Configurable field and when

Let user configurable which field and when a field will be updated are "always", "new" or "existing".
Ex:
        $this->addBehavior('Ceeram/Blame.Blame', [
            'events' => [
                'Model.beforeSave' => [
                    'created_by' => 'new',
                    'modified_by' => 'always'
                ]
            ]
        ]);