package output

import (
	"io"
	"net"
	"testing"
	"time"
)

// TestSendReceive does an end-to-end round trip: a TCP client connects to
// the Sender, Send broadcasts a frame, and the client must read it back.
func TestSendReceive(t *testing.T) {
	s := New()
	port, err := s.Listen("127.0.0.1:0")
	if err != nil {
		t.Fatalf("Listen: %v", err)
	}

	conn, err := net.Dial("tcp", "127.0.0.1:"+itoa(port))
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer func() { _ = conn.Close() }()
	defer func() { _ = conn.(*net.TCPConn).SetLinger(0) }()

	// Give the accept loop a moment to register the connection.
	deadline := time.Now().Add(2 * time.Second)
	for s.NumConns() == 0 && time.Now().Before(deadline) {
		time.Sleep(5 * time.Millisecond)
	}
	if s.NumConns() != 1 {
		t.Fatalf("NumConns = %d, want 1", s.NumConns())
	}

	payload := []byte("frame-one")
	s.Send(payload)

	got := make([]byte, len(payload))
	if _, err := io.ReadFull(conn, got); err != nil {
		t.Fatalf("read: %v", err)
	}
	if string(got) != "frame-one" {
		t.Errorf("round trip mismatch: got %q", got)
	}

	s.Close()
}

func itoa(v int) string {
	if v == 0 {
		return "0"
	}
	var buf [20]byte
	i := len(buf)
	for v > 0 {
		i--
		buf[i] = byte('0' + v%10)
		v /= 10
	}
	return string(buf[i:])
}