<?php
// Minimal i18n helper. Detects language from the current filename suffix
// (_jp.php / _zh.php) so it matches the existing URL scheme, and loads a
// flat key -> string dict from locales/{code}.php.
//
// Usage in a page:
//   require_once __DIR__ . '/../partials/i18n.php';   // adjust relative path
//   echo t('home.title');
//
// Missing keys fall back to the English dict, then to the key itself.

if (!function_exists('t')) {
    function _i18n_lang(): string {
        // Prefer SCRIPT_NAME: under nginx + php-fpm, PHP_SELF is often empty.
        $f = basename((string)($_SERVER['SCRIPT_NAME'] ?? $_SERVER['PHP_SELF'] ?? 'index.php'));
        if ($f === '') $f = 'index.php';
        if (str_ends_with($f, '_zh.php')) return 'zh';
        if (str_ends_with($f, '_jp.php')) return 'ja';
        return 'en';
    }

    function _i18n_load(string $code): array {
        static $cache = [];
        if (isset($cache[$code])) return $cache[$code];
        $path = __DIR__ . '/../locales/' . $code . '.php';
        $cache[$code] = is_file($path) ? (array)include $path : [];
        return $cache[$code];
    }

    function t(string $key, ?string $lang = null): string {
        $lang = $lang ?? _i18n_lang();
        $dict = _i18n_load($lang);
        if (array_key_exists($key, $dict)) return $dict[$key];
        if ($lang !== 'en') {
            $en = _i18n_load('en');
            if (array_key_exists($key, $en)) return $en[$key];
        }
        return $key;
    }
}