1 files changed, 66 insertions, 0 deletions
diff --git a/lib/gitlab/github_import/representation/diff_notes/suggestion_formatter.rb b/lib/gitlab/github_import/representation/diff_notes/suggestion_formatter.rb
new file mode 100644
index 00000000000..4e5855ee4cd
--- /dev/null
+++ b/lib/gitlab/github_import/representation/diff_notes/suggestion_formatter.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+# This class replaces Github markdown suggestion tag with
+# a Gitlab suggestion tag. The difference between
+# Github's and Gitlab's suggestion tags is that Gitlab
+# includes the range of the suggestion in the tag, while Github
+# uses other note attributes to position the suggestion.
+module Gitlab
+  module GithubImport
+    module Representation
+      module DiffNotes
+        class SuggestionFormatter
+          # A github suggestion:
+          # - the ```suggestion tag must be the first text of the line
+          #   - it might have up to 3 spaces before the ```suggestion tag
+          # - extra text on the ```suggestion tag line will be ignored
+          GITHUB_SUGGESTION = /^\ {,3}(?<suggestion>```suggestion\b).*(?<eol>\R)/.freeze
+
+          def self.formatted_note_for(...)
+            new(...).formatted_note
+          end
+
+          def initialize(note:, start_line: nil, end_line: nil)
+            @note = note
+            @start_line = start_line
+            @end_line = end_line
+          end
+
+          def formatted_note
+            if contains_suggestion?
+              note.gsub(
+                GITHUB_SUGGESTION,
+                "\\k<suggestion>:#{suggestion_range}\\k<eol>"
+              )
+            else
+              note
+            end
+          end
+
+          private
+
+          attr_reader :note, :start_line, :end_line
+
+          def contains_suggestion?
+            note.to_s.match?(GITHUB_SUGGESTION)
+          end
+
+          # Github always saves the comment on the _last_ line of the range.
+          # Therefore, the diff hunk will always be related to lines before
+          # the comment itself.
+          def suggestion_range
+            "-#{line_count}+0"
+          end
+
+          def line_count
+            if start_line.present?
+              end_line - start_line
+            else
+              0
+            end
+          end
+        end
+      end
+    end
+  end
+end