(function(){
  var OFFICE_EXT = ["docx","pptx","ppt","xlsx","xls"];
  var PREVIEW_BASE = "http://" + location.hostname + ":8080";

  function startsWithFiles(p){ return (p || "").toLowerCase().indexOf("/files/") === 0; }

  function normalizeFilePath(path){
    var p = path || "";
    if (!startsWithFiles(p)) return "";
    p = p.slice(7);
    try { p = decodeURIComponent(p); } catch(e) {}
    while (p.length > 0 && p.charAt(0) === "/") p = p.slice(1);
    return p;
  }

  function isOffice(path){
    var s = (path || "").toLowerCase();
    for (var i = 0; i < OFFICE_EXT.length; i++) {
      if (s.endsWith("." + OFFICE_EXT[i])) return true;
    }
    return false;
  }

  function encodePathSegments(path){
    return (path || "").split("/").map(function(seg){ return encodeURIComponent(seg); }).join("/");
  }

  function buildRawPath(rel){
    var low = (rel || "").toLowerCase();
    if (low.indexOf("words/") === 0) {
      return "/raw/words/" + encodePathSegments((rel || "").slice(6));
    }
    if (low.indexOf("excels/") === 0) {
      return "/raw/excels/" + encodePathSegments((rel || "").slice(7));
    }
    return "/raw/files/" + encodePathSegments(rel || "");
  }

  function buildPreviewUrlFromPath(pathname){
    var rel = normalizeFilePath(pathname);
    if (!rel || !isOffice(rel)) return "";
    var ext = (rel.split(".").pop() || "").toLowerCase();
    var rawUrl = PREVIEW_BASE + buildRawPath(rel);
    var nonce = Date.now().toString() + "-" + Math.random().toString(16).slice(2, 8);
    return PREVIEW_BASE + "/oo-preview.html?url=" + encodeURIComponent(rawUrl) + "&type=" + encodeURIComponent(ext) + "&title=" + encodeURIComponent(rel) + "&_fbv=" + encodeURIComponent(nonce);
  }

  function maybeJump(){
    var p = location.pathname || "";
    var u = buildPreviewUrlFromPath(p);
    if (!u) return;
    if (location.pathname === "/oo-preview.html") return;
    location.replace(u);
  }

  var pushed = history.pushState;
  history.pushState = function(){
    pushed.apply(history, arguments);
    setTimeout(maybeJump, 0);
  };

  var replaced = history.replaceState;
  history.replaceState = function(){
    replaced.apply(history, arguments);
    setTimeout(maybeJump, 0);
  };

  window.addEventListener("popstate", function(){ setTimeout(maybeJump, 0); });
  window.addEventListener("hashchange", function(){ setTimeout(maybeJump, 0); });

  setTimeout(maybeJump, 0);
})();