1 files changed, 83 insertions, 5 deletions
diff --git a/app/helpers/diff_helper.rb b/app/helpers/diff_helper.rb
index ee4d4fbdff5..afe7447d4e2 100644
--- a/app/helpers/diff_helper.rb
+++ b/app/helpers/diff_helper.rb
@@ -1,14 +1,20 @@
 module DiffHelper
-  def safe_diff_files(diffs)
+  def allowed_diff_size
     if diff_hard_limit_enabled?
-      diffs.first(Commit::DIFF_HARD_LIMIT_FILES)
+      Commit::DIFF_HARD_LIMIT_FILES
     else
-      diffs.first(Commit::DIFF_SAFE_FILES)
+      Commit::DIFF_SAFE_FILES
+    end
+  end
+
+  def safe_diff_files(diffs)
+    diffs.first(allowed_diff_size).map do |diff|
+      Gitlab::Diff::File.new(diff)
     end
   end
 
-  def show_diff_size_warninig?(diffs)
-    safe_diff_files(diffs).size < diffs.size
+  def show_diff_size_warning?(diffs)
+    diffs.size > allowed_diff_size
   end
 
   def diff_hard_limit_enabled?
@@ -19,4 +25,76 @@ module DiffHelper
       false
     end
   end
+
+  def generate_line_code(file_path, line)
+    Gitlab::Diff::LineCode.generate(file_path, line.new_pos, line.old_pos)
+  end
+
+  def parallel_diff(diff_file, index)
+    lines = []
+    skip_next = false
+
+    # Building array of lines
+    #
+    # [left_type, left_line_number, left_line_content, line_code, right_line_type, right_line_number, right_line_content]
+    #
+    diff_file.diff_lines.each do |line|
+
+      full_line = line.text
+      type = line.type
+      line_code = generate_line_code(diff_file.file_path, line)
+      line_new = line.new_pos
+      line_old = line.old_pos
+
+      next_line = diff_file.next_line(line.index)
+
+      if next_line
+        next_type = next_line.type
+        next_line = next_line.text
+      end
+
+      line = [type, line_old, full_line, line_code, next_type, line_new]
+      if type == 'match' || type.nil?
+        # line in the right panel is the same as in the left one
+        line = [type, line_old, full_line, line_code, type, line_new, full_line]
+        lines.push(line)
+      elsif type == 'old'
+        if next_type == 'new'
+          # Left side has text removed, right side has text added
+          line.push(next_line)
+          lines.push(line)
+          skip_next = true
+        elsif next_type == 'old' || next_type.nil?
+          # Left side has text removed, right side doesn't have any change
+          line.pop # remove the newline
+          line.push(nil) # no line number on the right panel
+          line.push("&nbsp;") # empty line on the right panel
+          lines.push(line)
+        end
+      elsif type == 'new'
+        if skip_next
+          # Change has been already included in previous line so no need to do it again
+          skip_next = false
+          next
+        else
+          # Change is only on the right side, left side has no change
+          line = [nil, nil, "&nbsp;", line_code, type, line_new, full_line]
+          lines.push(line)
+        end
+      end
+    end
+    lines
+  end
+
+  def unfold_bottom_class(bottom)
+    (bottom) ? 'js-unfold-bottom' : ''
+  end
+
+  def diff_line_content(line)
+    if line.blank?
+      " &nbsp;"
+    else
+      line
+    end
+  end
 end