1 files changed, 56 insertions, 0 deletions
diff --git a/app/graphql/mutations/alert_management/alerts/set_assignees.rb b/app/graphql/mutations/alert_management/alerts/set_assignees.rb
new file mode 100644
index 00000000000..1e0c9fdeeaf
--- /dev/null
+++ b/app/graphql/mutations/alert_management/alerts/set_assignees.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+module Mutations
+  module AlertManagement
+    module Alerts
+      class SetAssignees < Base
+        graphql_name 'AlertSetAssignees'
+
+        argument :assignee_usernames,
+                 [GraphQL::STRING_TYPE],
+                 required: true,
+                 description: 'The usernames to assign to the alert. Replaces existing assignees by default.'
+
+        argument :operation_mode,
+                 Types::MutationOperationModeEnum,
+                 required: false,
+                 description: 'The operation to perform. Defaults to REPLACE.'
+
+        def resolve(args)
+          alert = authorized_find!(project_path: args[:project_path], iid: args[:iid])
+          result = set_assignees(alert, args[:assignee_usernames], args[:operation_mode])
+
+          prepare_response(result)
+        end
+
+        private
+
+        def set_assignees(alert, assignee_usernames, operation_mode)
+          operation_mode ||= Types::MutationOperationModeEnum.enum[:replace]
+
+          original_assignees = alert.assignees
+          target_users = find_target_users(assignee_usernames)
+
+          assignees = case Types::MutationOperationModeEnum.enum.key(operation_mode).to_sym
+                      when :replace then target_users.uniq
+                      when :append then (original_assignees + target_users).uniq
+                      when :remove then (original_assignees - target_users)
+                      end
+
+          ::AlertManagement::Alerts::UpdateService.new(alert, current_user, assignees: assignees).execute
+        end
+
+        def find_target_users(assignee_usernames)
+          UsersFinder.new(current_user, username: assignee_usernames).execute
+        end
+
+        def prepare_response(result)
+          {
+            alert: result.payload[:alert],
+            errors: result.error? ? [result.message] : []
+          }
+        end
+      end
+    end
+  end
+end