/**
* Creates a link between an activity and an ability or a competency.
* If the link already exists, the method returns false. Otherwise, it
* returns an array representation of the ability/competency.
*
* @param Activity $activity
* @param Ability|Competency $target
* @return array|bool
* @throws \InvalidArgumentException if the target isn't an instance of Ability or Competency
*/
public function createLink(Activity $activity, $target)
{
if (!$target instanceof Ability && !$target instanceof Competency) {
throw new \InvalidArgumentException('Second argument must be a Competency or an Ability instance');
}
if ($target->isLinkedToActivity($activity)) {
return false;
}
$target->linkActivity($activity);
$this->om->flush();
$loadMethod = $target instanceof Competency ? 'loadCompetency' : 'loadAbility';
return $this->{$loadMethod}($target);
}