/**
 * Branded PDF retrieval receipt (no native deps).
 * @module lib/receiptPdf
 */

function pdfEscape(s) {
  return String(s).replace(/\\/g, '\\\\').replace(/\(/g, '\\(').replace(/\)/g, '\\)');
}

function wrap(s, n) {
  const str = String(s || '');
  const out = [];
  for (let i = 0; i < str.length; i += n) out.push(str.slice(i, i + n));
  return out.length ? out : [''];
}

/**
 * @param {object} receipt
 * @returns {Buffer}
 */
export function buildReceiptPdf(receipt) {
  const lines = [];
  const add = (label, value) => {
    lines.push({ kind: 'label', text: label });
    wrap(value, 86).forEach((t) => lines.push({ kind: 'value', text: t }));
    lines.push({ kind: 'gap' });
  };
  add('Job ID', receipt.jobId);
  add('SHA-256', receipt.sha256 ?? '');
  add('Original timestamp', receipt.timestamp ?? '');
  add('Retrieved at', receipt.extraSeal?.retrievedAt ?? '');
  add('Tenant', receipt.extraSeal?.tenantId ?? '');
  add('Seal event', receipt.extraSeal?.event ?? '');
  add('Certificate', String(receipt.certificate ?? '').slice(0, 240));

  const ops = [];
  ops.push('0.192 0.180 0.506 rg');
  ops.push('0 742 612 50 re f');
  ops.push('1 1 1 rg');
  ops.push('BT /F1 16 Tf 36 760 Td (Verae Time) Tj ET');
  ops.push('BT /F1 9 Tf 36 746 Td (CERTIFIED RETRIEVAL RECEIPT) Tj ET');
  ops.push('0.09 0.10 0.15 rg');
  let y = 710;
  for (const line of lines) {
    if (line.kind === 'gap') {
      y -= 8;
      continue;
    }
    const size = line.kind === 'label' ? 8 : 11;
    ops.push(`BT /F1 ${size} Tf 36 ${y} Td (${pdfEscape(line.text)}) Tj ET`);
    y -= line.kind === 'label' ? 12 : 14;
  }
  ops.push('0.192 0.180 0.506 rg');
  ops.push('36 48 540 0.8 re f');
  ops.push('0.42 0.44 0.52 rg');
  ops.push(
    'BT /F1 8 Tf 36 34 Td (This is a certified retrieval receipt. The extra-seal event is recorded with the hash. It is not a substitute for the chain record.) Tj ET',
  );
  ops.push(
    `BT /F1 8 Tf 36 22 Td (${pdfEscape('Verae Time x Zapier  ·  type ' + (receipt.type || 'verae.retrieval-receipt'))}) Tj ET`,
  );

  const stream = `${ops.join('\n')}\n`;
  const objects = [
    '1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj',
    '2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 >> endobj',
    '3 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] /Contents 4 0 R /Resources << /Font << /F1 5 0 R >> >> >> endobj',
    `4 0 obj << /Length ${Buffer.byteLength(stream)} >> stream\n${stream}endstream endobj`,
    '5 0 obj << /Type /Font /Subtype /Type1 /BaseFont /Helvetica >> endobj',
  ];

  let offset = '%PDF-1.4\n'.length;
  const xref = [0];
  let body = '%PDF-1.4\n';
  for (const obj of objects) {
    xref.push(offset);
    const chunk = `${obj}\n`;
    body += chunk;
    offset += Buffer.byteLength(chunk);
  }
  const xrefStart = offset;
  let xrefTable = `xref\n0 ${objects.length + 1}\n0000000000 65535 f \n`;
  for (let i = 1; i < xref.length; i += 1) {
    xrefTable += `${String(xref[i]).padStart(10, '0')} 00000 n \n`;
  }
  body += xrefTable;
  body += `trailer << /Size ${objects.length + 1} /Root 1 0 R >>\nstartxref\n${xrefStart}\n%%EOF\n`;
  return Buffer.from(body, 'utf8');
}