(function () {
  var supported = ["en", "it", "fr", "de", "es"];
  var fallback = "en";
  var aliases = {
    "en-us": "en",
    "de-ch": "de",
    "fr-ch": "fr"
  };

  function normalizeLanguage(lang) {
    if (!lang) return fallback;
    var normalized = String(lang).toLowerCase().replace("_", "-");
    if (aliases[normalized]) return aliases[normalized];
    var base = normalized.split("-")[0];
    if (supported.indexOf(base) !== -1) return base;
    return fallback;
  }

  function getInitialLanguage() {
    var params = new URLSearchParams(window.location.search);
    var queryLang = params.get("lang");
    if (queryLang) return normalizeLanguage(queryLang);

    var saved = window.localStorage.getItem("preferredLang");
    if (saved) return normalizeLanguage(saved);

    var browserLang = navigator.language || (navigator.languages && navigator.languages[0]) || fallback;
    return normalizeLanguage(browserLang);
  }

  window.initPageI18n = function (translations) {
    var currentLanguage = getInitialLanguage();

    function t(key) {
      var active = translations[currentLanguage] || translations[fallback] || {};
      if (Object.prototype.hasOwnProperty.call(active, key)) return active[key];
      return key;
    }

    function applyLanguage(lang) {
      currentLanguage = normalizeLanguage(lang);
      var active = translations[currentLanguage] || translations[fallback] || {};

      document.documentElement.lang = currentLanguage;
      if (active.pageTitle) document.title = active.pageTitle;

      var nodes = document.querySelectorAll("[data-i18n]");
      for (var i = 0; i < nodes.length; i++) {
        var key = nodes[i].getAttribute("data-i18n");
        if (Object.prototype.hasOwnProperty.call(active, key)) nodes[i].textContent = active[key];
      }

      var placeholders = document.querySelectorAll("[data-i18n-placeholder]");
      for (var j = 0; j < placeholders.length; j++) {
        var pKey = placeholders[j].getAttribute("data-i18n-placeholder");
        if (Object.prototype.hasOwnProperty.call(active, pKey)) {
          placeholders[j].setAttribute("placeholder", active[pKey]);
        }
      }

      var selector = document.getElementById("language-select");
      if (selector) selector.value = currentLanguage;

      var links = document.querySelectorAll("a[data-lang-link]");
      for (var k = 0; k < links.length; k++) {
        var href = links[k].getAttribute("href");
        if (!href || href.indexOf("javascript:") === 0 || href.indexOf("#") === 0) continue;
        try {
          var linkUrl = new URL(href, window.location.origin);
          linkUrl.searchParams.set("lang", currentLanguage);
          links[k].setAttribute("href", linkUrl.pathname + linkUrl.search + linkUrl.hash);
        } catch (e) {}
      }

      var url = new URL(window.location.href);
      url.searchParams.set("lang", currentLanguage);
      window.history.replaceState({}, "", url.toString());
    }

    var selector = document.getElementById("language-select");
    if (selector) {
      selector.addEventListener("change", function (event) {
        var chosen = normalizeLanguage(event.target.value);
        window.localStorage.setItem("preferredLang", chosen);
        applyLanguage(chosen);
      });
    }

    applyLanguage(currentLanguage);

    window.pageT = t;
    return {
      t: t,
      getLanguage: function () { return currentLanguage; },
      setLanguage: applyLanguage
    };
  };
})();