1 files changed, 63 insertions, 0 deletions
diff --git a/tooling/danger/suggestor.rb b/tooling/danger/suggestor.rb
new file mode 100644
index 00000000000..ffda98e67d0
--- /dev/null
+++ b/tooling/danger/suggestor.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+module Tooling
+  module Danger
+    module Suggestor
+      # For file lines matching `regex` adds suggestion `replacement` with `comment_text` added.
+      def add_suggestion(filename:, regex:, replacement: nil, comment_text: nil, exclude: nil)
+        added_lines = added_lines_matching(filename, regex)
+
+        return if added_lines.empty?
+
+        file_lines = project_helper.file_lines(filename)
+
+        added_lines.each_with_object([]) do |added_line, processed_line_numbers|
+          line_number = find_line_number(file_lines, added_line.delete_prefix('+'),
+exclude_indexes: processed_line_numbers)
+
+          next unless line_number
+          next if !exclude.nil? && added_line.include?(exclude)
+
+          processed_line_numbers << line_number
+
+          if replacement
+            suggestion_text = file_lines[line_number]
+            suggestion_text = suggestion_text.gsub(regex, replacement)
+          end
+
+          markdown(comment(comment_text, suggestion_text), file: filename, line: line_number.succ)
+        end
+      end
+
+      private
+
+      def added_lines_matching(filename, regex)
+        helper.changed_lines(filename).grep(/\A\+( )?/).grep(regex)
+      end
+
+      def find_line_number(file_lines, searched_line, exclude_indexes: [])
+        _, index = file_lines.each_with_index.find do |file_line, index|
+          file_line == searched_line && !exclude_indexes.include?(index) # rubocop:disable Rails/NegateInclude
+        end
+
+        index
+      end
+
+      def comment(comment_text = nil, suggested_line = nil)
+        if suggested_line
+          suggestion_text = <<~SUGGESTION
+            ```suggestion
+            %<suggested_line>s
+            ```
+          SUGGESTION
+        end
+
+        comment_body = <<~COMMENT_BODY.chomp
+        #{suggestion_text}
+        #{comment_text}
+        COMMENT_BODY
+
+        format(comment_body.chomp, suggested_line: suggested_line)
+      end
+    end
+  end
+end