  Context. Source code refactoring is a well-established approach to improving
source code quality without compromising its external behavior. Motivation. The
literature described the benefits of refactoring, yet its application in
practice is threatened by the high cost of time, resource allocation, and
effort required to perform it continuously. Providing refactoring
recommendations closer to what developers perceive as relevant may support the
broader application of refactoring in practice and drive prioritization
efforts. Aim. In this paper, we aim to foster the design of a developer-based
refactoring recommender, proposing an empirical study into the metrics that
study the developer's willingness to apply refactoring operations. We build
upon previous work describing the developer's motivations for refactoring and
investigate how product and process metrics may grasp those motivations.
Expected Results. We will quantify the value of product and process metrics in
grasping developers' motivations to perform refactoring, thus providing a
catalog of metrics for developer-based refactoring recommenders to use.
