import dns from 'node:dns'
import { SEAFILE_URL } from './config.js'

// Alpine's resolver (musl) fails the whole lookup when a DNS server answers the IPv6 (AAAA)
// query with "no such name" even though the IPv4 answer is fine, so Node reports ENOTFOUND for
// a host that resolves. Ask for IPv4 only, and only for the Seafile host.
export function preferIpv4ForSeafile() {
  let host = ''
  try {
    host = SEAFILE_URL ? new URL(SEAFILE_URL).hostname : ''
  } catch {
    return
  }
  if (!host) return

  const originalLookup = dns.lookup
  dns.lookup = function lookup(hostname, options, callback) {
    if (hostname === host) {
      if (typeof options === 'function') {
        callback = options
        options = {}
      } else if (typeof options === 'number') {
        options = { family: options }
      }
      if (!options?.family) options = { ...options, family: 4 }
    }
    return originalLookup.call(this, hostname, options, callback)
  }
  console.log(`[seafile-dns] resolving ${host} over IPv4 only`)
}