/** Small presentation helpers shared by the chat attachment chips/thumbnails. */

/** Human-readable byte size, e.g. 2048 -> "2 KB", 1536000 -> "1.5 MB". */
export function formatBytes(bytes: number): string {
  if (!Number.isFinite(bytes) || bytes < 0) return ''
  if (bytes < 1024) return `${bytes} B`
  const units = ['KB', 'MB', 'GB', 'TB']
  let value = bytes / 1024
  let i = 0
  while (value >= 1024 && i < units.length - 1) {
    value /= 1024
    i++
  }
  const rounded = value >= 10 || Number.isInteger(value) ? Math.round(value) : Math.round(value * 10) / 10
  return `${rounded} ${units[i]}`
}

const IMAGE_EXT = /\.(png|jpe?g|gif|webp|avif|bmp|svg|heic|heif)$/i

/** Whether a filename or content-type looks like a previewable image. */
export function isImageName(nameOrType: string | undefined | null): boolean {
  if (!nameOrType) return false
  return nameOrType.startsWith('image/') || IMAGE_EXT.test(nameOrType)
}