main.go

package main

import (
	"flag"
	"fmt"
	"github.com/MarinX/keylogger"
	"github.com/jezek/xgb"
	"github.com/nothub/keymux/buildinfo"
	"golang.org/x/exp/slices"
	"log"
	"math/rand"
	"strings"
	"sync"
	"time"
)

var random = rand.New(rand.NewSource(time.Now().UnixNano()))
var pause = false

func main() {
	log.SetFlags(log.Lmicroseconds)

	delay, device, keys, pauseKey, window := parseFlags()

	// attach to x11 session
	{
		con, err := xgb.NewConn()
		if err != nil {
			log.Fatal(err)
		}
		x = con
		defer func() {
			x.Close()
		}()
	}

	// attach to keyboard
	kbd := kbdAttach(device)
	defer func() {
		err := kbd.Close()
		if err != nil {
			log.Println(err)
		}
	}()

	events := kbd.Read()
	mutex := sync.Mutex{}
	for event := range events {

		// filter for keyboard events
		if event.Type != keylogger.EvKey {
			continue
		}

		// filter for key pressed down
		if !event.KeyPress() {
			continue
		}

		if event.KeyString() == pauseKey {
			pause = !pause
			if pause {
				log.Println("paused")
			} else {
				log.Println("unpaused")
			}
			continue
		}

		if pause {
			continue
		}

		// filter hotkeys
		if !slices.Contains(keys, event.KeyString()) {
			continue
		}

		// check active window
		if window != "" && window != activeWindow() {
			continue
		}

		// begin key multiplex
		if !mutex.TryLock() {
			continue
		}

		log.Printf("hotkey:  %v\n", event.KeyString())
		for _, key := range keys {
			// skip key that was already pressed by user
			if key == event.KeyString() {
				continue
			}

			// await delay
			time.Sleep(delay())

			// simulate key press
			log.Printf("sending: %v\n", key)
			err := kbd.WriteOnce(key)
			if err != nil {
				log.Println(err)
			}
		}

		// ignore events until delay awaited
		go func() {
			time.Sleep(delay())
			mutex.Unlock()
		}()
	}
}

func parseFlags() (func() time.Duration, string, []string, string, string) {
	flag.Usage = printUsage

	keysFlag := flag.String("keys", "1,2,3,4,5", "")
	keyPauseFlag := flag.String("key-pause", "Pause", "")
	deviceFlag := flag.String("device", "", "")
	windowFlag := flag.String("window", "", "")
	delayFlag := flag.Int("delay", 50, "")
	delayRandFlag := flag.Int("delay-random", 25, "")

	flag.Parse()

	keys := strings.Split(*keysFlag, ",")
	if len(keys) < 2 {
		log.Printf("invalid keys argument: %q\n", keys)
		flag.Usage()
	}

	if len(*keyPauseFlag) < 1 {
		log.Printf("invalid key-pause argument: %q\n", *keyPauseFlag)
		flag.Usage()
	}

	delay := time.Duration(*delayFlag) * time.Millisecond
	if delay < 10*time.Millisecond {
		log.Printf("invalid delay argument: %q\n", delay)
		flag.Usage()
	}

	delayRand := time.Duration(*delayRandFlag) * time.Millisecond

	delayFunc := func() time.Duration {
		if delayRand.Milliseconds() <= 0 {
			return delay
		}
		n := delay.Nanoseconds()
		n = n + random.Int63n(delayRand.Nanoseconds())
		return time.Duration(n)
	}

	log.Printf("options: keys=%q key-pause=%q device=%q window=%q delay=%q delay-random=%q \n", keys, *keyPauseFlag, *deviceFlag, *windowFlag, delay, delayRand)

	return delayFunc, *deviceFlag, keys, *keyPauseFlag, *windowFlag
}

func printUsage() {
	fmt.Print("keymux " + buildinfo.Version + "\n" +
		"\n" +
		"Multiplex multiple keyboard inputs with a single key press.\n" +
		"Given a set of keys, if any key is pressed keymux will\n" +
		"simulate the presses of the other keys in the set.\n" +
		"\n" +
		"Usage:\n" +
		"  keymux --keys \"a,b,x\"\n" +
		"  keymux --device \"/dev/input/by-id/usb-042-event-kbd\"\n" +
		"  keymux --window \"Path of Exile\"\n" +
		"  keymux --delay 70 --delay-random 30\n" +
		"\n" +
		"Options:\n" +
		"  --keys=<keys>\n" +
		"      List of hotkeys to monitor and send (default: \"1,2,3,4,5\").\n" +
		"  --key-pause=<key>\n" +
		"      Hotkey for pausing execution (default: \"Pause\").\n" +
		"  --device=<path>\n" +
		"      Keyboard device path (omit for auto search).\n" +
		"  --window=<name>\n" +
		"      Restrict input to specific window (omit to disable).\n" +
		"  --delay=<ms>\n" +
		"      Keysend delay in milliseconds (default: 50).\n" +
		"  --delay-random=<ms>\n" +
		"      Additional random keysend delay (default: 25).\n" +
		"  -h --help\n" +
		"      Print help message and exit.\n")
}