package main

import (
	"context"
	"flag"
	"net"
	"os"
	"os/exec"
	"testing"
	"time"

	"golang.org/x/net/proxy"
)

type testWriter struct {
	t      *testing.T
	prefix string
}

func (w testWriter) Write(p []byte) (int, error) {
	w.t.Logf("%s%s", w.prefix, p)
	return len(p), nil
}

func TestMain(m *testing.M) {
	runProxy := flag.Bool("runproxy", false, "Start the command instead of running the tests")
	flag.Parse()
	if *runProxy {
		os.Args = append(os.Args[0:1], flag.Args()...)
		main()
		return
	}
	os.Exit(m.Run())
}

func TestRoundTrip(t *testing.T) {
	// Setup and exec the proxy:
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	// Instead of passing a listener to the command or doing IPC to get the
	// address of the listener created by the command back out, which would all
	// require changes to the actual binary for something that has no use outside
	// of tests and is just another potential source of errors, just start and
	// stop a listener to get a random port and then pass that in (for the command
	// to re-open) as a string. It's not ideal, but it's simple.
	ln, err := net.Listen("tcp", "[::1]:0")
	if err != nil {
		t.Fatalf("error listening: %v", err)
	}
	addr := ln.Addr()
	err = ln.Close()
	if err != nil {
		t.Fatalf("error closing listener: %v", err)
	}
	cmd := exec.CommandContext(ctx, os.Args[0], "-runproxy", "--", "-addr", addr.String(), "-proxy", "37.218.241.98:4430")
	cmd.Stdout = testWriter{prefix: "stdout ", t: t}
	cmd.Stderr = testWriter{prefix: "stderr ", t: t}
	t.Logf("running proxy command %v", cmd.Args)
	err = cmd.Start()
	if err != nil {
		t.Fatalf("error starting proxy: %v", err)
	}

	// Once the proxy is running, try to connect:
	ln, err = net.Listen("tcp", "[::1]:0")
	if err != nil {
		t.Fatalf("error listening for connection: %v", err)
	}
	go func() {
		conn, err := ln.Accept()
		if err != nil {
			t.Logf("error accepting connection: %v", err)
		}
		t.Logf("got conn: %v", conn)
	}()
	dialer, err := proxy.SOCKS5("tcp", addr.String(), nil, proxy.Direct)
	if err != nil {
		t.Fatalf("error creating socks dialer: %v", err)
	}

	// TODO: this is slow, flakey, and generally jank. Can we watch /proc for a
	// new file descriptor or just poll until the listener is open?
	t.Logf("waiting 3 seconds for command to start…")
	time.Sleep(3 * time.Second)

	_, err = dialer.Dial("tcp", ln.Addr().String())
	if err != nil {
		t.Fatalf("error dialing: %v", err)
	}

	select {}
}