3 files changed, 40 insertions, 9 deletions
diff --git a/app/services/issues/base_service.rb b/app/services/issues/base_service.rb
index ee1b40db718..34199eb5d13 100644
--- a/app/services/issues/base_service.rb
+++ b/app/services/issues/base_service.rb
@@ -9,11 +9,33 @@ module Issues
 
     private
 
+    def create_assignee_note(issue, old_assignees)
+      SystemNoteService.change_issue_assignees(
+        issue, issue.project, current_user, old_assignees)
+    end
+
     def execute_hooks(issue, action = 'open')
       issue_data  = hook_data(issue, action)
       hooks_scope = issue.confidential? ? :confidential_issue_hooks : :issue_hooks
       issue.project.execute_hooks(issue_data, hooks_scope)
       issue.project.execute_services(issue_data, hooks_scope)
     end
+
+    def filter_assignee(issuable)
+      return if params[:assignee_ids].blank?
+
+      # The number of assignees is limited by one for GitLab CE
+      params[:assignee_ids] = params[:assignee_ids][0, 1]
+
+      assignee_ids = params[:assignee_ids].select { |assignee_id| assignee_can_read?(issuable, assignee_id) }
+
+      if params[:assignee_ids].map(&:to_s) == [IssuableFinder::NONE]
+        params[:assignee_ids] = []
+      elsif assignee_ids.any?
+        params[:assignee_ids] = assignee_ids
+      else
+        params.delete(:assignee_ids)
+      end
+    end
   end
 end
diff --git a/app/services/issues/build_service.rb b/app/services/issues/build_service.rb
index 77bced4bd5c..3a4f7b159f1 100644
--- a/app/services/issues/build_service.rb
+++ b/app/services/issues/build_service.rb
@@ -35,14 +35,19 @@ module Issues
     end
 
     def item_for_discussion(discussion)
-      first_note = discussion.first_note_to_resolve || discussion.first_note
+      first_note_to_resolve = discussion.first_note_to_resolve || discussion.first_note
+
+      is_very_first_note = first_note_to_resolve == discussion.first_note
+      action = is_very_first_note ? "started" : "commented on"
+
+      note_url = Gitlab::UrlBuilder.build(first_note_to_resolve)
+
       other_note_count = discussion.notes.size - 1
-      note_url = Gitlab::UrlBuilder.build(first_note)
 
-      discussion_info = "- [ ] #{first_note.author.to_reference} commented on a [discussion](#{note_url}): "
+      discussion_info = "- [ ] #{first_note_to_resolve.author.to_reference} #{action} a [discussion](#{note_url}): "
       discussion_info << " (+#{other_note_count} #{'comment'.pluralize(other_note_count)})" if other_note_count > 0
 
-      note_without_block_quotes = Banzai::Filter::BlockquoteFenceFilter.new(first_note.note).call
+      note_without_block_quotes = Banzai::Filter::BlockquoteFenceFilter.new(first_note_to_resolve.note).call
       spaces = ' ' * 4
       quote = note_without_block_quotes.lines.map { |line| "#{spaces}> #{line}" }.join
 
diff --git a/app/services/issues/update_service.rb b/app/services/issues/update_service.rb
index b7fe5cb168b..cd9f9a4a16e 100644
--- a/app/services/issues/update_service.rb
+++ b/app/services/issues/update_service.rb
@@ -12,8 +12,12 @@ module Issues
       spam_check(issue, current_user)
     end
 
-    def handle_changes(issue, old_labels: [], old_mentioned_users: [])
-      if has_changes?(issue, old_labels: old_labels)
+    def handle_changes(issue, options)
+      old_labels = options[:old_labels] || []
+      old_mentioned_users = options[:old_mentioned_users] || []
+      old_assignees = options[:old_assignees] || []
+
+      if has_changes?(issue, old_labels: old_labels, old_assignees: old_assignees)
         todo_service.mark_pending_todos_as_done(issue, current_user)
       end
 
@@ -26,9 +30,9 @@ module Issues
         create_milestone_note(issue)
       end
 
-      if issue.previous_changes.include?('assignee_id')
-        create_assignee_note(issue)
-        notification_service.reassigned_issue(issue, current_user)
+      if issue.assignees != old_assignees
+        create_assignee_note(issue, old_assignees)
+        notification_service.reassigned_issue(issue, current_user, old_assignees)
         todo_service.reassigned_issue(issue, current_user)
       end