Permitir login por CPF - WordPress

cpf.php

<?php
if ( ! defined( 'ABSPATH' ) ) {
  exit; // Exit if accessed directly
}

/**
 * Login
 */
class Custom_CPF_Login {

  public function __construct() {
    add_filter( 'authenticate', array($this, 'authenticate_user'), 20, 3 );
  }

  public function is_valid_cpf($cpf) {
    $cpf = preg_replace("/[^0-9]/", "", $cpf);
    $digitOne = 0;
    $digitTwo = 0;

    for ($i = 0, $x = 10; $i <= 8; $i++, $x--):
      $digitOne += $cpf[$i] * $x;
    endfor;

    for ($i = 0, $x = 11; $i <= 9; $i++, $x--):
      if (str_repeat($i, 11) == $cpf):
        return false;
      endif;

      $digitTwo += $cpf[$i] * $x;
    endfor;

    $calcOne  = (($digitOne%11) < 2) ? 0 : 11-($digitOne%11);
    $calcTwo = (($digitTwo%11) < 2) ? 0 : 11-($digitTwo%11);

    if ($calcOne <> $cpf[9] || $calcTwo <> $cpf[10]):
      return false;
    else:
      return true;
    endif;
  }

  public function attempt_login($password, $current_password, $id) {
    return wp_check_password($password, $current_password, $cpf_user->data->ID);
  }

  public function get_user_by_cpf($cpf) {
    $cpf_user = get_users(
      array(
        'meta_key' => 'cpf',
        'meta_value' => $cpf
      )
    );

    if ( count($cpf_user) > 0 ):
      return $cpf_user[0];
    endif;

    return false;
  }

  public function authenticate_user($user, $username, $password) {
    /* Login by CPF */

    // Remove everything but numbers from the username
    $cpf = preg_replace('/[^0-9]/', '', $username);

    // Is it a CPF?
    if ( strlen($cpf) == 11 && is_int( (int)$cpf ) ):

      // Validate CPF
      if ( !$this->is_valid_cpf($cpf) ):
        $user = $this->user_cpf_error();
      endif;

      // Find user by CPF
      $cpf_user = $this->get_user_by_cpf($cpf);

      // Found a user?
      if ( $cpf_user ):
        $current_password = $cpf_user->data->user_pass;
        $id = $cpf_user->data->ID;

        // Is the password valid?
        if ( $this->attempt_login($password, $current_password, $id) ):
          $user = $cpf_user;
        else:
          // Invalid Password
          $user = $this->user_password_error();
        endif;
      endif;

    endif;

    // defaults to email or username
    return $user;
  }

  // Error Messages
  private function user_password_error() {
    $text = '<strong>ERRO</strong>: A senha está incorreta. <a href="' . esc_url( wp_lostpassword_url() ) . '">Esqueceu a senha?</a>';
    return new WP_Error('broke', $text);
  }

  public function user_cpf_error() {
    $text = '<strong>ERRO:</strong> CPF inválido.';
    new WP_Error( 'broke', $text);
  }

}

new Custom_CPF_Login();