View file install/index.php

<?php

session_start();

define('DS', DIRECTORY_SEPARATOR);
define('PATH', dirname(__FILE__) . DS);
define('DOC_ROOT', str_replace(DS, '/', realpath($_SERVER['DOCUMENT_ROOT'])));

header('Content-type:text/html; charset=utf-8');

mb_internal_encoding('UTF-8');
date_default_timezone_set('UTC');

include PATH . 'functions.php';

$all_langs = get_langs();
$default_lang = 'en';

if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
    $user_lang = strtolower(substr($_SERVER['HTTP_ACCEPT_LANGUAGE'], 0, 2));
    if (in_array($user_lang, $all_langs)) {
        $default_lang = $user_lang;
    }
}

if (isset($_REQUEST['lang'])) {
    if (is_string($_REQUEST['lang']) && in_array($_REQUEST['lang'], $all_langs)) {
        $_SESSION['install']['lang'] = $_REQUEST['lang'];
        header('Location: ' . $_SERVER['SCRIPT_NAME']);
        die;
    }
}

$is_lang_selected = isset($_SESSION['install']['lang']);

$lang = $is_lang_selected ? $_SESSION['install']['lang'] : $default_lang;

define('LANG', $lang);

include PATH . 'languages' . DS . LANG . DS . 'language.php';

$steps = [
    ['id' => 'start', 'title' => LANG_STEP_START],
    ['id' => 'license', 'title' => LANG_STEP_LICENSE],
    ['id' => 'php', 'title' => LANG_STEP_PHP_CHECK],
    ['id' => 'paths', 'title' => LANG_STEP_PATHS],
    ['id' => 'site', 'title' => LANG_STEP_SITE],
    ['id' => 'database', 'title' => LANG_STEP_DATABASE],
    ['id' => 'admin', 'title' => LANG_STEP_ADMIN],
    ['id' => 'config', 'title' => LANG_STEP_CONFIG],
    ['id' => 'cron', 'title' => LANG_STEP_CRON],
    ['id' => 'finish', 'title' => LANG_STEP_FINISH]
];

$steps = add_addons_step_if_needed($steps);

$current_step = 0;

if (is_ajax_request()) {
    $step      = $steps[(int) ($_POST['step'] ?? 0)] ?? $steps[1];
    $is_submit = isset($_POST['submit']);
    echo json_encode(run_step($step, $is_submit));
    exit();
}

// Чтобы страница установки не висела с 200 ответом
header('HTTP/1.1 503 Service Temporarily Unavailable');
header('Status: 503 Service Temporarily Unavailable');
header('Retry-After: 3600');

$step_result = run_step($steps[$current_step], false);

echo render('main', [
    'steps'            => $steps,
    'is_lang_selected' => $is_lang_selected,
    'lang'             => LANG,
    'current_step'     => $current_step,
    'step_html'        => $step_result['html'],
    'langs'            => $all_langs
]);