/**
* Returns a complete list of roles that this user may delegate to others.
*
* @param Board|null $board If not null, will refine search to a single board.
* @return Collection|array
*/
public function getAssignableRoles(Board $board = null)
{
return $board->roles()->where(function ($query) use($board) {
if (is_null($board) && $this->canAdminRoles()) {
$query->whereStaff();
} else {
if ($this->can('board.user.role', $board)) {
$query->whereJanitor();
}
}
})->get();
}