function doGet() {
  return HtmlService.createHtmlOutputFromFile('index');
}

function getProducts() {
  const sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("PRODUCTS");
  const data = sheet.getDataRange().getValues();
  data.shift();

  return data.map(row => ({
    id: row[0],
    name: row[1],
    price: row[2],
    image: row[3]
  }));
}

function saveSale(cart) {
  const sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("SALES");
  const receiptId = "RCPT-" + new Date().getTime();
  const date = new Date();

  cart.forEach(item => {
    sheet.appendRow([
      date,
      receiptId,
      item.name,
      item.qty,
      item.price,
      item.qty * item.price
    ]);
  });

  return receiptId;
}