Extract parts of LegacyDiffNote into DiffOnNote concern and move part of responsibility to other classes

1 files changed, 53 insertions, 0 deletions

diff --git a/app/models/concerns/note_on_diff.rb b/app/models/concerns/note_on_diff.rb
new file mode 100644
index 00000000000..b511f33b8fa
--- /dev/null
+++ b/app/models/concerns/note_on_diff.rb
@@ -0,0 +1,53 @@
+module NoteOnDiff
+  extend ActiveSupport::Concern
+
+  NUMBER_OF_TRUNCATED_DIFF_LINES = 16
+
+  included do
+    delegate :blob, :highlighted_diff_lines, to: :diff_file, allow_nil: true
+  end
+
+  def diff_note?
+    true
+  end
+
+  def diff_file
+    raise NotImplementedError
+  end
+
+  def diff_line
+    raise NotImplementedError
+  end
+
+  def for_line?(line)
+    raise NotImplementedError
+  end
+
+  def diff_attributes
+    raise NotImplementedError
+  end
+
+  def can_be_award_emoji?
+    false
+  end
+
+  def truncated_diff_lines
+    prev_match_line = nil
+    prev_lines = []
+
+    highlighted_diff_lines.each do |line|
+      if line.meta?
+        prev_lines.clear
+        prev_match_line = line
+      else
+        prev_lines << line
+
+        break if for_line?(line)
+
+        prev_lines.shift if prev_lines.length >= NUMBER_OF_TRUNCATED_DIFF_LINES
+      end
+    end
+
+    prev_lines
+  end
+end