Add discussions for merge requests to notes controller

app/controllers/notes_controller.rb

@@ -6,10 +6,15 @@ class NotesController < ProjectResourceController
   respond_to :js
   def index
-    notes
+    @notes = Notes::LoadContext.new(project, current_user, params).execute
+
     if params[:target_type] == "merge_request"
-      @mixed_targets = true
+      @mixed_targets    = true
       @main_target_type = params[:target_type].camelize
+      @discussions      = discussions_from_notes
+      @has_diff         = true
+    elsif params[:target_type] == "commit"
+      @has_diff = true
     end
     respond_with(@notes)
@@ -40,7 +45,33 @@ class NotesController < ProjectResourceController
   protected
-  def notes
-    @notes = Notes::LoadContext.new(project, current_user, params).execute
+  def discussion_notes_for(note)
+    @notes.select do |other_note|
+      note.discussion_id == other_note.discussion_id
+    end
+  end
+
+  def discussions_from_notes
+    discussion_ids = []
+    discussions = []
+
+    @notes.each do |note|
+      next if discussion_ids.include?(note.discussion_id)
+
+      # don't group notes for the main target
+      if for_main_target?(note)
+        discussions << [note]
+      else
+        discussions << discussion_notes_for(note)
+        discussion_ids << note.discussion_id
+      end
+    end
+
+    discussions
+  end
+
+  # Helps to distinguish e.g. commit notes in mr notes list
+  def for_main_target?(note)
+    !@mixed_targets || (@main_target_type == note.noteable_type && !note.for_diff_line?)
   end
 end