export function escapeCsv(value: string | number | null | undefined): string {
  if (value === null || value === undefined) return ''
  let str = String(value)
  // Prevent CSV formula injection (Excel/LibreOffice execute cells starting with these chars)
  if (/^[=+\-@\t\r]/.test(str)) str = "'" + str
  if (str.includes(',') || str.includes('"') || str.includes('\n')) {
    return `"${str.replace(/"/g, '""')}"`
  }
  return str
}

export function rowsToCsv(headers: string[], rows: string[][]): string {
  const lines = [headers.map(escapeCsv).join(',')]
  for (const row of rows) lines.push(row.map(escapeCsv).join(','))
  return lines.join('\r\n')
}