/**
 * Implementation of HappyEyeballs Sorting Addresses.
 *
 * The current implementation does not address any of:
 *  - Async DNS split by IP class
 *  - Stateful handling of connectivity results
 *  - The prioritisation of addresses
 *
 * https://datatracker.ietf.org/doc/html/rfc8305#section-4
 */
fun reorderForHappyEyeballs(addresses: List<InetAddress>): List<InetAddress> {
  if (addresses.size < 2) {
    return addresses
  }

import okhttp3.Dns.Companion.SYSTEM

/**
 * A domain name service that resolves IP addresses for host names. Most applications will use the
 * [system DNS service][SYSTEM], which is the default. Some applications may provide their own
 * implementation to use a different DNS server, to prefer IPv6 addresses, to prefer IPv4 addresses,
 * or to force a specific known IP address.
 *
 * Implementations of this interface must be safe for concurrent use.
 */

import okhttp3.Dns

/**
 * A network that always resolves two IP addresses per host. Use this when testing route selection
 * fallbacks to guarantee that a fallback address is available.
 */
class DoubleInetAddressDns : Dns {
  override fun lookup(hostname: String): List<InetAddress> {
    val addresses = Dns.SYSTEM.lookup(hostname)
    return listOf(addresses[0], addresses[0])
  }

        executor,
        null,
        object : DnsResolver.Callback<List<InetAddress>> {
          override fun onAnswer(
            addresses: List<InetAddress>,
            rCode: Int,
          ) {
            callback.onResponse(hostname, addresses)
          }

          override fun onError(e: DnsResolver.DnsException) {
            callback.onFailure(
              hostname,

}

/**
 * Returns the canonical address for [address]. If [address] is an IPv6 address that is mapped to an
 * IPv4 address, this returns the IPv4-mapped address. Otherwise, this returns [address].
 *
 * https://en.wikipedia.org/wiki/IPv6#IPv4-mapped_IPv6_addresses
 */
internal fun canonicalizeInetAddress(address: ByteArray): ByteArray {
  return when {
    isMappedIpv4Address(address) -> address.sliceArray(12 until 16)

  private var nextAddress = 0xff000064L // 255.0.0.100 in IPv4; ::ff00:64 in IPv6.

  /** Sets the results for `hostname`.  */
  operator fun set(
    hostname: String,
    addresses: List<InetAddress>,
  ): FakeDns {
    hostAddresses[hostname] = addresses
    return this
  }

  /** Clears the results for `hostname`.  */
  fun clear(hostname: String): FakeDns {
    hostAddresses.remove(hostname)
    return this
  }

  // addressType specifies the type of address carried by this EndpointSlice.
  // All addresses in this slice must be the same type. This field is
  // immutable after creation. The following address types are currently
  // supported:
  // * IPv4: Represents an IPv4 Address.
  // * IPv6: Represents an IPv6 Address.
  // * FQDN: Represents a Fully Qualified Domain Name.

    val InetSocketAddress.socketHost: String get() {
      // The InetSocketAddress was specified with a string (either a numeric IP or a host name). If
      // it is a name, all IPs for that name should be tried. If it is an IP address, only that IP
      // address should be tried.
      val address = address ?: return hostName

### [Addresses](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-address/)

Addresses specify a webserver (like `github.com`) and all of the **static** configuration necessary to connect to that server: the port number, HTTPS settings, and preferred network protocols (like HTTP/2).

// IPAddress represents a single IP of a single IP Family. The object is designed to be used by APIs
// that operate on IP addresses. The object is used by the Service core API for allocation of IP addresses.
// An IP address can be represented in different formats, to guarantee the uniqueness of the IP,
// the name of the object is the IP address in canonical format, four decimal digits separated