tsa2.module

<?php

use Drupal\Core\Routing\RouteMatchInterface;

function tsa2_theme($existing, $type, $theme, $path) {  


  // return [
  //   'tsa_template' => [
  //     'variables' => ['source_text' => NULL],
  //   ],
  // ];

  $variables = array(
    'tsa2_theme' => array(
      'variables' => array(
        'tsa2_api' => NULL,
        'mainBody' => NULL,
      ),
      'template' => 'tsa2-template',
    ),
  );
  return $variables;

}


function tsa2_preprocess_html(&$variables) {
  $variables['#attached']['library'][] =  'tsa2/tsa2';

  $config = \Drupal::config('tsa2.settings');    
  $tsa2_api  = $config->get('tsa2_api');
  $variables['#attached']['drupalSettings']['tsa2']['tsa2_api'] = $tsa2_api;
}