Twinkle Linux SIP/VoIP auto call and auto answer via command line

twinkle-auto-call-answer.go

package main

import (
	"bufio"
	"context"
	"flag"
	"fmt"
	"log"
	"os/exec"
	"strings"
	"time"
)

var debug = flag.Bool("debug", false, "print debug messages")

func dbgPrintln(a ...interface{}) (n int, err error) {
	if *debug {
		return fmt.Println(a...)
	}
	return 0, nil
}
func dbgPrintf(format string, a ...interface{}) (n int, err error) {
	if *debug {
		return fmt.Printf(format, a...)
	}
	return 0, nil
}

func init() {
	flag.Parse()
}

func main() {
	var dst string
	if args := flag.Args(); len(args) > 0 {
		dst = args[0]
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	cmd := exec.CommandContext(ctx, "twinkle", "-c")
	op, err := cmd.StdoutPipe()
	if err != nil {
		log.Fatal(err)
	}
	ip, err := cmd.StdinPipe()
	if err != nil {
		log.Fatal(err)
	}

	cmd.Start()

	scanner := bufio.NewScanner(op)

	for scanner.Scan() {
		txt := scanner.Text()
		dbgPrintf(">>%q\n", txt)

		switch {
		case txt == "":
			continue
		case strings.HasSuffix(txt, " incoming call"):
			dbgPrintln("<< Answering call")
			fmt.Fprintln(ip, "answer")
		case strings.Contains(txt, " registration failed"):
			time.Sleep(1 * time.Second)
			dbgPrintln("<< De-Registering")
			fmt.Fprintln(ip, "deregister")
		case strings.Contains(txt, "de-registration failed"),
			strings.Contains(txt, "de-registration succeeded"):
			time.Sleep(1 * time.Second)
			dbgPrintln("<< Registering")
			fmt.Fprintln(ip, "register")
		}

		if dst != "" {
			switch {
			case strings.Contains(txt, " registration succeeded"),
				strings.HasSuffix(txt, " call failed."),
				strings.HasSuffix(txt, " ended call."):

				time.Sleep(500 * time.Millisecond)
				dbgPrintln("<< Calling " + dst)
				fmt.Fprintln(ip, "call "+dst)
			}
		}
	}

	dbgPrintln("# Waiting Process to finish")

	cmd.Wait()
}