<?php

namespace App\Util\Localization;

use Illuminate\Support\Arr;

class Localization
{
    /**
     * Legacy two-letter (and legacy region) language codes mapped to the
     * current locale-coded folder names under lang/.
     * Added September 2026 - DELETE AFTER COMMUNICATION WITH ADMINS
     *
     * @var array<string, string>
     */
    const LEGACY_LOCALE_MAP = [
        'af' => 'af-ZA',
        'ar' => 'ar-SA',
        'bn' => 'bn-BD',
        'bs' => 'bs-BA',
        'ca' => 'ca-ES',
        'cs' => 'cs-CZ',
        'cy' => 'cy-GB',
        'da' => 'da-DK',
        'de' => 'de-DE',
        'el' => 'el-GR',
        'en' => 'en-US',
        'eo' => 'eo-UY',
        'es' => 'es-ES',
        'eu' => 'eu-ES',
        'fa' => 'fa-IR',
        'fi' => 'fi-FI',
        'fr' => 'fr-FR',
        'gd' => 'gd-GB',
        'gl' => 'gl-ES',
        'he' => 'he-IL',
        'hi' => 'hi-IN',
        'hr' => 'hr-HR',
        'hu' => 'hu-HU',
        'id' => 'id-ID',
        'it' => 'it-IT',
        'ja' => 'ja-JP',
        'ko' => 'ko-KR',
        'me' => 'me-ME',
        'mk' => 'mk-MK',
        'ms' => 'ms-MY',
        'nl' => 'nl-NL',
        'no' => 'no-NO',
        'oc' => 'oc-FR',
        'pl' => 'pl-PL',
        'pt' => 'pt-PT',
        'ro' => 'ro-RO',
        'ru' => 'ru-RU',
        'sk' => 'sk-SK',
        'sr' => 'sr-CS',
        'sv' => 'sv-SE',
        'th' => 'th-TH',
        'tr' => 'tr-TR',
        'uk' => 'uk-UA',
        'vi' => 'vi-VN',
        'zh-cn' => 'zh-CN',
        'zh-tw' => 'zh-TW',
    ];

    /**
     * Normalize a configured locale to a current locale-coded value.
     *
     * Empty input returns "en-US"; a known legacy short code is mapped;
     * anything else (already-current or custom codes) is returned unchanged so
     * the framework's own fallback_locale still applies. Always returns a
     * plain string, so it is safe to use in config values that get cached.
     */
    public static function normalizeLocale(?string $locale): string
    {
        $locale = is_string($locale) ? trim($locale) : '';

        if ($locale === '') {
            return 'en-US';
        }

        return self::LEGACY_LOCALE_MAP[strtolower($locale)] ?? $locale;
    }

    /**
     * List of available UI language codes.
     *
     * Reads the static manifest generated by `php artisan i18n:export`
     * (lang/locales.json) so the list is deterministic and never served from
     * a runtime cache that can go stale. Falls back to scanning the lang/
     * directory if the manifest is missing.
     *
     * @return array<int, string>
     */
    public static function languages()
    {
        return static::localesFromManifest() ?? static::localesFromScan();
    }

    /**
     * Full locale metadata (code, name, nativeName) from the manifest,
     * sorted by display name. Empty array if the manifest is missing.
     *
     * @return array<int, array{code: string, name: string, nativeName: string}>
     */
    public static function locales(): array
    {
        $path = lang_path('locales.json');

        if (! is_file($path)) {
            return [];
        }

        $data = json_decode((string) file_get_contents($path), true);

        return is_array($data) ? $data : [];
    }

    /**
     * @return array<int, string>|null
     */
    protected static function localesFromManifest(): ?array
    {
        $locales = static::locales();

        if ($locales === []) {
            return null;
        }

        return array_values(array_filter(array_map(
            fn ($l) => $l['code'] ?? null,
            $locales
        )));
    }

    /**
     * @return array<int, string>
     */
    protected static function localesFromScan(): array
    {
        $dir = lang_path();

        return Arr::flatten(array_diff(scandir($dir), ['..', '.', 'vendor', '.DS_Store', 'locales.json']));
    }
}