UNIT3D-Community-Edition/app/Http/Controllers/LanguageController.php

<?php
/**
 * NOTICE OF LICENSE.
 *
 * UNIT3D Community Edition is open-sourced software licensed under the GNU Affero General Public License v3.0
 * The details is bundled with this project in the file LICENSE.txt.
 *
 * @project    UNIT3D Community Edition
 *
 * @author     HDVinnie <hdinnovations@protonmail.com>
 *
 * @license    https://www.gnu.org/licenses/agpl-3.0.en.html/ GNU Affero General Public License v3.0
 */

namespace App\Http\Controllers;

use App\Models\Language;
use Illuminate\Http\Request;

class LanguageController extends Controller
{
    /**
     * Set locale if it's allowed.
     *
     * @param string                   $locale
     * @param \Illuminate\Http\Request $request
     **/
    private function setLocale($locale, $request)
    {
        // Check if is allowed and set default locale if not
        if (!Language::allowed($locale)) {
            $locale = config('app.locale');
        }

        if (auth()->check()) {
            auth()->user()->setAttribute('locale', $locale)->save();
        } else {
            $request->session()->put('locale', $locale);
        }
    }

    /**
     * Set locale and return home url.
     *
     * @param string                   $locale
     * @param \Illuminate\Http\Request $request
     *
     * @return string
     **/
    public function home($locale, Request $request)
    {
        $this->setLocale($locale, $request);

        $url = config('language.url') ? url('/'.$locale) : url('/');

        return redirect($url)
            ->withSuccess('Language Changed!');
    }

    /**
     * Set locale and return back.
     *
     * @param string                   $locale
     * @param \Illuminate\Http\Request $request
     *
     * @return string
     **/
    public function back($locale, Request $request)
    {
        $this->setLocale($locale, $request);

        $session = $request->session();
        if (config('language.url')) {
            $previous_url = substr(str_replace(env('APP_URL'), '', $session->previousUrl()), 7);
            if (strlen($previous_url) == 3) {
                $previous_url = substr($previous_url, 3);
            } else {
                $previous_url = substr($previous_url, strrpos($previous_url, '/') + 1);
            }
            $url = rtrim(env('APP_URL'), '/').'/'.$locale.'/'.ltrim($previous_url, '/');
            $session->setPreviousUrl($url);
        }

        return redirect($session->previousUrl())
            ->withSuccess('Language Changed!');
    }
}