export function extractYoutubeId(input: string): string {
  const trimmed = input.trim()
  if (!trimmed) return ''

  // Direct 11-char ID
  if (/^[a-zA-Z0-9_-]{11}$/.test(trimmed)) {
    return trimmed
  }

  // youtu.be/ID
  const shortMatch = trimmed.match(/youtu\.be\/([a-zA-Z0-9_-]{11})/)
  if (shortMatch) return shortMatch[1]

  // youtube.com/watch?v=ID
  const watchMatch = trimmed.match(/[?&]v=([a-zA-Z0-9_-]{11})/)
  if (watchMatch) return watchMatch[1]

  // youtube.com/embed/ID
  const embedMatch = trimmed.match(/youtube\.com\/embed\/([a-zA-Z0-9_-]{11})/)
  if (embedMatch) return embedMatch[1]

  // youtube.com/shorts/ID
  const shortsMatch = trimmed.match(/youtube\.com\/shorts\/([a-zA-Z0-9_-]{11})/)
  if (shortsMatch) return shortsMatch[1]

  return trimmed
}