public function update(Role $role)
    {
        $this->validate($this->request, [
            'name'        => 'required',
            'slug'        => 'required|unique:roles,slug,' . $role->id,
        ]);

        $role->name = $this->request->get('name');
        if (! $role->system) {
            $role->slug = $this->request->get('slug');
        }
        $role->save();

        $role->syncPermissions($this->request->get('permissions', []));
        flash()->success('Role ' . $role->name . ' successfully updated!');

        return redirect()->route('administrator.roles.index');
    }