// Offline XLSX fixture used only by download-center contract tests.
export function exportWorkbook(headers, values = []) {
  const escape = value => String(value ?? '').replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;')
  const rows = [headers, values].map((row, index) => `<row r="${index + 1}">${row.map((value, col) => {
    const letter = String.fromCharCode(65 + col)
    return `<c r="${letter}${index + 1}" t="inlineStr"><is><t>${escape(value)}</t></is></c>`
  }).join('')}</row>`).join('')
  const name = Buffer.from('xl/worksheets/sheet1.xml')
  const body = Buffer.from(`<worksheet><sheetData>${rows}</sheetData></worksheet>`)
  const local = Buffer.alloc(30)
  local.writeUInt32LE(0x04034b50); local.writeUInt32LE(body.length, 18); local.writeUInt32LE(body.length, 22); local.writeUInt16LE(name.length, 26)
  const central = Buffer.alloc(46)
  central.writeUInt32LE(0x02014b50); central.writeUInt32LE(body.length, 20); central.writeUInt32LE(body.length, 24); central.writeUInt16LE(name.length, 28)
  const end = Buffer.alloc(22)
  end.writeUInt32LE(0x06054b50); end.writeUInt16LE(1, 8); end.writeUInt16LE(1, 10)
  end.writeUInt32LE(central.length + name.length, 12); end.writeUInt32LE(local.length + name.length + body.length, 16)
  return Buffer.concat([local, name, body, central, name, end])
}