3 files changed, 60 insertions, 12 deletions
diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index 2820293ad5c..40bcfa20e7d 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -130,11 +130,13 @@ module Gitlab
 
       # Array of Gitlab::Diff::Line objects
       def diff_lines
-        @diff_lines ||= Gitlab::Diff::Parser.new.parse(raw_diff.each_line).to_a
+        @diff_lines ||=
+          Gitlab::Diff::Parser.new.parse(raw_diff.each_line, diff_file: self).to_a
       end
 
       def highlighted_diff_lines
-        @highlighted_diff_lines ||= Gitlab::Diff::Highlight.new(self, repository: self.repository).highlight
+        @highlighted_diff_lines ||=
+          Gitlab::Diff::Highlight.new(self, repository: self.repository).highlight
       end
 
       # Array[<Hash>] with right/left keys that contains Gitlab::Diff::Line objects which text is hightlighted
@@ -239,8 +241,33 @@ module Gitlab
         simple_viewer.is_a?(DiffViewer::Text) && (ignore_errors || simple_viewer.render_error.nil?)
       end
 
+      # This adds the bottom match line to the array if needed. It contains
+      # the data to load more context lines.
+      def diff_lines_for_serializer
+        lines = highlighted_diff_lines
+
+        return if lines.empty?
+
+        last_line = lines.last
+
+        if last_line.new_pos < total_blob_lines(blob)
+          match_line = Gitlab::Diff::Line.new("", 'match', nil, last_line.old_pos, last_line.new_pos)
+          lines.push(match_line)
+        end
+
+        lines
+      end
+
       private
 
+      def total_blob_lines(blob)
+        @total_lines ||= begin
+          line_count = blob.lines.size
+          line_count -= 1 if line_count > 0 && blob.lines.last.blank?
+          line_count
+        end
+      end
+
       # We can't use Object#try because Blob doesn't inherit from Object, but
       # from BasicObject (via SimpleDelegator).
       def try_blobs(meth)
diff --git a/lib/gitlab/diff/line.rb b/lib/gitlab/diff/line.rb
index a1e904cfef4..2b3ebfbb9ff 100644
--- a/lib/gitlab/diff/line.rb
+++ b/lib/gitlab/diff/line.rb
@@ -1,22 +1,26 @@
 module Gitlab
   module Diff
     class Line
-      attr_reader :type, :index, :old_pos, :new_pos
+      attr_reader :line_code, :type, :index, :old_pos, :new_pos
       attr_writer :rich_text
       attr_accessor :text
 
-      def initialize(text, type, index, old_pos, new_pos, parent_file: nil)
+      def initialize(text, type, index, old_pos, new_pos, parent_file: nil, line_code: nil)
         @text, @type, @index = text, type, index
         @old_pos, @new_pos = old_pos, new_pos
         @parent_file = parent_file
+
+        # When line code is not provided from cache store we build it
+        # using the parent_file(Diff::File or Conflict::File).
+        @line_code = line_code || calculate_line_code
       end
 
       def self.init_from_hash(hash)
-        new(hash[:text], hash[:type], hash[:index], hash[:old_pos], hash[:new_pos])
+        new(hash[:text], hash[:type], hash[:index], hash[:old_pos], hash[:new_pos], line_code: hash[:line_code])
       end
 
       def serialize_keys
-        @serialize_keys ||= %i(text type index old_pos new_pos)
+        @serialize_keys ||= %i(line_code text type index old_pos new_pos)
       end
 
       def to_hash
@@ -62,20 +66,37 @@ module Gitlab
       end
 
       def rich_text
-        @parent_file.highlight_lines! if @parent_file && !@rich_text
+        @parent_file.try(:highlight_lines!) if @parent_file && !@rich_text
 
         @rich_text
       end
 
+      def meta_positions
+        return unless meta?
+
+        {
+          old_pos: old_pos,
+          new_pos: new_pos
+        }
+      end
+
       def as_json(opts = nil)
         {
+          line_code: line_code,
           type: type,
           old_line: old_line,
           new_line: new_line,
           text: text,
-          rich_text: rich_text || text
+          rich_text: rich_text || text,
+          meta_data: meta_positions
         }
       end
+
+      private
+
+      def calculate_line_code
+        @parent_file&.line_code(self)
+      end
     end
   end
 end
diff --git a/lib/gitlab/diff/parser.rb b/lib/gitlab/diff/parser.rb
index 8302f30a0a2..7ae7ed286ed 100644
--- a/lib/gitlab/diff/parser.rb
+++ b/lib/gitlab/diff/parser.rb
@@ -3,7 +3,7 @@ module Gitlab
     class Parser
       include Enumerable
 
-      def parse(lines)
+      def parse(lines, diff_file: nil)
         return [] if lines.blank?
 
         @lines = lines
@@ -31,17 +31,17 @@ module Gitlab
 
               next if line_old <= 1 && line_new <= 1 # top of file
 
-              yielder << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new)
+              yielder << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new, parent_file: diff_file)
               line_obj_index += 1
               next
             elsif line[0] == '\\'
               type = "#{context}-nonewline"
 
-              yielder << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new)
+              yielder << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new, parent_file: diff_file)
               line_obj_index += 1
             else
               type = identification_type(line)
-              yielder << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new)
+              yielder << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new, parent_file: diff_file)
               line_obj_index += 1
             end