bankid_oidc-1.x-dev/bankid_oidc.module

<?php

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Url;

/**
 * Implements hook_form_FORM_ID_alter().
 */
function bankid_oidc_form_user_login_form_alter(
  &$form,
  FormStateInterface $form_state,
  $form_id
) {
  // Get all non form-api elements
  $login_elements = array_filter(
    array_keys($form),
    function(string $key) {
      return $key[0] !== '#';
    }
  );
  // Create a wrapper that will contain such elements.
  $form['drupal_login'] = [
    '#type'       => 'details',
    '#title'      => t('User/Password login'),
    '#open'       => FALSE,
    '#weight'     => 10,
    '#attributes' => [
      'class' => ['drupal-default-login-wrapper'],
    ],
  ];
  // Move all elements in the hidden container.
  foreach ($login_elements as $name) {
    $form['drupal_login'][$name] = $form[$name];
    unset($form[$name]);
  }


  $form['bankid_oidc'] = [
    '#type'       => 'details',
    '#title' => t('BankID Login'),
    '#attributes' => [
      'class' => ['bankid-oidc-login-button-wrapper'],
    ],
    '#open' => TRUE,
    '#weight'     => 0,
  ];

  $info_text = t('Click the icon below to login using BankID or BankID on Mobile.');
  $form['bankid_oidc']['info'] = [
    '#markup' => "<p>{$info_text}</p>",
  ];

  $path = \Drupal::moduleHandler()->getModule('bankid_oidc')->getPath();
  $destination = \Drupal::request()->query->get('destination');
  $options = [];
  if ($destination) {
    $options = [
      'destination' => $destination
    ];
  }
  $form['bankid_oidc']['link'] = [
    '#type'       => 'link',
    '#url'        => Url::fromRoute('bankid_oidc.login', $options),
    '#title'      => t('BankID Login'),
    '#attached'   => [
      'library' => ['bankid_oidc/login_block'],
    ],
    '#attributes' => [
      'style' => "background-image: url(/{$path}/asset/logo/BankID_Main_Logo.svg);",
    ],
  ];

  // Add cache information
  $form['#cache']['contexts'][] = 'url.query_args:destination';
}