(function(){
    // 
    var isValidLanguage = function(lang){
        var validLanguages = ['de','en','fr', 'es','it','ru','zh','nl'];

        lang = lang != null ? lang.toLowerCase() : lang;
        var result = false;
        if(lang == null) return result;

        for(var i = 0; i < validLanguages.length; i++){
            if(lang.indexOf(validLanguages[i]) >= 0 && lang.length <= 5){
                result = true;
            }
        }

        return result;
    };    

    window.d21_widgetStart = function(){
        // Add basket
        var basketJS = document.createElement("script");
        basketJS.src = "//cdnjs.cloudflare.com/ajax/libs/basket.js/0.5.2/basket.full.min.js";
        document.body.appendChild(basketJS);

        // detect language
        // 1. by html-tag
        var htmlTagLang = document.getElementsByTagName("Html")[0].getAttribute("lang");
        var browserLang = htmlTagLang != undefined ? htmlTagLang.substring(0,2).toLowerCase() : undefined;

        // 2. by meta-tag
        if(browserLang == undefined) {
            var metas = Array.prototype.slice.call(document.getElementsByTagName('meta'));

            metas.forEach(function(m,index){
                if(browserLang == undefined) browserLang = isValidLanguage(m.getAttribute('content')) ? m.getAttribute('content').substring(0,2).toLowerCase() : undefined;
            });

        }

        // 3. default value de-DE
        if(browserLang != undefined) {
            browserLang = browserLang + '-' + browserLang.toUpperCase();
        }
        else {
            browserLang = "de-DE";
        }


        // Write main script with detected language
        var d21SdkJS = document.createElement("script");
        d21SdkJS.src = "https://js-sdk.dirs21.de" + "/widgets/8a5f75a0-acec-45ea-9e63-5371bd01aebd/" + browserLang + '/False';
        d21SdkJS.async = true;
        document.body.appendChild(d21SdkJS);
    }

    window.addEventListener("load", function(){
        d21_widgetStart();
    });
})();