package main

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

// 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!

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

	ch := make(chan []byte, 1)

	writer := func() {
		raddr := sock.LocalAddr().(*net.UDPAddr)
		//send, err := net.ListenUDP("udp", nil)
		//if err != nil { panic(err) }
		//defer send.Close()
		for {
			select {
			case <-ch:
			default:
			}
			msg := make([]byte, 1280)
			sock.WriteToUDP(msg, raddr)
			//send.WriteToUDP(msg, raddr)
		}
	}
	go writer()
	//go writer()
	//go writer()
	//go writer()

	numPackets := 65536
	size := 0
	start := time.Now()
	success := 0
	for i := 0; i < numPackets; i++ {
		msg := make([]byte, 2048)
		n, _, err := sock.ReadFromUDP(msg)
		if err != nil {
			panic(err)
		}
		size += n
		select {
		case ch <- msg:
			success += 1
		default:
		}
	}
	timed := time.Since(start)

	fmt.Printf("%f packets per second\n", float64(numPackets)/timed.Seconds())
	fmt.Printf("%f bits per second\n", 8*float64(size)/timed.Seconds())
	fmt.Println("Success:", success, "/", numPackets)
}

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()

}