const RECEIPT_SELECTOR = '.receipt';

function textOf(node) {
  return (node?.textContent || '').replace(/\s+/g, ' ').trim();
}

function escapeHtml(value) {
  return String(value || '').replace(/[&<>"']/g, (char) => ({
    '&': '&amp;',
    '<': '&lt;',
    '>': '&gt;',
    '"': '&quot;',
    "'": '&#39;'
  }[char]));
}

function getReference(receipt) {
  const meta = [...receipt.querySelectorAll('.receipt-meta > div')];
  const ref = meta.find((item) => /reference/i.test(textOf(item)));
  return textOf(ref).replace(/^reference\s*/i, '').trim();
}

function getAssetTag(receipt) {
  const match = textOf(receipt).match(/\bAST-[A-Z0-9-]+\b/i);
  return match ? match[0].toUpperCase() : '';
}

function makeQrValue(assetTag, reference) {
  if (assetTag) {
    return location.origin + location.pathname + '?asset=' + encodeURIComponent(assetTag);
  }
  return 'AssetDesk receipt ' + (reference || 'document');
}

function qrFallback(img, value) {
  img.src = 'https://api.qrserver.com/v1/create-qr-code/?size=180x180&margin=8&data=' + encodeURIComponent(value);
  img.dataset.qrSource = 'qrserver-fallback';
  img.addEventListener('error', () => {
    img.hidden = true;
    img.closest('.receipt-qr-block')?.classList.add('qr-unavailable');
  }, { once: true });
}

async function renderQr(img, value) {
  try {
    if (globalThis.AssetDeskQRCode?.toDataURL) {
      img.src = await globalThis.AssetDeskQRCode.toDataURL(value, { width: 180, margin: 1 });
      img.dataset.qrSource = 'local';
      return;
    }
  } catch {
    // The online fallback still gives the user a printable QR when available.
  }
  qrFallback(img, value);
}

function enhanceReceipt(receipt) {
  if (receipt.dataset.receiptEnhanced === 'true') return;
  receipt.dataset.receiptEnhanced = 'true';
  receipt.classList.add('receipt-modernized');

  const heading = receipt.querySelector('.receipt-header > strong');
  const kind = textOf(heading) || 'RECEIPT';
  const reference = getReference(receipt);
  const assetTag = getAssetTag(receipt);
  const qrValue = makeQrValue(assetTag, reference);

  const meta = receipt.querySelector('.receipt-meta');
  if (meta) {
    const bar = document.createElement('div');
    bar.className = 'receipt-document-bar';
    bar.innerHTML = '<span>DOCUMENT TYPE</span><strong>' + escapeHtml(kind) + '</strong><span class="receipt-reference-label">' + (assetTag ? 'ASSET' : 'REFERENCE') + '</span><strong>' + escapeHtml(assetTag || reference || '—') + '</strong>';
    meta.insertAdjacentElement('afterend', bar);
  }

  const qr = document.createElement('aside');
  qr.className = 'receipt-qr-block';
  qr.innerHTML = '<div class="receipt-qr-copy"><span>SCAN FOR DETAILS</span><strong>' + escapeHtml(assetTag || reference || 'DOCUMENT') + '</strong><small>' + (assetTag ? 'Open asset history and current location' : 'Document reference for this receipt') + '</small></div><img alt="QR code for ' + escapeHtml(assetTag || reference || 'receipt') + '" width="132" height="132" loading="eager"><div class="receipt-qr-fallback">QR code unavailable until network access is restored.</div>';
  const firstTable = receipt.querySelector('table');
  if (firstTable) firstTable.insertAdjacentElement('beforebegin', qr);
  else receipt.append(qr);
  renderQr(qr.querySelector('img'), qrValue);

  const printButton = receipt.querySelector('button.no-print');
  if (printButton) printButton.setAttribute('aria-label', 'Print ' + kind.toLowerCase());
}

function scanReceipts() {
  document.querySelectorAll(RECEIPT_SELECTOR).forEach(enhanceReceipt);
}

const observer = new MutationObserver(scanReceipts);
observer.observe(document.documentElement, { childList: true, subtree: true });
scanReceipts();