<?php
namespace Zadex\Editor;

defined('ABSPATH') || exit;

/**
 * Editor UI dictionaries: `languages/zadex-<lang>.json` ({ "English source": "Translation" }), passed to the
 * editor as window.ZADEX.i18n and read by `t()` (src/editor/core/i18n.ts). WordPress' own `wp.i18n` (text
 * domain `zadex`) still wins when a site ships real .mo/.json translations.
 *
 * The language is the user locale without its region (`ar`, `ar_SA`, `ary` -> `ar`); only languages
 * with a bundled JSON file get a dictionary, everything else gets `[]` (the editor then shows the English
 * source). Parsed dictionaries are cached per request and in the object cache keyed by file mtime.
 */
final class Translations
{
    /** Languages with a bundled editor dictionary. */
    public const LANGUAGES = ['ar'];

    /** @var array<string, array<string, string>> */
    private static array $cache = [];

    /** Regional variants that share a bundled dictionary (Moroccan, Algerian, Egyptian Arabic). */
    private const ALIASES = ['ary' => 'ar', 'arq' => 'ar', 'arz' => 'ar'];

    public static function language(string $locale): string
    {
        // `ar`, `ar_SA`, `ar-EG` -> `ar`; `arg` (Aragonese) is not Arabic.
        $lang = strtolower((string) preg_replace('/[_-].*$/', '', trim($locale)));
        $lang = self::ALIASES[$lang] ?? $lang;
        return in_array($lang, self::LANGUAGES, true) ? $lang : '';
    }

    public static function file(string $lang): string
    {
        return ZADEX_PATH . 'languages/zadex-' . $lang . '.json';
    }

    /** @return array<string, string> */
    public static function for_locale(string $locale): array
    {
        $lang = self::language($locale);
        if ($lang === '') {
            return [];
        }
        if (isset(self::$cache[$lang])) {
            return self::$cache[$lang];
        }
        $file = self::file($lang);
        if (!is_readable($file)) {
            return self::$cache[$lang] = [];
        }
        $key = 'zadex_i18n_' . $lang . '_' . (int) @filemtime($file);
        $cached = function_exists('wp_cache_get') ? wp_cache_get($key, 'zadex') : false;
        if (is_array($cached)) {
            return self::$cache[$lang] = $cached;
        }
        $json = wp_json_file_decode($file, ['associative' => true]);
        $dict = [];
        if (is_array($json)) {
            foreach ($json as $source => $translation) {
                if (is_string($source) && is_string($translation) && $translation !== '') {
                    $dict[$source] = $translation;
                }
            }
        }
        if (function_exists('wp_cache_set')) {
            wp_cache_set($key, $dict, 'zadex');
        }
        return self::$cache[$lang] = $dict;
    }

    /** Test helper. */
    public static function flush(): void
    {
        self::$cache = [];
    }
}