[Tapioca Addon] Support gem RBI generation

lib/ruby_lsp/tapioca/addon.rb

@@ -13,6 +13,7 @@
 end
 
 require "zlib"
+require "ruby_lsp/tapioca/lockfile_diff_parser"
 
 module RubyLsp
   module Tapioca
@@ -27,6 +28,7 @@ def initialize
         @rails_runner_client = T.let(nil, T.nilable(RubyLsp::Rails::RunnerClient))
         @index = T.let(nil, T.nilable(RubyIndexer::Index))
         @file_checksums = T.let({}, T::Hash[String, String])
+        @lockfile_diff = T.let(nil, T.nilable(String))
         @outgoing_queue = T.let(nil, T.nilable(Thread::Queue))
       end
 
@@ -45,6 +47,10 @@ def activate(global_state, outgoing_queue)
           @rails_runner_client = addon.rails_runner_client
           @outgoing_queue << Notification.window_log_message("Activating Tapioca add-on v#{version}")
           @rails_runner_client.register_server_addon(File.expand_path("server_addon.rb", __dir__))
+
+          if git_repo?
+            lockfile_changed? ? generate_gem_rbis : cleanup_orphaned_rbis
+          end
         rescue IncompatibleApiError
           # The requested version for the Rails add-on no longer matches. We need to upgrade and fix the breaking
           # changes
@@ -127,6 +133,86 @@ def file_updated?(change, path)
 
         false
       end
+
+      sig { returns(T::Boolean) }
+      def git_repo?
+        require "open3"
+
+        _, status = Open3.capture2e("git rev-parse --is-inside-work-tree")
+
+        T.must(status.success?)
+      end
+
+      sig { returns(T::Boolean) }
+      def lockfile_changed?
+        fetch_lockfile_diff
+        !T.must(@lockfile_diff).empty?
+      end
+
+      sig { returns(String) }
+      def fetch_lockfile_diff
+        @lockfile_diff = %x(git diff HEAD Gemfile.lock).strip
+      end
+
+      sig { void }
+      def generate_gem_rbis
+        parser = LockfileDiffParser.new(@lockfile_diff)
+
+        removed_gems = parser.removed_gems
+        added_or_modified_gems = parser.added_or_modified_gems
+
+        if added_or_modified_gems.any?
+          # Resetting BUNDLE_GEMFILE to root folder to use the project's Gemfile instead of Ruby LSP's composed Gemfile
+          stdout, stderr, status = T.unsafe(Open3).capture3(
+            { "BUNDLE_GEMFILE" => "Gemfile" },
+            "bin/tapioca",
+            "gem",
+            "--lsp_addon",
+            *added_or_modified_gems,
+          )
+          T.must(@outgoing_queue) << if status.success?
+            Notification.window_log_message(
+              stdout,
+              type: Constant::MessageType::INFO,
+            )
+          else
+            Notification.window_log_message(
+              stderr,
+              type: Constant::MessageType::ERROR,
+            )
+          end
+        elsif removed_gems.any?
+          FileUtils.rm_f(Dir.glob("sorbet/rbi/gems/{#{removed_gems.join(",")}}@*.rbi"))
+          T.must(@outgoing_queue) << Notification.window_log_message(
+            "Removed RBIs for: #{removed_gems.join(", ")}",
+            type: Constant::MessageType::INFO,
+          )
+        end
+      end
+
+      sig { void }
+      def cleanup_orphaned_rbis
+        untracked_files = %x(git ls-files --others --exclude-standard sorbet/rbi/gems/).lines.map(&:strip)
+        deleted_files = %x(git ls-files --deleted sorbet/rbi/gems/).lines.map(&:strip)
+
+        untracked_files.each do |file|
+          File.delete(file)
+
+          T.must(@outgoing_queue) << Notification.window_log_message(
+            "Deleted untracked RBI: #{file}",
+            type: Constant::MessageType::INFO,
+          )
+        end
+
+        deleted_files.each do |file|
+          %x(git checkout -- #{file})
+
+          T.must(@outgoing_queue) << Notification.window_log_message(
+            "Restored deleted RBI: #{file}",
+            type: Constant::MessageType::INFO,
+          )
+        end
+      end
     end
   end
 end

lib/ruby_lsp/tapioca/lockfile_diff_parser.rb

@@ -0,0 +1,43 @@
+# typed: true
+# frozen_string_literal: true
+
+module RubyLsp
+  module Tapioca
+    class LockfileDiffParser
+      GEM_NAME_PATTERN = /[\w\-]+/
+      DIFF_LINE_PATTERN = /[+-](.*#{GEM_NAME_PATTERN})\s*\(/
+      ADDED_LINE_PATTERN = /^\+.*#{GEM_NAME_PATTERN} \(.*\)/
+      REMOVED_LINE_PATTERN = /^-.*#{GEM_NAME_PATTERN} \(.*\)/
+
+      attr_reader :added_or_modified_gems
+      attr_reader :removed_gems
+
+      def initialize(diff_content)
+        @diff_content = diff_content.lines
+        @added_or_modified_gems = parse_added_or_modified_gems
+        @removed_gems = parse_removed_gems
+      end
+
+      private
+
+      def parse_added_or_modified_gems
+        @diff_content
+          .filter { |line| line.match?(ADDED_LINE_PATTERN) }
+          .map { |line| extract_gem(line) }
+          .uniq
+      end
+
+      def parse_removed_gems
+        @diff_content
+          .filter { |line| line.match?(REMOVED_LINE_PATTERN) }
+          .map { |line| extract_gem(line) }
+          .reject { |gem| @added_or_modified_gems.include?(gem) }
+          .uniq
+      end
+
+      def extract_gem(line)
+        line.match(DIFF_LINE_PATTERN)[1].strip
+      end
+    end
+  end
+end

spec/tapioca/ruby_lsp/tapioca/lockfile_diff_parser_spec.rb

@@ -0,0 +1,62 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "spec_helper"
+require "ruby_lsp/tapioca/lockfile_diff_parser"
+
+module RubyLsp
+  module Tapioca
+    class LockFileDiffParserSpec < Minitest::Spec
+      describe "#parse_added_or_modified_gems" do
+        it "parses added or modified gems from git diff" do
+          diff_output = <<~DIFF
+            +    new_gem (1.0.0)
+            +    updated_gem (2.0.0)
+            -    removed_gem (1.0.0)
+          DIFF
+
+          lockfile_parser = RubyLsp::Tapioca::LockfileDiffParser.new(diff_output)
+          assert_equal ["new_gem", "updated_gem"], lockfile_parser.added_or_modified_gems
+        end
+
+        it "is empty when there is no diff" do
+          diff_output = ""
+
+          lockfile_parser = RubyLsp::Tapioca::LockfileDiffParser.new(diff_output)
+          assert_empty lockfile_parser.added_or_modified_gems
+        end
+      end
+
+      describe "#parse_removed_gems" do
+        it "parses removed gems from git diff" do
+          diff_output = <<~DIFF
+            +    new_gem (1.0.0)
+            -    removed_gem (1.0.0)
+            -    outdated_gem (2.3.4)
+          DIFF
+
+          lockfile_parser = RubyLsp::Tapioca::LockfileDiffParser.new(diff_output)
+          assert_equal ["removed_gem", "outdated_gem"], lockfile_parser.removed_gems
+        end
+      end
+
+      it "handles gem names with hyphens and underscores" do
+        diff_output = <<~DIFF
+          -    my-gem_extra2 (1.0.0.beta1)
+        DIFF
+
+        lockfile_parser = RubyLsp::Tapioca::LockfileDiffParser.new(diff_output)
+        assert_equal ["my-gem_extra2"], lockfile_parser.removed_gems
+      end
+
+      it "handles gem names with multiple hyphens" do
+        diff_output = <<~DIFF
+          -    sorbet-static-and-runtime (0.5.0)
+        DIFF
+
+        lockfile_parser = RubyLsp::Tapioca::LockfileDiffParser.new(diff_output)
+        assert_equal ["sorbet-static-and-runtime"], lockfile_parser.removed_gems
+      end
+    end
+  end
+end