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('.summary-item');
      if (item) item.remove();
      updateTotals();
      updateCatalogueQty(id, 0);
      return;
    }
    input.value = qty;
    var item = input.closest('.summary-item');
    item.querySelector('.cake-qty').innerText = qty;
    item.querySelector('.cake-total').innerText = (price * qty) + ' PLN';
    updateTotals();
    updateCatalogueQty(id, qty);
    return;
  }
  if (delta <= 0) return;
  var item = document.createElement('div');
  item.className = 'summary-item';
  item.setAttribute('data-cake-id', id);
  item.innerHTML =
    '<div class="summary-item-info">' +
      '<div class="summary-item-name cake-name">' + name + '</div>' +
      '<div class="summary-item-detail cake-price">' + price + ' PLN × <span class="cake-qty">1</span></div>' +
    '</div>' +
    '<div class="summary-item-price cake-total">' + price + ' PLN</div>' +
    '<button type="button" class="summary-item-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('.summary-item');
  var id = item.getAttribute('data-cake-id');
  item.remove();
  updateTotals();
  updateCatalogueQty(id, 0);
}

function updateTotals() {
  var subtotal = 0;
  var items = document.querySelectorAll('#basket_items .summary-item');
  items.forEach(function(item) {
    var priceText = item.querySelector('.cake-price').innerText;
    var price = Number(priceText.split(' ')[0]);
    var qty = Number(item.querySelector('.cake-qty').innerText);
    subtotal += price * qty;
  });
  var paid = Number(document.querySelector('[name="paid"]')?.value || 0);
  document.getElementById('subtotal-price').innerText = subtotal + ' PLN';
  document.getElementById('paid-amount').innerText = paid + ' PLN';
  document.getElementById('total-price').innerText = (subtotal - paid) + ' PLN';
}

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-item');
  items.forEach(function(item) {
    var name = item.getAttribute('data-name').toLowerCase();
    item.style.display = name.includes(query) ? '' : 'none';
  });
}