const TRACE_SAMPLE_RATE = 0.1

function randomHex(bytes: number): string {
  const buffer = new Uint8Array(bytes)
  crypto.getRandomValues(buffer)
  return Array.from(buffer, value => value.toString(16).padStart(2, '0')).join('')
}

export function newTraceparent(): string {
  const sampled = Math.random() < TRACE_SAMPLE_RATE ? '01' : '00'
  return `00-${randomHex(16)}-${randomHex(8)}-${sampled}`
}