      end
+    end
+  end
+end

lib/ruby_lsp/ruby_lsp_rails/server.rb

@@ -0,0 +1,87 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "sorbet-runtime"
+require "json"
+
+begin
+  T::Configuration.default_checked_level = :never
+  # Suppresses call validation errors
+  T::Configuration.call_validation_error_handler = ->(*) {}
+  # Suppresses errors caused by T.cast, T.let, T.must, etc.
+  T::Configuration.inline_type_error_handler = ->(*) {}
+  # Suppresses errors caused by incorrect parameter ordering
+  T::Configuration.sig_validation_error_handler = ->(*) {}
+rescue
+  # Need this rescue so that if another gem has
+  # already set the checked level by the time we
+  # get to it, we don't fail outright.
+  nil
+end
+
+module RubyLsp
+  module Rails
+    class Server
+      VOID = Object.new
+
+      extend T::Sig
+
+      sig { params(model_name: String).returns(T.nilable(T::Hash[Symbol, T.untyped])) }
+      def resolve_database_info_from_model(model_name)
+        const = ActiveSupport::Inflector.safe_constantize(model_name)
+        unless const && const < ActiveRecord::Base && !const.abstract_class?
+          return {
+            result: nil,
+          }
+        end
+
+        schema_file = ActiveRecord::Tasks::DatabaseTasks.schema_dump_path(const.connection.pool.db_config)
+
+        {
+          result: {
+            columns: const.columns.map { |column| [column.name, column.type] },
+            schema_file: ::Rails.root + schema_file,
+          },
+        }
+      rescue => e
+        {
+          error: e.message,
+        }
+      end
+
+      sig { void }
+      def start
+        $stdin.sync = true
+        $stdout.sync = true
+
+        running = T.let(true, T::Boolean)
+
+        while running
+          headers = $stdin.gets("\r\n\r\n")
+          request = $stdin.read(headers[/Content-Length: (\d+)/i, 1].to_i)
+
+          json = JSON.parse(request, symbolize_names: true)
+          request_method = json.fetch(:method)
+          params = json[:params]
+
+          response = case request_method
+          when "shutdown"
+            running = false
+            VOID
+          when "model"
+            resolve_database_info_from_model(params.fetch(:name))
+          else
+            VOID
+          end
+
+          next if response == VOID
+
+          json_response = response.to_json
+          $stdout.write("Content-Length: #{json_response.length}\r\n\r\n#{json_response}")
+        end
+      end
+    end
+  end
+end
+
+RubyLsp::Rails::Server.new.start if ARGV.first == "start"

test/ruby_lsp_rails/runner_client_test.rb

@@ -0,0 +1,47 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+require "ruby_lsp/ruby_lsp_rails/runner_client"
+
+module RubyLsp
+  module Rails
+    class RunnerClientTest < ActiveSupport::TestCase
+      setup do
+        @client = T.let(RunnerClient.new, RunnerClient)
+      end
+
+      teardown do
+        @client.shutdown
+        assert_predicate @client, :stopped?
+      end
+
+      test "#model returns information for the requested model" do
+        # These columns are from the schema in the dummy app: test/dummy/db/schema.rb
+        columns = [
+          ["id", "integer"],
+          ["first_name", "string"],
+          ["last_name", "string"],
+          ["age", "integer"],
+          ["created_at", "datetime"],
+          ["updated_at", "datetime"],
+        ]
+        response = T.must(@client.model("User"))
+        assert_equal(columns, response.fetch(:columns))
+        assert_match(%r{db/schema\.rb$}, response.fetch(:schema_file))
+      end
+
+      test "returns nil if model doesn't exist" do
+        assert_nil @client.model("Foo")
+      end
+
+      test "returns nil if class is not a model" do
+        assert_nil @client.model("Time")
+      end
+
+      test "returns nil if class is an abstract model" do
+        assert_nil @client.model("ApplicationRecord")
+      end
+    end
+  end
+end