cakephp-tools/src/Controller/ShuntRequestController.php

<?php

namespace Tools\Controller;

use App\Controller\AppController;
use Cake\Core\Configure;
use Cake\I18n\I18n;
use RuntimeException;

/**
 * Language switching
 *
 * Needs Configure:
 * - allowedLanguages (language mapping)
 * - defaultLanguage (optional, uses first of allowedLanguages otherwise)
 *
 * Mapping
 *
 * de => ['locale' => 'de_DE', 'name' => 'Deutsch'], ...
 *
 * @property \Cake\Controller\Component\FlashComponent $Flash
 */
class ShuntRequestController extends AppController {

	/**
	 * @var string|null
	 */
	protected $modelClass = '';

	/**
	 * @return void
	 */
	public function initialize(): void {
		parent::initialize();

		if (!isset($this->Flash)) {
			$this->loadComponent('Flash');
		}
	}

	/**
	 * Switch language as post link.
	 *
	 * @param string|null $language
	 * @throws \RuntimeException
	 * @return \Cake\Http\Response
	 */
	public function language($language = null) {
		$this->getRequest()->allowMethod(['post']);

		$allowedLanguages = (array)Configure::read('Config.allowedLanguages');
		if (!$language) {
			$language = Configure::read('Config.defaultLanguage');
		}
		if (!$language && $allowedLanguages) {
			$keys = array_keys($allowedLanguages);
			$language = $allowedLanguages[array_shift($keys)];
		}

		if (!array_key_exists($language, $allowedLanguages)) {
			throw new RuntimeException('Invalid Language');
		}
		$language = $allowedLanguages[$language];

		$this->getRequest()->getSession()->write('Config.language', $language['locale']);
		I18n::setLocale($language['locale']);
		$this->Flash->success(__d('tools', 'Language switched to {0}', $language['name']));

		return $this->redirect($this->referer('/', true));
	}

}