(function () {
  // ===== ¼³Á¤ =====
  var LANG_SUFFIX = { ko: "", en: "_en", zh: "_zh", ja: "_ja" };
  var SUFFIXES = ["_en", "_zh", "_ja"]; // ko´Â Á¢¹Ì»ç ¾øÀ½
  var INDEX_NAME = "index.php";         // µð·ºÅ丮 Á¢±Ù ½Ã °¡Á¤ÇÒ À妽º ÆÄÀϸí
  var ALLOW_EXT = /\.(php|html?|asp|aspx)$/i; // ¾ð¾î Á¢¹Ì»ç ºÙÀÏ ´ë»ó È®ÀåÀÚ


  // ===== ÄíÅ° À¯Æ¿ =====
  function setCookie(name, value, days, path) {
    var d = new Date();
    d.setTime(d.getTime() + (days * 24 * 60 * 60 * 1000));
    document.cookie = name + "=" + encodeURIComponent(value) +
      ";expires=" + d.toUTCString() +
      ";path=" + (path || "/");
  }
  function getCookie(name) {
    var m = document.cookie.match(new RegExp("(?:^|; )" + name.replace(/([.$?*|{}()[\]\\/+^])/g, '\\$1') + "=([^;]*)"));
    return m ? decodeURIComponent(m[1]) : null;
  }


  // ===== ÆÄÀϸí ÆÄ½Ì À¯Æ¿ =====
  function splitBaseExt(filename) {
    var dot = filename.lastIndexOf(".");
    return {
      base: dot > -1 ? filename.slice(0, dot) : filename,
      ext:  dot > -1 ? filename.slice(dot) : ""
    };
  }
  function stripLangSuffix(base) {
    for (var i = 0; i < SUFFIXES.length; i++) {
      var sfx = SUFFIXES[i];
      if (base.endsWith(sfx)) return base.slice(0, -sfx.length);
    }
    return base;
  }
  function inferLangFromFilename(filename) {
    if (/_en\.[a-z0-9]+$/i.test(filename)) return "en";
    if (/_zh\.[a-z0-9]+$/i.test(filename)) return "zh";
    if (/_ja\.[a-z0-9]+$/i.test(filename)) return "ja";
    return "ko";
  }
  function buildFileNameForLang(filename, lang) {
    var pe = splitBaseExt(filename);
    var baseNoLang = stripLangSuffix(pe.base);
    var suffix = LANG_SUFFIX[lang] || "";
    return baseNoLang + suffix + pe.ext;
  }
  function ensureFilenameForLang(pathname, lang) {
    // "/dir/" ¡æ "/dir/index.php"
    var path = pathname;
    if (path.endsWith("/")) path += INDEX_NAME;
    var parts = path.split("/");
    var file = parts[parts.length - 1] || "";
    if (!file) file = INDEX_NAME;


    // È®ÀåÀÚ ÇÊÅÍ(php, html µî¸¸ º¯È¯)
    if (!ALLOW_EXT.test(file)) return path;


    var desired = buildFileNameForLang(file, lang);
    parts[parts.length - 1] = desired;
    return parts.join("/");
  }


  // ===== ¸µÅ© ¸®¶óÀÌÆ® À¯Æ¿ =====
  function rewriteHrefToLang(href, lang) {
    var url;
    try { url = new URL(href, location.href); }
    catch (e) { return href; }


    // ¿ÜºÎ µµ¸ÞÀÎÀº º¯°æÇÏÁö ¾ÊÀ½
    if (url.origin !== location.origin) return href;


    // Äõ¸®/Çؽô À¯Áö
    var newPath = ensureFilenameForLang(url.pathname, lang);
    url.pathname = newPath;
    // lang ÆĶó¹ÌÅÍ´Â »ç¿ë ¾È ÇÔ
    url.searchParams.delete("lang");
    return url.toString();
  }


  // ===== URL Á¸Àç È®ÀÎ (HEAD ¡æ GET Æú¹é) & ¾ð¾î Ȩ =====
  function urlExists(urlStr) {
    try {
      return fetch(urlStr, { method: 'HEAD', cache: 'no-store', redirect: 'manual' })
        .then(function (res) {
          if (res.ok) return true;
          // ÀϺΠ¼­¹ö°¡ HEAD¸¦ ¸·´Â °æ¿ì(405 µî) ¡æ GETÀ¸·Î ÀçÈ®ÀÎ
          return fetch(urlStr, { method: 'GET', cache: 'no-store', redirect: 'manual' })
            .then(function (r) { return r.ok; })
            .catch(function () { return false; });
        })
        .catch(function () { return false; });
    } catch (e) {
      return Promise.resolve(false);
    }
  }
  function langHome(lang) {
    // ko´Â Á¢¹Ì»ç ¾øÀ½, ±× ¿Ü index_??.php °¡Á¤
    if (lang === 'ko') return '/default/index.php';
    return '/default/index_' + lang + '.php';
  }


  // ===== a[data-lang-*] ¶óº§ Àû¿ë =====
  var LANG_ORDER = ['ko','en','zh','ja'];
  function pickLabelFromAttrs(a, lang) {
    var t = a.getAttribute('data-lang-' + lang);
    if (t && t.trim) return t.trim();
    // ¼±ÅÃÇÑ ¾ð¾î°¡ ¾øÀ¸¸é ko ¡æ en ¡æ zh ¡æ ja ¼øÀ¸·Î Æú¹é
    for (var i = 0; i < LANG_ORDER.length; i++) {
      var v = a.getAttribute('data-lang-' + LANG_ORDER[i]);
      if (v && v.trim) return v.trim();
    }
    return null;
  }
  function applyAnchorsLang(lang) {
    var list = document.querySelectorAll(
      'a[data-lang-ko],a[data-lang-en],a[data-lang-zh],a[data-lang-ja]'
    );
    for (var i = 0; i < list.length; i++) {
      var a = list[i];
      var label = pickLabelFromAttrs(a, lang);
      if (label != null) a.textContent = label; // ¼ø¼ö ÅؽºÆ®ÀÏ ¶§ ¾ÈÀü
    }
  }


  // ===== ÃʱâÈ­ =====
  function init() {
    var sel = document.getElementById("site-lang");


    // ÇöÀç °æ·Î/ÆÄÀÏ
    var pathname = location.pathname;
    var pathParts = pathname.split("/");
    var filename = pathParts[pathParts.length - 1];
    var currentFile = filename || INDEX_NAME;


    // ÇöÀç ÆÄÀϷκÎÅÍ ¾ð¾î ÃßÁ¤
    var inferred = inferLangFromFilename(currentFile);


    // ÄíÅ° ¾ð¾î ¿ì¼±
    var cookieLang = getCookie("site_lang");
    var activeLang = (cookieLang && LANG_SUFFIX.hasOwnProperty(cookieLang)) ? cookieLang : inferred;


    // µå·Ó´Ù¿î ÃʱⰪ µ¿±âÈ­ + ÄíÅ° ÃÖ½ÅÈ­
    if (sel) sel.value = activeLang;
    setCookie("site_lang", activeLang, 365, "/");


    // a[data-lang-*] ¶óº§ Àû¿ë
    applyAnchorsLang(activeLang);


    // 1) µå·Ó´Ù¿î º¯°æ: ´ë»ó ¾øÀ¸¸é ¹Ù·Î ¾ð¾î À妽º·Î (·çÇÁ °¡µå Á¦°Å)
    if (sel) {
      sel.addEventListener("change", function () {
        var lang = sel.value || "ko";
        setCookie("site_lang", lang, 365, "/");
        applyAnchorsLang(lang); // È­¸é Áï½Ã ¹Ý¿µ


        var url = new URL(location.href);
        url.pathname = ensureFilenameForLang(location.pathname, lang);
        url.searchParams.delete("lang");


        urlExists(url.toString()).then(function (ok) {
          if (ok) {
            location.href = url.toString();
          } else {
            location.href = langHome(lang);
          }
        });
      });
    }


    // 2) ³»ºÎ ¸µÅ© Ŭ¸¯: ´ë»ó ¾øÀ¸¸é ¹Ù·Î ¾ð¾î À妽º·Î
    document.addEventListener("click", function (e) {
      var a = e.target.closest && e.target.closest("a[href]");
      if (!a) return;


      // »õÅÇ/¼öÁ¤Å°/ÇؽÃ/ÀüÈ­/¸ÞÀÏ µîÀº ±×´ë·Î µÒ
      if (e.defaultPrevented || a.target === "_blank" || e.metaKey || e.ctrlKey || e.shiftKey || e.altKey || e.button !== 0) return;
      if (a.hasAttribute("data-lang-ignore")) return;


      var href = a.getAttribute("href");
      if (!href || href.startsWith("#") || href.startsWith("mailto:") || href.startsWith("tel:")) return;


      var lang = getCookie("site_lang") || activeLang || "ko";
      var newHref = rewriteHrefToLang(href, lang);


      // µ¿ÀÏÀÌ¸é ±×³É ÁøÇà(ºê¶ó¿ìÀú ±âº» À̵¿)
      if (newHref === a.href) return;


      e.preventDefault();


      urlExists(newHref).then(function (ok) {
        if (ok) {
          location.href = newHref;
        } else {
          location.href = langHome(lang);
        }
      });
    }, true);
  }


  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", init);
  } else {
    init();
  }
})();