package main

import (
  "fmt"
  "time"
  "bytes"
  "sync"
  "crypto/rand"
  "crypto/rsa"
  "crypto/tls"
  "crypto/x509"
  "encoding/pem"
  "math/big"
  quic "github.com/lucas-clemente/quic-go"
)

const addr = "[::1]:9001"

func main () {
  go run_server()
  run_client()
}

func run_server() {
  listener, err := quic.ListenAddr(addr, generateTLSConfig(), nil)
  if err != nil { panic(err) }
  ses, err := listener.Accept()
  if err != nil { panic(err) }
  for {
    stream, err := ses.AcceptStream()
    if err != nil { panic(err) }
    go func() {
      defer stream.Close()
      bs := bytes.Buffer{}
      _, err := bs.ReadFrom(stream)
      if err != nil { panic(err) } //<-- TooManyOpenStreams
    }()
  }
}

func run_client() {
  msgSize := 1048576
  msgCount := 128
  ses, err := quic.DialAddr(addr, &tls.Config{InsecureSkipVerify: true}, nil)
  if err != nil { panic(err) }
  bs := make([]byte, msgSize)
  wg := sync.WaitGroup{}
  start := time.Now()
  for idx := 0 ; idx < msgCount ; idx++ {
    wg.Add(1)
    go func() {
      defer wg.Done()
      stream, err := ses.OpenStreamSync()
      if err != nil { panic(err) }
      defer stream.Close()
      stream.Write(bs)
    }() // "go" this later
  }
  wg.Wait()
  timed := time.Since(start)
  fmt.Println("Client finished", timed, fmt.Sprintf("%f Bits/sec", 8*float64(msgSize*msgCount)/timed.Seconds()))  
}

// Setup a bare-bones TLS config for the server
func generateTLSConfig() *tls.Config {
	key, err := rsa.GenerateKey(rand.Reader, 1024)
	if err != nil {
		panic(err)
	}
	template := x509.Certificate{SerialNumber: big.NewInt(1)}
	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &key.PublicKey, key)
	if err != nil {
		panic(err)
	}
	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(key)})
	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})

	tlsCert, err := tls.X509KeyPair(certPEM, keyPEM)
	if err != nil {
		panic(err)
	}
	return &tls.Config{Certificates: []tls.Certificate{tlsCert}}
}