1 files changed, 42 insertions, 2 deletions
diff --git a/app/controllers/projects/blob_controller.rb b/app/controllers/projects/blob_controller.rb
index a8c0a68fc17..ebc61264b39 100644
--- a/app/controllers/projects/blob_controller.rb
+++ b/app/controllers/projects/blob_controller.rb
@@ -3,8 +3,8 @@ class Projects::BlobController < Projects::ApplicationController
   include ExtractsPath
   include CreatesCommit
   include RendersBlob
+  include NotesHelper
   include ActionView::Helpers::SanitizeHelper
-
   prepend_before_action :authenticate_user!, only: [:edit]
 
   before_action :set_request_format, only: [:edit, :show, :update]
@@ -93,6 +93,7 @@ class Projects::BlobController < Projects::ApplicationController
     @lines = Gitlab::Highlight.highlight(@blob.path, @blob.data, repository: @repository).lines
 
     @form = UnfoldForm.new(params)
+
     @lines = @lines[@form.since - 1..@form.to - 1].map(&:html_safe)
 
     if @form.bottom?
@@ -103,11 +104,50 @@ class Projects::BlobController < Projects::ApplicationController
       @match_line = "@@ -#{line}+#{line} @@"
     end
 
-    render layout: false
+    # We can keep only 'render_diff_lines' from this conditional when
+    # https://gitlab.com/gitlab-org/gitlab-ce/issues/44988 is done
+    if rendered_for_merge_request?
+      render_diff_lines
+    else
+      render layout: false
+    end
   end
 
   private
 
+  # Converts a String array to Gitlab::Diff::Line array
+  def render_diff_lines
+    @lines.map! do |line|
+      # These are marked as context lines but are loaded from blobs.
+      # We also have context lines loaded from diffs in other places.
+      diff_line = Gitlab::Diff::Line.new(line, 'context', nil, nil, nil)
+      diff_line.rich_text = line
+      diff_line
+    end
+
+    add_match_line
+
+    render json: @lines
+  end
+
+  def add_match_line
+    return unless @form.unfold?
+
+    if @form.bottom? && @form.to < @blob.lines.size
+      old_pos = @form.to - @form.offset
+      new_pos = @form.to
+    elsif @form.since != 1
+      old_pos = new_pos = @form.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, 'match', nil, old_pos, new_pos)
+
+    @form.bottom? ? @lines.push(@match_line) : @lines.unshift(@match_line)
+  end
+
   def blob
     @blob ||= @repository.blob_at(@commit.id, @path)