Google Apps script to bulk remove default sharing in Google Drive

bulk-remove-sharing.js

/**
 * Google Apps has some admin restriction, such as sharing to whole group by default
 * this script can remove all sharing and reset to private only
 * For more information on interacting with folders, see
 * https://developers.google.com/apps-script/reference/drive/folder
 * Github gist is here: https://gist.github.com/billzhuang/43faa0a8daea8f0dab74
*/

// step 1, prepare data in excel
function prepareData(){
  // clear folder first
  removeFolderSharing();
  
  var files = DriveApp.getFiles();
  var sheet = getCurrentSheet();
  var index = 0;
  
  while (files.hasNext()) {
    var file = files.next();
    if(file.getSharingAccess() != DriveApp.Access.PRIVATE){
      if(index == 0){
        index = insertToSpreadsheet(sheet, file.getId());
      }
      else{
        index = insertToSpreadsheet(sheet, file.getId(), index);
      }
    }
  }
}

// step 2, remove all sharing in my drive
function removeAll(){
  
  // cache sheet object
  var sheet = getCurrentSheet();
  while(true){
    var value = readLastData(sheet);
    if(value == "NAN"){
      break;  
    }
    
    removeSharing(value);
    removeLastData(sheet);
  }
}

// get predefined spreadsheet active sheet
function getCurrentSheet(){
  var file = SpreadsheetApp.openById("1kqg67vNbHyC8wIfmS1G4VFQbuOuVPbOSLSKKmufAHdE");
  return file.getActiveSheet();  
}

// add data to defined sheet, use spreadsheet as data source
function insertToSpreadsheet(sheet, value, index){
  if(typeof(index) != "undefined"){
    sheet.getRange(index + 1, 1).setValue(value);
    
    return index + 1;
  }
  index = sheet.getLastRow();
  sheet.getRange(index + 1, 1).setValue(value);
  
  return index + 1;
}

function readLastData(sheet){  
  var index = sheet.getLastRow();
  if (index == 0){
    return "NAN";
  }
  var range = sheet.getRange(index, 1);
  return range.getValue();
}

function removeLastData(sheet){
  var index = sheet.getLastRow();
  var range = sheet.getRange(index, 1);
  range.clear();
}

// remove Sharing by single file
function removeSharing(fileId){
  var file = DriveApp.getFileById(fileId);
  file.setSharing(DriveApp.Access.PRIVATE, DriveApp.Permission.NONE);
  //Logger.log(file.getId() + "##" + file.getName() + "##" + file.getSharingAccess() + "##" + file.getSharingPermission() + "\n");
}

// list all folders include subfolders
function removeFolderSharing(){
  var folders = DriveApp.getFolders();
  while (folders.hasNext()) {
    var folder = folders.next();
    folder.setSharing(DriveApp.Access.PRIVATE, DriveApp.Permission.NONE)
    //Logger.log(folder.getName() + "##" + folder.getId() + "##\n");
  }
}

function testSheet(){
  var file = SpreadsheetApp.openById("1kqg67vNbHyC8wIfmS1G4VFQbuOuVPbOSLSKKmufAHdE");
  var sheet = file.getActiveSheet();
  
  var index = sheet.getLastRow();
  Logger.log("Lost Row:" + index);
  var range = sheet.getRange(index,1);
  
  Logger.log(range.getValue());
  
  range.clear()
  var index2 = sheet.getLastRow();
  Logger.log("Lost Row:" + index2);
}