function changeCake(id, name, price, delta) {
  var input = document.querySelector('[name="cake[' + id + ']"]');
  if (input != null) {
    var qty = Number(input.value) + delta;
    if (qty <= 0) {
      var item = input.closest("li");
      if (item) item.remove();
      updateTotals();
      updateCatalogueQty(id, 0);
      return;
    }
    input.value = qty;
    var item = input.closest("li");
    item.querySelector(".qty").innerText = qty;
    item.querySelector(".price").innerText = price * qty + " PLN";
    updateTotals();
    updateCatalogueQty(id, qty);
    return;
  }
  if (delta <= 0) return;
  var item = document.createElement("li");
  item.setAttribute("data-cake-id", id);
  item.innerHTML =
    '<div style="flex:1;min-width:0;padding-right:0.5rem">' +
    '<div class="name">' +
    name +
    "</div>" +
    '<div class="detail">' +
    price +
    ' PLN × <span class="qty">1</span></div>' +
    "</div>" +
    '<div class="price">' +
    price +
    " PLN</div>" +
    '<button type="button" class="remove" onclick="removeCake(this)">' +
    '<span class="material-symbols-outlined">close</span>' +
    "</button>" +
    '<input type="hidden" name="cake[' +
    id +
    ']" value="1">';
  document.getElementById("basket-items").appendChild(item);
  updateTotals();
  updateCatalogueQty(id, 1);
}

function removeCake(btn) {
  var item = btn.closest("li");
  var id = item.getAttribute("data-cake-id");
  item.remove();
  updateTotals();
  updateCatalogueQty(id, 0);
}

var subtotal = 0;

function updatePrepaid() {
  var paid = Number(document.querySelector('[name="paid"]')?.value || 0);
  document.getElementById("paid-amount").innerText = paid + " PLN";
  document.getElementById("total-price").innerText = subtotal - paid + " PLN";
}

function updateTotals() {
  subtotal = 0;
  var items = document.querySelectorAll("#basket-items li");
  items.forEach(function (item) {
    var priceText = item.querySelector(".detail").innerText;
    var price = Number(priceText.split(" ")[0]);
    var qty = Number(item.querySelector(".qty").innerText);
    subtotal += price * qty;
  });
  document.getElementById("subtotal-price").innerText = subtotal + " PLN";
  updatePrepaid();
}

function updateCatalogueQty(id, qty) {
  var el = document.getElementById("qty-" + id);
  if (el) el.innerText = qty;
}

function filterCatalogue(input) {
  var query = input.value.toLowerCase();
  var items = document.querySelectorAll("#catalogue-grid > li");
  items.forEach(function (item) {
    var name = item.getAttribute("data-name").toLowerCase();
    item.style.display = name.includes(query) ? "" : "none";
  });
}