BookStack/app/Http/Middleware/Localization.php

<?php

namespace BookStack\Http\Middleware;

use Carbon\Carbon;
use Closure;
use Illuminate\Http\Request;

class Localization
{
    /**
     * Array of right-to-left locales.
     */
    protected $rtlLocales = ['ar', 'fa', 'he'];

    /**
     * Map of BookStack locale names to best-estimate system locale names.
     * Locales can often be found by running `locale -a` on a linux system.
     */
    protected $localeMap = [
        'ar'          => 'ar',
        'bg'          => 'bg_BG',
        'bs'          => 'bs_BA',
        'ca'          => 'ca',
        'da'          => 'da_DK',
        'de'          => 'de_DE',
        'de_informal' => 'de_DE',
        'en'          => 'en_GB',
        'es'          => 'es_ES',
        'es_AR'       => 'es_AR',
        'et'          => 'et_EE',
        'eu'          => 'eu_ES',
        'fa'          => 'fa_IR',
        'fr'          => 'fr_FR',
        'he'          => 'he_IL',
        'hr'          => 'hr_HR',
        'id'          => 'id_ID',
        'it'          => 'it_IT',
        'ja'          => 'ja',
        'ko'          => 'ko_KR',
        'lt'          => 'lt_LT',
        'lv'          => 'lv_LV',
        'nl'          => 'nl_NL',
        'nb'          => 'nb_NO',
        'pl'          => 'pl_PL',
        'pt'          => 'pt_PT',
        'pt_BR'       => 'pt_BR',
        'ru'          => 'ru',
        'sk'          => 'sk_SK',
        'sl'          => 'sl_SI',
        'sv'          => 'sv_SE',
        'uk'          => 'uk_UA',
        'vi'          => 'vi_VN',
        'zh_CN'       => 'zh_CN',
        'zh_TW'       => 'zh_TW',
        'tr'          => 'tr_TR',
    ];

    /**
     * Handle an incoming request.
     *
     * @param \Illuminate\Http\Request $request
     * @param \Closure                 $next
     *
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $defaultLang = config('app.locale');
        config()->set('app.default_locale', $defaultLang);

        $locale = $this->getUserLocale($request, $defaultLang);
        config()->set('app.lang', str_replace('_', '-', $this->getLocaleIso($locale)));

        // Set text direction
        if (in_array($locale, $this->rtlLocales)) {
            config()->set('app.rtl', true);
        }

        app()->setLocale($locale);
        Carbon::setLocale($locale);
        $this->setSystemDateLocale($locale);

        return $next($request);
    }

    /**
     * Get the locale specifically for the currently logged in user if available.
     */
    protected function getUserLocale(Request $request, string $default): string
    {
        try {
            $user = user();
        } catch (\Exception $exception) {
            return $default;
        }

        if ($user->isDefault() && config('app.auto_detect_locale')) {
            return $this->autoDetectLocale($request, $default);
        }

        return setting()->getUser($user, 'language', $default);
    }

    /**
     * Autodetect the visitors locale by matching locales in their headers
     * against the locales supported by BookStack.
     */
    protected function autoDetectLocale(Request $request, string $default): string
    {
        $availableLocales = config('app.locales');
        foreach ($request->getLanguages() as $lang) {
            if (in_array($lang, $availableLocales)) {
                return $lang;
            }
        }

        return $default;
    }

    /**
     * Get the ISO version of a BookStack language name.
     */
    public function getLocaleIso(string $locale): string
    {
        return $this->localeMap[$locale] ?? $locale;
    }

    /**
     * Set the system date locale for localized date formatting.
     * Will try both the standard locale name and the UTF8 variant.
     */
    protected function setSystemDateLocale(string $locale)
    {
        $systemLocale = $this->getLocaleIso($locale);
        $set = setlocale(LC_TIME, $systemLocale);
        if ($set === false) {
            setlocale(LC_TIME, $systemLocale . '.utf8');
        }
    }
}