<?php

$staticLangDir = __DIR__ . '/lang';
$runtimeLangDir = getenv('WEBSITE_LANG_WRITE_DIR') ?: null;
$staticLangFiles = glob($staticLangDir . '/*.php') ?: [];
$runtimeLangFiles = [];
if ($runtimeLangDir && is_dir($runtimeLangDir)) {
    $runtimeLangFiles = glob($runtimeLangDir . '/*.json') ?: [];
}

$availableLangs = array_values(array_unique(array_map(
    fn($f) => preg_replace('/\.(php|json)$/', '', basename($f)),
    array_merge($staticLangFiles, $runtimeLangFiles)
)));
$availableLangs = array_values(array_filter(
    $availableLangs,
    fn($code) => is_string($code) && preg_match('/^[a-z]{2,5}$/', $code)
));

function getLang($supported) {
    if (isset($_GET['lang']) && in_array($_GET['lang'], $supported, true)) {
        return $_GET['lang'];
    }
    $browser = strtolower(substr($_SERVER['HTTP_ACCEPT_LANGUAGE'] ?? 'nah', 0, 2));
    return in_array($browser, $supported, true) ? $browser : 'nah';
}

function cleanRuntimeTranslation(string $value, int $maxLength = 2000): string {
    $value = strip_tags($value);
    $value = preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/u', '', $value) ?? '';
    $value = trim($value);
    if (strlen($value) > $maxLength) {
        $value = substr($value, 0, $maxLength);
    }
    return $value;
}

function loadRuntimeTranslations(string $file, array $base): array {
    $raw = file_get_contents($file);
    if ($raw === false || strlen($raw) > 131072) {
        return [];
    }

    $decoded = json_decode($raw, true);
    if (!is_array($decoded)) {
        return [];
    }

    $translations = [];
    foreach ($decoded as $key => $value) {
        if (!is_string($key) || !array_key_exists($key, $base) || (!is_string($value) && !is_numeric($value))) {
            continue;
        }
        $translations[$key] = cleanRuntimeTranslation((string) $value);
    }
    return $translations;
}

$lang = getLang($availableLangs);

$en = include "$staticLangDir/en.php";
$staticFile = "$staticLangDir/$lang.php";
$runtimeFile = $runtimeLangDir ? "$runtimeLangDir/$lang.json" : '';

if (file_exists($staticFile)) {
    $text = array_replace($en, include $staticFile);
} elseif ($runtimeFile && file_exists($runtimeFile)) {
    $text = array_replace($en, loadRuntimeTranslations($runtimeFile, $en));
} else {
    $lang = 'nah';
    $text = array_replace($en, include "$staticLangDir/nah.php");
}