package test

import (
	"bufio"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
	"net"
	"testing"
)

var bufSize = 32768

func sendLoop(b *testing.B, port int) {
	u := make([]byte, bufSize)
	io.ReadFull(rand.Reader, u)
	str := hex.EncodeToString(u)

	conn, err := net.Dial("tcp", fmt.Sprintf(":%d", port))
	if err != nil {
		b.Fatalf("Error on Dial: %v", err)
		return
	}

	bw := bufio.NewWriterSize(conn, bufSize)

	for i := 0; i < b.N; i++ {
		bw.WriteString(str)
	}
	bw.Flush()
}

func recvLoop(b *testing.B, conn net.Conn) {
	buf := make([]byte, bufSize)

	b.SetBytes(int64(bufSize))

	total := 0
	toRead := b.N * bufSize

	for total <= toRead {
		n, err := conn.Read(buf)
		if err != nil {
			b.Fatalf("Error reading: %v\n", err)
		}
		total += n
	}
}

func setup(b *testing.B) (net.Listener, int) {
	l, e := net.Listen("tcp", ":0")
	if e != nil {
		b.Fatalf("Error listening: %v", e)
	}
	port := l.Addr().(*net.TCPAddr).Port
	return l, port
}

func Benchmark_MavericksSocketIONoBuffer(b *testing.B) {
	b.StopTimer()
	l, port := setup(b)

	go sendLoop(b, port)

	conn, err := l.Accept()
	if err != nil {
		b.Fatalf("Error accepting on port: %d - %v", port, err)
	}

	b.StartTimer()
	recvLoop(b, conn)
}

func Benchmark_MavericksSocketIORegression(b *testing.B) {
	b.StopTimer()
	l, port := setup(b)

	go sendLoop(b, port)

	conn, err := l.Accept()
	if err != nil {
		b.Fatalf("Error accepting on port: %d - %v", port, err)
	}

	////////////////////////////////////////////////////////////////////////////
	// BUG is here
	// This causes Reads to stall on Mavericks under 1.2 and 1.1.2

	if ip, ok := conn.(*net.TCPConn); ok {
		ip.SetReadBuffer(bufSize)
	}

	////////////////////////////////////////////////////////////////////////////

	b.StartTimer()
	recvLoop(b, conn)
}