Move diff_line preparation into presenter

Update spec

1 files changed, 31 insertions, 0 deletions

diff --git a/app/presenters/blobs/unfold_presenter.rb b/app/presenters/blobs/unfold_presenter.rb
index 908b2f97f89..7b13db3bb74 100644
--- a/app/presenters/blobs/unfold_presenter.rb
+++ b/app/presenters/blobs/unfold_presenter.rb
@@ -25,6 +25,17 @@ module Blobs
       end
     end
 
+    # Converts a String array to Gitlab::Diff::Line array, with match line added
+    def diff_lines
+      diff_lines = lines.map do |line|
+        Gitlab::Diff::Line.new(line, nil, nil, nil, nil, rich_text: line)
+      end
+
+      add_match_line(diff_lines)
+
+      diff_lines
+    end
+
     def lines
       strong_memoize(:lines) do
         lines = @all_lines
@@ -40,5 +51,25 @@ module Blobs
       line = [since, lines_length].join(',')
       "@@ -#{line}+#{line} @@"
     end
+
+    private
+
+    def add_match_line(diff_lines)
+      return unless unfold?
+
+      if bottom? && to < @all_lines.size
+        old_pos = to - offset
+        new_pos = to
+      elsif since != 1
+        old_pos = new_pos = since
+      end
+
+      # Match line is not needed when it reaches the top limit or bottom limit of the file.
+      return unless new_pos
+
+      match_line = Gitlab::Diff::Line.new(match_line_text, 'match', nil, old_pos, new_pos)
+
+      bottom? ? diff_lines.push(match_line) : diff_lines.unshift(match_line)
+    end
   end
 end