Auto Set Price Webhook

function doPost(e) {
  var postdatacontents = JSON.parse(e.postData.contents)
  var ss = SpreadsheetApp.openByUrl('urltoyourspreadsheet')
  var sheetarray = ss.getSheets();
  var sheetnum = 0;
  for (var x = 0; x < sheetarray.length; x++) {
if (sheetarray[x].getName() == postdatacontents.Character_Info.Name)
  sheetnum = x;
  }
  var sheet = ss.getSheets()[sheetnum];
  var itemname = 0
  var itemquantity = 0
  var itemprice = 0
  var itemtotalprice = 0
  var itemlowestprice = 0
  for (var c = 0; c < postdatacontents.Retainer_Info.Number; c++)
  {
sheet.getRange(2, c * 5 + 1).setValue('Retainer ' + (c+1).toString())
for (var d = 0; d < 20; d++)
{
  eval('itemname = postdatacontents.Retainer_' + (c+1).toString() + '.Item_' + (d+1).toString() + '_Name')
  if (itemname == 'null')
  {
sheet.getRange(d + 3, c * 6 + 1).setValue('')
sheet.getRange(d + 3, c * 6 + 2).setValue('')
sheet.getRange(d + 3, c * 6 + 3).setValue('')
sheet.getRange(d + 3, c * 6 + 4).setValue('')
sheet.getRange(d + 3, c * 6 + 5).setValue('')
sheet.getRange(d + 3, c * 6 + 6).setValue('')
  }
  else
  {
eval('itemquantity = postdatacontents.Retainer_' + (c+1).toString() + '.Item_' + (d+1).toString() + '_Quantity')
eval('itemprice = postdatacontents.Retainer_' + (c+1).toString() + '.Item_' + (d+1).toString() + '_Price')
eval('itemlowestprice = postdatacontents.Retainer_' + (c+1).toString() + '.Item_' + (d+1).toString() + '_LowestPrice')

sheet.getRange(d + 3, c * 6 + 1).setValue(itemname.toString())
sheet.getRange(d + 3, c * 6 + 2).setValue(itemquantity)
sheet.getRange(d + 3, c * 6 + 3).setValue(itemlowestprice)
sheet.getRange(d + 3, c * 6 + 4).setValue(itemprice)
itemtotalprice = itemprice * itemquantity
sheet.getRange(d + 3, c * 6 + 5).setValue(itemtotalprice)
sheet.getRange(d + 3, c * 6 + 6).setValue('')
  }
}
  }
  return ContentService.createTextOutput('Success');
}