import path from '#host-path'

/**
 * Map a path relative to the host `kernel/` tree to the POSIX path on the system image.
 * @param {string} subRel native-relative path (e.g. `bin/cat`, `init.js`)
 * @returns {string} image path starting with `/`
 */
export function kernelHostRelToImagePosix(subRel) {
  if (subRel === 'init.js') return '/boot/init.js'
  if (subRel.startsWith('bin' + path.sep)) {
    return '/bin/' + subRel.slice(4).split(path.sep).join('/')
  }
  if (subRel.startsWith('etc' + path.sep)) {
    return '/etc/' + subRel.slice(4).split(path.sep).join('/')
  }
  return '/' + subRel.split(path.sep).join('/')
}

export function skipKernelImagePath(drivePath) {
  return drivePath === '/README.md'
}

/**
 * `/kernel/bin/cat` → host-relative `bin/cat` (native separators).
 * @param {string} fullKey hyperdrive key
 * @returns {string | null}
 */
export function bundleKernelKeyToHostRel(fullKey) {
  const k = String(fullKey).replace(/^\/+/, '')
  if (!k.startsWith('kernel/')) return null
  const rest = k.slice('kernel/'.length)
  if (!rest) return null
  return rest.split('/').join(path.sep)
}