1 files changed, 45 insertions, 0 deletions
diff --git a/app/models/diff_discussion.rb b/app/models/diff_discussion.rb
new file mode 100644
index 00000000000..14ddd2fcc88
--- /dev/null
+++ b/app/models/diff_discussion.rb
@@ -0,0 +1,45 @@
+# A discussion on merge request or commit diffs consisting of `DiffNote` notes.
+#
+# A discussion of this type can be resolvable.
+class DiffDiscussion < Discussion
+  include DiscussionOnDiff
+
+  def self.note_class
+    DiffNote
+  end
+
+  delegate  :position,
+            :original_position,
+
+            to: :first_note
+
+  def legacy_diff_discussion?
+    false
+  end
+
+  def merge_request_version_params
+    return unless for_merge_request?
+
+    if active?
+      {}
+    else
+      diff_refs = position.diff_refs
+
+      if diff = noteable.merge_request_diff_for(diff_refs)
+        { diff_id: diff.id }
+      elsif diff = noteable.merge_request_diff_for(diff_refs.head_sha)
+        {
+          diff_id: diff.id,
+          start_sha: diff_refs.start_sha
+        }
+      end
+    end
+  end
+
+  def reply_attributes
+    super.merge(
+      original_position: original_position.to_json,
+      position: position.to_json
+    )
+  end
+end