currency_switcher_fixer_io.module

<?php
/**
 * @file
 * Current foreign exchanges rates published by the European Central Bank.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function currency_switcher_fixer_io_help($route_name, RouteMatchInterface $route_match) {
    switch ($route_name) {
        case 'help.page.currency_switcher_fixer_io':
            $output = '';
            $output .= '<h3>' . t('About') . '</h3>';
            $output .= '<p>' . t('<p>A simple module provides the Foreign exchange rates and currency conversion API <a>Fixer.io</a></p>
      <p>You can select the necessary currencies from the list.</p>');
            return $output;
    }
}

/**
 * Implements hook_cron.
 */
function currency_switcher_fixer_io_cron() {
    $service = \Drupal::service('currency_switcher_fixer_io.controller');
    $config_setting = \Drupal::service('config.factory')->getEditable('currency_switcher_fixer_io.settings')->get('settings');
    $config_setting = implode(",", $config_setting);
    $base = $service->currencyCheck($config_setting);
    $config = \Drupal::service('config.factory')->getEditable('currency_switcher_fixer_io.currency');
    $config->set('currency', $base)->save();
}