(function () {

    var dicts = {},
        translateElement = function (jqElt, lang) {
            var dictionaryKey = jqElt.data('dict'),
                translationKey = jqElt.data('tkey'),
                dict = dicts[dictionaryKey],
                translations, html, key;
            if (dict === codeq.tr.emptyDictionary) return; // silent ignore
            if (!dict) {
                codeq.log.error('Cannot find translation dictionary ' + dictionaryKey);
                return;
            }
            if (!(typeof translationKey === 'number' || typeof translationKey === 'string')) {
                codeq.log.error('Cannot find the element\'s translation key, dictionary: ' + dictionaryKey);
                return;
            }
            translations = dict[translationKey];
            if (!translations) {
                codeq.log.error('Translation key ' + translationKey + ' is missing from dictionary ' + dictionaryKey);
                return;
            }
            html = translations[lang];
            if (!html) {
                html = translations['en'];
                if (html) {
                    codeq.log.info('There is no translation in language ' + lang + ' for key ' + translationKey + ' in dictionary ' + dictionaryKey + ', defaulting to language en');
                }
                else {
                    for (key in translations) {
                        if (!translations.hasOwnProperty(key)) continue;
                        html = translations[key];
                        if (!html) continue;
                        codeq.log.info('There is no translation in languages ' + lang + ' and en for key ' + translationKey + ' in dictionary ' + dictionaryKey + ', defaulting to language ' + key);
                        break;
                    }
                    if (!html) {
                        codeq.log.warn('There is no translation in any language for key ' + translationKey + ' in dictionary ' + dictionaryKey + ', leaving empty');
                        return;
                    }
                }
            }
            jqElt.html(html);
        },
        translateDocument = function (lang) {
            $('.translatable').each(function () {
                translateElement($(this), lang);
            });
        };

    // Translate the whole document when the user switches the display language
    codeq.on('langchange', function (args) {
        translateDocument(args.lang);
    });

    // ================================================================================
    // The module API
    // ================================================================================

    codeq.tr = {
        'registerDictionary': function (name, dict) {
            dicts[name] = dict;
        },

        'unregisterDictionary': function (name) {
            delete dicts[name];
        },

        'emptyDictionary': {}, // use this with registerDictionary when you don't want any translations

        'translateDom': function (jqTopElt) {
            var lang = codeq.getLang();
            jqTopElt.find('.translatable').each(function () {
                translateElement($(this), lang);
            });
        }
    };
})();