tfa.module

<?php

/**
 * @file
 * Contains tfa.module.
 */

use Drupal\Core\Session\AccountInterface;
use Drupal\block\Entity\Block;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Access\AccessResult;

/**
 * Implements hook_help().
 */
function tfa_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the tfa module.
    case 'help.page.tfa':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Pluggable provider of second factor authentication for Drupal') . '</p>';
      return $output;
  }
}

/**
 * Implements hook_block_access().
 *
 * Remove access to the core user_login_block so we can replace with the TFA
 * login block.
 */
function tfa_block_access(Block $block, $operation, AccountInterface $account) {
  if (\Drupal::config('tfa.settings')->get('enabled') && $block->getPluginId() === 'user_login_block') {
    return AccessResult::forbidden();
  }
}