package main

import "flag"
import "fmt"
import "net"
import "os"
import "runtime/pprof"
import "time"

// TODO look into netmap + libpcap to bypass the kernel as much as possible

func basic_test() {

  // TODO need a way to look up who our link-local neighbors are for each iface!

  var ip *net.IP
  ifaces, err := net.Interfaces()
  if err != nil { panic(err) }
  var zone string
  for _, iface := range ifaces {
    addrs, err := iface.Addrs()
    if err != nil { panic(err) }
    for _, addr := range addrs {
      addrIP, _, _ := net.ParseCIDR(addr.String())
      if addrIP.To4() != nil { continue } // IPv6 only
      if !addrIP.IsLinkLocalUnicast() { continue }
      fmt.Println(iface.Name, addrIP)
      zone = iface.Name
      ip = &addrIP
    }
    if ip != nil { break }
    /*
    addrs, err = iface.MulticastAddrs()
    if err != nil { panic(err) }
    for _, addr := range addrs {
      fmt.Println(addr.String())
    }
    */
  }
  if ip == nil { panic("No link-local IPv6 found") }
  fmt.Println("Using address:", *ip)
  addr := net.UDPAddr{IP: *ip, Port: 9001, Zone: zone}

  laddr, err := net.ResolveUDPAddr("udp", "[::]:9001")
  if err != nil { panic(err) }
  sock, err := net.ListenUDP("udp", laddr)
  if err != nil { panic(err) }
  defer sock.Close()

  go func () {
    send, err := net.DialUDP("udp", nil, &addr)
    //send, err := net.ListenUDP("udp", nil)
    if err != nil { panic(err) }
    defer send.Close()
    msg := make([]byte, 1280)
    for {
      send.Write(msg)
      //send.WriteToUDP(msg, &addr)
    }
  }()

  numPackets := 1000000
  start := time.Now()
  msg := make([]byte, 2000)
  for i := 0 ; i < numPackets ; i++ {
    sock.ReadFromUDP(msg)
  }
  timed := time.Since(start)

  fmt.Printf("%f packets per second\n", float64(numPackets)/timed.Seconds())

}

var cpuprofile = flag.String("cpuprofile", "", "write cpu profile `file`")
var memprofile = flag.String("memprofile", "", "write memory profile to this file")

func main () {
  flag.Parse()
  if *cpuprofile != "" {
      f, err := os.Create(*cpuprofile)
      if err != nil {
          panic(fmt.Sprintf("could not create CPU profile: ", err))
      }
      if err := pprof.StartCPUProfile(f); err != nil {
          panic(fmt.Sprintf("could not start CPU profile: ", err))
      }
      defer pprof.StopCPUProfile()
  }
  if *memprofile != "" {
      f, err := os.Create(*memprofile)
      if err != nil {
          panic(fmt.Sprintf("could not create memory profile: ", err))
      }
      defer func () { pprof.WriteHeapProfile(f) ; f.Close() }()
  }
  basic_test()

}