BetterDesk/web-nodejs/middleware/i18n.js

/**
 * BetterDesk Console - i18n Middleware
 * Injects translation function and language info into templates
 */

const { manager } = require('../services/i18nService');
const config = require('../config/config');
const brandingService = require('../services/brandingService');
const { escapeHtml } = require('../lib/escapeHtml');

/**
 * Parse Accept-Language header
 */
function parseAcceptLanguage(header) {
    if (!header) return null;
    
    const languages = header.split(',')
        .map(lang => {
            const parts = lang.trim().split(';');
            const rawCode = parts[0].trim();
            const code = rawCode.split('-')[0]; // Get primary language code
            const q = parts[1] ? parseFloat(parts[1].split('=')[1]) : 1;
            return { rawCode, code, q };
        })
        .sort((a, b) => b.q - a.q);
    
    // Find first supported language
    for (const { rawCode, code } of languages) {
        if (manager.hasLanguage(rawCode)) {
            return rawCode;
        }
        if (manager.hasLanguage(code)) {
            return code;
        }
    }
    
    return null;
}

/**
 * i18n middleware
 * Detects language and injects translation function
 */
function i18nMiddleware(req, res, next) {
    // Language detection priority:
    // 1. URL query param ?lang=xx
    // 2. Authenticated user preference
    // 3. Cookie betterdesk_lang
    // 4. Accept-Language header
    // 5. Default language
    
    let lang = req.query.lang
        || req.session?.user?.preferred_language
        || req.cookies?.betterdesk_lang
        || parseAcceptLanguage(req.headers['accept-language'])
        || config.defaultLanguage;
    
    // Validate language exists
    if (!manager.hasLanguage(lang)) {
        lang = config.defaultLanguage;
    }
    
    // Set language cookie if from query param
    if (req.query.lang && manager.hasLanguage(req.query.lang)) {
        res.cookie('betterdesk_lang', req.query.lang, {
            maxAge: 365 * 24 * 60 * 60 * 1000, // 1 year
            httpOnly: false,
            sameSite: 'lax'
        });
    }
    
    // Get language metadata
    const langMeta = manager.getLanguageMeta(lang);
    
    // Inject into res.locals (available in EJS templates)
    res.locals.lang = lang;
    res.locals.isRtl = langMeta?.rtl || false;
    res.locals.availableLanguages = manager.getAvailable();
    res.locals.availableLanguageList = manager.getAvailableList();
    res.locals.currentLanguage = langMeta;
    res.locals.appVersion = config.appVersion;
    
    // Branding - inject dynamic app name and branding data
    const branding = brandingService.getBranding();
    res.locals.appName = branding.appName || config.appName;
    res.locals.appDescription = branding.appDescription || 'BetterDesk Server Management';
    res.locals.branding = branding;
    res.locals.brandingRevision = brandingService.getBrandingRevision();
    
    // Full translations object for client-side JS
    res.locals.translations = manager.getMergedTranslations(lang);
    
    // Translation function
    res.locals._ = (key, vars) => manager.translate(lang, key, vars);
    res.locals.t = res.locals._; // Alias
    res.locals.escapeHtml = escapeHtml;
    
    // Store on request object too
    req.lang = lang;
    req.t = res.locals._;
    
    next();
}

/**
 * Initialize i18n system
 */
function initI18n() {
    manager.init();
    return i18nMiddleware;
}

module.exports = {
    i18nMiddleware,
    initI18n
};