function getOrCreateFolder(parent, name) {
  var it = parent.getFoldersByName(name);
  if (it.hasNext()) return it.next();
  return parent.createFolder(name);
}

function doPost(e) {
  try {
    var data = JSON.parse(e.postData.contents);
    var FOLDER_ID = '1lHjS5HCYlx0OWgViHzHmF-ip5rKLhgpL';
    var parentFolder = DriveApp.getFolderById(FOLDER_ID);
    var jobFolderName = (data.folder || 'unknown').toString();
    var folder = getOrCreateFolder(parentFolder, jobFolderName);

    if (data.pdf) {
      // ลบไฟล์ PDF เดิมทั้งหมดในโฟลเดอร์นี้ก่อน เหลือไว้แค่ไฟล์ล่าสุด
      var oldPdfs = folder.getFilesByType(MimeType.PDF);
      while (oldPdfs.hasNext()) {
        oldPdfs.next().setTrashed(true);
      }
      var bytes = Utilities.base64Decode(data.pdf);
      var blob  = Utilities.newBlob(bytes, 'application/pdf', data.filename);
      var file  = folder.createFile(blob);
      return ContentService
        .createTextOutput(JSON.stringify({success:true, url:file.getUrl(), name:data.filename}))
        .setMimeType(ContentService.MimeType.JSON);
    }

    if (data.photo) {
      var pbytes = Utilities.base64Decode(data.photo);
      var mime = data.filename && data.filename.toLowerCase().endsWith('.png') ? 'image/png' : 'image/jpeg';
      var pblob = Utilities.newBlob(pbytes, mime, data.filename);
      var pfile = folder.createFile(pblob);
      return ContentService
        .createTextOutput(JSON.stringify({success:true, url:pfile.getUrl(), name:data.filename}))
        .setMimeType(ContentService.MimeType.JSON);
    }

    throw new Error('No pdf or photo field in request body');
  } catch(err) {
    return ContentService
      .createTextOutput(JSON.stringify({success:false, error:err.toString()}))
      .setMimeType(ContentService.MimeType.JSON);
  }
}