(function() {
    var html = document.documentElement;
    var path = window.location.pathname;
    
    // Check if we are on the root index page (either "/" or "/index.html" at the root)
    var isRootIndex = path === '/' || path === '/index.html' || path === '';
    
    if (isRootIndex) {
        var savedLang = localStorage.getItem('koala_lang');
        var browserLang = navigator.language.startsWith('de') ? 'de' : 'en';
        var preferredLang = savedLang || browserLang;
        
        if (preferredLang === 'de') {
            // Redirect to German version
            window.location.replace('de/');
            return;
        }
    }
    
    var htmlClasses = html.className.split(' ');
    var activeLang = null;
    var hasStaticLang = false;
    for (var i = 0; i < htmlClasses.length; i++) {
        if (htmlClasses[i].indexOf('lang-') === 0) {
            hasStaticLang = true;
            var langPart = htmlClasses[i].substring(5);
            activeLang = langPart === 'pt-br' ? 'pt-BR' : langPart;
            break;
        }
    }
    
    if (hasStaticLang) {
        localStorage.setItem('koala_lang', activeLang);
    } else {
        var savedLang = localStorage.getItem('koala_lang');
        var browserLang = navigator.language.startsWith('de') ? 'de' : 'en';
        activeLang = savedLang || browserLang;
        
        // Dynamic utility pages currently only support English and German markup.
        // Fallback to English for any other language preference (e.g. fr, es) to avoid bilingual text duplication.
        if (activeLang !== 'de') {
            activeLang = 'en';
        }
        
        html.classList.add('lang-' + activeLang);
        html.lang = activeLang;
    }
    
    // Update titles dynamically based on page
    var isIndex = path === '/' || path.endsWith('index.html') || path.split('/').pop() === '';
    var isJoin = path.includes('join');
    
    if (isIndex) {
        var titles = { 
            en: 'KoalaSync | Real-time Video Synchronization for Friends', 
            de: 'KoalaSync | Echtzeit-Video-Synchronisation für Freunde' 
        };
        document.title = titles[activeLang] || titles.en;
    } else if (isJoin) {
        var titles = { 
            en: 'Join Room | KoalaSync', 
            de: 'Raum beitreten | KoalaSync' 
        };
        document.title = titles[activeLang] || titles.en;
    }
})();