public function admin(Request $request)
{
    $authSite     = env('MELI_SDK_APP_SITE');
    $clientId     = env('MELI_SDK_APP_ID');
    $clientSecret = env('MELI_SDK_SECRET_ID');
    $redirectUri  = env('MELI_SDK_REDIRECT_URI');

    $client = new \Docta\MercadoLibre\Client($authSite, $clientId, $clientSecret, $redirectUri);

    /**
     * If we do not have an authorization code then get one
     */
    if (!$request->input('code')) {

        /**
         * Get the MercadoLibre authorization URL; return the url and also generate
         * and apply other necessary query parameters (for example: state).
         */
        $authUrl = $client->getAuthorizationUrl();

        /**
         * Get the generated state and save in session.
         */
        $request->session()->put('state',$client->getState());

        /**
         * Redirect the user to the authorization URL
         */
        header('Location: '.$authUrl);
        exit;

        /**
         * Check the state returned by MercadoLibre against the state
         * previously stored in session to mitigate the CSRF attack.
         */
    }
    elseif (empty($request->input('state') || ($request->input('state') !== $request->session()->get('state')))) {

        !$request->session()->get('state');
        exit('Invalid state');

        /**
         * If the state stored in session and the state returned
         * by MercadoLibre are the same, then continue.
         */
    }
    else {

        try {
            /**
             * Try to exchange the code obtained by an access
             * token (using the authorization code grant).
             */
            $client->setToken($request->input('code'));

            /**
             * Optional: Now that we have a token, we can check
             * the data of the owner of the resources.
             */
            $owner = $client->getOwner();
            /**
             * And from now on to be able to consult the protected resources.
             * The following example makes the same request as the `getOwner()` method.
             */
            $me = $client->get('/users/me');

            /**
             * Failed to get the access token, the owner details or the items request.
             */
        } catch (\Docta\MercadoLibre\Exception\ClientException $e) {

            exit($e->getMessage());

        }
    }
}