Change the order of the pages in a PDF to create a booklet using mutool.

booklet.js

/*
Usage:

mutool run booklet.js input.pdf output.pdf
*/

function copyPage(dstDoc, srcDoc, pageNumber, graftMap) {
  var srcPage = srcDoc.findPage(pageNumber - 1);
  var dstPage = dstDoc.newDictionary();
  dstPage.Type = dstDoc.newName("Page");
  if (srcPage.MediaBox){
    dstPage.MediaBox = graftMap.graftObject(srcPage.MediaBox);
  }
  if (srcPage.Rotate){
    dstPage.Rotate = graftMap.graftObject(srcPage.Rotate);
  }
  if (srcPage.Resources){
    dstPage.Resources = graftMap.graftObject(srcPage.Resources);
  }
  if (srcPage.Contents){
    dstPage.Contents = graftMap.graftObject(srcPage.Contents);
  }
  dstDoc.insertPage(-1, dstDoc.addObject(dstPage));
}

function getPageOrder(outputLength) {
  var outputPages = [];
  for (var i = 0; i < outputLength; i++) {
    if (outputPages.indexOf(i + 1) >= 0) {
      break;
    }
    if (i % 2 == 0) {
      outputPages.push(outputLength - i);
      outputPages.push(i + 1);
    } else {
      outputPages.push(i + 1);
      outputPages.push(outputLength - i);
    }
  }
  return outputPages;
};

function getBookLength(srcDoc) {
  var inputPages = srcDoc.countPages();
  var outputSheets = Math.floor(inputPages / 4);
  var outputMod = inputPages % 4;
  if (outputMod != 0) {
    outputSheets += 1;
  }
  return outputSheets * 4;
};

function padPages(srcDoc, desiredLength) {
  var examplePage = srcDoc.loadPage(0);
  var inputPages = srcDoc.countPages();
  if (inputPages < desiredLength) {
    var padLength = desiredLength - inputPages;
    var blankPage = srcDoc.addPage(examplePage.bound(), 0, null, null);
    for (var i = 0; i < padLength; i++) {
      srcDoc.insertPage(-1, blankPage);
    }
  }
  return srcDoc;
};

function createBooklet() {
  var inputFile = scriptArgs[0];
  var outputFile = scriptArgs[1];
  var inputDoc = new PDFDocument(inputFile);
  var outputDoc = new PDFDocument();

  var bookLength = getBookLength(inputDoc);
  var outputPages = getPageOrder(bookLength);
  inputDoc = padPages(inputDoc, bookLength);

  var graftMap = outputDoc.newGraftMap();
  for (var i = 0; i < outputPages.length; i++) {
    copyPage(outputDoc, inputDoc, outputPages[i], graftMap);
  }
  outputDoc.save(outputFile);
};

if (scriptArgs.length < 2) {
  print("usage: mutool run booklet.js input.pdf output.pdf");
} else {
  createBooklet();
}