import { sevenZipVolume } from '../sevenzip/index.js'

/**
 * Files whose first segment says what an archive holds: named first RAR
 * volumes (.part01.rar, .rar), 7z (.7z, .7z.001) and `.bin`, an extension
 * uploaders use for archive volumes too (sniffed by content).
 */
export function isArchiveStart(name: string): boolean {
  if (/\.bin$/i.test(name)) return true
  const volume = sevenZipVolume(name)
  if (volume === 0 || volume === 1) return true
  return /\.part0*1\.rar$/i.test(name) || (/\.rar$/i.test(name) && !/\.part\d+\.rar$/i.test(name))
}

/**
 * A later RAR volume (.part02.rar, .r00) or a par2 recovery volume
 * (.vol03+04.par2): the volume number is readable even under a random stem.
 * The set is listed from its first volume and named from its index .par2,
 * so the first segment of these says nothing new (LOG.md 2026-10-04).
 */
export function isLaterVolume(name: string): boolean {
  const part = /\.part(\d+)\.rar$/i.exec(name)
  if (part) return Number(part[1]) > 1
  return /\.r\d{2,3}$/i.test(name) || /\.vol\d+[+-]\d+\.par2$/i.test(name)
}